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31073a53d8
Now with read consolidation which uses SYSCALL_CANCEL macro, a frame
pointer is created in the syscall code and this makes the powerpc
backtrace obtain a bogus entry for the signal handling patch.
It is because it does not setup the correct frame pointer register
(r1) based on the saved value from the kernel sigreturn. It was not
failing because the syscall frame pointer register was the same one
for the next frame (the function that actually called the syscall).
This patch fixes it by setup the next stack frame using the saved
one by the kernel sigreturn. It fixes tst-backtrace{5,6} from
the read consolidation patch.
Checked on powerpc-linux-gnu and powerpc64le-linux-gnu.
* sysdeps/powerpc/powerpc32/backtrace.c (is_sigtramp_address): Use
void* for argument type and use VDSO_SYMBOL macro.
(is_sigtramp_address_rt): Likewise.
(__backtrace): Setup expected frame pointer address for signal
handling.
* sysdeps/powerpc/powerpc64/backtrace.c (is_sigtramp_address): Use
void* for argumetn type and use VSDO_SYMBOL macro.
(__backtrace): Setup expected frame pointer address for signal
handling.
132 lines
3.8 KiB
C
132 lines
3.8 KiB
C
/* Return backtrace of current program state.
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Copyright (C) 1998-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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 <execinfo.h>
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#include <stddef.h>
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#include <string.h>
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#include <signal.h>
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#include <libc-vdso.h>
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/* This is the stack layout we see with every stack frame.
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Note that every routine is required by the ABI to lay out the stack
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like this.
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+----------------+ +-----------------+
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%r1 -> | %r1 last frame--------> | %r1 last frame--->... --> NULL
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| | | |
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| (unused) | | return address |
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+----------------+ +-----------------+
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*/
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struct layout
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{
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struct layout *next;
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void *return_address;
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};
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#define SIGNAL_FRAMESIZE 64
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/* Since the signal handler is just like any other function it needs to
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save/restore its LR and it will save it into callers stack frame.
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Since a signal handler doesn't have a caller, the kernel creates a
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dummy frame to make it look like it has a caller. */
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struct signal_frame_32 {
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char dummy[SIGNAL_FRAMESIZE];
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struct sigcontext sctx;
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mcontext_t mctx;
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/* We don't care about the rest, since IP value is at 'mctx' field. */
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};
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static inline int
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is_sigtramp_address (void *nip)
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{
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#ifdef SHARED
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if (nip == VDSO_SYMBOL (sigtramp32))
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return 1;
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#endif
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return 0;
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}
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struct rt_signal_frame_32 {
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char dummy[SIGNAL_FRAMESIZE + 16];
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siginfo_t info;
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struct ucontext uc;
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/* We don't care about the rest, since IP value is at 'uc' field. */
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};
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static inline int
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is_sigtramp_address_rt (void * nip)
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{
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#ifdef SHARED
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if (nip == VDSO_SYMBOL (sigtramp_rt32))
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return 1;
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#endif
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return 0;
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}
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int
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__backtrace (void **array, int size)
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{
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struct layout *current;
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int count;
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/* Force gcc to spill LR. */
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asm volatile ("" : "=l"(current));
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/* Get the address on top-of-stack. */
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asm volatile ("lwz %0,0(1)" : "=r"(current));
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for ( count = 0;
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current != NULL && count < size;
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current = current->next, count++)
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{
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gregset_t *gregset = NULL;
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array[count] = current->return_address;
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/* Check if the symbol is the signal trampoline and get the interrupted
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* symbol address from the trampoline saved area. */
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if (is_sigtramp_address (current->return_address))
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{
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struct signal_frame_32 *sigframe =
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(struct signal_frame_32*) current;
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gregset = &sigframe->mctx.gregs;
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}
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else if (is_sigtramp_address_rt (current->return_address))
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{
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struct rt_signal_frame_32 *sigframe =
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(struct rt_signal_frame_32*) current;
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gregset = &sigframe->uc.uc_mcontext.uc_regs->gregs;
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}
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if (gregset)
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{
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array[++count] = (void*)((*gregset)[PT_NIP]);
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current = (void*)((*gregset)[PT_R1]);
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}
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}
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/* It's possible the second-last stack frame can't return
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(that is, it's __libc_start_main), in which case
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the CRT startup code will have set its LR to 'NULL'. */
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if (count > 0 && array[count-1] == NULL)
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count--;
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return count;
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}
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weak_alias (__backtrace, backtrace)
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libc_hidden_def (__backtrace)
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