nptl: Move legacy unwinding implementation into libc

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>

3 files changed, 31 insertions, 58 deletions

diff --git a/sysdeps/nptl/libc-lock.h b/sysdeps/nptl/libc-lock.h
index dea9612..e8a5e68 100644
--- a/sysdeps/nptl/libc-lock.h
+++ b/sysdeps/nptl/libc-lock.h
@@ -143,39 +143,40 @@ typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
   __libc_maybe_call (__pthread_mutex_unlock, (&(NAME).mutex), 0)
 #endif
 
-/* Note that for I/O cleanup handling we are using the old-style
-   cancel handling.  It does not have to be integrated with C++ since
-   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_defer (struct _pthread_cleanup_buffer *buffer,
-					 void (*routine) (void *), void *arg);
-extern void _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer,
-					  int execute);
+/* Put the unwind buffer BUFFER on the per-thread callback stack.  The
+   caller must fill BUFFER->__routine and BUFFER->__arg before calling
+   this function.  */
+void __libc_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer);
+libc_hidden_proto (__libc_cleanup_push_defer)
+/* Remove BUFFER from the unwind callback stack.  The caller must invoke
+   the callback if desired.  */
+void __libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer);
+libc_hidden_proto (__libc_cleanup_pop_restore)
 
 /* Start critical region with cleanup.  */
-#define __libc_cleanup_region_start(DOIT, FCT, ARG) \
-  { struct _pthread_cleanup_buffer _buffer;				      \
-    int _avail;								      \
-    if (DOIT) {								      \
-      _avail = PTFAVAIL (_pthread_cleanup_push_defer);			      \
-      if (_avail) {							      \
-	__libc_ptf_call_always (_pthread_cleanup_push_defer, (&_buffer, FCT,  \
-							      ARG));	      \
-      } else {								      \
-	_buffer.__routine = (FCT);					      \
-	_buffer.__arg = (ARG);						      \
-      }									      \
-    } else {								      \
-      _avail = 0;							      \
-    }
+#define __libc_cleanup_region_start(DOIT, FCT, ARG)			\
+  {   bool _cleanup_start_doit;						\
+  struct _pthread_cleanup_buffer _buffer;				\
+  /* Non-addressable copy of FCT, so that we avoid indirect calls on	\
+     the non-unwinding path.  */					\
+  void (*_cleanup_routine) (void *) = (FCT);				\
+  _buffer.__arg = (ARG);						\
+  if (DOIT)								\
+    {									\
+      _cleanup_start_doit = true;					\
+      _buffer.__routine = _cleanup_routine;				\
+      __libc_cleanup_push_defer (&_buffer);				\
+    }									\
+  else									\
+      _cleanup_start_doit = false;
 
 /* End critical region with cleanup.  */
-#define __libc_cleanup_region_end(DOIT) \
-    if (_avail) {							      \
-      __libc_ptf_call_always (_pthread_cleanup_pop_restore, (&_buffer, DOIT));\
-    } else if (DOIT)							      \
-      _buffer.__routine (_buffer.__arg);				      \
-  }
+#define __libc_cleanup_region_end(DOIT)		\
+  if (_cleanup_start_doit)			\
+    __libc_cleanup_pop_restore (&_buffer);	\
+  if (DOIT)					\
+    _cleanup_routine (_buffer.__arg);		\
+  } /* matches __libc_cleanup_region_start */
 
 
 /* Hide the definitions which are only supposed to be used inside libc in
diff --git a/sysdeps/nptl/libc-lockP.h b/sysdeps/nptl/libc-lockP.h
index 63b605d..2c928b7 100644
--- a/sysdeps/nptl/libc-lockP.h
+++ b/sysdeps/nptl/libc-lockP.h
@@ -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
 
diff --git a/sysdeps/nptl/pthread-functions.h b/sysdeps/nptl/pthread-functions.h
index 97a5c48..4268084 100644
--- a/sysdeps/nptl/pthread-functions.h
+++ b/sysdeps/nptl/pthread-functions.h
@@ -57,10 +57,6 @@ struct pthread_functions
   int (*ptr___pthread_key_create) (pthread_key_t *, void (*) (void *));
   void *(*ptr___pthread_getspecific) (pthread_key_t);
   int (*ptr___pthread_setspecific) (pthread_key_t, const void *);
-  void (*ptr__pthread_cleanup_push_defer) (struct _pthread_cleanup_buffer *,
-					   void (*) (void *), void *);
-  void (*ptr__pthread_cleanup_pop_restore) (struct _pthread_cleanup_buffer *,
-					    int);
 #define HAVE_PTR_NTHREADS
   unsigned int *ptr_nthreads;
   void (*ptr___pthread_unwind) (__pthread_unwind_buf_t *)