selftests/x86/ptrace_syscall: Fix for yet more glibc interference

glibc keeps getting cleverer, and my version now turns raise() into
more than one syscall.  Since the test relies on ptrace seeing an
exact set of syscalls, this breaks the test.  Replace raise(SIGSTOP)
with syscall(SYS_tgkill, ...) to force glibc to get out of our way.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kselftest@vger.kernel.org
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/bc80338b453afa187bc5f895bd8e2c8d6e264da2.1521300271.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c
index 1ae1c5a7392ead3c8b8a108f70bdddbf0d4f100e..6f22238f32173db4ef4d710666807cb5397f7dc0 100644 (file)
--- a/tools/testing/selftests/x86/ptrace_syscall.c
+++ b/tools/testing/selftests/x86/ptrace_syscall.c
@@ -183,8 +183,10 @@ static void test_ptrace_syscall_restart(void)
                if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
                        err(1, "PTRACE_TRACEME");
 
+               pid_t pid = getpid(), tid = syscall(SYS_gettid);
+
                printf("\tChild will make one syscall\n");
-               raise(SIGSTOP);
+               syscall(SYS_tgkill, pid, tid, SIGSTOP);
 
                syscall(SYS_gettid, 10, 11, 12, 13, 14, 15);
                _exit(0);
@@ -301,9 +303,11 @@ static void test_restart_under_ptrace(void)
                if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
                        err(1, "PTRACE_TRACEME");
 
+               pid_t pid = getpid(), tid = syscall(SYS_gettid);
+
                printf("\tChild will take a nap until signaled\n");
                setsigign(SIGUSR1, SA_RESTART);
-               raise(SIGSTOP);
+               syscall(SYS_tgkill, pid, tid, SIGSTOP);
 
                syscall(SYS_pause, 0, 0, 0, 0, 0, 0);
                _exit(0);