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author | H.J. Lu <hjl.tools@gmail.com> | 2018-05-02 06:17:20 -0700 |
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committer | H.J. Lu <hjl.tools@gmail.com> | 2018-05-02 06:17:41 -0700 |
commit | d6cc1829aa31b6fb060f24dffd28aa6705cdd33a (patch) | |
tree | 197e7983f66d43765505f94a5a29d254d27f6d02 /libof-iterator.mk | |
parent | b109fbfe4dd2ca77656157ddaded773e0da630a2 (diff) | |
download | glibc-d6cc1829aa31b6fb060f24dffd28aa6705cdd33a.tar.gz glibc-d6cc1829aa31b6fb060f24dffd28aa6705cdd33a.tar.xz glibc-d6cc1829aa31b6fb060f24dffd28aa6705cdd33a.zip |
x86: Use pad in pthread_unwind_buf to preserve shadow stack register
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.
Diffstat (limited to 'libof-iterator.mk')
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