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original_kernel/arch/mips/lib/memcpy.S

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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
#ifdef CONFIG_CPU_MIPSR6
#undef CONFIG_CPU_HAS_PREFETCH
#endif
#include <linux/export.h>
#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_WD 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_WD 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)
#ifdef CONFIG_CPU_HAS_PREFETCH
# define _PREF(hint, addr, type) \
.if \mode == LEGACY_MODE; \
kernel_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; \
user_pref(hint, addr); \
.set noat; \
.else; \
kernel_pref(hint, addr); \
.endif; \
.endif
#else
# define _PREF(hint, addr, type)
#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
* Arguments:
* 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) )
#ifndef CONFIG_CPU_NO_LOAD_STORE_LR
bnez t1, .Ldst_unaligned\@
nop
bnez t0, .Lsrc_unaligned_dst_aligned\@
#else /* CONFIG_CPU_NO_LOAD_STORE_LR */
or t0, t0, t1
bnez t0, .Lcopy_unaligned_bytes\@
#endif /* CONFIG_CPU_NO_LOAD_STORE_LR */
/*
* 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
#ifndef CONFIG_CPU_NO_LOAD_STORE_LR
/*
* 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
#endif /* !CONFIG_CPU_NO_LOAD_STORE_LR */
.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
nop
#ifdef CONFIG_CPU_NO_LOAD_STORE_LR
.Lcopy_unaligned_bytes\@:
1:
COPY_BYTE(0)
COPY_BYTE(1)
COPY_BYTE(2)
COPY_BYTE(3)
COPY_BYTE(4)
COPY_BYTE(5)
COPY_BYTE(6)
COPY_BYTE(7)
ADD src, src, 8
b 1b
ADD dst, dst, 8
#endif /* CONFIG_CPU_NO_LOAD_STORE_LR */
.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
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
#ifndef CONFIG_HAVE_PLAT_MEMCPY
.align 5
LEAF(memmove)
EXPORT_SYMBOL(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)
/*
* 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 */
EXPORT_SYMBOL(memcpy)
move v0, dst /* return value */
.L__memcpy:
#ifndef CONFIG_EVA
FEXPORT(__raw_copy_from_user)
EXPORT_SYMBOL(__raw_copy_from_user)
FEXPORT(__raw_copy_to_user)
EXPORT_SYMBOL(__raw_copy_to_user)
#endif
/* Legacy Mode, user <-> user */
__BUILD_COPY_USER LEGACY_MODE USEROP USEROP
#endif
#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
*/
/*
* __copy_from_user (EVA)
*/
LEAF(__raw_copy_from_user)
EXPORT_SYMBOL(__raw_copy_from_user)
__BUILD_COPY_USER EVA_MODE USEROP KERNELOP
END(__raw_copy_from_user)
/*
* __copy_to_user (EVA)
*/
LEAF(__raw_copy_to_user)
EXPORT_SYMBOL(__raw_copy_to_user)
__BUILD_COPY_USER EVA_MODE KERNELOP USEROP
END(__raw_copy_to_user)
#endif
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