This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
[COMMITTED PATCH] Add __safe_fatal and use it in __pthread_unwind forwarder fallback.
- From: Roland McGrath <roland at hack dot frob dot com>
- To: "GNU C. Library" <libc-alpha at sourceware dot org>
- Date: Thu, 31 Jul 2014 14:07:31 -0700 (PDT)
- Subject: [COMMITTED PATCH] Add __safe_fatal and use it in __pthread_unwind forwarder fallback.
- Authentication-results: sourceware.org; auth=none
This both removes a Linuxism from nptl/forward.c and makes the code
actually work. The old code was a bogus attempt at a one-argument kill
system call, which means it actually attempted to send a random register
value as signal number, to PID 9. The new code (for Linux) takes care to
make a getpid system call and then a proper kill system call.
Build-tested and eyeballed code on x86_64-linux-gnu and arm-linux-gnueabihf.
* sysdeps/generic/safe-fatal.h: New file.
* sysdeps/unix/sysv/linux/safe-fatal.h: New file.
* nptl/forward.c: Include it.
(__pthread_unwind): Use __safe_fatal as default action, rather
than a bogus use of INTERNAL_SYSCALL that could never work.
--- a/nptl/forward.c
+++ b/nptl/forward.c
@@ -23,7 +23,7 @@
#include <shlib-compat.h>
#include <atomic.h>
-#include <sysdep.h>
+#include <safe-fatal.h>
/* Pointers to the libc functions. */
@@ -202,11 +202,8 @@ FORWARD (pthread_setcancelstate, (int state, int *oldstate), (state, oldstate),
FORWARD (pthread_setcanceltype, (int type, int *oldtype), (type, oldtype), 0)
-FORWARD_NORETURN(__pthread_unwind,
- void attribute_hidden __attribute ((noreturn)) __cleanup_fct_attribute
- attribute_compat_text_section,
- (__pthread_unwind_buf_t *buf), (buf), {
- /* We cannot call abort() here. */
- INTERNAL_SYSCALL_DECL (err);
- INTERNAL_SYSCALL (kill, err, 1, SIGKILL);
- })
+FORWARD_NORETURN (__pthread_unwind,
+ void attribute_hidden __attribute ((noreturn))
+ __cleanup_fct_attribute attribute_compat_text_section,
+ (__pthread_unwind_buf_t *buf), (buf),
+ __safe_fatal ())
--- /dev/null
+++ b/sysdeps/generic/safe-fatal.h
@@ -0,0 +1,37 @@
+/* Crash the process immediately, without possibility of deadlock. Generic.
+ Copyright (C) 2014 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _SAFE_FATAL_H
+#define _SAFE_FATAL_H 1
+
+#include <abort-instr.h>
+
+static inline void
+__safe_fatal (void)
+{
+#ifdef ABORT_INSTRUCTION
+ /* This is not guaranteed to be free from the possibility of deadlock,
+ since it might generate a signal that can be caught. But it's better
+ than nothing. */
+ ABORT_INSTRUCTION;
+#else
+# error Need an OS-specific or machine-specific safe-fatal.h
+#endif
+}
+
+#endif /* safe-fatal.h */
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/safe-fatal.h
@@ -0,0 +1,33 @@
+/* Crash the process immediately, without possibility of deadlock. Linux.
+ Copyright (C) 2014 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _SAFE_FATAL_H
+#define _SAFE_FATAL_H 1
+
+#include <sysdep.h>
+#include <unistd.h>
+
+static inline void
+__safe_fatal (void)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ pid_t self = INTERNAL_SYSCALL (getpid, err, 0);
+ INTERNAL_SYSCALL (kill, err, 2, self, SIGKILL);
+}
+
+#endif /* safe-fatal.h */