selftests/powerpc: Add test for real address error handling

Add test for real address or control memory address access
error handling, using NX-GZIP engine.

The error is injected by accessing the control memory address
using illegal instruction, on successful handling the process
attempting to access control memory address using illegal
instruction receives SIGBUS.

Signed-off-by: Ganesh Goudar <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/powerpc/Makefile

···
 	   vphn         \
 	   math		\
 	   ptrace	\
-	   security
+	   security	\
+	   mce
 
 endif
 

tools/testing/selftests/powerpc/mce/Makefile

···
+#SPDX-License-Identifier: GPL-2.0-or-later
+
+TEST_GEN_PROGS := inject-ra-err
+
+include ../../lib.mk
+
+$(TEST_GEN_PROGS): ../harness.c

tools/testing/selftests/powerpc/mce/inject-ra-err.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "vas-api.h"
+#include "utils.h"
+
+static bool faulted;
+
+static void sigbus_handler(int n, siginfo_t *info, void *ctxt_v)
+{
+	ucontext_t *ctxt = (ucontext_t *)ctxt_v;
+	struct pt_regs *regs = ctxt->uc_mcontext.regs;
+
+	faulted = true;
+	regs->nip += 4;
+}
+
+static int test_ra_error(void)
+{
+	struct vas_tx_win_open_attr attr;
+	int fd, *paste_addr;
+	char *devname = "/dev/crypto/nx-gzip";
+	struct sigaction act = {
+		.sa_sigaction = sigbus_handler,
+		.sa_flags = SA_SIGINFO,
+	};
+
+	memset(&attr, 0, sizeof(attr));
+	attr.version = 1;
+	attr.vas_id = 0;
+
+	SKIP_IF(access(devname, F_OK));
+
+	fd = open(devname, O_RDWR);
+	FAIL_IF(fd < 0);
+	FAIL_IF(ioctl(fd, VAS_TX_WIN_OPEN, &attr) < 0);
+	FAIL_IF(sigaction(SIGBUS, &act, NULL) != 0);
+
+	paste_addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0ULL);
+
+	/* The following assignment triggers exception */
+	mb();
+	*paste_addr = 1;
+	mb();
+
+	FAIL_IF(!faulted);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test_ra_error, "inject-ra-err");
+}
+