[v2,08/21] nptl: aarch64: Fix Race conditions in pthread cancellation (BZ#12683)
Commit Message
This patch adds the aarch64 modifications required for the BZ#12683.
It basically adds the required ucontext_get_pc function.
The built cancelable syscall wrapper for aarch64 using GCC 7.2.1 and
default configuration flags shows an expected optimized version:
---
__GI___syscall_cancel_arch:
.LFB38:
.cfi_startproc
.global __syscall_cancel_arch_start
.type __syscall_cancel_arch_start,@function
__syscall_cancel_arch_start:
ldr w9, [x0]
tbnz x9, 2, .L7
mov x8, x1
mov x0, x2
mov x1, x3
mov x2, x4
mov x3, x5
mov x4, x6
mov x5, x7
svc 0 // syscall nr
.global __syscall_cancel_arch_end
.type __syscall_cancel_arch_end,@function
__syscall_cancel_arch_end:
ret
---
A similar code is obtained with GCC 5.3.1, so I see to need to provide
an arch-specific syscall_cancel.S for aarch64.
Checked on aarch64-linux-gnu.
[BZ #12683]
* sysdeps/unix/sysv/linux/aarch64/sysdep-cancel.h (PSEUDO): Redefine
to call __syscall_cancel function for cancellable syscalls.
(__pthread_get_ip): Add implementation.
* sysdeps/unix/sysv/linux/aarch64/sysdep.h (SYSCALL_CANCEL_ERROR): Add
definition.
(SYSCALL_CANCEL_ERRNO): Likewise.
---
ChangeLog | 4 ++++
sysdeps/unix/sysv/linux/aarch64/sigcontextinfo.h | 11 +++++++++++
2 files changed, 15 insertions(+)
@@ -16,6 +16,9 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#ifndef _SIGCONTEXTINFO_H
+#define _SIGCONTEXTINFO_H
+
#include <stdint.h>
#include <sys/ucontext.h>
@@ -33,3 +36,11 @@
(act)->sa_flags |= SA_SIGINFO; \
(sigaction) (sig, act, oact); \
})
+
+static inline uintptr_t
+ucontext_get_pc (const ucontext_t *uc)
+{
+ return uc->uc_mcontext.pc;
+}
+
+#endif