tools/testing/selftests/proc/proc-pid-vm.c: hide "segfault at ffffffffff600000" dmesg...

Test tries to access vsyscall page and if it doesn't exist gets SIGSEGV
which can spam into dmesg.  However the segfault happens by design.
Handle it and carry information via exit code to parent.

Link: http://lkml.kernel.org/r/20190524181256.GA2260@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/proc/proc-pid-vm.c b/tools/testing/selftests/proc/proc-pid-vm.c
index 853aa164a401e054914cccf2a9663111e1c83939..18a3bde8bc961eaf36c222cee19f00973c011640 100644 (file)
--- a/tools/testing/selftests/proc/proc-pid-vm.c
+++ b/tools/testing/selftests/proc/proc-pid-vm.c
@@ -215,6 +215,11 @@ static const char str_vsyscall[] =
 "ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]\n";
 
 #ifdef __x86_64__
+static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
+{
+       _exit(1);
+}
+
 /*
  * vsyscall page can't be unmapped, probe it with memory load.
  */
@@ -231,11 +236,19 @@ static void vsyscall(void)
        if (pid == 0) {
                struct rlimit rlim = {0, 0};
                (void)setrlimit(RLIMIT_CORE, &rlim);
+
+               /* Hide "segfault at ffffffffff600000" messages. */
+               struct sigaction act;
+               memset(&act, 0, sizeof(struct sigaction));
+               act.sa_flags = SA_SIGINFO;
+               act.sa_sigaction = sigaction_SIGSEGV;
+               (void)sigaction(SIGSEGV, &act, NULL);
+
                *(volatile int *)0xffffffffff600000UL;
                exit(0);
        }
-       wait(&wstatus);
-       if (WIFEXITED(wstatus)) {
+       waitpid(pid, &wstatus, 0);
+       if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0) {
                g_vsyscall = true;
        }
 }