diff options
| author | H.J. Lu <hjl.tools@gmail.com> | 2018-05-02 06:17:20 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2018-05-02 06:17:41 -0700 |
| commit | d6cc1829aa31b6fb060f24dffd28aa6705cdd33a (patch) | |
| tree | 197e7983f66d43765505f94a5a29d254d27f6d02 /setjmp | |
| parent | b109fbfe4dd2ca77656157ddaded773e0da630a2 (diff) | |
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 'setjmp')
| -rw-r--r-- | setjmp/longjmp.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/setjmp/longjmp.c b/setjmp/longjmp.c index a2a7065a85..453889e103 100644 --- a/setjmp/longjmp.c +++ b/setjmp/longjmp.c @@ -40,9 +40,11 @@ __libc_siglongjmp (sigjmp_buf env, int val) } #ifndef __libc_siglongjmp +# ifndef __libc_longjmp /* __libc_longjmp is a private interface for cancellation implementation in libpthread. */ strong_alias (__libc_siglongjmp, __libc_longjmp) +# endif weak_alias (__libc_siglongjmp, _longjmp) weak_alias (__libc_siglongjmp, longjmp) weak_alias (__libc_siglongjmp, siglongjmp) |