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linux/arch/mips/lib/memcpy.S
Markos Chandras cd26cb41ec MIPS: lib: memcpy: Add EVA support 
Add copy_{to,from,in}_user when the CPU operates in EVA mode.
This is necessary so the EVA specific instructions can be used
to perform the virtual to physical translation for user space
addresses. We will use the non-EVA functions to read from kernel
if needed.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
2014-03-26 23:09:14 +01:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Unified implementation of memcpy, memmove and the __copy_user backend.
*
* Copyright (C) 1998, 99, 2000, 01, 2002 Ralf Baechle (ralf@gnu.org)
* Copyright (C) 1999, 2000, 01, 2002 Silicon Graphics, Inc.
* Copyright (C) 2002 Broadcom, Inc.
* memcpy/copy_user author: Mark Vandevoorde
* Copyright (C) 2007 Maciej W. Rozycki
* Copyright (C) 2014 Imagination Technologies Ltd.
*
* Mnemonic names for arguments to memcpy/__copy_user
*/
/*
* Hack to resolve longstanding prefetch issue
*
* Prefetching may be fatal on some systems if we're prefetching beyond the
* end of memory on some systems. It's also a seriously bad idea on non
* dma-coherent systems.
*/
#ifdef CONFIG_DMA_NONCOHERENT
#undef CONFIG_CPU_HAS_PREFETCH
#endif
#ifdef CONFIG_MIPS_MALTA
#undef CONFIG_CPU_HAS_PREFETCH
#endif
#include <asm/asm.h>
#include <asm/asm-offsets.h>
#include <asm/regdef.h>
#define dst a0
#define src a1
#define len a2
/*
* Spec
*
* memcpy copies len bytes from src to dst and sets v0 to dst.
* It assumes that
* - src and dst don't overlap
* - src is readable
* - dst is writable
* memcpy uses the standard calling convention
*
* __copy_user copies up to len bytes from src to dst and sets a2 (len) to
* the number of uncopied bytes due to an exception caused by a read or write.
* __copy_user assumes that src and dst don't overlap, and that the call is
* implementing one of the following:
* copy_to_user
* - src is readable (no exceptions when reading src)
* copy_from_user
* - dst is writable (no exceptions when writing dst)
* __copy_user uses a non-standard calling convention; see
* include/asm-mips/uaccess.h
*
* When an exception happens on a load, the handler must
# ensure that all of the destination buffer is overwritten to prevent
* leaking information to user mode programs.
*/
/*
* Implementation
*/
/*
* The exception handler for loads requires that:
* 1- AT contain the address of the byte just past the end of the source
* of the copy,
* 2- src_entry <= src < AT, and
* 3- (dst - src) == (dst_entry - src_entry),
* The _entry suffix denotes values when __copy_user was called.
*
* (1) is set up up by uaccess.h and maintained by not writing AT in copy_user
* (2) is met by incrementing src by the number of bytes copied
* (3) is met by not doing loads between a pair of increments of dst and src
*
* The exception handlers for stores adjust len (if necessary) and return.
* These handlers do not need to overwrite any data.
*
* For __rmemcpy and memmove an exception is always a kernel bug, therefore
* they're not protected.
*/
/* Instruction type */
#define LD_INSN 1
#define ST_INSN 2
/* Pretech type */
#define SRC_PREFETCH 1
#define DST_PREFETCH 2
#define LEGACY_MODE 1
#define EVA_MODE 2
#define USEROP 1
#define KERNELOP 2
/*
* Wrapper to add an entry in the exception table
* in case the insn causes a memory exception.
* Arguments:
* insn : Load/store instruction
* type : Instruction type
* reg : Register
* addr : Address
* handler : Exception handler
*/
#define EXC(insn, type, reg, addr, handler) \
.if \mode == LEGACY_MODE; \
9: insn reg, addr; \
.section __ex_table,"a"; \
PTR 9b, handler; \
.previous; \
/* This is assembled in EVA mode */ \
.else; \
/* If loading from user or storing to user */ \
.if ((\from == USEROP) && (type == LD_INSN)) || \
((\to == USEROP) && (type == ST_INSN)); \
9: __BUILD_EVA_INSN(insn##e, reg, addr); \
.section __ex_table,"a"; \
PTR 9b, handler; \
.previous; \
.else; \
/* \
* Still in EVA, but no need for \
* exception handler or EVA insn \
*/ \
insn reg, addr; \
.endif; \
.endif
/*
* Only on the 64-bit kernel we can made use of 64-bit registers.
*/
#ifdef CONFIG_64BIT
#define USE_DOUBLE
#endif
#ifdef USE_DOUBLE
#define LOADK ld /* No exception */
#define LOAD(reg, addr, handler) EXC(ld, LD_INSN, reg, addr, handler)
#define LOADL(reg, addr, handler) EXC(ldl, LD_INSN, reg, addr, handler)
#define LOADR(reg, addr, handler) EXC(ldr, LD_INSN, reg, addr, handler)
#define STOREL(reg, addr, handler) EXC(sdl, ST_INSN, reg, addr, handler)
#define STORER(reg, addr, handler) EXC(sdr, ST_INSN, reg, addr, handler)
#define STORE(reg, addr, handler) EXC(sd, ST_INSN, reg, addr, handler)
#define ADD daddu
#define SUB dsubu
#define SRL dsrl
#define SRA dsra
#define SLL dsll
#define SLLV dsllv
#define SRLV dsrlv
#define NBYTES 8
#define LOG_NBYTES 3
/*
* As we are sharing code base with the mips32 tree (which use the o32 ABI
* register definitions). We need to redefine the register definitions from
* the n64 ABI register naming to the o32 ABI register naming.
*/
#undef t0
#undef t1
#undef t2
#undef t3
#define t0 $8
#define t1 $9
#define t2 $10
#define t3 $11
#define t4 $12
#define t5 $13
#define t6 $14
#define t7 $15
#else
#define LOADK lw /* No exception */
#define LOAD(reg, addr, handler) EXC(lw, LD_INSN, reg, addr, handler)
#define LOADL(reg, addr, handler) EXC(lwl, LD_INSN, reg, addr, handler)
#define LOADR(reg, addr, handler) EXC(lwr, LD_INSN, reg, addr, handler)
#define STOREL(reg, addr, handler) EXC(swl, ST_INSN, reg, addr, handler)
#define STORER(reg, addr, handler) EXC(swr, ST_INSN, reg, addr, handler)
#define STORE(reg, addr, handler) EXC(sw, ST_INSN, reg, addr, handler)
#define ADD addu
#define SUB subu
#define SRL srl
#define SLL sll
#define SRA sra
#define SLLV sllv
#define SRLV srlv
#define NBYTES 4
#define LOG_NBYTES 2
#endif /* USE_DOUBLE */
#define LOADB(reg, addr, handler) EXC(lb, LD_INSN, reg, addr, handler)
#define STOREB(reg, addr, handler) EXC(sb, ST_INSN, reg, addr, handler)
#define _PREF(hint, addr, type) \
.if \mode == LEGACY_MODE; \
PREF(hint, addr); \
.else; \
.if ((\from == USEROP) && (type == SRC_PREFETCH)) || \
((\to == USEROP) && (type == DST_PREFETCH)); \
/* \
* PREFE has only 9 bits for the offset \
* compared to PREF which has 16, so it may \
* need to use the $at register but this \
* register should remain intact because it's \
* used later on. Therefore use $v1. \
*/ \
.set at=v1; \
PREFE(hint, addr); \
.set noat; \
.else; \
PREF(hint, addr); \
.endif; \
.endif
#define PREFS(hint, addr) _PREF(hint, addr, SRC_PREFETCH)
#define PREFD(hint, addr) _PREF(hint, addr, DST_PREFETCH)
#ifdef CONFIG_CPU_LITTLE_ENDIAN
#define LDFIRST LOADR
#define LDREST LOADL
#define STFIRST STORER
#define STREST STOREL
#define SHIFT_DISCARD SLLV
#else
#define LDFIRST LOADL
#define LDREST LOADR
#define STFIRST STOREL
#define STREST STORER
#define SHIFT_DISCARD SRLV
#endif
#define FIRST(unit) ((unit)*NBYTES)
#define REST(unit) (FIRST(unit)+NBYTES-1)
#define UNIT(unit) FIRST(unit)
#define ADDRMASK (NBYTES-1)
.text
.set noreorder
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
.set noat
#else
.set at=v1
#endif
.align 5
/*
* Macro to build the __copy_user common code
* Arguements:
* mode : LEGACY_MODE or EVA_MODE
* from : Source operand. USEROP or KERNELOP
* to : Destination operand. USEROP or KERNELOP
*/
.macro __BUILD_COPY_USER mode, from, to
/* initialize __memcpy if this the first time we execute this macro */
.ifnotdef __memcpy
.set __memcpy, 1
.hidden __memcpy /* make sure it does not leak */
.endif
/*
* Note: dst & src may be unaligned, len may be 0
* Temps
*/
#define rem t8
R10KCBARRIER(0(ra))
/*
* The "issue break"s below are very approximate.
* Issue delays for dcache fills will perturb the schedule, as will
* load queue full replay traps, etc.
*
* If len < NBYTES use byte operations.
*/
PREFS( 0, 0(src) )
PREFD( 1, 0(dst) )
sltu t2, len, NBYTES
and t1, dst, ADDRMASK
PREFS( 0, 1*32(src) )
PREFD( 1, 1*32(dst) )
bnez t2, .Lcopy_bytes_checklen\@
and t0, src, ADDRMASK
PREFS( 0, 2*32(src) )
PREFD( 1, 2*32(dst) )
bnez t1, .Ldst_unaligned\@
nop
bnez t0, .Lsrc_unaligned_dst_aligned\@
/*
* use delay slot for fall-through
* src and dst are aligned; need to compute rem
*/
.Lboth_aligned\@:
SRL t0, len, LOG_NBYTES+3 # +3 for 8 units/iter
beqz t0, .Lcleanup_both_aligned\@ # len < 8*NBYTES
and rem, len, (8*NBYTES-1) # rem = len % (8*NBYTES)
PREFS( 0, 3*32(src) )
PREFD( 1, 3*32(dst) )
.align 4
1:
R10KCBARRIER(0(ra))
LOAD(t0, UNIT(0)(src), .Ll_exc\@)
LOAD(t1, UNIT(1)(src), .Ll_exc_copy\@)
LOAD(t2, UNIT(2)(src), .Ll_exc_copy\@)
LOAD(t3, UNIT(3)(src), .Ll_exc_copy\@)
SUB len, len, 8*NBYTES
LOAD(t4, UNIT(4)(src), .Ll_exc_copy\@)
LOAD(t7, UNIT(5)(src), .Ll_exc_copy\@)
STORE(t0, UNIT(0)(dst), .Ls_exc_p8u\@)
STORE(t1, UNIT(1)(dst), .Ls_exc_p7u\@)
LOAD(t0, UNIT(6)(src), .Ll_exc_copy\@)
LOAD(t1, UNIT(7)(src), .Ll_exc_copy\@)
ADD src, src, 8*NBYTES
ADD dst, dst, 8*NBYTES
STORE(t2, UNIT(-6)(dst), .Ls_exc_p6u\@)
STORE(t3, UNIT(-5)(dst), .Ls_exc_p5u\@)
STORE(t4, UNIT(-4)(dst), .Ls_exc_p4u\@)
STORE(t7, UNIT(-3)(dst), .Ls_exc_p3u\@)
STORE(t0, UNIT(-2)(dst), .Ls_exc_p2u\@)
STORE(t1, UNIT(-1)(dst), .Ls_exc_p1u\@)
PREFS( 0, 8*32(src) )
PREFD( 1, 8*32(dst) )
bne len, rem, 1b
nop
/*
* len == rem == the number of bytes left to copy < 8*NBYTES
*/
.Lcleanup_both_aligned\@:
beqz len, .Ldone\@
sltu t0, len, 4*NBYTES
bnez t0, .Lless_than_4units\@
and rem, len, (NBYTES-1) # rem = len % NBYTES
/*
* len >= 4*NBYTES
*/
LOAD( t0, UNIT(0)(src), .Ll_exc\@)
LOAD( t1, UNIT(1)(src), .Ll_exc_copy\@)
LOAD( t2, UNIT(2)(src), .Ll_exc_copy\@)
LOAD( t3, UNIT(3)(src), .Ll_exc_copy\@)
SUB len, len, 4*NBYTES
ADD src, src, 4*NBYTES
R10KCBARRIER(0(ra))
STORE(t0, UNIT(0)(dst), .Ls_exc_p4u\@)
STORE(t1, UNIT(1)(dst), .Ls_exc_p3u\@)
STORE(t2, UNIT(2)(dst), .Ls_exc_p2u\@)
STORE(t3, UNIT(3)(dst), .Ls_exc_p1u\@)
.set reorder /* DADDI_WAR */
ADD dst, dst, 4*NBYTES
beqz len, .Ldone\@
.set noreorder
.Lless_than_4units\@:
/*
* rem = len % NBYTES
*/
beq rem, len, .Lcopy_bytes\@
nop
1:
R10KCBARRIER(0(ra))
LOAD(t0, 0(src), .Ll_exc\@)
ADD src, src, NBYTES
SUB len, len, NBYTES
STORE(t0, 0(dst), .Ls_exc_p1u\@)
.set reorder /* DADDI_WAR */
ADD dst, dst, NBYTES
bne rem, len, 1b
.set noreorder
/*
* src and dst are aligned, need to copy rem bytes (rem < NBYTES)
* A loop would do only a byte at a time with possible branch
* mispredicts. Can't do an explicit LOAD dst,mask,or,STORE
* because can't assume read-access to dst. Instead, use
* STREST dst, which doesn't require read access to dst.
*
* This code should perform better than a simple loop on modern,
* wide-issue mips processors because the code has fewer branches and
* more instruction-level parallelism.
*/
#define bits t2
beqz len, .Ldone\@
ADD t1, dst, len # t1 is just past last byte of dst
li bits, 8*NBYTES
SLL rem, len, 3 # rem = number of bits to keep
LOAD(t0, 0(src), .Ll_exc\@)
SUB bits, bits, rem # bits = number of bits to discard
SHIFT_DISCARD t0, t0, bits
STREST(t0, -1(t1), .Ls_exc\@)
jr ra
move len, zero
.Ldst_unaligned\@:
/*
* dst is unaligned
* t0 = src & ADDRMASK
* t1 = dst & ADDRMASK; T1 > 0
* len >= NBYTES
*
* Copy enough bytes to align dst
* Set match = (src and dst have same alignment)
*/
#define match rem
LDFIRST(t3, FIRST(0)(src), .Ll_exc\@)
ADD t2, zero, NBYTES
LDREST(t3, REST(0)(src), .Ll_exc_copy\@)
SUB t2, t2, t1 # t2 = number of bytes copied
xor match, t0, t1
R10KCBARRIER(0(ra))
STFIRST(t3, FIRST(0)(dst), .Ls_exc\@)
beq len, t2, .Ldone\@
SUB len, len, t2
ADD dst, dst, t2
beqz match, .Lboth_aligned\@
ADD src, src, t2
.Lsrc_unaligned_dst_aligned\@:
SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter
PREFS( 0, 3*32(src) )
beqz t0, .Lcleanup_src_unaligned\@
and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES
PREFD( 1, 3*32(dst) )
1:
/*
* Avoid consecutive LD*'s to the same register since some mips
* implementations can't issue them in the same cycle.
* It's OK to load FIRST(N+1) before REST(N) because the two addresses
* are to the same unit (unless src is aligned, but it's not).
*/
R10KCBARRIER(0(ra))
LDFIRST(t0, FIRST(0)(src), .Ll_exc\@)
LDFIRST(t1, FIRST(1)(src), .Ll_exc_copy\@)
SUB len, len, 4*NBYTES
LDREST(t0, REST(0)(src), .Ll_exc_copy\@)
LDREST(t1, REST(1)(src), .Ll_exc_copy\@)
LDFIRST(t2, FIRST(2)(src), .Ll_exc_copy\@)
LDFIRST(t3, FIRST(3)(src), .Ll_exc_copy\@)
LDREST(t2, REST(2)(src), .Ll_exc_copy\@)
LDREST(t3, REST(3)(src), .Ll_exc_copy\@)
PREFS( 0, 9*32(src) ) # 0 is PREF_LOAD (not streamed)
ADD src, src, 4*NBYTES
#ifdef CONFIG_CPU_SB1
nop # improves slotting
#endif
STORE(t0, UNIT(0)(dst), .Ls_exc_p4u\@)
STORE(t1, UNIT(1)(dst), .Ls_exc_p3u\@)
STORE(t2, UNIT(2)(dst), .Ls_exc_p2u\@)
STORE(t3, UNIT(3)(dst), .Ls_exc_p1u\@)
PREFD( 1, 9*32(dst) ) # 1 is PREF_STORE (not streamed)
.set reorder /* DADDI_WAR */
ADD dst, dst, 4*NBYTES
bne len, rem, 1b
.set noreorder
.Lcleanup_src_unaligned\@:
beqz len, .Ldone\@
and rem, len, NBYTES-1 # rem = len % NBYTES
beq rem, len, .Lcopy_bytes\@
nop
1:
R10KCBARRIER(0(ra))
LDFIRST(t0, FIRST(0)(src), .Ll_exc\@)
LDREST(t0, REST(0)(src), .Ll_exc_copy\@)
ADD src, src, NBYTES
SUB len, len, NBYTES
STORE(t0, 0(dst), .Ls_exc_p1u\@)
.set reorder /* DADDI_WAR */
ADD dst, dst, NBYTES
bne len, rem, 1b
.set noreorder
.Lcopy_bytes_checklen\@:
beqz len, .Ldone\@
nop
.Lcopy_bytes\@:
/* 0 < len < NBYTES */
R10KCBARRIER(0(ra))
#define COPY_BYTE(N) \
LOADB(t0, N(src), .Ll_exc\@); \
SUB len, len, 1; \
beqz len, .Ldone\@; \
STOREB(t0, N(dst), .Ls_exc_p1\@)
COPY_BYTE(0)
COPY_BYTE(1)
#ifdef USE_DOUBLE
COPY_BYTE(2)
COPY_BYTE(3)
COPY_BYTE(4)
COPY_BYTE(5)
#endif
LOADB(t0, NBYTES-2(src), .Ll_exc\@)
SUB len, len, 1
jr ra
STOREB(t0, NBYTES-2(dst), .Ls_exc_p1\@)
.Ldone\@:
jr ra
.if __memcpy == 1
END(memcpy)
.set __memcpy, 0
.hidden __memcpy
.endif
.Ll_exc_copy\@:
/*
* Copy bytes from src until faulting load address (or until a
* lb faults)
*
* When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28)
* may be more than a byte beyond the last address.
* Hence, the lb below may get an exception.
*
* Assumes src < THREAD_BUADDR($28)
*/
LOADK t0, TI_TASK($28)
nop
LOADK t0, THREAD_BUADDR(t0)
1:
LOADB(t1, 0(src), .Ll_exc\@)
ADD src, src, 1
sb t1, 0(dst) # can't fault -- we're copy_from_user
.set reorder /* DADDI_WAR */
ADD dst, dst, 1
bne src, t0, 1b
.set noreorder
.Ll_exc\@:
LOADK t0, TI_TASK($28)
nop
LOADK t0, THREAD_BUADDR(t0) # t0 is just past last good address
nop
SUB len, AT, t0 # len number of uncopied bytes
bnez t6, .Ldone\@ /* Skip the zeroing part if inatomic */
/*
* Here's where we rely on src and dst being incremented in tandem,
* See (3) above.
* dst += (fault addr - src) to put dst at first byte to clear
*/
ADD dst, t0 # compute start address in a1
SUB dst, src
/*
* Clear len bytes starting at dst. Can't call __bzero because it
* might modify len. An inefficient loop for these rare times...
*/
.set reorder /* DADDI_WAR */
SUB src, len, 1
beqz len, .Ldone\@
.set noreorder
1: sb zero, 0(dst)
ADD dst, dst, 1
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
bnez src, 1b
SUB src, src, 1
#else
.set push
.set noat
li v1, 1
bnez src, 1b
SUB src, src, v1
.set pop
#endif
jr ra
nop
#define SEXC(n) \
.set reorder; /* DADDI_WAR */ \
.Ls_exc_p ## n ## u\@: \
ADD len, len, n*NBYTES; \
jr ra; \
.set noreorder
SEXC(8)
SEXC(7)
SEXC(6)
SEXC(5)
SEXC(4)
SEXC(3)
SEXC(2)
SEXC(1)
.Ls_exc_p1\@:
.set reorder /* DADDI_WAR */
ADD len, len, 1
jr ra
.set noreorder
.Ls_exc\@:
jr ra
nop
.endm
.align 5
LEAF(memmove)
ADD t0, a0, a2
ADD t1, a1, a2
sltu t0, a1, t0 # dst + len <= src -> memcpy
sltu t1, a0, t1 # dst >= src + len -> memcpy
and t0, t1
beqz t0, .L__memcpy
move v0, a0 /* return value */
beqz a2, .Lr_out
END(memmove)
/* fall through to __rmemcpy */
LEAF(__rmemcpy) /* a0=dst a1=src a2=len */
sltu t0, a1, a0
beqz t0, .Lr_end_bytes_up # src >= dst
nop
ADD a0, a2 # dst = dst + len
ADD a1, a2 # src = src + len
.Lr_end_bytes:
R10KCBARRIER(0(ra))
lb t0, -1(a1)
SUB a2, a2, 0x1
sb t0, -1(a0)
SUB a1, a1, 0x1
.set reorder /* DADDI_WAR */
SUB a0, a0, 0x1
bnez a2, .Lr_end_bytes
.set noreorder
.Lr_out:
jr ra
move a2, zero
.Lr_end_bytes_up:
R10KCBARRIER(0(ra))
lb t0, (a1)
SUB a2, a2, 0x1
sb t0, (a0)
ADD a1, a1, 0x1
.set reorder /* DADDI_WAR */
ADD a0, a0, 0x1
bnez a2, .Lr_end_bytes_up
.set noreorder
jr ra
move a2, zero
END(__rmemcpy)
/*
* t6 is used as a flag to note inatomic mode.
*/
LEAF(__copy_user_inatomic)
b __copy_user_common
li t6, 1
END(__copy_user_inatomic)
/*
* A combined memcpy/__copy_user
* __copy_user sets len to 0 for success; else to an upper bound of
* the number of uncopied bytes.
* memcpy sets v0 to dst.
*/
.align 5
LEAF(memcpy) /* a0=dst a1=src a2=len */
move v0, dst /* return value */
.L__memcpy:
FEXPORT(__copy_user)
li t6, 0 /* not inatomic */
__copy_user_common:
/* Legacy Mode, user <-> user */
__BUILD_COPY_USER LEGACY_MODE USEROP USEROP
#ifdef CONFIG_EVA
/*
* For EVA we need distinct symbols for reading and writing to user space.
* This is because we need to use specific EVA instructions to perform the
* virtual <-> physical translation when a virtual address is actually in user
* space
*/
LEAF(__copy_user_inatomic_eva)
b __copy_from_user_common
li t6, 1
END(__copy_user_inatomic_eva)
/*
* __copy_from_user (EVA)
*/
LEAF(__copy_from_user_eva)
li t6, 0 /* not inatomic */
__copy_from_user_common:
__BUILD_COPY_USER EVA_MODE USEROP KERNELOP
END(__copy_from_user_eva)
/*
* __copy_to_user (EVA)
*/
LEAF(__copy_to_user_eva)
__BUILD_COPY_USER EVA_MODE KERNELOP USEROP
END(__copy_to_user_eva)
/*
* __copy_in_user (EVA)
*/
LEAF(__copy_in_user_eva)
__BUILD_COPY_USER EVA_MODE USEROP USEROP
END(__copy_in_user_eva)
#endif
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