From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Subject: [PATCH] Refactor Linux raise implementation (BZ#15368)
Date: Fri, 17 Jun 2016 18:43:00 -0000 [thread overview]
Message-ID: <1466188988-19954-1-git-send-email-adhemerval.zanella@linaro.org> (raw)
This patch changes both the nptl and libc Linux raise implementation
to avoid the issues described in BZ#15368. The strategy used is
summarized in bug report first comment:
1. Block all signals (including internal NPTL ones);
2. Get pid and tid directly from syscall (not relying on cached
values);
3. Call tgkill;
4. Restore old signal mask.
Tested on x86_64 and i686.
* sysdeps/unix/sysv/linux/nptl-signals.h
(__nptl_clear_internal_signals): New function.
(__libc_signal_block_all): Likewise.
(__libc_signal_block_app): Likewise.
(__libc_signal_restore_set): Likewise.
* sysdeps/unix/sysv/linux/pt-raise.c (raise): Use Linux raise.c
implementation.
* sysdeps/unix/sysv/linux/raise.c (raise): Reimplement to not use
the cached pid/tid value in pthread structure.
---
ChangeLog | 12 +++++++++
sysdeps/unix/sysv/linux/nptl-signals.h | 37 ++++++++++++++++++++++++++++
sysdeps/unix/sysv/linux/pt-raise.c | 23 +++--------------
sysdeps/unix/sysv/linux/raise.c | 45 ++++++++++++----------------------
4 files changed, 67 insertions(+), 50 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/nptl-signals.h b/sysdeps/unix/sysv/linux/nptl-signals.h
index 01f34c2..88a0a32 100644
--- a/sysdeps/unix/sysv/linux/nptl-signals.h
+++ b/sysdeps/unix/sysv/linux/nptl-signals.h
@@ -39,5 +39,42 @@ __nptl_is_internal_signal (int sig)
return (sig == SIGCANCEL) || (sig == SIGTIMER) || (sig == SIGSETXID);
}
+static inline void
+__nptl_clear_internal_signals (sigset_t *set)
+{
+ __sigdelset (set, SIGCANCEL);
+ __sigdelset (set, SIGTIMER);
+ __sigdelset (set, SIGSETXID);
+}
+
+#define SIGALL_SET \
+ ((__sigset_t) { .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 } })
+
+static inline int
+__libc_signal_block_all (const sigset_t *set)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
+ set, _NSIG / 8);
+}
+
+static inline int
+__libc_signal_block_app (const sigset_t *set)
+{
+ sigset_t allset = SIGALL_SET;
+ __nptl_clear_internal_signals (&allset);
+ INTERNAL_SYSCALL_DECL (err);
+ return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset, set,
+ _NSIG / 8);
+}
+
+static inline int
+__libc_signal_restore_set (const sigset_t *set)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, set, NULL,
+ _NSIG / 8);
+}
+
/* Used to communicate with signal handler. */
extern struct xid_command *__xidcmd attribute_hidden;
diff --git a/sysdeps/unix/sysv/linux/pt-raise.c b/sysdeps/unix/sysv/linux/pt-raise.c
index 715bbe9..5f6dea1 100644
--- a/sysdeps/unix/sysv/linux/pt-raise.c
+++ b/sysdeps/unix/sysv/linux/pt-raise.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2002-2016 Free Software Foundation, Inc.
+/* ISO C raise function for libpthread.
+ Copyright (C) 2002-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
@@ -16,22 +17,4 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <errno.h>
-#include <signal.h>
-#include <sysdep.h>
-#include <tls.h>
-
-
-int
-raise (int sig)
-{
- /* raise is an async-safe function. It could be called while the
- fork function temporarily invalidated the PID field. Adjust for
- that. */
- pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
- if (__glibc_unlikely (pid < 0))
- pid = -pid;
-
- return INLINE_SYSCALL (tgkill, 3, pid, THREAD_GETMEM (THREAD_SELF, tid),
- sig);
-}
+#include <sysdeps/unix/sysv/linux/raise.c>
diff --git a/sysdeps/unix/sysv/linux/raise.c b/sysdeps/unix/sysv/linux/raise.c
index 3795e6e..c6ecd66 100644
--- a/sysdeps/unix/sysv/linux/raise.c
+++ b/sysdeps/unix/sysv/linux/raise.c
@@ -16,42 +16,27 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <errno.h>
-#include <limits.h>
#include <signal.h>
#include <sysdep.h>
-#include <nptl/pthreadP.h>
-
+#include <errno.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <nptl-signals.h>
int
raise (int sig)
{
- struct pthread *pd = THREAD_SELF;
- pid_t pid = THREAD_GETMEM (pd, pid);
- pid_t selftid = THREAD_GETMEM (pd, tid);
- if (selftid == 0)
- {
- /* This system call is not supposed to fail. */
-#ifdef INTERNAL_SYSCALL
- INTERNAL_SYSCALL_DECL (err);
- selftid = INTERNAL_SYSCALL (gettid, err, 0);
-#else
- selftid = INLINE_SYSCALL (gettid, 0);
-#endif
- THREAD_SETMEM (pd, tid, selftid);
-
- /* We do not set the PID field in the TID here since we might be
- called from a signal handler while the thread executes fork. */
- pid = selftid;
- }
- else
- /* raise is an async-safe function. It could be called while the
- fork/vfork function temporarily invalidated the PID field. Adjust for
- that. */
- if (__glibc_unlikely (pid <= 0))
- pid = (pid & INT_MAX) == 0 ? selftid : -pid;
-
- return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
+ sigset_t set;
+ __libc_signal_block_app (&set);
+
+ pid_t pid = __getpid ();
+ pid_t tid = INLINE_SYSCALL (gettid, 0);
+
+ int ret = INLINE_SYSCALL (tgkill, 3, pid, tid, sig);
+
+ __libc_signal_restore_set (&set);
+
+ return ret;
}
libc_hidden_def (raise)
weak_alias (raise, gsignal)
--
2.7.4
next reply other threads:[~2016-06-17 18:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-17 18:43 Adhemerval Zanella [this message]
2016-06-18 14:09 ` Zack Weinberg
2016-06-18 17:26 ` Adhemerval Zanella
2016-06-29 12:57 ` Adhemerval Zanella
2016-07-07 15:16 ` Adhemerval Zanella
2016-07-07 15:30 ` Andreas Schwab
2016-07-07 16:13 ` Adhemerval Zanella
2016-07-11 7:08 ` Andreas Schwab
2016-07-11 8:06 ` Adhemerval Zanella
2016-09-03 23:50 ` Aurelien Jarno
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