mirror of
https://github.com/torvalds/linux.git
synced 2026-05-31 10:33:41 +02:00
arm64: lib: Import latest version of Arm Optimized Routines' strcmp
Import the latest version of the Arm Optimized Routines strcmp function based on the upstream code of string/aarch64/strcmp.S at commit 189dfefe37d5 from: https://github.com/ARM-software/optimized-routines This latest version includes MTE support. Note that for simplicity Arm have chosen to contribute this code to Linux under GPLv2 rather than the original MIT OR Apache-2.0 WITH LLVM-exception license. Arm is the sole copyright holder for this code. Signed-off-by: Joey Gouly <joey.gouly@arm.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220301101435.19327-2-joey.gouly@arm.com Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Joey Gouly
Will Deacon
parent
dfd42facf1
commit
507f788d05
|
|
@ -1,9 +1,9 @@
|
|||
/* SPDX-License-Identifier: GPL-2.0-only */
|
||||
/*
|
||||
* Copyright (c) 2012-2021, Arm Limited.
|
||||
* Copyright (c) 2012-2022, Arm Limited.
|
||||
*
|
||||
* Adapted from the original at:
|
||||
* https://github.com/ARM-software/optimized-routines/blob/afd6244a1f8d9229/string/aarch64/strcmp.S
|
||||
* https://github.com/ARM-software/optimized-routines/blob/189dfefe37d54c5b/string/aarch64/strcmp.S
|
||||
*/
|
||||
|
||||
#include <linux/linkage.h>
|
||||
|
|
@ -11,161 +11,175 @@
|
|||
|
||||
/* Assumptions:
|
||||
*
|
||||
* ARMv8-a, AArch64
|
||||
* ARMv8-a, AArch64.
|
||||
* MTE compatible.
|
||||
*/
|
||||
|
||||
#define L(label) .L ## label
|
||||
|
||||
#define REP8_01 0x0101010101010101
|
||||
#define REP8_7f 0x7f7f7f7f7f7f7f7f
|
||||
#define REP8_80 0x8080808080808080
|
||||
|
||||
/* Parameters and result. */
|
||||
#define src1 x0
|
||||
#define src2 x1
|
||||
#define result x0
|
||||
|
||||
/* Internal variables. */
|
||||
#define data1 x2
|
||||
#define data1w w2
|
||||
#define data2 x3
|
||||
#define data2w w3
|
||||
#define has_nul x4
|
||||
#define diff x5
|
||||
#define off1 x5
|
||||
#define syndrome x6
|
||||
#define tmp1 x7
|
||||
#define tmp2 x8
|
||||
#define tmp3 x9
|
||||
#define zeroones x10
|
||||
#define pos x11
|
||||
#define tmp x6
|
||||
#define data3 x7
|
||||
#define zeroones x8
|
||||
#define shift x9
|
||||
#define off2 x10
|
||||
|
||||
/* On big-endian early bytes are at MSB and on little-endian LSB.
|
||||
LS_FW means shifting towards early bytes. */
|
||||
#ifdef __AARCH64EB__
|
||||
# define LS_FW lsl
|
||||
#else
|
||||
# define LS_FW lsr
|
||||
#endif
|
||||
|
||||
/* NUL detection works on the principle that (X - 1) & (~X) & 0x80
|
||||
(=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and
|
||||
can be done in parallel across the entire word.
|
||||
Since carry propagation makes 0x1 bytes before a NUL byte appear
|
||||
NUL too in big-endian, byte-reverse the data before the NUL check. */
|
||||
|
||||
|
||||
/* Start of performance-critical section -- one 64B cache line. */
|
||||
.align 6
|
||||
SYM_FUNC_START_WEAK_PI(strcmp)
|
||||
eor tmp1, src1, src2
|
||||
mov zeroones, #REP8_01
|
||||
tst tmp1, #7
|
||||
sub off2, src2, src1
|
||||
mov zeroones, REP8_01
|
||||
and tmp, src1, 7
|
||||
tst off2, 7
|
||||
b.ne L(misaligned8)
|
||||
ands tmp1, src1, #7
|
||||
b.ne L(mutual_align)
|
||||
/* NUL detection works on the principle that (X - 1) & (~X) & 0x80
|
||||
(=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and
|
||||
can be done in parallel across the entire word. */
|
||||
L(loop_aligned):
|
||||
ldr data1, [src1], #8
|
||||
ldr data2, [src2], #8
|
||||
L(start_realigned):
|
||||
sub tmp1, data1, zeroones
|
||||
orr tmp2, data1, #REP8_7f
|
||||
eor diff, data1, data2 /* Non-zero if differences found. */
|
||||
bic has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
|
||||
orr syndrome, diff, has_nul
|
||||
cbz syndrome, L(loop_aligned)
|
||||
/* End of performance-critical section -- one 64B cache line. */
|
||||
cbnz tmp, L(mutual_align)
|
||||
|
||||
.p2align 4
|
||||
|
||||
L(loop_aligned):
|
||||
ldr data2, [src1, off2]
|
||||
ldr data1, [src1], 8
|
||||
L(start_realigned):
|
||||
#ifdef __AARCH64EB__
|
||||
rev tmp, data1
|
||||
sub has_nul, tmp, zeroones
|
||||
orr tmp, tmp, REP8_7f
|
||||
#else
|
||||
sub has_nul, data1, zeroones
|
||||
orr tmp, data1, REP8_7f
|
||||
#endif
|
||||
bics has_nul, has_nul, tmp /* Non-zero if NUL terminator. */
|
||||
ccmp data1, data2, 0, eq
|
||||
b.eq L(loop_aligned)
|
||||
#ifdef __AARCH64EB__
|
||||
rev has_nul, has_nul
|
||||
#endif
|
||||
eor diff, data1, data2
|
||||
orr syndrome, diff, has_nul
|
||||
L(end):
|
||||
#ifndef __AARCH64EB__
|
||||
#ifndef __AARCH64EB__
|
||||
rev syndrome, syndrome
|
||||
rev data1, data1
|
||||
/* The MS-non-zero bit of the syndrome marks either the first bit
|
||||
that is different, or the top bit of the first zero byte.
|
||||
Shifting left now will bring the critical information into the
|
||||
top bits. */
|
||||
clz pos, syndrome
|
||||
rev data2, data2
|
||||
lsl data1, data1, pos
|
||||
lsl data2, data2, pos
|
||||
/* But we need to zero-extend (char is unsigned) the value and then
|
||||
perform a signed 32-bit subtraction. */
|
||||
lsr data1, data1, #56
|
||||
sub result, data1, data2, lsr #56
|
||||
ret
|
||||
#else
|
||||
/* For big-endian we cannot use the trick with the syndrome value
|
||||
as carry-propagation can corrupt the upper bits if the trailing
|
||||
bytes in the string contain 0x01. */
|
||||
/* However, if there is no NUL byte in the dword, we can generate
|
||||
the result directly. We can't just subtract the bytes as the
|
||||
MSB might be significant. */
|
||||
cbnz has_nul, 1f
|
||||
cmp data1, data2
|
||||
cset result, ne
|
||||
cneg result, result, lo
|
||||
ret
|
||||
1:
|
||||
/* Re-compute the NUL-byte detection, using a byte-reversed value. */
|
||||
rev tmp3, data1
|
||||
sub tmp1, tmp3, zeroones
|
||||
orr tmp2, tmp3, #REP8_7f
|
||||
bic has_nul, tmp1, tmp2
|
||||
rev has_nul, has_nul
|
||||
orr syndrome, diff, has_nul
|
||||
clz pos, syndrome
|
||||
/* The MS-non-zero bit of the syndrome marks either the first bit
|
||||
that is different, or the top bit of the first zero byte.
|
||||
#endif
|
||||
clz shift, syndrome
|
||||
/* The most-significant-non-zero bit of the syndrome marks either the
|
||||
first bit that is different, or the top bit of the first zero byte.
|
||||
Shifting left now will bring the critical information into the
|
||||
top bits. */
|
||||
lsl data1, data1, pos
|
||||
lsl data2, data2, pos
|
||||
lsl data1, data1, shift
|
||||
lsl data2, data2, shift
|
||||
/* But we need to zero-extend (char is unsigned) the value and then
|
||||
perform a signed 32-bit subtraction. */
|
||||
lsr data1, data1, #56
|
||||
sub result, data1, data2, lsr #56
|
||||
lsr data1, data1, 56
|
||||
sub result, data1, data2, lsr 56
|
||||
ret
|
||||
#endif
|
||||
|
||||
.p2align 4
|
||||
|
||||
L(mutual_align):
|
||||
/* Sources are mutually aligned, but are not currently at an
|
||||
alignment boundary. Round down the addresses and then mask off
|
||||
the bytes that preceed the start point. */
|
||||
bic src1, src1, #7
|
||||
bic src2, src2, #7
|
||||
lsl tmp1, tmp1, #3 /* Bytes beyond alignment -> bits. */
|
||||
ldr data1, [src1], #8
|
||||
neg tmp1, tmp1 /* Bits to alignment -64. */
|
||||
ldr data2, [src2], #8
|
||||
mov tmp2, #~0
|
||||
#ifdef __AARCH64EB__
|
||||
/* Big-endian. Early bytes are at MSB. */
|
||||
lsl tmp2, tmp2, tmp1 /* Shift (tmp1 & 63). */
|
||||
#else
|
||||
/* Little-endian. Early bytes are at LSB. */
|
||||
lsr tmp2, tmp2, tmp1 /* Shift (tmp1 & 63). */
|
||||
#endif
|
||||
orr data1, data1, tmp2
|
||||
orr data2, data2, tmp2
|
||||
the bytes that precede the start point. */
|
||||
bic src1, src1, 7
|
||||
ldr data2, [src1, off2]
|
||||
ldr data1, [src1], 8
|
||||
neg shift, src2, lsl 3 /* Bits to alignment -64. */
|
||||
mov tmp, -1
|
||||
LS_FW tmp, tmp, shift
|
||||
orr data1, data1, tmp
|
||||
orr data2, data2, tmp
|
||||
b L(start_realigned)
|
||||
|
||||
L(misaligned8):
|
||||
/* Align SRC1 to 8 bytes and then compare 8 bytes at a time, always
|
||||
checking to make sure that we don't access beyond page boundary in
|
||||
SRC2. */
|
||||
tst src1, #7
|
||||
b.eq L(loop_misaligned)
|
||||
checking to make sure that we don't access beyond the end of SRC2. */
|
||||
cbz tmp, L(src1_aligned)
|
||||
L(do_misaligned):
|
||||
ldrb data1w, [src1], #1
|
||||
ldrb data2w, [src2], #1
|
||||
cmp data1w, #1
|
||||
ccmp data1w, data2w, #0, cs /* NZCV = 0b0000. */
|
||||
ldrb data1w, [src1], 1
|
||||
ldrb data2w, [src2], 1
|
||||
cmp data1w, 0
|
||||
ccmp data1w, data2w, 0, ne /* NZCV = 0b0000. */
|
||||
b.ne L(done)
|
||||
tst src1, #7
|
||||
tst src1, 7
|
||||
b.ne L(do_misaligned)
|
||||
|
||||
L(loop_misaligned):
|
||||
/* Test if we are within the last dword of the end of a 4K page. If
|
||||
yes then jump back to the misaligned loop to copy a byte at a time. */
|
||||
and tmp1, src2, #0xff8
|
||||
eor tmp1, tmp1, #0xff8
|
||||
cbz tmp1, L(do_misaligned)
|
||||
ldr data1, [src1], #8
|
||||
ldr data2, [src2], #8
|
||||
L(src1_aligned):
|
||||
neg shift, src2, lsl 3
|
||||
bic src2, src2, 7
|
||||
ldr data3, [src2], 8
|
||||
#ifdef __AARCH64EB__
|
||||
rev data3, data3
|
||||
#endif
|
||||
lsr tmp, zeroones, shift
|
||||
orr data3, data3, tmp
|
||||
sub has_nul, data3, zeroones
|
||||
orr tmp, data3, REP8_7f
|
||||
bics has_nul, has_nul, tmp
|
||||
b.ne L(tail)
|
||||
|
||||
sub tmp1, data1, zeroones
|
||||
orr tmp2, data1, #REP8_7f
|
||||
eor diff, data1, data2 /* Non-zero if differences found. */
|
||||
bic has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
|
||||
sub off1, src2, src1
|
||||
|
||||
.p2align 4
|
||||
|
||||
L(loop_unaligned):
|
||||
ldr data3, [src1, off1]
|
||||
ldr data2, [src1, off2]
|
||||
#ifdef __AARCH64EB__
|
||||
rev data3, data3
|
||||
#endif
|
||||
sub has_nul, data3, zeroones
|
||||
orr tmp, data3, REP8_7f
|
||||
ldr data1, [src1], 8
|
||||
bics has_nul, has_nul, tmp
|
||||
ccmp data1, data2, 0, eq
|
||||
b.eq L(loop_unaligned)
|
||||
|
||||
lsl tmp, has_nul, shift
|
||||
#ifdef __AARCH64EB__
|
||||
rev tmp, tmp
|
||||
#endif
|
||||
eor diff, data1, data2
|
||||
orr syndrome, diff, tmp
|
||||
cbnz syndrome, L(end)
|
||||
L(tail):
|
||||
ldr data1, [src1]
|
||||
neg shift, shift
|
||||
lsr data2, data3, shift
|
||||
lsr has_nul, has_nul, shift
|
||||
#ifdef __AARCH64EB__
|
||||
rev data2, data2
|
||||
rev has_nul, has_nul
|
||||
#endif
|
||||
eor diff, data1, data2
|
||||
orr syndrome, diff, has_nul
|
||||
cbz syndrome, L(loop_misaligned)
|
||||
b L(end)
|
||||
|
||||
L(done):
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user