321 lines
8.2 KiB
ArmAsm
321 lines
8.2 KiB
ArmAsm
/*
|
|
* arch/xtensa/lib/usercopy.S
|
|
*
|
|
* Copy to/from user space (derived from arch/xtensa/lib/hal/memcopy.S)
|
|
*
|
|
* DO NOT COMBINE this function with <arch/xtensa/lib/hal/memcopy.S>.
|
|
* It needs to remain separate and distinct. The hal files are part
|
|
* of the Xtensa link-time HAL, and those files may differ per
|
|
* processor configuration. Patching the kernel for another
|
|
* processor configuration includes replacing the hal files, and we
|
|
* could lose the special functionality for accessing user-space
|
|
* memory during such a patch. We sacrifice a little code space here
|
|
* in favor to simplify code maintenance.
|
|
*
|
|
* 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.
|
|
*
|
|
* Copyright (C) 2002 Tensilica Inc.
|
|
*/
|
|
|
|
|
|
/*
|
|
* size_t __xtensa_copy_user (void *dst, const void *src, size_t len);
|
|
*
|
|
* The returned value is the number of bytes not copied. Implies zero
|
|
* is success.
|
|
*
|
|
* The general case algorithm is as follows:
|
|
* If the destination and source are both aligned,
|
|
* do 16B chunks with a loop, and then finish up with
|
|
* 8B, 4B, 2B, and 1B copies conditional on the length.
|
|
* If destination is aligned and source unaligned,
|
|
* do the same, but use SRC to align the source data.
|
|
* If destination is unaligned, align it by conditionally
|
|
* copying 1B and 2B and then retest.
|
|
* This code tries to use fall-through braches for the common
|
|
* case of aligned destinations (except for the branches to
|
|
* the alignment label).
|
|
*
|
|
* Register use:
|
|
* a0/ return address
|
|
* a1/ stack pointer
|
|
* a2/ return value
|
|
* a3/ src
|
|
* a4/ length
|
|
* a5/ dst
|
|
* a6/ tmp
|
|
* a7/ tmp
|
|
* a8/ tmp
|
|
* a9/ tmp
|
|
* a10/ tmp
|
|
* a11/ original length
|
|
*/
|
|
|
|
#include <variant/core.h>
|
|
|
|
#ifdef __XTENSA_EB__
|
|
#define ALIGN(R, W0, W1) src R, W0, W1
|
|
#define SSA8(R) ssa8b R
|
|
#else
|
|
#define ALIGN(R, W0, W1) src R, W1, W0
|
|
#define SSA8(R) ssa8l R
|
|
#endif
|
|
|
|
/* Load or store instructions that may cause exceptions use the EX macro. */
|
|
|
|
#define EX(insn,reg1,reg2,offset,handler) \
|
|
9: insn reg1, reg2, offset; \
|
|
.section __ex_table, "a"; \
|
|
.word 9b, handler; \
|
|
.previous
|
|
|
|
|
|
.text
|
|
.align 4
|
|
.global __xtensa_copy_user
|
|
.type __xtensa_copy_user,@function
|
|
__xtensa_copy_user:
|
|
entry sp, 16 # minimal stack frame
|
|
# a2/ dst, a3/ src, a4/ len
|
|
mov a5, a2 # copy dst so that a2 is return value
|
|
mov a11, a4 # preserve original len for error case
|
|
.Lcommon:
|
|
bbsi.l a2, 0, .Ldst1mod2 # if dst is 1 mod 2
|
|
bbsi.l a2, 1, .Ldst2mod4 # if dst is 2 mod 4
|
|
.Ldstaligned: # return here from .Ldstunaligned when dst is aligned
|
|
srli a7, a4, 4 # number of loop iterations with 16B
|
|
# per iteration
|
|
movi a8, 3 # if source is also aligned,
|
|
bnone a3, a8, .Laligned # then use word copy
|
|
SSA8( a3) # set shift amount from byte offset
|
|
bnez a4, .Lsrcunaligned
|
|
movi a2, 0 # return success for len==0
|
|
retw
|
|
|
|
/*
|
|
* Destination is unaligned
|
|
*/
|
|
|
|
.Ldst1mod2: # dst is only byte aligned
|
|
bltui a4, 7, .Lbytecopy # do short copies byte by byte
|
|
|
|
# copy 1 byte
|
|
EX(l8ui, a6, a3, 0, l_fixup)
|
|
addi a3, a3, 1
|
|
EX(s8i, a6, a5, 0, s_fixup)
|
|
addi a5, a5, 1
|
|
addi a4, a4, -1
|
|
bbci.l a5, 1, .Ldstaligned # if dst is now aligned, then
|
|
# return to main algorithm
|
|
.Ldst2mod4: # dst 16-bit aligned
|
|
# copy 2 bytes
|
|
bltui a4, 6, .Lbytecopy # do short copies byte by byte
|
|
EX(l8ui, a6, a3, 0, l_fixup)
|
|
EX(l8ui, a7, a3, 1, l_fixup)
|
|
addi a3, a3, 2
|
|
EX(s8i, a6, a5, 0, s_fixup)
|
|
EX(s8i, a7, a5, 1, s_fixup)
|
|
addi a5, a5, 2
|
|
addi a4, a4, -2
|
|
j .Ldstaligned # dst is now aligned, return to main algorithm
|
|
|
|
/*
|
|
* Byte by byte copy
|
|
*/
|
|
.align 4
|
|
.byte 0 # 1 mod 4 alignment for LOOPNEZ
|
|
# (0 mod 4 alignment for LBEG)
|
|
.Lbytecopy:
|
|
#if XCHAL_HAVE_LOOPS
|
|
loopnez a4, .Lbytecopydone
|
|
#else /* !XCHAL_HAVE_LOOPS */
|
|
beqz a4, .Lbytecopydone
|
|
add a7, a3, a4 # a7 = end address for source
|
|
#endif /* !XCHAL_HAVE_LOOPS */
|
|
.Lnextbyte:
|
|
EX(l8ui, a6, a3, 0, l_fixup)
|
|
addi a3, a3, 1
|
|
EX(s8i, a6, a5, 0, s_fixup)
|
|
addi a5, a5, 1
|
|
#if !XCHAL_HAVE_LOOPS
|
|
blt a3, a7, .Lnextbyte
|
|
#endif /* !XCHAL_HAVE_LOOPS */
|
|
.Lbytecopydone:
|
|
movi a2, 0 # return success for len bytes copied
|
|
retw
|
|
|
|
/*
|
|
* Destination and source are word-aligned.
|
|
*/
|
|
# copy 16 bytes per iteration for word-aligned dst and word-aligned src
|
|
.align 4 # 1 mod 4 alignment for LOOPNEZ
|
|
.byte 0 # (0 mod 4 alignment for LBEG)
|
|
.Laligned:
|
|
#if XCHAL_HAVE_LOOPS
|
|
loopnez a7, .Loop1done
|
|
#else /* !XCHAL_HAVE_LOOPS */
|
|
beqz a7, .Loop1done
|
|
slli a8, a7, 4
|
|
add a8, a8, a3 # a8 = end of last 16B source chunk
|
|
#endif /* !XCHAL_HAVE_LOOPS */
|
|
.Loop1:
|
|
EX(l32i, a6, a3, 0, l_fixup)
|
|
EX(l32i, a7, a3, 4, l_fixup)
|
|
EX(s32i, a6, a5, 0, s_fixup)
|
|
EX(l32i, a6, a3, 8, l_fixup)
|
|
EX(s32i, a7, a5, 4, s_fixup)
|
|
EX(l32i, a7, a3, 12, l_fixup)
|
|
EX(s32i, a6, a5, 8, s_fixup)
|
|
addi a3, a3, 16
|
|
EX(s32i, a7, a5, 12, s_fixup)
|
|
addi a5, a5, 16
|
|
#if !XCHAL_HAVE_LOOPS
|
|
blt a3, a8, .Loop1
|
|
#endif /* !XCHAL_HAVE_LOOPS */
|
|
.Loop1done:
|
|
bbci.l a4, 3, .L2
|
|
# copy 8 bytes
|
|
EX(l32i, a6, a3, 0, l_fixup)
|
|
EX(l32i, a7, a3, 4, l_fixup)
|
|
addi a3, a3, 8
|
|
EX(s32i, a6, a5, 0, s_fixup)
|
|
EX(s32i, a7, a5, 4, s_fixup)
|
|
addi a5, a5, 8
|
|
.L2:
|
|
bbci.l a4, 2, .L3
|
|
# copy 4 bytes
|
|
EX(l32i, a6, a3, 0, l_fixup)
|
|
addi a3, a3, 4
|
|
EX(s32i, a6, a5, 0, s_fixup)
|
|
addi a5, a5, 4
|
|
.L3:
|
|
bbci.l a4, 1, .L4
|
|
# copy 2 bytes
|
|
EX(l16ui, a6, a3, 0, l_fixup)
|
|
addi a3, a3, 2
|
|
EX(s16i, a6, a5, 0, s_fixup)
|
|
addi a5, a5, 2
|
|
.L4:
|
|
bbci.l a4, 0, .L5
|
|
# copy 1 byte
|
|
EX(l8ui, a6, a3, 0, l_fixup)
|
|
EX(s8i, a6, a5, 0, s_fixup)
|
|
.L5:
|
|
movi a2, 0 # return success for len bytes copied
|
|
retw
|
|
|
|
/*
|
|
* Destination is aligned, Source is unaligned
|
|
*/
|
|
|
|
.align 4
|
|
.byte 0 # 1 mod 4 alignement for LOOPNEZ
|
|
# (0 mod 4 alignment for LBEG)
|
|
.Lsrcunaligned:
|
|
# copy 16 bytes per iteration for word-aligned dst and unaligned src
|
|
and a10, a3, a8 # save unalignment offset for below
|
|
sub a3, a3, a10 # align a3 (to avoid sim warnings only; not needed for hardware)
|
|
EX(l32i, a6, a3, 0, l_fixup) # load first word
|
|
#if XCHAL_HAVE_LOOPS
|
|
loopnez a7, .Loop2done
|
|
#else /* !XCHAL_HAVE_LOOPS */
|
|
beqz a7, .Loop2done
|
|
slli a12, a7, 4
|
|
add a12, a12, a3 # a12 = end of last 16B source chunk
|
|
#endif /* !XCHAL_HAVE_LOOPS */
|
|
.Loop2:
|
|
EX(l32i, a7, a3, 4, l_fixup)
|
|
EX(l32i, a8, a3, 8, l_fixup)
|
|
ALIGN( a6, a6, a7)
|
|
EX(s32i, a6, a5, 0, s_fixup)
|
|
EX(l32i, a9, a3, 12, l_fixup)
|
|
ALIGN( a7, a7, a8)
|
|
EX(s32i, a7, a5, 4, s_fixup)
|
|
EX(l32i, a6, a3, 16, l_fixup)
|
|
ALIGN( a8, a8, a9)
|
|
EX(s32i, a8, a5, 8, s_fixup)
|
|
addi a3, a3, 16
|
|
ALIGN( a9, a9, a6)
|
|
EX(s32i, a9, a5, 12, s_fixup)
|
|
addi a5, a5, 16
|
|
#if !XCHAL_HAVE_LOOPS
|
|
blt a3, a12, .Loop2
|
|
#endif /* !XCHAL_HAVE_LOOPS */
|
|
.Loop2done:
|
|
bbci.l a4, 3, .L12
|
|
# copy 8 bytes
|
|
EX(l32i, a7, a3, 4, l_fixup)
|
|
EX(l32i, a8, a3, 8, l_fixup)
|
|
ALIGN( a6, a6, a7)
|
|
EX(s32i, a6, a5, 0, s_fixup)
|
|
addi a3, a3, 8
|
|
ALIGN( a7, a7, a8)
|
|
EX(s32i, a7, a5, 4, s_fixup)
|
|
addi a5, a5, 8
|
|
mov a6, a8
|
|
.L12:
|
|
bbci.l a4, 2, .L13
|
|
# copy 4 bytes
|
|
EX(l32i, a7, a3, 4, l_fixup)
|
|
addi a3, a3, 4
|
|
ALIGN( a6, a6, a7)
|
|
EX(s32i, a6, a5, 0, s_fixup)
|
|
addi a5, a5, 4
|
|
mov a6, a7
|
|
.L13:
|
|
add a3, a3, a10 # readjust a3 with correct misalignment
|
|
bbci.l a4, 1, .L14
|
|
# copy 2 bytes
|
|
EX(l8ui, a6, a3, 0, l_fixup)
|
|
EX(l8ui, a7, a3, 1, l_fixup)
|
|
addi a3, a3, 2
|
|
EX(s8i, a6, a5, 0, s_fixup)
|
|
EX(s8i, a7, a5, 1, s_fixup)
|
|
addi a5, a5, 2
|
|
.L14:
|
|
bbci.l a4, 0, .L15
|
|
# copy 1 byte
|
|
EX(l8ui, a6, a3, 0, l_fixup)
|
|
EX(s8i, a6, a5, 0, s_fixup)
|
|
.L15:
|
|
movi a2, 0 # return success for len bytes copied
|
|
retw
|
|
|
|
|
|
.section .fixup, "ax"
|
|
.align 4
|
|
|
|
/* a2 = original dst; a5 = current dst; a11= original len
|
|
* bytes_copied = a5 - a2
|
|
* retval = bytes_not_copied = original len - bytes_copied
|
|
* retval = a11 - (a5 - a2)
|
|
*
|
|
* Clearing the remaining pieces of kernel memory plugs security
|
|
* holes. This functionality is the equivalent of the *_zeroing
|
|
* functions that some architectures provide.
|
|
*/
|
|
|
|
.Lmemset:
|
|
.word memset
|
|
|
|
s_fixup:
|
|
sub a2, a5, a2 /* a2 <-- bytes copied */
|
|
sub a2, a11, a2 /* a2 <-- bytes not copied */
|
|
retw
|
|
|
|
l_fixup:
|
|
sub a2, a5, a2 /* a2 <-- bytes copied */
|
|
sub a2, a11, a2 /* a2 <-- bytes not copied == return value */
|
|
|
|
/* void *memset(void *s, int c, size_t n); */
|
|
mov a6, a5 /* s */
|
|
movi a7, 0 /* c */
|
|
mov a8, a2 /* n */
|
|
l32r a4, .Lmemset
|
|
callx4 a4
|
|
/* Ignore memset return value in a6. */
|
|
/* a2 still contains bytes not copied. */
|
|
retw
|