From b2db21997f43907f54500edaf063253ca2a186f9 Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Tue, 17 May 2011 15:44:11 -0700 Subject: [PATCH] um: fix abort 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/os-Linux/util.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c index 6ea77979531..42827cafa6a 100644 --- a/arch/um/os-Linux/util.c +++ b/arch/um/os-Linux/util.c @@ -5,6 +5,7 @@ #include #include +#include #include #include #include @@ -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(); } -- 2.11.4.GIT