kselftest/arm64: SVE signal handling tests

index f96baf1cef1a..ebe8694dbef0 100644
@@ -33,10 +33,12 @@
  */
 enum {
 	FSSBS_BIT,
+	FSVE_BIT,
 	FMAX_END
 };
 
 #define FEAT_SSBS		(1UL << FSSBS_BIT)
+#define FEAT_SVE		(1UL << FSVE_BIT)
 
 /*
  * A descriptor used to describe and configure a test case.

index 2de6e5ed5e25..6836510a522f 100644
@@ -26,6 +26,7 @@ static int sig_copyctx = SIGTRAP;
 
 static char const *const feats_names[FMAX_END] = {
 	" SSBS ",
+	" SVE ",
 };
 
 #define MAX_FEATS_SZ	128

@@ -263,6 +264,8 @@ int test_init(struct tdescr *td)
 		 */
 		if (getauxval(AT_HWCAP) & HWCAP_SSBS)
 			td->feats_supported |= FEAT_SSBS;
+		if (getauxval(AT_HWCAP) & HWCAP_SVE)
+			td->feats_supported |= FEAT_SVE;
 		if (feats_ok(td))
 			fprintf(stderr,
 				"Required Features: [%s] supported\n",

index 61ebcdf63831..8c2a57fc2f9c 100644
@@ -50,12 +50,38 @@ bool validate_extra_context(struct extra_context *extra, char **err)
 	return true;
 }
 
+bool validate_sve_context(struct sve_context *sve, char **err)
+{
+	/* Size will be rounded up to a multiple of 16 bytes */
+	size_t regs_size
+		= ((SVE_SIG_CONTEXT_SIZE(sve_vq_from_vl(sve->vl)) + 15) / 16) * 16;
+
+	if (!sve || !err)
+		return false;
+
+	/* Either a bare sve_context or a sve_context followed by regs data */
+	if ((sve->head.size != sizeof(struct sve_context)) &&
+	    (sve->head.size != regs_size)) {
+		*err = "bad size for SVE context";
+		return false;
+	}
+
+	if (!sve_vl_valid(sve->vl)) {
+		*err = "SVE VL invalid";
+
+		return false;
+	}
+
+	return true;
+}
+
 bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err)
 {
 	bool terminated = false;
 	size_t offs = 0;
 	int flags = 0;
 	struct extra_context *extra = NULL;
+	struct sve_context *sve = NULL;
 	struct _aarch64_ctx *head =
 		(struct _aarch64_ctx *)uc->uc_mcontext.__reserved;
 

@@ -90,9 +116,8 @@ bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err)
 		case SVE_MAGIC:
 			if (flags & SVE_CTX)
 				*err = "Multiple SVE_MAGIC";
-			else if (head->size !=
-				 sizeof(struct sve_context))
-				*err = "Bad size for sve_context";
+			/* Size is validated in validate_sve_context() */
+			sve = (struct sve_context *)head;
 			flags |= SVE_CTX;
 			break;
 		case EXTRA_MAGIC:

@@ -137,6 +162,9 @@ bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err)
 		if (flags & EXTRA_CTX)
 			if (!validate_extra_context(extra, err))
 				return false;
+		if (flags & SVE_CTX)
+			if (!validate_sve_context(sve, err))
+				return false;
 
 		head = GET_RESV_NEXT_HEAD(head);
 	}

68 lines not on this page · raw message

new file mode 100644
index 000000000000..bb50b5adbf10
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 ARM Limited
+ *
+ * Attempt to change the SVE vector length in a signal hander, this is not
+ * supported and is expected to segfault.
+ */
+
+#include <signal.h>
+#include <ucontext.h>
+#include <sys/prctl.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+struct fake_sigframe sf;
+static unsigned int vls[SVE_VQ_MAX];
+unsigned int nvls = 0;
+
+static bool sve_get_vls(struct tdescr *td)
+{
+	int vq, vl;
+
+	/*
+	 * Enumerate up to SVE_VQ_MAX vector lengths
+	 */
+	for (vq = SVE_VQ_MAX; vq > 0; --vq) {
+		vl = prctl(PR_SVE_SET_VL, vq * 16);
+		if (vl == -1)
+			return false;
+
+		vl &= PR_SVE_VL_LEN_MASK;
+
+		/* Skip missing VLs */
+		vq = sve_vq_from_vl(vl);
+
+		vls[nvls++] = vl;
+	}
+
+	/* We need at least two VLs */
+	if (nvls < 2) {
+		fprintf(stderr, "Only %d VL supported\n", nvls);
+		return false;
+	}
+
+	return true;
+}
+
+static int fake_sigreturn_sve_change_vl(struct tdescr *td,
+					siginfo_t *si, ucontext_t *uc)
+{
+	size_t resv_sz, offset;
+	struct _aarch64_ctx *head = GET_SF_RESV_HEAD(sf);
+	struct sve_context *sve;
+
+	/* Get a signal context with a SVE frame in it */
+	if (!get_current_context(td, &sf.uc))
+		return 1;
+
+	resv_sz = GET_SF_RESV_SIZE(sf);
+	head = get_header(head, SVE_MAGIC, resv_sz, &offset);
+	if (!head) {
+		fprintf(stderr, "No SVE context\n");
+		return 1;
+	}
+
+	if (head->size != sizeof(struct sve_context)) {
+		fprintf(stderr, "SVE register state active, skipping\n");
+		return 1;
+	}
+
+	sve = (struct sve_context *)head;
+
+	/* No changes are supported; init left us at minimum VL so go to max */
+	fprintf(stderr, "Attempting to change VL from %d to %d\n",
+		sve->vl, vls[0]);
+	sve->vl = vls[0];
+
+	fake_sigreturn(&sf, sizeof(sf), 0);
+
+	return 1;
+}
+
+struct tdescr tde = {
+	.name = "FAKE_SIGRETURN_SVE_CHANGE",
+	.descr = "Attempt to change SVE VL",
+	.feats_required = FEAT_SVE,
+	.sig_ok = SIGSEGV,
+	.timeout = 3,
+	.init = sve_get_vls,
+	.run = fake_sigreturn_sve_change_vl,
+};

new file mode 100644
index 000000000000..4b2418aa08a9
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 ARM Limited
+ *
+ * Verify that the SVE register context in signal frames is set up as
+ * expected.
+ */
+
+#include <signal.h>
+#include <ucontext.h>
+#include <sys/prctl.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+struct fake_sigframe sf;
+static unsigned int vls[SVE_VQ_MAX];
+unsigned int nvls = 0;
+
+static bool sve_get_vls(struct tdescr *td)
+{
+	int vq, vl;
+
+	/*
+	 * Enumerate up to SVE_VQ_MAX vector lengths
+	 */
+	for (vq = SVE_VQ_MAX; vq > 0; --vq) {
+		vl = prctl(PR_SVE_SET_VL, vq * 16);
+		if (vl == -1)
+			return false;
+
+		vl &= PR_SVE_VL_LEN_MASK;
+
+		/* Skip missing VLs */
+		vq = sve_vq_from_vl(vl);
+
+		vls[nvls++] = vl;
+	}
+
+	/* We need at least one VL */
+	if (nvls < 1) {
+		fprintf(stderr, "Only %d VL supported\n", nvls);
+		return false;
+	}
+
+	return true;
+}
+
+static void setup_sve_regs(void)
+{
+	/* RDVL x16, #1 so we should have SVE regs; real data is TODO */
+	asm volatile(".inst 0x04bf5030" : : : "x16" );
+}
+
+static int do_one_sve_vl(struct tdescr *td, siginfo_t *si, ucontext_t *uc,
+			 unsigned int vl)
+{
+	size_t resv_sz, offset;
+	struct _aarch64_ctx *head = GET_SF_RESV_HEAD(sf);
+	struct sve_context *sve;
+
+	fprintf(stderr, "Testing VL %d\n", vl);
+
+	if (prctl(PR_SVE_SET_VL, vl) == -1) {
+		fprintf(stderr, "Failed to set VL\n");
+		return 1;
+	}
+
+	/*
+	 * Get a signal context which should have a SVE frame and registers
+	 * in it.
+	 */
+	setup_sve_regs();
+	if (!get_current_context(td, &sf.uc))
+		return 1;
+
+	resv_sz = GET_SF_RESV_SIZE(sf);
+	head = get_header(head, SVE_MAGIC, resv_sz, &offset);
+	if (!head) {
+		fprintf(stderr, "No SVE context\n");
+		return 1;
+	}
+
+	sve = (struct sve_context *)head;
+	if (sve->vl != vl) {
+		fprintf(stderr, "Got VL %d, expected %d\n", sve->vl, vl);
+		return 1;
+	}
+
+	/* The actual size validation is done in get_current_context() */
+	fprintf(stderr, "Got expected size %u and VL %d\n",
+		head->size, sve->vl);
+
+	return 0;
+}
+
+static int sve_regs(struct tdescr *td, siginfo_t *si, ucontext_t *uc)
+{
+	int i;
+
+	for (i = 0; i < nvls; i++) {
+		/*
+		 * TODO: the signal test helpers can't currently cope
+		 * with signal frames bigger than struct sigcontext,
+		 * skip VLs that will trigger that.
+		 */
+		if (vls[i] > 64)
+			continue;
+
+		if (do_one_sve_vl(td, si, uc, vls[i]))
+			return 1;
+	}
+
+	td->pass = 1;
+
+	return 0;
+}
+
+struct tdescr tde = {
+	.name = "SVE registers",
+	.descr = "Check that we get the right SVE registers reported",
+	.feats_required = FEAT_SVE,
+	.timeout = 3,
+	.init = sve_get_vls,
+	.run = sve_regs,
+};