The patch titled
um: fix abort
has been added to the -mm tree. Its filename is
um-fix-abort.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: um: fix abort
From: Richard Weinberger <richard@xxxxxx>
os_dump_core() uses abort() to terminate UML in case of an fatal error.
glibc's abort() calls raise(SIGABRT) which makes use of tgkill().
tgkill() has no effect within UML's kernel threads because they are not
pthreads. As fallback abort() executes an invalid instruction to
terminate the process. Therefore UML gets killed by SIGSEGV and leaves a
ugly log entry in the host's kernel ring buffer.
To get rid of this we use our own abort routine.
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/um/os-Linux/util.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff -puN arch/um/os-Linux/util.c~um-fix-abort arch/um/os-Linux/util.c
--- a/arch/um/os-Linux/util.c~um-fix-abort
+++ a/arch/um/os-Linux/util.c
@@ -5,6 +5,7 @@
#include <stdio.h>
#include <stdlib.h>
+#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
@@ -75,6 +76,26 @@ void setup_hostinfo(char *buf, int len)
host.release, host.version, host.machine);
}
+/*
+ * We cannot use glibc's abort(). It makes use of tgkill() which
+ * has no effect within UML's kernel threads.
+ * After that glibc would execute an invalid instruction to kill
+ * the calling process and UML crashes with SIGSEGV.
+ */
+static inline void __attribute__ ((noreturn)) uml_abort(void)
+{
+ sigset_t sig;
+
+ fflush(NULL);
+
+ if (!sigemptyset(&sig) && !sigaddset(&sig, SIGABRT))
+ sigprocmask(SIG_UNBLOCK, &sig, 0);
+
+ for (;;)
+ if (kill(getpid(), SIGABRT) < 0)
+ exit(127);
+}
+
void os_dump_core(void)
{
int pid;
@@ -116,5 +137,5 @@ void os_dump_core(void)
while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0)
os_kill_ptraced_process(pid, 0);
- abort();
+ uml_abort();
}
_
Patches currently in -mm which might be from richard@xxxxxx are
x86-remove-warning-and-warning_symbol-from-struct-stacktrace_ops.patch
mm-mmu_gather-rework.patch
powerpc-mmu_gather-rework.patch
sparc-mmu_gather-rework.patch
s390-mmu_gather-rework.patch
arm-mmu_gather-rework.patch
sh-mmu_gather-rework.patch
ia64-mmu_gather-rework.patch
um-mmu_gather-rework.patch
mm-now-that-all-old-mmu_gather-code-is-gone-remove-the-storage.patch
mm-powerpc-move-the-rcu-page-table-freeing-into-generic-code.patch
mm-extended-batches-for-generic-mmu_gather.patch
lockdep-mutex-provide-mutex_lock_nest_lock.patch
mm-remove-i_mmap_lock-lockbreak.patch
mm-convert-i_mmap_lock-to-a-mutex.patch
mm-revert-page_lock_anon_vma-lock-annotation.patch
mm-improve-page_lock_anon_vma-comment.patch
mm-use-refcounts-for-page_lock_anon_vma.patch
mm-convert-anon_vma-lock-to-a-mutex.patch
mm-optimize-page_lock_anon_vma-fast-path.patch
sh-remove-warning-and-warning_symbol-from-struct-stacktrace_ops.patch
um-fix-uml_lib_path.patch
um-fix-abort.patch
um-remove-sighup-handler.patch
um-os_dump_core-cleanup.patch
lib-consolidate-debug_stack_usage-option.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
