kselftest/arm64: Check that SVCR is 0 in signal handlers

We don't currently validate that we exit streaming mode and clear ZA when
we enter a signal handler. Add simple checks for this in the SSVE and ZA
tests.

Signed-off-by: Mark Brown <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[[e-mail]: Use %lx in fprintf() as uint64_t seems to be unsigned long in glibc]
Signed-off-by: Catalin Marinas <[e-mail]>

tools/testing/selftests/arm64/signal/sve_helpers.h

···
 
 int sve_fill_vls(bool use_sme, int min_vls);
 
+static inline uint64_t get_svcr(void)
+{
+	uint64_t val;
+
+	asm volatile (
+		"mrs	%0, S3_3_C4_C2_2\n"
+		: "=r"(val)
+		:
+		: "cc");
+
+	return val;
+}
+
 #endif

tools/testing/selftests/arm64/signal/testcases/ssve_regs.c

···
 	fprintf(stderr, "Got expected size %u and VL %d\n",
 		head->size, ssve->vl);
 
+	if (get_svcr() != 0) {
+		fprintf(stderr, "Unexpected SVCR %lx\n", get_svcr());
+		return 1;
+	}
+
 	return 0;
 }
 

tools/testing/selftests/arm64/signal/testcases/za_regs.c

···
 		return 1;
 	}
 
+	if (get_svcr() != 0) {
+		fprintf(stderr, "Unexpected SVCR %lx\n", get_svcr());
+		return 1;
+	}
+
 	return 0;
 }