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nptl: Move legacy unwinding implementation into libc

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It is still used internally.  Since unwinding is now available
unconditionally, avoid indirect calls through function pointers loaded
from the stack by inlining the non-cancellation cleanup code.  This
avoids a regression in security hardening.

The out-of-line  __libc_cleanup_routine implementation is no longer
needed because the inline definition is now static __always_inline.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
2021-04-21 19:49:50 +02:00
parent 5715c29e91
commit f79f206581
7 changed files with 98 additions and 117 deletions
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26
sysdeps/nptl/libc-lockP.h
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@@ -251,32 +251,12 @@ _Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0");
/* Get once control variable. */
#define __libc_once_get(ONCE_CONTROL) ((ONCE_CONTROL) != PTHREAD_ONCE_INIT)
/* Note that for I/O cleanup handling we are using the old-style
cancel handling. It does not have to be integrated with C++ snce
no C++ code is called in the middle. The old-style handling is
faster and the support is not going away. */
extern void _pthread_cleanup_push (struct _pthread_cleanup_buffer *buffer,
void (*routine) (void *), void *arg);
extern void _pthread_cleanup_pop (struct _pthread_cleanup_buffer *buffer,
int execute);
extern void _pthread_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer,
void (*routine) (void *), void *arg);
extern void _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer,
int execute);
/* Sometimes we have to exit the block in the middle. */
#define __libc_cleanup_end(DOIT) \
if (_avail) { \
__libc_ptf_call_always (_pthread_cleanup_pop_restore, (&_buffer, DOIT));\
} else if (DOIT) \
_buffer.__routine (_buffer.__arg)
/* __libc_cleanup_push and __libc_cleanup_pop depend on exception
handling and stack unwinding. */
#ifdef __EXCEPTIONS
/* Normal cleanup handling, based on C cleanup attribute. */
__extern_inline void
static __always_inline void
__libc_cleanup_routine (struct __pthread_cleanup_frame *f)
{
if (f->__do_it)
@@ -388,8 +368,6 @@ weak_extern (__pthread_once)
weak_extern (__pthread_initialize)
weak_extern (__pthread_atfork)
weak_extern (__pthread_setcancelstate)
weak_extern (_pthread_cleanup_push_defer)
weak_extern (_pthread_cleanup_pop_restore)
# else
# pragma weak __pthread_mutex_init
# pragma weak __pthread_mutex_destroy
@@ -412,8 +390,6 @@ weak_extern (_pthread_cleanup_pop_restore)
# pragma weak __pthread_initialize
# pragma weak __pthread_atfork
# pragma weak __pthread_setcancelstate
# pragma weak _pthread_cleanup_push_defer
# pragma weak _pthread_cleanup_pop_restore
# endif
#endif