Fix strcpy_chk and stpcpy_chk performance.
Hi, as I wrote in previous patches a performance of checked strcpy and
stpcpy is terrible as these don't use sse2 and are around four times
slower that strcpy and stpcpy now.
As this bug shows that these functions are not performance sensitive I
decided just to improve generic implementation instead for easier
maintainance.
* debug/strcpy_chk.c: Improve performance.
* debug/stpcpy_chk.c: Likewise.
* sysdeps/x86_64/strcpy_chk.S: Remove.
* sysdeps/x86_64/stpcpy_chk.S: Remove.
This commit is contained in:
Ondřej Bílka
parent
f3dcae82d5
commit
0d0325ed4b
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@ -24,21 +24,11 @@
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/* Copy SRC to DEST, returning the address of the terminating '\0' in DEST. */
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char *
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__stpcpy_chk (dest, src, destlen)
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char *dest;
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const char *src;
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size_t destlen;
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__stpcpy_chk (char *dest, const char *src, size_t destlen)
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{
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char *d = dest;
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const char *s = src;
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size_t len = strlen (src);
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if (len >= destlen)
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__chk_fail ();
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do
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{
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if (__glibc_unlikely (destlen-- == 0))
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__chk_fail ();
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*d++ = *s;
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}
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while (*s++ != '\0');
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return d - 1;
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return memcpy (dest, src, len + 1) + len;
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}
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@ -23,45 +23,11 @@
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/* Copy SRC to DEST with checking of destination buffer overflow. */
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char *
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__strcpy_chk (dest, src, destlen)
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char *dest;
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const char *src;
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size_t destlen;
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__strcpy_chk (char *dest, const char *src, size_t destlen)
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{
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char c;
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char *s = (char *) src;
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const ptrdiff_t off = dest - s;
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size_t len = strlen (src);
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if (len >= destlen)
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__chk_fail ();
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while (__builtin_expect (destlen >= 4, 0))
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{
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c = s[0];
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s[off] = c;
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if (c == '\0')
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return dest;
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c = s[1];
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s[off + 1] = c;
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if (c == '\0')
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return dest;
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c = s[2];
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s[off + 2] = c;
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if (c == '\0')
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return dest;
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c = s[3];
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s[off + 3] = c;
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if (c == '\0')
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return dest;
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destlen -= 4;
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s += 4;
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}
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do
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{
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if (__glibc_unlikely (destlen-- == 0))
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__chk_fail ();
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c = *s;
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*(s++ + off) = c;
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}
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while (c != '\0');
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return dest;
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return memcpy (dest, src, len + 1);
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}
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@ -1,3 +0,0 @@
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#define USE_AS_STPCPY_CHK
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#define STRCPY_CHK __stpcpy_chk
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#include <sysdeps/x86_64/strcpy_chk.S>
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@ -1,208 +0,0 @@
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/* strcpy/stpcpy checking implementation for x86-64.
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Copyright (C) 2002-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Andreas Jaeger <aj@suse.de>, 2002.
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Adopted into checking version by Jakub Jelinek <jakub@redhat.com>.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include "asm-syntax.h"
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#ifndef USE_AS_STPCPY_CHK
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# define STRCPY_CHK __strcpy_chk
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#endif
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.text
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ENTRY (STRCPY_CHK)
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movq %rsi, %rcx /* Source register. */
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andl $7, %ecx /* mask alignment bits */
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#ifndef USE_AS_STPCPY_CHK
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movq %rdi, %r10 /* Duplicate destination pointer. */
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#endif
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jz 5f /* aligned => start loop */
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cmpq $8, %rdx /* Check if only few bytes left in
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destination. */
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jb 50f
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subq $8, %rcx /* We need to align to 8 bytes. */
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addq %rcx, %rdx /* Subtract count of stored bytes
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in the cycle below from destlen. */
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/* Search the first bytes directly. */
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0:
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movb (%rsi), %al /* Fetch a byte */
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testb %al, %al /* Is it NUL? */
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movb %al, (%rdi) /* Store it */
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jz 4f /* If it was NUL, done! */
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incq %rsi
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incq %rdi
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incl %ecx
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jnz 0b
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5:
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movq $0xfefefefefefefeff,%r8
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cmpq $32, %rdx /* Are there enough bytes in destination
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for the next unrolled round? */
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jb 60f /* If not, avoid the unrolled loop. */
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/* Now the sources is aligned. Unfortunatly we cannot force
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to have both source and destination aligned, so ignore the
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alignment of the destination. */
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.p2align 4
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1:
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/* 1st unroll. */
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movq (%rsi), %rax /* Read double word (8 bytes). */
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addq $8, %rsi /* Adjust pointer for next word. */
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movq %rax, %r9 /* Save a copy for NUL finding. */
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addq %r8, %r9 /* add the magic value to the word. We get
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carry bits reported for each byte which
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is *not* 0 */
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jnc 3f /* highest byte is NUL => return pointer */
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xorq %rax, %r9 /* (word+magic)^word */
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orq %r8, %r9 /* set all non-carry bits */
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incq %r9 /* add 1: if one carry bit was *not* set
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the addition will not result in 0. */
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jnz 3f /* found NUL => return pointer */
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movq %rax, (%rdi) /* Write value to destination. */
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addq $8, %rdi /* Adjust pointer. */
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/* 2nd unroll. */
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movq (%rsi), %rax /* Read double word (8 bytes). */
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addq $8, %rsi /* Adjust pointer for next word. */
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movq %rax, %r9 /* Save a copy for NUL finding. */
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addq %r8, %r9 /* add the magic value to the word. We get
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carry bits reported for each byte which
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is *not* 0 */
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jnc 3f /* highest byte is NUL => return pointer */
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xorq %rax, %r9 /* (word+magic)^word */
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orq %r8, %r9 /* set all non-carry bits */
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incq %r9 /* add 1: if one carry bit was *not* set
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the addition will not result in 0. */
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jnz 3f /* found NUL => return pointer */
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movq %rax, (%rdi) /* Write value to destination. */
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addq $8, %rdi /* Adjust pointer. */
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/* 3rd unroll. */
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movq (%rsi), %rax /* Read double word (8 bytes). */
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addq $8, %rsi /* Adjust pointer for next word. */
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movq %rax, %r9 /* Save a copy for NUL finding. */
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addq %r8, %r9 /* add the magic value to the word. We get
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carry bits reported for each byte which
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is *not* 0 */
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jnc 3f /* highest byte is NUL => return pointer */
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xorq %rax, %r9 /* (word+magic)^word */
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orq %r8, %r9 /* set all non-carry bits */
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incq %r9 /* add 1: if one carry bit was *not* set
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the addition will not result in 0. */
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jnz 3f /* found NUL => return pointer */
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movq %rax, (%rdi) /* Write value to destination. */
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addq $8, %rdi /* Adjust pointer. */
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/* 4th unroll. */
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movq (%rsi), %rax /* Read double word (8 bytes). */
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addq $8, %rsi /* Adjust pointer for next word. */
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movq %rax, %r9 /* Save a copy for NUL finding. */
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addq %r8, %r9 /* add the magic value to the word. We get
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carry bits reported for each byte which
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is *not* 0 */
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jnc 3f /* highest byte is NUL => return pointer */
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xorq %rax, %r9 /* (word+magic)^word */
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orq %r8, %r9 /* set all non-carry bits */
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incq %r9 /* add 1: if one carry bit was *not* set
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the addition will not result in 0. */
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jnz 3f /* found NUL => return pointer */
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subq $32, %rdx /* Adjust destlen. */
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movq %rax, (%rdi) /* Write value to destination. */
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addq $8, %rdi /* Adjust pointer. */
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cmpq $32, %rdx /* Are there enough bytes in destination
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for the next unrolled round? */
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jae 1b /* Next iteration. */
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60:
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cmpq $8, %rdx /* Are there enough bytes in destination
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for the next unrolled round? */
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jb 50f /* Now, copy and check byte by byte. */
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movq (%rsi), %rax /* Read double word (8 bytes). */
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addq $8, %rsi /* Adjust pointer for next word. */
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movq %rax, %r9 /* Save a copy for NUL finding. */
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addq %r8, %r9 /* add the magic value to the word. We get
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carry bits reported for each byte which
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is *not* 0 */
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jnc 3f /* highest byte is NUL => return pointer */
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xorq %rax, %r9 /* (word+magic)^word */
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orq %r8, %r9 /* set all non-carry bits */
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incq %r9 /* add 1: if one carry bit was *not* set
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the addition will not result in 0. */
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jnz 3f /* found NUL => return pointer */
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subq $8, %rdx /* Adjust destlen. */
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movq %rax, (%rdi) /* Write value to destination. */
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addq $8, %rdi /* Adjust pointer. */
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jmp 60b /* Next iteration. */
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/* Do the last few bytes. %rax contains the value to write.
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The loop is unrolled twice. */
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.p2align 4
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3:
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/* Note that stpcpy needs to return with the value of the NUL
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byte. */
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movb %al, (%rdi) /* 1st byte. */
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testb %al, %al /* Is it NUL. */
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jz 4f /* yes, finish. */
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incq %rdi /* Increment destination. */
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movb %ah, (%rdi) /* 2nd byte. */
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testb %ah, %ah /* Is it NUL?. */
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jz 4f /* yes, finish. */
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incq %rdi /* Increment destination. */
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shrq $16, %rax /* Shift... */
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jmp 3b /* and look at next two bytes in %rax. */
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51:
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/* Search the bytes directly, checking for overflows. */
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incq %rsi
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incq %rdi
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decq %rdx
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jz HIDDEN_JUMPTARGET (__chk_fail)
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52:
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movb (%rsi), %al /* Fetch a byte */
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testb %al, %al /* Is it NUL? */
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movb %al, (%rdi) /* Store it */
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jnz 51b /* If it was NUL, done! */
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4:
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#ifdef USE_AS_STPCPY_CHK
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movq %rdi, %rax /* Destination is return value. */
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#else
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movq %r10, %rax /* Source is return value. */
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#endif
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retq
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50:
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testq %rdx, %rdx
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jnz 52b
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jmp HIDDEN_JUMPTARGET (__chk_fail)
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END (STRCPY_CHK)
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