mirror of
https://github.com/torvalds/linux.git
synced 2024-11-15 16:41:58 +00:00
d4d9eab4ad
This may fix a reported bug where an R_TILEGX_64 in a module was not pointing to an aligned address. Reported-by: Simon Marchi <simon.marchi@polymtl.ca> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
198 lines
6.6 KiB
ArmAsm
198 lines
6.6 KiB
ArmAsm
/*
|
|
* Copyright 2010 Tilera Corporation. All Rights Reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation, version 2.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
|
|
* NON INFRINGEMENT. See the GNU General Public License for
|
|
* more details.
|
|
*
|
|
* Support routines for atomic operations. Each function takes:
|
|
*
|
|
* r0: address to manipulate
|
|
* r1: pointer to atomic lock guarding this operation (for ATOMIC_LOCK_REG)
|
|
* r2: new value to write, or for cmpxchg/add_unless, value to compare against
|
|
* r3: (cmpxchg/xchg_add_unless) new value to write or add;
|
|
* (atomic64 ops) high word of value to write
|
|
* r4/r5: (cmpxchg64/add_unless64) new value to write or add
|
|
*
|
|
* The 32-bit routines return a "struct __get_user" so that the futex code
|
|
* has an opportunity to return -EFAULT to the user if needed.
|
|
* The 64-bit routines just return a "long long" with the value,
|
|
* since they are only used from kernel space and don't expect to fault.
|
|
* Support for 16-bit ops is included in the framework but we don't provide
|
|
* any (x86_64 has an atomic_inc_short(), so we might want to some day).
|
|
*
|
|
* Note that the caller is advised to issue a suitable L1 or L2
|
|
* prefetch on the address being manipulated to avoid extra stalls.
|
|
* In addition, the hot path is on two icache lines, and we start with
|
|
* a jump to the second line to make sure they are both in cache so
|
|
* that we never stall waiting on icache fill while holding the lock.
|
|
* (This doesn't work out with most 64-bit ops, since they consume
|
|
* too many bundles, so may take an extra i-cache stall.)
|
|
*
|
|
* These routines set the INTERRUPT_CRITICAL_SECTION bit, just
|
|
* like sys_cmpxchg(), so that NMIs like PERF_COUNT will not interrupt
|
|
* the code, just page faults.
|
|
*
|
|
* If the load or store faults in a way that can be directly fixed in
|
|
* the do_page_fault_ics() handler (e.g. a vmalloc reference) we fix it
|
|
* directly, return to the instruction that faulted, and retry it.
|
|
*
|
|
* If the load or store faults in a way that potentially requires us
|
|
* to release the atomic lock, then retry (e.g. a migrating PTE), we
|
|
* reset the PC in do_page_fault_ics() to the "tns" instruction so
|
|
* that on return we will reacquire the lock and restart the op. We
|
|
* are somewhat overloading the exception_table_entry notion by doing
|
|
* this, since those entries are not normally used for migrating PTEs.
|
|
*
|
|
* If the main page fault handler discovers a bad address, it will see
|
|
* the PC pointing to the "tns" instruction (due to the earlier
|
|
* exception_table_entry processing in do_page_fault_ics), and
|
|
* re-reset the PC to the fault handler, atomic_bad_address(), which
|
|
* effectively takes over from the atomic op and can either return a
|
|
* bad "struct __get_user" (for user addresses) or can just panic (for
|
|
* bad kernel addresses).
|
|
*
|
|
* Note that if the value we would store is the same as what we
|
|
* loaded, we bypass the store. Other platforms with true atomics can
|
|
* make the guarantee that a non-atomic __clear_bit(), for example,
|
|
* can safely race with an atomic test_and_set_bit(); this example is
|
|
* from bit_spinlock.h in slub_lock() / slub_unlock(). We can't do
|
|
* that on Tile since the "atomic" op is really just a
|
|
* read/modify/write, and can race with the non-atomic
|
|
* read/modify/write. However, if we can short-circuit the write when
|
|
* it is not needed, in the atomic case, we avoid the race.
|
|
*/
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/atomic_32.h>
|
|
#include <asm/page.h>
|
|
#include <asm/processor.h>
|
|
|
|
.section .text.atomic,"ax"
|
|
ENTRY(__start_atomic_asm_code)
|
|
|
|
.macro atomic_op, name, bitwidth, body
|
|
.align 64
|
|
STD_ENTRY_SECTION(__atomic\name, .text.atomic)
|
|
{
|
|
movei r24, 1
|
|
j 4f /* branch to second cache line */
|
|
}
|
|
1: {
|
|
.ifc \bitwidth,16
|
|
lh r22, r0
|
|
.else
|
|
lw r22, r0
|
|
addi r28, r0, 4
|
|
.endif
|
|
}
|
|
.ifc \bitwidth,64
|
|
lw r23, r28
|
|
.endif
|
|
\body /* set r24, and r25 if 64-bit */
|
|
{
|
|
seq r26, r22, r24
|
|
seq r27, r23, r25
|
|
}
|
|
.ifc \bitwidth,64
|
|
bbnst r27, 2f
|
|
.endif
|
|
bbs r26, 3f /* skip write-back if it's the same value */
|
|
2: {
|
|
.ifc \bitwidth,16
|
|
sh r0, r24
|
|
.else
|
|
sw r0, r24
|
|
.endif
|
|
}
|
|
.ifc \bitwidth,64
|
|
sw r28, r25
|
|
.endif
|
|
mf
|
|
3: {
|
|
move r0, r22
|
|
.ifc \bitwidth,64
|
|
move r1, r23
|
|
.else
|
|
move r1, zero
|
|
.endif
|
|
sw ATOMIC_LOCK_REG_NAME, zero
|
|
}
|
|
mtspr INTERRUPT_CRITICAL_SECTION, zero
|
|
jrp lr
|
|
4: {
|
|
move ATOMIC_LOCK_REG_NAME, r1
|
|
mtspr INTERRUPT_CRITICAL_SECTION, r24
|
|
}
|
|
#ifndef CONFIG_SMP
|
|
j 1b /* no atomic locks */
|
|
#else
|
|
{
|
|
tns r21, ATOMIC_LOCK_REG_NAME
|
|
moveli r23, 2048 /* maximum backoff time in cycles */
|
|
}
|
|
{
|
|
bzt r21, 1b /* branch if lock acquired */
|
|
moveli r25, 32 /* starting backoff time in cycles */
|
|
}
|
|
5: mtspr INTERRUPT_CRITICAL_SECTION, zero
|
|
mfspr r26, CYCLE_LOW /* get start point for this backoff */
|
|
6: mfspr r22, CYCLE_LOW /* test to see if we've backed off enough */
|
|
sub r22, r22, r26
|
|
slt r22, r22, r25
|
|
bbst r22, 6b
|
|
{
|
|
mtspr INTERRUPT_CRITICAL_SECTION, r24
|
|
shli r25, r25, 1 /* double the backoff; retry the tns */
|
|
}
|
|
{
|
|
tns r21, ATOMIC_LOCK_REG_NAME
|
|
slt r26, r23, r25 /* is the proposed backoff too big? */
|
|
}
|
|
{
|
|
bzt r21, 1b /* branch if lock acquired */
|
|
mvnz r25, r26, r23
|
|
}
|
|
j 5b
|
|
#endif
|
|
STD_ENDPROC(__atomic\name)
|
|
.ifc \bitwidth,32
|
|
.pushsection __ex_table,"a"
|
|
.align 4
|
|
.word 1b, __atomic\name
|
|
.word 2b, __atomic\name
|
|
.word __atomic\name, __atomic_bad_address
|
|
.popsection
|
|
.endif
|
|
.endm
|
|
|
|
atomic_op _cmpxchg, 32, "seq r26, r22, r2; { bbns r26, 3f; move r24, r3 }"
|
|
atomic_op _xchg, 32, "move r24, r2"
|
|
atomic_op _xchg_add, 32, "add r24, r22, r2"
|
|
atomic_op _xchg_add_unless, 32, \
|
|
"sne r26, r22, r2; { bbns r26, 3f; add r24, r22, r3 }"
|
|
atomic_op _or, 32, "or r24, r22, r2"
|
|
atomic_op _andn, 32, "nor r2, r2, zero; and r24, r22, r2"
|
|
atomic_op _xor, 32, "xor r24, r22, r2"
|
|
|
|
atomic_op 64_cmpxchg, 64, "{ seq r26, r22, r2; seq r27, r23, r3 }; \
|
|
{ bbns r26, 3f; move r24, r4 }; { bbns r27, 3f; move r25, r5 }"
|
|
atomic_op 64_xchg, 64, "{ move r24, r2; move r25, r3 }"
|
|
atomic_op 64_xchg_add, 64, "{ add r24, r22, r2; add r25, r23, r3 }; \
|
|
slt_u r26, r24, r22; add r25, r25, r26"
|
|
atomic_op 64_xchg_add_unless, 64, \
|
|
"{ sne r26, r22, r2; sne r27, r23, r3 }; \
|
|
{ bbns r26, 3f; add r24, r22, r4 }; \
|
|
{ bbns r27, 3f; add r25, r23, r5 }; \
|
|
slt_u r26, r24, r22; add r25, r25, r26"
|
|
|
|
jrp lr /* happy backtracer */
|
|
|
|
ENTRY(__end_atomic_asm_code)
|