From 71a5bd3e177e7748cf8993b0577d65d8986b44bc Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Sun, 15 Mar 2009 09:03:38 +0000 Subject: [PATCH] [BZ #5807] 2009-03-15 Ulrich Drepper [BZ #5807] * string/strlen.c (strlen): Fix omission in the expression to test for NUL bytes. --- ChangeLog | 6 + nptl/ChangeLog | 6 + .../linux/x86_64/pthread_cond_timedwait.S | 123 +++--------------- string/strlen.c | 52 +------- 4 files changed, 36 insertions(+), 151 deletions(-) diff --git a/ChangeLog b/ChangeLog index 83c355e8ab..6e7c4febf4 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2009-03-15 Ulrich Drepper + + [BZ #5807] + * string/strlen.c (strlen): Fix omission in the expression to test + for NUL bytes. + 2009-03-14 Ulrich Drepper * crypt/sha256test.c (main): Perform 100,000 'a' test in a second way. diff --git a/nptl/ChangeLog b/nptl/ChangeLog index 15e79efdd4..049d3ce395 100644 --- a/nptl/ChangeLog +++ b/nptl/ChangeLog @@ -1,3 +1,9 @@ +2009-03-15 Ulrich Drepper + + * sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S + (__pthread_cond_timedwait): Change to use cfi directives instead of + hand-coded unwind sections. + 2009-03-10 Ulrich Drepper * init.c (nptl_freeres): Compile only for SHARED. diff --git a/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S b/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S index 20bc59db9c..ddcf106a6d 100644 --- a/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S +++ b/nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S @@ -1,4 +1,4 @@ -/* Copyright (C) 2002, 2003, 2004, 2005, 2007 Free Software Foundation, Inc. +/* Copyright (C) 2002-2005, 2007, 2009 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 2002. @@ -37,16 +37,19 @@ .type __pthread_cond_timedwait, @function .align 16 __pthread_cond_timedwait: -.LSTARTCODE: + cfi_startproc pushq %r12 -.Lpush_r12: + cfi_adjust_cfa_offset(8) + cfi_rel_offset(%r12, 0) pushq %r13 -.Lpush_r13: + cfi_adjust_cfa_offset(8) + cfi_rel_offset(%r13, 0) pushq %r14 -.Lpush_r14: + cfi_adjust_cfa_offset(8) + cfi_rel_offset(%r14, 0) #define FRAME_SIZE 80 subq $FRAME_SIZE, %rsp -.Lsubq: + cfi_adjust_cfa_offset(FRAME_SIZE) cmpq $1000000000, 8(%rdx) movl $EINVAL, %eax @@ -305,19 +308,25 @@ __pthread_cond_timedwait: cmoveq %r14, %rax 18: addq $FRAME_SIZE, %rsp -.Laddq: + cfi_adjust_cfa_offset(-FRAME_SIZE) popq %r14 -.Lpop_r14: + cfi_adjust_cfa_offset(-8) + cfi_restore(%r14) popq %r13 -.Lpop_r13: + cfi_adjust_cfa_offset(-8) + cfi_restore(%r13) popq %r12 -.Lpop_r12: + cfi_adjust_cfa_offset(-8) + cfi_restore(%r12) retq /* Initial locking failed. */ 1: -.LSbl1: + cfi_adjust_cfa_offset(3 * 8 + FRAME_SIZE) + cfi_rel_offset(%r12, FRAME_SIZE + 16) + cfi_rel_offset(%r13, FRAME_SIZE + 8) + cfi_rel_offset(%r14, FRAME_SIZE) #if cond_lock != 0 addq $cond_lock, %rdi #endif @@ -414,97 +423,7 @@ __pthread_cond_timedwait: js 6b jmp 21b #endif -.LENDCODE: + cfi_endproc .size __pthread_cond_timedwait, .-__pthread_cond_timedwait versioned_symbol (libpthread, __pthread_cond_timedwait, pthread_cond_timedwait, GLIBC_2_3_2) - - - .section .eh_frame,"a",@progbits -.LSTARTFRAME: - .long L(ENDCIE)-L(STARTCIE) # Length of the CIE. -.LSTARTCIE: - .long 0 # CIE ID. - .byte 1 # Version number. -#ifdef SHARED - .string "zR" # NUL-terminated augmentation - # string. -#else - .ascii "\0" # NUL-terminated augmentation - # string. -#endif - .uleb128 1 # Code alignment factor. - .sleb128 -8 # Data alignment factor. - .byte 16 # Return address register - # column. -#ifdef SHARED - .uleb128 1 # Augmentation value length. - .byte 0x1b # Encoding: DW_EH_PE_pcrel - # + DW_EH_PE_sdata4. -#endif - .byte 0x0c # DW_CFA_def_cfa - .uleb128 7 - .uleb128 8 - .byte 0x90 # DW_CFA_offset, column 0x8 - .uleb128 1 - .align 8 -.LENDCIE: - - .long .LENDFDE-.LSTARTFDE # Length of the FDE. -.LSTARTFDE: - .long .LSTARTFDE-.LSTARTFRAME # CIE pointer. -#ifdef SHARED - .long .LSTARTCODE-. # PC-relative start address - # of the code -#else - .long .LSTARTCODE # Start address of the code. -#endif - .long .LENDCODE-.LSTARTCODE # Length of the code. -#ifdef SHARED - .uleb128 0 # No augmentation data. -#endif - .byte 0x40+.Lpush_r12-.LSTARTCODE # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 16 - .byte 0x8c # DW_CFA_offset %r12 - .uleb128 2 - .byte 0x40+.Lpush_r13-.Lpush_r12 # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 24 - .byte 0x8d # DW_CFA_offset %r13 - .uleb128 3 - .byte 0x40+.Lpush_r14-.Lpush_r13 # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 32 - .byte 0x84 # DW_CFA_offset %r14 - .uleb128 4 - .byte 0x40+.Lsubq-.Lpush_r14 # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 32+FRAME_SIZE - .byte 3 # DW_CFA_advance_loc2 - .2byte .Laddq-.Lsubq - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 32 - .byte 0x40+.Lpop_r14-.Laddq # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 24 - .byte 0xce # DW_CFA_restore %r14 - .byte 0x40+.Lpop_r13-.Lpop_r14 # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 16 - .byte 0xcd # DW_CFA_restore %r13 - .byte 0x40+.Lpop_r12-.Lpop_r13 # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 8 - .byte 0xcc # DW_CFA_restore %r12 - .byte 0x40+.LSbl1-.Lpop_r12 # DW_CFA_advance_loc+N - .byte 14 # DW_CFA_def_cfa_offset - .uleb128 32+FRAME_SIZE - .byte 0x8c # DW_CFA_offset %r12 - .uleb128 2 - .byte 0x8d # DW_CFA_offset %r13 - .uleb128 3 - .byte 0x84 # DW_CFA_offset %r14 - .uleb128 4 - .align 8 -.LENDFDE: diff --git a/string/strlen.c b/string/strlen.c index 9bc9db68f7..5f22ce9509 100644 --- a/string/strlen.c +++ b/string/strlen.c @@ -1,4 +1,4 @@ -/* Copyright (C) 1991, 1993, 1997, 2000, 2003 Free Software Foundation, Inc. +/* Copyright (C) 1991,1993,1997,2000,2003,2009 Free Software Foundation, Inc. This file is part of the GNU C Library. Written by Torbjorn Granlund (tege@sics.se), with help from Dan Sahlin (dan@sics.se); @@ -32,7 +32,7 @@ strlen (str) { const char *char_ptr; const unsigned long int *longword_ptr; - unsigned long int longword, magic_bits, himagic, lomagic; + unsigned long int longword, himagic, lomagic; /* Handle the first few characters by reading one character at a time. Do this until CHAR_PTR is aligned on a longword boundary. */ @@ -56,14 +56,12 @@ strlen (str) The 1-bits make sure that carries propagate to the next 0-bit. The 0-bits provide holes for carries to fall into. */ - magic_bits = 0x7efefeffL; himagic = 0x80808080L; lomagic = 0x01010101L; if (sizeof (longword) > 4) { /* 64-bit version of the magic. */ /* Do the shift in two steps to avoid a warning if long has 32 bits. */ - magic_bits = ((0x7efefefeL << 16) << 16) | 0xfefefeffL; himagic = ((himagic << 16) << 16) | himagic; lomagic = ((lomagic << 16) << 16) | lomagic; } @@ -75,53 +73,9 @@ strlen (str) if *any of the four* bytes in the longword in question are zero. */ for (;;) { - /* We tentatively exit the loop if adding MAGIC_BITS to - LONGWORD fails to change any of the hole bits of LONGWORD. - - 1) Is this safe? Will it catch all the zero bytes? - Suppose there is a byte with all zeros. Any carry bits - propagating from its left will fall into the hole at its - least significant bit and stop. Since there will be no - carry from its most significant bit, the LSB of the - byte to the left will be unchanged, and the zero will be - detected. - - 2) Is this worthwhile? Will it ignore everything except - zero bytes? Suppose every byte of LONGWORD has a bit set - somewhere. There will be a carry into bit 8. If bit 8 - is set, this will carry into bit 16. If bit 8 is clear, - one of bits 9-15 must be set, so there will be a carry - into bit 16. Similarly, there will be a carry into bit - 24. If one of bits 24-30 is set, there will be a carry - into bit 31, so all of the hole bits will be changed. - - The one misfire occurs when bits 24-30 are clear and bit - 31 is set; in this case, the hole at bit 31 is not - changed. If we had access to the processor carry flag, - we could close this loophole by putting the fourth hole - at bit 32! - - So it ignores everything except 128's, when they're aligned - properly. */ - longword = *longword_ptr++; - if ( -#if 0 - /* Add MAGIC_BITS to LONGWORD. */ - (((longword + magic_bits) - - /* Set those bits that were unchanged by the addition. */ - ^ ~longword) - - /* Look at only the hole bits. If any of the hole bits - are unchanged, most likely one of the bytes was a - zero. */ - & ~magic_bits) -#else - ((longword - lomagic) & himagic) -#endif - != 0) + if (((longword - lomagic) & ~longword & himagic) != 0) { /* Which of the bytes was the zero? If none of them were, it was a misfire; continue the search. */