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/* Architecture-specific backtrace implementation. x86-64 version.
Copyright (C) 2024 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 <stdbool.h>
#include <sysdep.h>
/* From libc_sigaction.c. */
extern void restore_rt (void) asm ("__restore_rt") attribute_hidden;
/* Copy addresses from the shadow stack if available. */
static inline __always_inline int
__arch_backtrace (void **array, int size)
{
#if CET_ENABLED
void **ssp;
asm ("rdsspq %0"
: "=r" (ssp)
: "0" (0));
if (ssp == NULL)
return -1;
void **ssp_base = (void **) THREAD_GETMEM (THREAD_SELF, header.ssp_base);
if (ssp_base < ssp)
/* Covers the NULL case. */
return 0;
long int limit = ssp_base - ssp;
if (limit > size)
limit = size;
#if 1
__builtin_memcpy (array, ssp, limit * sizeof (*array));
return limit;
#else
/* We cannot use memcpy because we need to filter out signal
frames. */
int count = 0;
for (unsigned int i = 0; i < limit; ++i)
if (ssp[i] != restore_rt)
array[count++] = ssp[i];
return count;
#endif
#else /* !CET_ENABLED */
return -1;
#endif
}
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