kselftest/arm64: Add framework support for GCS to signal handling tests

Teach the framework about the GCS signal context, avoiding warnings on
the unknown context.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20241001-arm64-gcs-v13-31-222b78d87eee@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: broonie

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

@@ -198,6 +198,13 @@ bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err)
 				*err = "Bad size for fpmr_context";
 			new_flags |= FPMR_CTX;
 			break;
+		case GCS_MAGIC:
+			if (flags & GCS_CTX)
+				*err = "Multiple GCS_MAGIC";
+			if (head->size != sizeof(struct gcs_context))
+				*err = "Bad size for gcs_context";
+			new_flags |= GCS_CTX;
+			break;
 		case EXTRA_MAGIC:
 			if (flags & EXTRA_CTX)
 				*err = "Multiple EXTRA_MAGIC";

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

@@ -20,6 +20,7 @@
 #define EXTRA_CTX	(1 << 3)
 #define ZT_CTX		(1 << 4)
 #define FPMR_CTX	(1 << 5)
+#define GCS_CTX		(1 << 6)
 
 #define KSFT_BAD_MAGIC	0xdeadbeef