selftests/powerpc: Add checks for transactional VMXs in signal contexts

If a thread receives a signal while transactional the kernel creates a
second context to show the transactional state of the process. This
test loads some known values and waits for a signal and confirms that
the expected values are in the signal context.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/tm/Makefile

-SIGNAL_CONTEXT_CHK_TESTS := tm-signal-context-chk-gpr tm-signal-context-chk-fpu
+SIGNAL_CONTEXT_CHK_TESTS := tm-signal-context-chk-gpr tm-signal-context-chk-fpu \
+	tm-signal-context-chk-vmx
 
 TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-signal-stack \
 	tm-vmxcopy tm-fork tm-tar tm-tmspr $(SIGNAL_CONTEXT_CHK_TESTS)

tools/testing/selftests/powerpc/tm/tm-signal-context-chk-vmx.c

+/*
+ * Copyright 2016, Cyril Bur, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ *
+ * Test the kernel's signal frame code.
+ *
+ * The kernel sets up two sets of ucontexts if the signal was to be
+ * delivered while the thread was in a transaction.
+ * Expected behaviour is that the checkpointed state is in the user
+ * context passed to the signal handler. The speculated state can be
+ * accessed with the uc_link pointer.
+ *
+ * The rationale for this is that if TM unaware code (which linked
+ * against TM libs) installs a signal handler it will not know of the
+ * speculative nature of the 'live' registers and may infer the wrong
+ * thing.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <altivec.h>
+
+#include "utils.h"
+#include "tm.h"
+
+#define MAX_ATTEMPT 500000
+
+#define NV_VMX_REGS 12
+
+long tm_signal_self_context_load(pid_t pid, long *gprs, double *fps, vector int *vms, vector int *vss);
+
+static sig_atomic_t fail;
+
+vector int vms[] = {
+	{1, 2, 3, 4 },{5, 6, 7, 8 },{9, 10,11,12},
+	{13,14,15,16},{17,18,19,20},{21,22,23,24},
+	{25,26,27,28},{29,30,31,32},{33,34,35,36},
+	{37,38,39,40},{41,42,43,44},{45,46,47,48},
+	{-1, -2, -3, -4}, {-5, -6, -7, -8}, {-9, -10,-11,-12},
+	{-13,-14,-15,-16},{-17,-18,-19,-20},{-21,-22,-23,-24},
+	{-25,-26,-27,-28},{-29,-30,-31,-32},{-33,-34,-35,-36},
+	{-37,-38,-39,-40},{-41,-42,-43,-44},{-45,-46,-47,-48}
+};
+
+static void signal_usr1(int signum, siginfo_t *info, void *uc)
+{
+	int i;
+	ucontext_t *ucp = uc;
+	ucontext_t *tm_ucp = ucp->uc_link;
+
+	for (i = 0; i < NV_VMX_REGS && !fail; i++) {
+		fail = memcmp(ucp->uc_mcontext.v_regs->vrregs[i + 20],
+				&vms[i], sizeof(vector int));
+		fail |= memcmp(tm_ucp->uc_mcontext.v_regs->vrregs[i + 20],
+				&vms[i + NV_VMX_REGS], sizeof (vector int));
+
+		if (fail) {
+			int j;
+
+			fprintf(stderr, "Failed on %d vmx 0x", i);
+			for (j = 0; j < 4; j++)
+				fprintf(stderr, "%04x", ucp->uc_mcontext.v_regs->vrregs[i + 20][j]);
+			fprintf(stderr, " vs 0x");
+			for (j = 0 ; j < 4; j++)
+				fprintf(stderr, "%04x", tm_ucp->uc_mcontext.v_regs->vrregs[i + 20][j]);
+			fprintf(stderr, "\n");
+		}
+	}
+}
+
+static int tm_signal_context_chk()
+{
+	struct sigaction act;
+	int i;
+	long rc;
+	pid_t pid = getpid();
+
+	SKIP_IF(!have_htm());
+
+	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);
+	}
+
+	i = 0;
+	while (i < MAX_ATTEMPT && !fail) {
+		rc = tm_signal_self_context_load(pid, NULL, NULL, vms, NULL);
+		FAIL_IF(rc != pid);
+		i++;
+	}
+
+	return fail;
+}
+
+int main(void)
+{
+	return test_harness(tm_signal_context_chk, "tm_signal_context_chk_vmx");
+}