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author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-02-12 19:20:27 +0300 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-10-20 10:40:53 -0300 |
commit | 82fd7314c7df8c5555dce027df6f2c98ca5a927f (patch) | |
tree | 2d16a8c07c1fc6d03405c79a695075c4432ece87 /sysdeps/powerpc/powerpc32 | |
parent | 2c6cabb3a442f467e78c702cffbd5f003f87f44f (diff) | |
download | glibc-82fd7314c7df8c5555dce027df6f2c98ca5a927f.zip glibc-82fd7314c7df8c5555dce027df6f2c98ca5a927f.tar.gz glibc-82fd7314c7df8c5555dce027df6f2c98ca5a927f.tar.bz2 |
powerpc: Remove backtrace implementation
The powerpc optimization to provide a fast stacktrace requires some
ad-hoc code to handle Linux signal frames and the change is fragile
once the kernel decides to slight change its execution sequence [1].
The generic implementation work as-is and it should be future proof
since the kernel provides the expected CFI directives in vDSO shared
page.
Checked on powerpc-linux-gnu, powerpc64le-linux-gnu, and
powerpc64-linux-gnu.
[1] https://sourceware.org/pipermail/libc-alpha/2021-January/122027.html
Diffstat (limited to 'sysdeps/powerpc/powerpc32')
-rw-r--r-- | sysdeps/powerpc/powerpc32/backtrace.c | 133 |
1 files changed, 0 insertions, 133 deletions
diff --git a/sysdeps/powerpc/powerpc32/backtrace.c b/sysdeps/powerpc/powerpc32/backtrace.c deleted file mode 100644 index 6031477..0000000 --- a/sysdeps/powerpc/powerpc32/backtrace.c +++ /dev/null @@ -1,133 +0,0 @@ -/* Return backtrace of current program state. - Copyright (C) 1998-2021 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - <https://www.gnu.org/licenses/>. */ - -#include <execinfo.h> -#include <stddef.h> -#include <string.h> -#include <signal.h> -#include <libc-vdso.h> - -/* This is the stack layout we see with every stack frame. - Note that every routine is required by the ABI to lay out the stack - like this. - - +----------------+ +-----------------+ - %r1 -> | %r1 last frame--------> | %r1 last frame--->... --> NULL - | | | | - | (unused) | | return address | - +----------------+ +-----------------+ -*/ -struct layout -{ - struct layout *next; - void *return_address; -}; - -#define SIGNAL_FRAMESIZE 64 - -/* Since the signal handler is just like any other function it needs to - save/restore its LR and it will save it into callers stack frame. - Since a signal handler doesn't have a caller, the kernel creates a - dummy frame to make it look like it has a caller. */ -struct signal_frame_32 { - char dummy[SIGNAL_FRAMESIZE]; - struct sigcontext sctx; - mcontext_t mctx; - /* We don't care about the rest, since IP value is at 'mctx' field. */ -}; - -static inline bool -is_sigtramp_address (void *nip) -{ -#ifdef HAVE_SIGTRAMP_RT32 - if (nip == GLRO (dl_vdso_sigtramp_32)) - return true; -#endif - return false; -} - -struct rt_signal_frame_32 { - char dummy[SIGNAL_FRAMESIZE + 16]; - siginfo_t info; - ucontext_t uc; - /* We don't care about the rest, since IP value is at 'uc' field. */ -}; - -static inline bool -is_sigtramp_address_rt (void * nip) -{ -#ifdef HAVE_SIGTRAMP_32 - if (nip == GLRO (dl_vdso_sigtramp_rt32)) - return true; -#endif - return false; -} - -int -__backtrace (void **array, int size) -{ - struct layout *current; - int count; - - /* Force gcc to spill LR. */ - asm volatile ("" : "=l"(current)); - - /* Get the address on top-of-stack. */ - asm volatile ("lwz %0,0(1)" : "=r"(current)); - - for ( count = 0; - current != NULL && count < size; - current = current->next, count++) - { - gregset_t *gregset = NULL; - - array[count] = current->return_address; - - /* Check if the symbol is the signal trampoline and get the interrupted - * symbol address from the trampoline saved area. */ - if (is_sigtramp_address (current->return_address)) - { - struct signal_frame_32 *sigframe = - (struct signal_frame_32*) current; - gregset = &sigframe->mctx.gregs; - } - else if (is_sigtramp_address_rt (current->return_address)) - { - struct rt_signal_frame_32 *sigframe = - (struct rt_signal_frame_32*) current; - gregset = &sigframe->uc.uc_mcontext.uc_regs->gregs; - } - if (gregset) - { - if (count + 1 == size) - break; - array[++count] = (void*)((*gregset)[PT_NIP]); - current = (void*)((*gregset)[PT_R1]); - } - } - - /* It's possible the second-last stack frame can't return - (that is, it's __libc_start_main), in which case - the CRT startup code will have set its LR to 'NULL'. */ - if (count > 0 && array[count-1] == NULL) - count--; - - return count; -} -weak_alias (__backtrace, backtrace) -libc_hidden_def (__backtrace) |