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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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66
nptl/libc-cleanup.c
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@ -17,11 +17,69 @@
<https://www.gnu.org/licenses/>. */
#include "pthreadP.h"
#include <tls.h>
#include <libc-lock.h>
void
__libc_cleanup_routine (struct __pthread_cleanup_frame *f)
__libc_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer)
{
if (f->__do_it)
f->__cancel_routine (f->__cancel_arg);
struct pthread *self = THREAD_SELF;
buffer->__prev = THREAD_GETMEM (self, cleanup);
int cancelhandling = THREAD_GETMEM (self, cancelhandling);
/* Disable asynchronous cancellation for now. */
if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
while (1)
{
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
cancelhandling
& ~CANCELTYPE_BITMASK,
cancelhandling);
if (__glibc_likely (curval == cancelhandling))
/* Successfully replaced the value. */
break;
/* Prepare for the next round. */
cancelhandling = curval;
}
buffer->__canceltype = (cancelhandling & CANCELTYPE_BITMASK
? PTHREAD_CANCEL_ASYNCHRONOUS
: PTHREAD_CANCEL_DEFERRED);
THREAD_SETMEM (self, cleanup, buffer);
}
libc_hidden_def (__libc_cleanup_push_defer)
void
__libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer)
{
struct pthread *self = THREAD_SELF;
THREAD_SETMEM (self, cleanup, buffer->__prev);
int cancelhandling;
if (__builtin_expect (buffer->__canceltype != PTHREAD_CANCEL_DEFERRED, 0)
&& ((cancelhandling = THREAD_GETMEM (self, cancelhandling))
& CANCELTYPE_BITMASK) == 0)
{
while (1)
{
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
cancelhandling
| CANCELTYPE_BITMASK,
cancelhandling);
if (__glibc_likely (curval == cancelhandling))
/* Successfully replaced the value. */
break;
/* Prepare for the next round. */
cancelhandling = curval;
}
CANCELLATION_P (self);
}
}
libc_hidden_def (__libc_cleanup_pop_restore)