2019-06-03 05:44:50 +00:00
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/* SPDX-License-Identifier: GPL-2.0-only */
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2015-02-03 12:39:03 +00:00
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/*
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* Based on arch/arm/include/asm/atomic.h
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*
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* Copyright (C) 1996 Russell King.
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* Copyright (C) 2002 Deep Blue Solutions Ltd.
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* Copyright (C) 2012 ARM Ltd.
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*/
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#ifndef __ASM_ATOMIC_LSE_H
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#define __ASM_ATOMIC_LSE_H
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2016-04-22 17:01:32 +00:00
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#define ATOMIC_OP(op, asm_op) \
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arm64: atomics: format whitespace consistently
The code for the atomic ops is formatted inconsistently, and while this
is not a functional problem it is rather distracting when working on
them.
Some have ops have consistent indentation, e.g.
| #define ATOMIC_OP_ADD_RETURN(name, mb, cl...) \
| static inline int __lse_atomic_add_return##name(int i, atomic_t *v) \
| { \
| u32 tmp; \
| \
| asm volatile( \
| __LSE_PREAMBLE \
| " ldadd" #mb " %w[i], %w[tmp], %[v]\n" \
| " add %w[i], %w[i], %w[tmp]" \
| : [i] "+r" (i), [v] "+Q" (v->counter), [tmp] "=&r" (tmp) \
| : "r" (v) \
| : cl); \
| \
| return i; \
| }
While others have negative indentation for some lines, and/or have
misaligned trailing backslashes, e.g.
| static inline void __lse_atomic_##op(int i, atomic_t *v) \
| { \
| asm volatile( \
| __LSE_PREAMBLE \
| " " #asm_op " %w[i], %[v]\n" \
| : [i] "+r" (i), [v] "+Q" (v->counter) \
| : "r" (v)); \
| }
This patch makes the indentation consistent and also aligns the trailing
backslashes. This makes the code easier to read for those (like myself)
who are easily distracted by these inconsistencies.
This is intended as a cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:06 +00:00
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static inline void __lse_atomic_##op(int i, atomic_t *v) \
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2016-04-22 17:01:32 +00:00
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{ \
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2019-08-28 17:50:07 +00:00
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asm volatile( \
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2019-10-31 19:57:05 +00:00
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__LSE_PREAMBLE \
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arm64: atomics: format whitespace consistently
The code for the atomic ops is formatted inconsistently, and while this
is not a functional problem it is rather distracting when working on
them.
Some have ops have consistent indentation, e.g.
| #define ATOMIC_OP_ADD_RETURN(name, mb, cl...) \
| static inline int __lse_atomic_add_return##name(int i, atomic_t *v) \
| { \
| u32 tmp; \
| \
| asm volatile( \
| __LSE_PREAMBLE \
| " ldadd" #mb " %w[i], %w[tmp], %[v]\n" \
| " add %w[i], %w[i], %w[tmp]" \
| : [i] "+r" (i), [v] "+Q" (v->counter), [tmp] "=&r" (tmp) \
| : "r" (v) \
| : cl); \
| \
| return i; \
| }
While others have negative indentation for some lines, and/or have
misaligned trailing backslashes, e.g.
| static inline void __lse_atomic_##op(int i, atomic_t *v) \
| { \
| asm volatile( \
| __LSE_PREAMBLE \
| " " #asm_op " %w[i], %[v]\n" \
| : [i] "+r" (i), [v] "+Q" (v->counter) \
| : "r" (v)); \
| }
This patch makes the indentation consistent and also aligns the trailing
backslashes. This makes the code easier to read for those (like myself)
who are easily distracted by these inconsistencies.
This is intended as a cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:06 +00:00
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" " #asm_op " %w[i], %[v]\n" \
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arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
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: [v] "+Q" (v->counter) \
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: [i] "r" (i)); \
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2015-02-03 16:14:13 +00:00
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}
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2016-04-22 17:01:32 +00:00
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ATOMIC_OP(andnot, stclr)
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ATOMIC_OP(or, stset)
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ATOMIC_OP(xor, steor)
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ATOMIC_OP(add, stadd)
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2015-02-03 16:14:13 +00:00
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arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
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static inline void __lse_atomic_sub(int i, atomic_t *v)
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{
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__lse_atomic_add(-i, v);
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}
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2016-04-22 17:01:32 +00:00
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#undef ATOMIC_OP
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2015-02-03 16:14:13 +00:00
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locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
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#define ATOMIC_FETCH_OP(name, mb, op, asm_op, cl...) \
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2019-08-28 17:50:07 +00:00
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static inline int __lse_atomic_fetch_##op##name(int i, atomic_t *v) \
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locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
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{ \
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arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
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int old; \
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\
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2019-08-28 17:50:07 +00:00
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asm volatile( \
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2019-10-31 19:57:05 +00:00
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__LSE_PREAMBLE \
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arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
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" " #asm_op #mb " %w[i], %w[old], %[v]" \
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: [v] "+Q" (v->counter), \
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[old] "=r" (old) \
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: [i] "r" (i) \
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2019-08-28 17:50:07 +00:00
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: cl); \
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locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
\
|
arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
|
|
|
return old; \
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
#define ATOMIC_FETCH_OPS(op, asm_op) \
|
|
|
|
|
ATOMIC_FETCH_OP(_relaxed, , op, asm_op) \
|
|
|
|
|
ATOMIC_FETCH_OP(_acquire, a, op, asm_op, "memory") \
|
|
|
|
|
ATOMIC_FETCH_OP(_release, l, op, asm_op, "memory") \
|
|
|
|
|
ATOMIC_FETCH_OP( , al, op, asm_op, "memory")
|
|
|
|
|
|
|
|
|
|
ATOMIC_FETCH_OPS(andnot, ldclr)
|
|
|
|
|
ATOMIC_FETCH_OPS(or, ldset)
|
|
|
|
|
ATOMIC_FETCH_OPS(xor, ldeor)
|
|
|
|
|
ATOMIC_FETCH_OPS(add, ldadd)
|
|
|
|
|
|
|
|
|
|
#undef ATOMIC_FETCH_OP
|
|
|
|
|
#undef ATOMIC_FETCH_OPS
|
|
|
|
|
|
arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
|
|
|
#define ATOMIC_FETCH_OP_SUB(name) \
|
|
|
|
|
static inline int __lse_atomic_fetch_sub##name(int i, atomic_t *v) \
|
|
|
|
|
{ \
|
|
|
|
|
return __lse_atomic_fetch_add##name(-i, v); \
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
ATOMIC_FETCH_OP_SUB(_relaxed)
|
|
|
|
|
ATOMIC_FETCH_OP_SUB(_acquire)
|
|
|
|
|
ATOMIC_FETCH_OP_SUB(_release)
|
|
|
|
|
ATOMIC_FETCH_OP_SUB( )
|
|
|
|
|
|
|
|
|
|
#undef ATOMIC_FETCH_OP_SUB
|
|
|
|
|
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
#define ATOMIC_OP_ADD_SUB_RETURN(name) \
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline int __lse_atomic_add_return##name(int i, atomic_t *v) \
|
2015-10-08 19:15:18 +00:00
|
|
|
{ \
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
return __lse_atomic_fetch_add##name(i, v) + i; \
|
arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
|
|
|
} \
|
|
|
|
|
\
|
|
|
|
|
static inline int __lse_atomic_sub_return##name(int i, atomic_t *v) \
|
|
|
|
|
{ \
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
return __lse_atomic_fetch_sub(i, v) - i; \
|
2015-10-08 19:15:18 +00:00
|
|
|
}
|
2015-02-03 16:14:13 +00:00
|
|
|
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
ATOMIC_OP_ADD_SUB_RETURN(_relaxed)
|
|
|
|
|
ATOMIC_OP_ADD_SUB_RETURN(_acquire)
|
|
|
|
|
ATOMIC_OP_ADD_SUB_RETURN(_release)
|
|
|
|
|
ATOMIC_OP_ADD_SUB_RETURN( )
|
2015-02-03 16:14:13 +00:00
|
|
|
|
arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
|
|
|
#undef ATOMIC_OP_ADD_SUB_RETURN
|
2015-02-03 16:14:13 +00:00
|
|
|
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline void __lse_atomic_and(int i, atomic_t *v)
|
2015-02-03 16:14:13 +00:00
|
|
|
{
|
arm64: atomics: lse: define ANDs in terms of ANDNOTs
The FEAT_LSE atomic instructions include atomic bit-clear instructions
(`ldclr*` and `stclr*`) which can be used to directly implement ANDNOT
operations. Each AND op is implemented as a copy of the corresponding
ANDNOT op with a leading `mvn` instruction to apply a bitwise NOT to the
`i` argument.
As the compiler has no visibility of the `mvn`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __lse_atomic_fetch_and(0xf, v) can be compiled to:
mov w1, #0xf
mvn w1, w1
ldclral w1, w1, [x2]
This patch improves this by replacing the `mvn` with NOT in C before the
inline assembly block, e.g.
i = ~i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xfffffff0
ldclral w1, w1, [x2]
With this change the assembly for each AND op is identical to the
corresponding ANDNOT op (including barriers and clobbers), so I've
removed the inline assembly and rewritten each AND op in terms of the
corresponding ANDNOT op, e.g.
| static inline void __lse_atomic_and(int i, atomic_t *v)
| {
| return __lse_atomic_andnot(~i, v);
| }
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:08 +00:00
|
|
|
return __lse_atomic_andnot(~i, v);
|
2015-02-03 16:14:13 +00:00
|
|
|
}
|
|
|
|
|
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
#define ATOMIC_FETCH_OP_AND(name, mb, cl...) \
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline int __lse_atomic_fetch_and##name(int i, atomic_t *v) \
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
{ \
|
arm64: atomics: lse: define ANDs in terms of ANDNOTs
The FEAT_LSE atomic instructions include atomic bit-clear instructions
(`ldclr*` and `stclr*`) which can be used to directly implement ANDNOT
operations. Each AND op is implemented as a copy of the corresponding
ANDNOT op with a leading `mvn` instruction to apply a bitwise NOT to the
`i` argument.
As the compiler has no visibility of the `mvn`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __lse_atomic_fetch_and(0xf, v) can be compiled to:
mov w1, #0xf
mvn w1, w1
ldclral w1, w1, [x2]
This patch improves this by replacing the `mvn` with NOT in C before the
inline assembly block, e.g.
i = ~i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xfffffff0
ldclral w1, w1, [x2]
With this change the assembly for each AND op is identical to the
corresponding ANDNOT op (including barriers and clobbers), so I've
removed the inline assembly and rewritten each AND op in terms of the
corresponding ANDNOT op, e.g.
| static inline void __lse_atomic_and(int i, atomic_t *v)
| {
| return __lse_atomic_andnot(~i, v);
| }
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:08 +00:00
|
|
|
return __lse_atomic_fetch_andnot##name(~i, v); \
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
ATOMIC_FETCH_OP_AND(_relaxed, )
|
|
|
|
|
ATOMIC_FETCH_OP_AND(_acquire, a, "memory")
|
|
|
|
|
ATOMIC_FETCH_OP_AND(_release, l, "memory")
|
|
|
|
|
ATOMIC_FETCH_OP_AND( , al, "memory")
|
|
|
|
|
|
|
|
|
|
#undef ATOMIC_FETCH_OP_AND
|
|
|
|
|
|
2016-04-22 17:01:32 +00:00
|
|
|
#define ATOMIC64_OP(op, asm_op) \
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline void __lse_atomic64_##op(s64 i, atomic64_t *v) \
|
2016-04-22 17:01:32 +00:00
|
|
|
{ \
|
2019-08-28 17:50:07 +00:00
|
|
|
asm volatile( \
|
2019-10-31 19:57:05 +00:00
|
|
|
__LSE_PREAMBLE \
|
arm64: atomics: format whitespace consistently
The code for the atomic ops is formatted inconsistently, and while this
is not a functional problem it is rather distracting when working on
them.
Some have ops have consistent indentation, e.g.
| #define ATOMIC_OP_ADD_RETURN(name, mb, cl...) \
| static inline int __lse_atomic_add_return##name(int i, atomic_t *v) \
| { \
| u32 tmp; \
| \
| asm volatile( \
| __LSE_PREAMBLE \
| " ldadd" #mb " %w[i], %w[tmp], %[v]\n" \
| " add %w[i], %w[i], %w[tmp]" \
| : [i] "+r" (i), [v] "+Q" (v->counter), [tmp] "=&r" (tmp) \
| : "r" (v) \
| : cl); \
| \
| return i; \
| }
While others have negative indentation for some lines, and/or have
misaligned trailing backslashes, e.g.
| static inline void __lse_atomic_##op(int i, atomic_t *v) \
| { \
| asm volatile( \
| __LSE_PREAMBLE \
| " " #asm_op " %w[i], %[v]\n" \
| : [i] "+r" (i), [v] "+Q" (v->counter) \
| : "r" (v)); \
| }
This patch makes the indentation consistent and also aligns the trailing
backslashes. This makes the code easier to read for those (like myself)
who are easily distracted by these inconsistencies.
This is intended as a cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:06 +00:00
|
|
|
" " #asm_op " %[i], %[v]\n" \
|
arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
|
|
|
: [v] "+Q" (v->counter) \
|
|
|
|
|
: [i] "r" (i)); \
|
2015-02-03 16:14:13 +00:00
|
|
|
}
|
|
|
|
|
|
2016-04-22 17:01:32 +00:00
|
|
|
ATOMIC64_OP(andnot, stclr)
|
|
|
|
|
ATOMIC64_OP(or, stset)
|
|
|
|
|
ATOMIC64_OP(xor, steor)
|
|
|
|
|
ATOMIC64_OP(add, stadd)
|
2015-02-03 16:14:13 +00:00
|
|
|
|
arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
|
|
|
static inline void __lse_atomic64_sub(s64 i, atomic64_t *v)
|
|
|
|
|
{
|
|
|
|
|
__lse_atomic64_add(-i, v);
|
|
|
|
|
}
|
|
|
|
|
|
2016-04-22 17:01:32 +00:00
|
|
|
#undef ATOMIC64_OP
|
2015-02-03 16:14:13 +00:00
|
|
|
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
#define ATOMIC64_FETCH_OP(name, mb, op, asm_op, cl...) \
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline long __lse_atomic64_fetch_##op##name(s64 i, atomic64_t *v)\
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
{ \
|
arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
|
|
|
s64 old; \
|
|
|
|
|
\
|
2019-08-28 17:50:07 +00:00
|
|
|
asm volatile( \
|
2019-10-31 19:57:05 +00:00
|
|
|
__LSE_PREAMBLE \
|
arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
|
|
|
" " #asm_op #mb " %[i], %[old], %[v]" \
|
|
|
|
|
: [v] "+Q" (v->counter), \
|
|
|
|
|
[old] "=r" (old) \
|
|
|
|
|
: [i] "r" (i) \
|
2019-08-28 17:50:07 +00:00
|
|
|
: cl); \
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
\
|
arm64: atomics: lse: improve constraints for simple ops
We have overly conservative assembly constraints for the basic FEAT_LSE
atomic instructions, and using more accurate and permissive constraints
will allow for better code generation.
The FEAT_LSE basic atomic instructions have come in two forms:
LD{op}{order}{size} <Rs>, <Rt>, [<Rn>]
ST{op}{order}{size} <Rs>, [<Rn>]
The ST* forms are aliases of the LD* forms where:
ST{op}{order}{size} <Rs>, [<Rn>]
Is:
LD{op}{order}{size} <Rs>, XZR, [<Rn>]
For either form, both <Rs> and <Rn> are read but not written back to,
and <Rt> is written with the original value of the memory location.
Where (<Rt> == <Rs>) or (<Rt> == <Rn>), <Rt> is written *after* the
other register value(s) are consumed. There are no UNPREDICTABLE or
CONSTRAINED UNPREDICTABLE behaviours when any pair of <Rs>, <Rt>, or
<Rn> are the same register.
Our current inline assembly always uses <Rs> == <Rt>, treating this
register as both an input and an output (using a '+r' constraint). This
forces the compiler to do some unnecessary register shuffling and/or
redundant value generation.
For example, the compiler cannot reuse the <Rs> value, and currently GCC
11.1.0 will compile:
__lse_atomic_add(1, a);
__lse_atomic_add(1, b);
__lse_atomic_add(1, c);
As:
mov w3, #0x1
mov w4, w3
stadd w4, [x0]
mov w0, w3
stadd w0, [x1]
stadd w3, [x2]
We can improve this with more accurate constraints, separating <Rs> and
<Rt>, where <Rs> is an input-only register ('r'), and <Rt> is an
output-only value ('=r'). As <Rt> is written back after <Rs> is
consumed, it does not need to be earlyclobber ('=&r'), leaving the
compiler free to use the same register for both <Rs> and <Rt> where this
is desirable.
At the same time, the redundant 'r' constraint for `v` is removed, as
the `+Q` constraint is sufficient.
With this change, the above example becomes:
mov w3, #0x1
stadd w3, [x0]
stadd w3, [x1]
stadd w3, [x2]
I've made this change for the non-value-returning and FETCH ops. The
RETURN ops have a multi-instruction sequence for which we cannot use the
same constraints, and a subsequent patch will rewrite hte RETURN ops in
terms of the FETCH ops, relying on the ability for the compiler to reuse
the <Rs> value.
This is intended as an optimization.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:09 +00:00
|
|
|
return old; \
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
#define ATOMIC64_FETCH_OPS(op, asm_op) \
|
|
|
|
|
ATOMIC64_FETCH_OP(_relaxed, , op, asm_op) \
|
|
|
|
|
ATOMIC64_FETCH_OP(_acquire, a, op, asm_op, "memory") \
|
|
|
|
|
ATOMIC64_FETCH_OP(_release, l, op, asm_op, "memory") \
|
|
|
|
|
ATOMIC64_FETCH_OP( , al, op, asm_op, "memory")
|
|
|
|
|
|
|
|
|
|
ATOMIC64_FETCH_OPS(andnot, ldclr)
|
|
|
|
|
ATOMIC64_FETCH_OPS(or, ldset)
|
|
|
|
|
ATOMIC64_FETCH_OPS(xor, ldeor)
|
|
|
|
|
ATOMIC64_FETCH_OPS(add, ldadd)
|
|
|
|
|
|
|
|
|
|
#undef ATOMIC64_FETCH_OP
|
|
|
|
|
#undef ATOMIC64_FETCH_OPS
|
|
|
|
|
|
arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
|
|
|
#define ATOMIC64_FETCH_OP_SUB(name) \
|
|
|
|
|
static inline long __lse_atomic64_fetch_sub##name(s64 i, atomic64_t *v) \
|
|
|
|
|
{ \
|
|
|
|
|
return __lse_atomic64_fetch_add##name(-i, v); \
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
ATOMIC64_FETCH_OP_SUB(_relaxed)
|
|
|
|
|
ATOMIC64_FETCH_OP_SUB(_acquire)
|
|
|
|
|
ATOMIC64_FETCH_OP_SUB(_release)
|
|
|
|
|
ATOMIC64_FETCH_OP_SUB( )
|
|
|
|
|
|
|
|
|
|
#undef ATOMIC64_FETCH_OP_SUB
|
|
|
|
|
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
#define ATOMIC64_OP_ADD_SUB_RETURN(name) \
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline long __lse_atomic64_add_return##name(s64 i, atomic64_t *v)\
|
2015-10-08 19:15:18 +00:00
|
|
|
{ \
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
return __lse_atomic64_fetch_add##name(i, v) + i; \
|
arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
|
|
|
} \
|
|
|
|
|
\
|
|
|
|
|
static inline long __lse_atomic64_sub_return##name(s64 i, atomic64_t *v)\
|
|
|
|
|
{ \
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
return __lse_atomic64_fetch_sub##name(i, v) - i; \
|
2015-10-08 19:15:18 +00:00
|
|
|
}
|
2015-02-03 16:14:13 +00:00
|
|
|
|
arm64: atomics: lse: define RETURN ops in terms of FETCH ops
The FEAT_LSE atomic instructions include LD* instructions which return
the original value of a memory location can be used to directly
implement FETCH opertations. Each RETURN op is implemented as a copy of
the corresponding FETCH op with a trailing instruction to generate the
new value of the memory location. We only directly implement
*_fetch_add*(), for which we have a trailing `add` instruction.
As the compiler has no visibility of the `add`, this leads to less than
optimal code generation when consuming the result.
For example, the compiler cannot constant-fold the addition into later
operations, and currently GCC 11.1.0 will compile:
return __lse_atomic_sub_return(1, v) == 0;
As:
mov w1, #0xffffffff
ldaddal w1, w2, [x0]
add w1, w1, w2
cmp w1, #0x0
cset w0, eq // eq = none
ret
This patch improves this by replacing the `add` with C addition after
the inline assembly block, e.g.
ret += i;
This allows the compiler to manipulate `i`. This permits the compiler to
merge the `add` and `cmp` for the above, e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x0]
cmp w1, #0x1
cset w0, eq // eq = none
ret
With this change the assembly for each RETURN op is identical to the
corresponding FETCH op (including barriers and clobbers) so I've removed
the inline assembly and rewritten each RETURN op in terms of the
corresponding FETCH op, e.g.
| static inline void __lse_atomic_add_return(int i, atomic_t *v)
| {
| return __lse_atomic_fetch_add(i, v) + i
| }
The new construction does not adversely affect the common case, and
before and after this patch GCC 11.1.0 can compile:
__lse_atomic_add_return(i, v)
As:
ldaddal w0, w2, [x1]
add w0, w0, w2
... while having the freedom to do better elsewhere.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:10 +00:00
|
|
|
ATOMIC64_OP_ADD_SUB_RETURN(_relaxed)
|
|
|
|
|
ATOMIC64_OP_ADD_SUB_RETURN(_acquire)
|
|
|
|
|
ATOMIC64_OP_ADD_SUB_RETURN(_release)
|
|
|
|
|
ATOMIC64_OP_ADD_SUB_RETURN( )
|
2015-02-03 16:14:13 +00:00
|
|
|
|
arm64: atomics lse: define SUBs in terms of ADDs
The FEAT_LSE atomic instructions include atomic ADD instructions
(`stadd*` and `ldadd*`), but do not include atomic SUB instructions, so
we must build all of the SUB operations using the ADD instructions. We
open-code these today, with each SUB op implemented as a copy of the
corresponding ADD op with a leading `neg` instruction in the inline
assembly to negate the `i` argument.
As the compiler has no visibility of the `neg`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __les_atomic_fetch_sub(1, v) can be compiled to:
mov w1, #0x1
neg w1, w1
ldaddal w1, w1, [x2]
This patch improves this by replacing the `neg` with negation in C
before the inline assembly block, e.g.
i = -i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xffffffff
ldaddal w1, w1, [x2]
With this change the assembly for each SUB op is identical to the
corresponding ADD op (including barriers and clobbers), so I've removed
the inline assembly and rewritten each SUB op in terms of the
corresponding ADD op, e.g.
| static inline void __lse_atomic_sub(int i, atomic_t *v)
| {
| __lse_atomic_add(-i, v);
| }
For clarity I've moved the definition of each SUB op immediately after
the corresponding ADD op, and used a single macro to create the RETURN
forms of both ops.
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:07 +00:00
|
|
|
#undef ATOMIC64_OP_ADD_SUB_RETURN
|
2015-02-03 16:14:13 +00:00
|
|
|
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline void __lse_atomic64_and(s64 i, atomic64_t *v)
|
2015-02-03 16:14:13 +00:00
|
|
|
{
|
arm64: atomics: lse: define ANDs in terms of ANDNOTs
The FEAT_LSE atomic instructions include atomic bit-clear instructions
(`ldclr*` and `stclr*`) which can be used to directly implement ANDNOT
operations. Each AND op is implemented as a copy of the corresponding
ANDNOT op with a leading `mvn` instruction to apply a bitwise NOT to the
`i` argument.
As the compiler has no visibility of the `mvn`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __lse_atomic_fetch_and(0xf, v) can be compiled to:
mov w1, #0xf
mvn w1, w1
ldclral w1, w1, [x2]
This patch improves this by replacing the `mvn` with NOT in C before the
inline assembly block, e.g.
i = ~i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xfffffff0
ldclral w1, w1, [x2]
With this change the assembly for each AND op is identical to the
corresponding ANDNOT op (including barriers and clobbers), so I've
removed the inline assembly and rewritten each AND op in terms of the
corresponding ANDNOT op, e.g.
| static inline void __lse_atomic_and(int i, atomic_t *v)
| {
| return __lse_atomic_andnot(~i, v);
| }
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:08 +00:00
|
|
|
return __lse_atomic64_andnot(~i, v);
|
2015-02-03 16:14:13 +00:00
|
|
|
}
|
|
|
|
|
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
#define ATOMIC64_FETCH_OP_AND(name, mb, cl...) \
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline long __lse_atomic64_fetch_and##name(s64 i, atomic64_t *v) \
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
{ \
|
arm64: atomics: lse: define ANDs in terms of ANDNOTs
The FEAT_LSE atomic instructions include atomic bit-clear instructions
(`ldclr*` and `stclr*`) which can be used to directly implement ANDNOT
operations. Each AND op is implemented as a copy of the corresponding
ANDNOT op with a leading `mvn` instruction to apply a bitwise NOT to the
`i` argument.
As the compiler has no visibility of the `mvn`, this leads to less than
optimal code generation when generating `i` into a register. For
example, __lse_atomic_fetch_and(0xf, v) can be compiled to:
mov w1, #0xf
mvn w1, w1
ldclral w1, w1, [x2]
This patch improves this by replacing the `mvn` with NOT in C before the
inline assembly block, e.g.
i = ~i;
This allows the compiler to generate `i` into a register more optimally,
e.g.
mov w1, #0xfffffff0
ldclral w1, w1, [x2]
With this change the assembly for each AND op is identical to the
corresponding ANDNOT op (including barriers and clobbers), so I've
removed the inline assembly and rewritten each AND op in terms of the
corresponding ANDNOT op, e.g.
| static inline void __lse_atomic_and(int i, atomic_t *v)
| {
| return __lse_atomic_andnot(~i, v);
| }
This is intended as an optimization and cleanup.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211210151410.2782645-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-10 15:14:08 +00:00
|
|
|
return __lse_atomic64_fetch_andnot##name(~i, v); \
|
locking/atomic, arch/arm64: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() for LSE instructions
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
This patch implements the LSE variants.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1461344493-8262-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-22 17:01:33 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
ATOMIC64_FETCH_OP_AND(_relaxed, )
|
|
|
|
|
ATOMIC64_FETCH_OP_AND(_acquire, a, "memory")
|
|
|
|
|
ATOMIC64_FETCH_OP_AND(_release, l, "memory")
|
|
|
|
|
ATOMIC64_FETCH_OP_AND( , al, "memory")
|
|
|
|
|
|
|
|
|
|
#undef ATOMIC64_FETCH_OP_AND
|
|
|
|
|
|
2019-08-28 17:50:07 +00:00
|
|
|
static inline s64 __lse_atomic64_dec_if_positive(atomic64_t *v)
|
2015-02-03 12:39:03 +00:00
|
|
|
{
|
2019-08-28 17:50:08 +00:00
|
|
|
unsigned long tmp;
|
|
|
|
|
|
2019-08-28 17:50:07 +00:00
|
|
|
asm volatile(
|
2019-10-31 19:57:05 +00:00
|
|
|
__LSE_PREAMBLE
|
2019-08-28 17:50:08 +00:00
|
|
|
"1: ldr %x[tmp], %[v]\n"
|
|
|
|
|
" subs %[ret], %x[tmp], #1\n"
|
2015-05-29 13:44:06 +00:00
|
|
|
" b.lt 2f\n"
|
2019-08-28 17:50:08 +00:00
|
|
|
" casal %x[tmp], %[ret], %[v]\n"
|
|
|
|
|
" sub %x[tmp], %x[tmp], #1\n"
|
|
|
|
|
" sub %x[tmp], %x[tmp], %[ret]\n"
|
|
|
|
|
" cbnz %x[tmp], 1b\n"
|
2019-08-28 17:50:07 +00:00
|
|
|
"2:"
|
2019-08-28 17:50:08 +00:00
|
|
|
: [ret] "+&r" (v), [v] "+Q" (v->counter), [tmp] "=&r" (tmp)
|
2015-02-03 12:39:03 +00:00
|
|
|
:
|
2019-08-28 17:50:08 +00:00
|
|
|
: "cc", "memory");
|
2015-02-03 12:39:03 +00:00
|
|
|
|
2019-08-28 17:50:07 +00:00
|
|
|
return (long)v;
|
2015-02-03 12:39:03 +00:00
|
|
|
}
|
|
|
|
|
|
2018-09-13 12:30:45 +00:00
|
|
|
#define __CMPXCHG_CASE(w, sfx, name, sz, mb, cl...) \
|
2019-10-01 10:43:13 +00:00
|
|
|
static __always_inline u##sz \
|
|
|
|
|
__lse__cmpxchg_case_##name##sz(volatile void *ptr, \
|
2018-09-13 13:28:33 +00:00
|
|
|
u##sz old, \
|
2018-09-13 12:30:45 +00:00
|
|
|
u##sz new) \
|
2015-04-23 19:08:49 +00:00
|
|
|
{ \
|
|
|
|
|
register unsigned long x0 asm ("x0") = (unsigned long)ptr; \
|
2018-09-13 13:28:33 +00:00
|
|
|
register u##sz x1 asm ("x1") = old; \
|
2018-09-13 12:30:45 +00:00
|
|
|
register u##sz x2 asm ("x2") = new; \
|
2019-08-28 17:50:08 +00:00
|
|
|
unsigned long tmp; \
|
2015-04-23 19:08:49 +00:00
|
|
|
\
|
2019-08-28 17:50:07 +00:00
|
|
|
asm volatile( \
|
2019-10-31 19:57:05 +00:00
|
|
|
__LSE_PREAMBLE \
|
2019-08-28 17:50:08 +00:00
|
|
|
" mov %" #w "[tmp], %" #w "[old]\n" \
|
|
|
|
|
" cas" #mb #sfx "\t%" #w "[tmp], %" #w "[new], %[v]\n" \
|
|
|
|
|
" mov %" #w "[ret], %" #w "[tmp]" \
|
arm64: atomics: lse: Dereference matching size
When building with -Warray-bounds, the following warning is generated:
In file included from ./arch/arm64/include/asm/lse.h:16,
from ./arch/arm64/include/asm/cmpxchg.h:14,
from ./arch/arm64/include/asm/atomic.h:16,
from ./include/linux/atomic.h:7,
from ./include/asm-generic/bitops/atomic.h:5,
from ./arch/arm64/include/asm/bitops.h:25,
from ./include/linux/bitops.h:33,
from ./include/linux/kernel.h:22,
from kernel/printk/printk.c:22:
./arch/arm64/include/asm/atomic_lse.h:247:9: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'atomic_t[1]' [-Warray-bounds]
247 | asm volatile( \
| ^~~
./arch/arm64/include/asm/atomic_lse.h:266:1: note: in expansion of macro '__CMPXCHG_CASE'
266 | __CMPXCHG_CASE(w, , acq_, 32, a, "memory")
| ^~~~~~~~~~~~~~
kernel/printk/printk.c:3606:17: note: while referencing 'printk_cpulock_owner'
3606 | static atomic_t printk_cpulock_owner = ATOMIC_INIT(-1);
| ^~~~~~~~~~~~~~~~~~~~
This is due to the compiler seeing an unsigned long * cast against
something (atomic_t) that is int sized. Replace the cast with the
matching size cast. This results in no change in binary output.
Note that __ll_sc__cmpxchg_case_##name##sz already uses the same
constraint:
[v] "+Q" (*(u##sz *)ptr
Which is why only the LSE form needs updating and not the
LL/SC form, so this change is unlikely to be problematic.
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220112202259.3950286-1-keescook@chromium.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2022-01-12 20:22:59 +00:00
|
|
|
: [ret] "+r" (x0), [v] "+Q" (*(u##sz *)ptr), \
|
2019-08-28 17:50:08 +00:00
|
|
|
[tmp] "=&r" (tmp) \
|
2015-04-23 19:08:49 +00:00
|
|
|
: [old] "r" (x1), [new] "r" (x2) \
|
2019-08-28 17:50:08 +00:00
|
|
|
: cl); \
|
2015-04-23 19:08:49 +00:00
|
|
|
\
|
|
|
|
|
return x0; \
|
|
|
|
|
}
|
|
|
|
|
|
2018-09-13 12:30:45 +00:00
|
|
|
__CMPXCHG_CASE(w, b, , 8, )
|
|
|
|
|
__CMPXCHG_CASE(w, h, , 16, )
|
|
|
|
|
__CMPXCHG_CASE(w, , , 32, )
|
|
|
|
|
__CMPXCHG_CASE(x, , , 64, )
|
|
|
|
|
__CMPXCHG_CASE(w, b, acq_, 8, a, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, h, acq_, 16, a, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, , acq_, 32, a, "memory")
|
|
|
|
|
__CMPXCHG_CASE(x, , acq_, 64, a, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, b, rel_, 8, l, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, h, rel_, 16, l, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, , rel_, 32, l, "memory")
|
|
|
|
|
__CMPXCHG_CASE(x, , rel_, 64, l, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, b, mb_, 8, al, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, h, mb_, 16, al, "memory")
|
|
|
|
|
__CMPXCHG_CASE(w, , mb_, 32, al, "memory")
|
|
|
|
|
__CMPXCHG_CASE(x, , mb_, 64, al, "memory")
|
2015-04-23 19:08:49 +00:00
|
|
|
|
|
|
|
|
#undef __CMPXCHG_CASE
|
|
|
|
|
|
2015-05-14 17:05:50 +00:00
|
|
|
#define __CMPXCHG_DBL(name, mb, cl...) \
|
2019-10-01 10:43:13 +00:00
|
|
|
static __always_inline long \
|
|
|
|
|
__lse__cmpxchg_double##name(unsigned long old1, \
|
2015-05-14 17:05:50 +00:00
|
|
|
unsigned long old2, \
|
|
|
|
|
unsigned long new1, \
|
|
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unsigned long new2, \
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volatile void *ptr) \
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{ \
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unsigned long oldval1 = old1; \
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unsigned long oldval2 = old2; \
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register unsigned long x0 asm ("x0") = old1; \
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register unsigned long x1 asm ("x1") = old2; \
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register unsigned long x2 asm ("x2") = new1; \
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register unsigned long x3 asm ("x3") = new2; \
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register unsigned long x4 asm ("x4") = (unsigned long)ptr; \
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\
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2019-08-28 17:50:07 +00:00
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asm volatile( \
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2019-10-31 19:57:05 +00:00
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__LSE_PREAMBLE \
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2015-05-14 17:05:50 +00:00
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" casp" #mb "\t%[old1], %[old2], %[new1], %[new2], %[v]\n"\
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" eor %[old1], %[old1], %[oldval1]\n" \
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" eor %[old2], %[old2], %[oldval2]\n" \
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2019-08-28 17:50:07 +00:00
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" orr %[old1], %[old1], %[old2]" \
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2018-05-21 16:44:57 +00:00
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: [old1] "+&r" (x0), [old2] "+&r" (x1), \
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2015-05-14 17:05:50 +00:00
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[v] "+Q" (*(unsigned long *)ptr) \
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: [new1] "r" (x2), [new2] "r" (x3), [ptr] "r" (x4), \
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[oldval1] "r" (oldval1), [oldval2] "r" (oldval2) \
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2019-08-28 17:50:07 +00:00
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: cl); \
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2015-05-14 17:05:50 +00:00
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\
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return x0; \
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}
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__CMPXCHG_DBL( , )
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__CMPXCHG_DBL(_mb, al, "memory")
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#undef __CMPXCHG_DBL
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2015-02-03 12:39:03 +00:00
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#endif /* __ASM_ATOMIC_LSE_H */
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