[PATCH v2 2/3] selftests/powerpc: Add TM signal return test

[Michael Neuling <mikey@neuling.org>]

Test the kernel's signal return code to ensure that it doesn't crash
when both the transactional and suspend MSR bits are set in the signal
context.

Signed-off-by: Michael Neuling <mikey@neuling.org>
---
 tools/testing/selftests/powerpc/tm/.gitignore      |  1 +
 tools/testing/selftests/powerpc/tm/Makefile        |  2 +-
 .../selftests/powerpc/tm/tm-signal-msr-resv.c      | 71 ++++++++++++++++++++++
 3 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/powerpc/tm/tm-signal-msr-resv.c

diff --git a/tools/testing/selftests/powerpc/tm/.gitignore b/tools/testing/selftests/powerpc/tm/.gitignore
index 2699635d..61c318f 100644
--- a/tools/testing/selftests/powerpc/tm/.gitignore
+++ b/tools/testing/selftests/powerpc/tm/.gitignore
@@ -1,2 +1,3 @@
 tm-resched-dscr
 tm-syscall
+tm-signal-msr-resv
diff --git a/tools/testing/selftests/powerpc/tm/Makefile b/tools/testing/selftests/powerpc/tm/Makefile
index 4bea62a..0c28db7 100644
--- a/tools/testing/selftests/powerpc/tm/Makefile
+++ b/tools/testing/selftests/powerpc/tm/Makefile
@@ -1,4 +1,4 @@
-TEST_PROGS := tm-resched-dscr tm-syscall
+TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv
 
 all: $(TEST_PROGS)
 
diff --git a/tools/testing/selftests/powerpc/tm/tm-signal-msr-resv.c b/tools/testing/selftests/powerpc/tm/tm-signal-msr-resv.c
new file mode 100644
index 0000000..bdad348
--- /dev/null
+++ b/tools/testing/selftests/powerpc/tm/tm-signal-msr-resv.c
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2015, Michael Neuling, IBM Corp.
+ * Licensed under GPLv2.
+ *
+ * Test the kernel's signal return code to ensure that it doesn't
+ * crash when both the transactional and suspend MSR bits are set in
+ * the signal context.
+ *
+ * For this test, we send ourselves a SIGUSR1.  In the SIGUSR1 handler
+ * we modify the signal context to set both MSR TM S and T bits (which
+ * is "reserved" by the PowerISA). When we return from the signal
+ * handler (implicit sigreturn), the kernel should detect reserved MSR
+ * value and send us with a SIGSEGV.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+int segv_expected = 0;
+
+void signal_segv(int signum)
+{
+	if (segv_expected && (signum == SIGSEGV))
+		_exit(0);
+	_exit(1);
+}
+
+void signal_usr1(int signum, siginfo_t *info, void *uc)
+{
+	ucontext_t *ucp = uc;
+
+	/* Link tm checkpointed context to normal context */
+	ucp->uc_link = ucp;
+	/* Set all TM bits so that the context is now invalid */
+#ifdef __powerpc64__
+	ucp->uc_mcontext.gp_regs[PT_MSR] |= (7ULL << 32);
+#else
+	ucp->uc_mcontext.regs->gpr[PT_MSR] |= (7ULL);
+#endif
+	/* Should segv on return becuase of invalid context */
+	segv_expected = 1;
+}
+
+int tm_signal_msr_resv()
+{
+	struct sigaction act;
+
+	act.sa_sigaction = signal_usr1;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = SA_SIGINFO;
+	if (sigaction(SIGUSR1, &act, NULL) < 0) {
+		perror("sigaction sigusr1");
+		exit(1);
+	}
+	if (signal(SIGSEGV, signal_segv) == SIG_ERR)
+		exit(1);
+
+	raise(SIGUSR1);
+
+	/* We shouldn't get here as we exit in the segv handler */
+	return 1;
+}
+
+int main(void)
+{
+	return test_harness(tm_signal_msr_resv, "tm_signal_msr_resv");
+}
-- 
2.5.0