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The pad array in struct pthread_unwind_buf is used by setjmp to save shadow stack register. We assert that size of struct pthread_unwind_buf is no less than offset of shadow stack pointer + shadow stack pointer size. Since functions, like LIBC_START_MAIN, START_THREAD_DEFN as well as these with thread cancellation, call setjmp, but never return after __libc_unwind_longjmp, __libc_unwind_longjmp, which is defined as __libc_longjmp on x86, doesn't need to restore shadow stack register. __libc_longjmp, which is a private interface for thread cancellation implementation in libpthread, is changed to call __longjmp_cancel, instead of __longjmp. __longjmp_cancel is a new internal function in libc, which is similar to __longjmp, but doesn't restore shadow stack register. The compatibility longjmp and siglongjmp in libpthread.so are changed to call __libc_siglongjmp, instead of __libc_longjmp, so that they will restore shadow stack register. Tested with build-many-glibcs.py. Signed-off-by: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com> * nptl/pthread_create.c (START_THREAD_DEFN): Clear previous handlers after setjmp. * setjmp/longjmp.c (__libc_longjmp): Don't define alias if defined. * sysdeps/unix/sysv/linux/x86/setjmpP.h: Include <libc-pointer-arith.h>. (_JUMP_BUF_SIGSET_BITS_PER_WORD): New. (_JUMP_BUF_SIGSET_NSIG): Changed to 96. (_JUMP_BUF_SIGSET_NWORDS): Changed to use ALIGN_UP and _JUMP_BUF_SIGSET_BITS_PER_WORD. * sysdeps/x86/Makefile (sysdep_routines): Add __longjmp_cancel. * sysdeps/x86/__longjmp_cancel.S: New file. * sysdeps/x86/longjmp.c: Likewise. * sysdeps/x86/nptl/pt-longjmp.c: Likewise.
52 lines
1.8 KiB
C
52 lines
1.8 KiB
C
/* Copyright (C) 1991-2018 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 <stddef.h>
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#include <setjmpP.h>
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#include <signal.h>
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/* Set the signal mask to the one specified in ENV, and jump
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to the position specified in ENV, causing the setjmp
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call there to return VAL, or 1 if VAL is 0. */
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void
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__libc_siglongjmp (sigjmp_buf env, int val)
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{
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/* Perform any cleanups needed by the frames being unwound. */
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_longjmp_unwind (env, val);
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if (env[0].__mask_was_saved)
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/* Restore the saved signal mask. */
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(void) __sigprocmask (SIG_SETMASK,
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(sigset_t *) &env[0].__saved_mask,
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(sigset_t *) NULL);
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/* Call the machine-dependent function to restore machine state. */
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__longjmp (env[0].__jmpbuf, val ?: 1);
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}
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#ifndef __libc_siglongjmp
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# ifndef __libc_longjmp
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/* __libc_longjmp is a private interface for cancellation implementation
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in libpthread. */
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strong_alias (__libc_siglongjmp, __libc_longjmp)
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# endif
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weak_alias (__libc_siglongjmp, _longjmp)
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weak_alias (__libc_siglongjmp, longjmp)
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weak_alias (__libc_siglongjmp, siglongjmp)
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#endif
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