kselftest/arm64: Only enumerate VLs once in syscall-abi

Currently syscall-abi not only enumerates the SVE VLs twice while working
out how many tests are planned, it also repeats the enumeration process
while doing the actual tests. Record the VLs when we enumerate and use that
list when we are performing the tests, removing some duplicated logic.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221223-arm64-syscall-abi-sme-only-v1-2-4fabfbd62087@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

tools/testing/selftests/arm64/abi/syscall-abi.c

@@ -24,6 +24,11 @@
 
 static int default_sme_vl;
 
+static int sve_vl_count;
+static unsigned int sve_vls[SVE_VQ_MAX];
+static int sme_vl_count;
+static unsigned int sme_vls[SVE_VQ_MAX];
+
 extern void do_syscall(int sve_vl, int sme_vl);
 
 static void fill_random(void *buf, size_t size)
@@ -355,72 +360,55 @@ static bool do_test(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
 
 static void test_one_syscall(struct syscall_cfg *cfg)
 {
-	int sve_vq, sve_vl;
-	int sme_vq, sme_vl;
+	int sve, sme;
+	int ret;
 
 	/* FPSIMD only case */
 	ksft_test_result(do_test(cfg, 0, default_sme_vl, 0),
 			 "%s FPSIMD\n", cfg->name);
 
-	if (!(getauxval(AT_HWCAP) & HWCAP_SVE))
-		return;
-
-	for (sve_vq = SVE_VQ_MAX; sve_vq > 0; --sve_vq) {
-		sve_vl = prctl(PR_SVE_SET_VL, sve_vq * 16);
-		if (sve_vl == -1)
+	for (sve = 0; sve < sve_vl_count; sve++) {
+		ret = prctl(PR_SVE_SET_VL, sve_vls[sve]);
+		if (ret == -1)
 			ksft_exit_fail_msg("PR_SVE_SET_VL failed: %s (%d)\n",
 					   strerror(errno), errno);
 
-		sve_vl &= PR_SVE_VL_LEN_MASK;
-
-		if (sve_vq != sve_vq_from_vl(sve_vl))
-			sve_vq = sve_vq_from_vl(sve_vl);
+		ksft_test_result(do_test(cfg, sve_vls[sve], default_sme_vl, 0),
+				 "%s SVE VL %d\n", cfg->name, sve_vls[sve]);
 
-		ksft_test_result(do_test(cfg, sve_vl, default_sme_vl, 0),
-				 "%s SVE VL %d\n", cfg->name, sve_vl);
-
-		if (!(getauxval(AT_HWCAP2) & HWCAP2_SME))
-			continue;
-
-		for (sme_vq = SVE_VQ_MAX; sme_vq > 0; --sme_vq) {
-			sme_vl = prctl(PR_SME_SET_VL, sme_vq * 16);
-			if (sme_vl == -1)
+		for (sme = 0; sme < sme_vl_count; sme++) {
+			ret = prctl(PR_SME_SET_VL, sme_vls[sme]);
+			if (ret == -1)
 				ksft_exit_fail_msg("PR_SME_SET_VL failed: %s (%d)\n",
 						   strerror(errno), errno);
 
-			sme_vl &= PR_SME_VL_LEN_MASK;
-
-			/* Found lowest VL */
-			if (sve_vq_from_vl(sme_vl) > sme_vq)
-				break;
-
-			if (sme_vq != sve_vq_from_vl(sme_vl))
-				sme_vq = sve_vq_from_vl(sme_vl);
-
-			ksft_test_result(do_test(cfg, sve_vl, sme_vl,
+			ksft_test_result(do_test(cfg, sve_vls[sve],
+						 sme_vls[sme],
 						 SVCR_ZA_MASK | SVCR_SM_MASK),
 					 "%s SVE VL %d/SME VL %d SM+ZA\n",
-					 cfg->name, sve_vl, sme_vl);
-			ksft_test_result(do_test(cfg, sve_vl, sme_vl,
-						 SVCR_SM_MASK),
+					 cfg->name, sve_vls[sve],
+					 sme_vls[sme]);
+			ksft_test_result(do_test(cfg, sve_vls[sve],
+						 sme_vls[sme], SVCR_SM_MASK),
 					 "%s SVE VL %d/SME VL %d SM\n",
-					 cfg->name, sve_vl, sme_vl);
-			ksft_test_result(do_test(cfg, sve_vl, sme_vl,
-						 SVCR_ZA_MASK),
+					 cfg->name, sve_vls[sve],
+					 sme_vls[sme]);
+			ksft_test_result(do_test(cfg, sve_vls[sve],
+						 sme_vls[sme], SVCR_ZA_MASK),
 					 "%s SVE VL %d/SME VL %d ZA\n",
-					 cfg->name, sve_vl, sme_vl);
+					 cfg->name, sve_vls[sve],
+					 sme_vls[sme]);
 		}
 	}
 }
 
-int sve_count_vls(void)
+void sve_count_vls(void)
 {
 	unsigned int vq;
-	int vl_count = 0;
 	int vl;
 
 	if (!(getauxval(AT_HWCAP) & HWCAP_SVE))
-		return 0;
+		return;
 
 	/*
 	 * Enumerate up to SVE_VQ_MAX vector lengths
@@ -436,23 +424,17 @@ int sve_count_vls(void)
 		if (vq != sve_vq_from_vl(vl))
 			vq = sve_vq_from_vl(vl);
 
-		vl_count++;
+		sve_vls[sve_vl_count++] = vl;
 	}
-
-	return vl_count;
 }
 
-int sme_count_vls(void)
+void sme_count_vls(void)
 {
 	unsigned int vq;
-	int vl_count = 0;
 	int vl;
 
 	if (!(getauxval(AT_HWCAP2) & HWCAP2_SME))
-		return 0;
-
-	/* Ensure we configure a SME VL, used to flag if SVCR is set */
-	default_sme_vl = 16;
+		return;
 
 	/*
 	 * Enumerate up to SVE_VQ_MAX vector lengths
@@ -472,10 +454,11 @@ int sme_count_vls(void)
 		if (vq != sve_vq_from_vl(vl))
 			vq = sve_vq_from_vl(vl);
 
-		vl_count++;
+		sme_vls[sme_vl_count++] = vl;
 	}
 
-	return vl_count;
+	/* Ensure we configure a SME VL, used to flag if SVCR is set */
+	default_sme_vl = sme_vls[0];
 }
 
 int main(void)
@@ -486,8 +469,12 @@ int main(void)
 	srandom(getpid());
 
 	ksft_print_header();
-	tests += sve_count_vls();
-	tests += (sve_count_vls() * sme_count_vls()) * 3;
+
+	sve_count_vls();
+	sme_count_vls();
+
+	tests += sve_vl_count;
+	tests += (sve_vl_count * sme_vl_count) * 3;
 	ksft_set_plan(ARRAY_SIZE(syscalls) * tests);
 
 	if (getauxval(AT_HWCAP2) & HWCAP2_SME_FA64)