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linux-next/arch/xtensa/lib/usercopy.S
Max Filippov d6d5f19e21 xtensa: abstract 'entry' and 'retw' in assembly code 
Provide abi_entry, abi_entry_default, abi_ret and abi_ret_default macros
that allocate aligned stack frame in windowed and call0 ABIs.
Provide XTENSA_SPILL_STACK_RESERVE macro that specifies required stack
frame size when register spilling is involved.
Replace all uses of 'entry' and 'retw' with the above macros.
This makes most of the xtensa assembly code ready for XEA3 and call0 ABI.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2019-07-08 10:04:48 -07:00

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/*
* 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 <linux/linkage.h>
#include <asm/asmmacro.h>
#include <asm/core.h>
.text
ENTRY(__xtensa_copy_user)
abi_entry_default
# 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
abi_ret_default
/*
* Destination is unaligned
*/
.Ldst1mod2: # dst is only byte aligned
bltui a4, 7, .Lbytecopy # do short copies byte by byte
# copy 1 byte
EX(10f) l8ui a6, a3, 0
addi a3, a3, 1
EX(10f) s8i a6, a5, 0
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(10f) l8ui a6, a3, 0
EX(10f) l8ui a7, a3, 1
addi a3, a3, 2
EX(10f) s8i a6, a5, 0
EX(10f) s8i a7, a5, 1
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(10f) l8ui a6, a3, 0
addi a3, a3, 1
EX(10f) s8i a6, a5, 0
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
abi_ret_default
/*
* 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(10f) l32i a6, a3, 0
EX(10f) l32i a7, a3, 4
EX(10f) s32i a6, a5, 0
EX(10f) l32i a6, a3, 8
EX(10f) s32i a7, a5, 4
EX(10f) l32i a7, a3, 12
EX(10f) s32i a6, a5, 8
addi a3, a3, 16
EX(10f) s32i a7, a5, 12
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(10f) l32i a6, a3, 0
EX(10f) l32i a7, a3, 4
addi a3, a3, 8
EX(10f) s32i a6, a5, 0
EX(10f) s32i a7, a5, 4
addi a5, a5, 8
.L2:
bbci.l a4, 2, .L3
# copy 4 bytes
EX(10f) l32i a6, a3, 0
addi a3, a3, 4
EX(10f) s32i a6, a5, 0
addi a5, a5, 4
.L3:
bbci.l a4, 1, .L4
# copy 2 bytes
EX(10f) l16ui a6, a3, 0
addi a3, a3, 2
EX(10f) s16i a6, a5, 0
addi a5, a5, 2
.L4:
bbci.l a4, 0, .L5
# copy 1 byte
EX(10f) l8ui a6, a3, 0
EX(10f) s8i a6, a5, 0
.L5:
movi a2, 0 # return success for len bytes copied
abi_ret_default
/*
* 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(10f) l32i a6, a3, 0 # 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(10f) l32i a7, a3, 4
EX(10f) l32i a8, a3, 8
__src_b a6, a6, a7
EX(10f) s32i a6, a5, 0
EX(10f) l32i a9, a3, 12
__src_b a7, a7, a8
EX(10f) s32i a7, a5, 4
EX(10f) l32i a6, a3, 16
__src_b a8, a8, a9
EX(10f) s32i a8, a5, 8
addi a3, a3, 16
__src_b a9, a9, a6
EX(10f) s32i a9, a5, 12
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(10f) l32i a7, a3, 4
EX(10f) l32i a8, a3, 8
__src_b a6, a6, a7
EX(10f) s32i a6, a5, 0
addi a3, a3, 8
__src_b a7, a7, a8
EX(10f) s32i a7, a5, 4
addi a5, a5, 8
mov a6, a8
.L12:
bbci.l a4, 2, .L13
# copy 4 bytes
EX(10f) l32i a7, a3, 4
addi a3, a3, 4
__src_b a6, a6, a7
EX(10f) s32i a6, a5, 0
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(10f) l8ui a6, a3, 0
EX(10f) l8ui a7, a3, 1
addi a3, a3, 2
EX(10f) s8i a6, a5, 0
EX(10f) s8i a7, a5, 1
addi a5, a5, 2
.L14:
bbci.l a4, 0, .L15
# copy 1 byte
EX(10f) l8ui a6, a3, 0
EX(10f) s8i a6, a5, 0
.L15:
movi a2, 0 # return success for len bytes copied
abi_ret_default
ENDPROC(__xtensa_copy_user)
.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)
*/
10:
sub a2, a5, a2 /* a2 <-- bytes copied */
sub a2, a11, a2 /* a2 <-- bytes not copied */
abi_ret_default
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