Re: [PATCH v11 40/40] kselftest/arm64: Add SME support to syscall ABI test

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On 2/7/22 8:21 AM, Mark Brown wrote:
For every possible combination of SVE and SME vector length verify that for
each possible value of SVCR after a syscall we leave streaming mode and ZA
is preserved. We don't need to take account of any streaming/non streaming
SVE vector length changes in the assembler code since the store instructions
will handle the vector length for us. We log if the system supports FA64 and
only try to set FFR in streaming mode if it does.

Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
  .../selftests/arm64/abi/syscall-abi-asm.S     |  69 +++++-
  .../testing/selftests/arm64/abi/syscall-abi.c | 204 ++++++++++++++++--
  .../testing/selftests/arm64/abi/syscall-abi.h |  15 ++
  3 files changed, 265 insertions(+), 23 deletions(-)
  create mode 100644 tools/testing/selftests/arm64/abi/syscall-abi.h


diff --git a/tools/testing/selftests/arm64/abi/syscall-abi.c b/tools/testing/selftests/arm64/abi/syscall-abi.c
index 1e13b7523918..b632bfe9e022 100644
--- a/tools/testing/selftests/arm64/abi/syscall-abi.c
+++ b/tools/testing/selftests/arm64/abi/syscall-abi.c
@@ -18,9 +18,13 @@
#include "../../kselftest.h" +#include "syscall-abi.h"
+
  #define NUM_VL ((SVE_VQ_MAX - SVE_VQ_MIN) + 1)
-extern void do_syscall(int sve_vl);
+static int default_sme_vl;
+
+extern void do_syscall(int sve_vl, int sme_vl);
static void fill_random(void *buf, size_t size)
  {
@@ -48,14 +52,15 @@ static struct syscall_cfg {
  uint64_t gpr_in[NUM_GPR];
  uint64_t gpr_out[NUM_GPR];
-static void setup_gpr(struct syscall_cfg *cfg, int sve_vl)
+static void setup_gpr(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		      uint64_t svcr)
  {
  	fill_random(gpr_in, sizeof(gpr_in));
  	gpr_in[8] = cfg->syscall_nr;
  	memset(gpr_out, 0, sizeof(gpr_out));
  }
-static int check_gpr(struct syscall_cfg *cfg, int sve_vl)
+static int check_gpr(struct syscall_cfg *cfg, int sve_vl, int sme_vl, uint64_t svcr)
  {
  	int errors = 0;
  	int i;
@@ -79,13 +84,15 @@ static int check_gpr(struct syscall_cfg *cfg, int sve_vl)
  uint64_t fpr_in[NUM_FPR * 2];
  uint64_t fpr_out[NUM_FPR * 2];
-static void setup_fpr(struct syscall_cfg *cfg, int sve_vl)
+static void setup_fpr(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		      uint64_t svcr)
  {
  	fill_random(fpr_in, sizeof(fpr_in));
  	memset(fpr_out, 0, sizeof(fpr_out));
  }
-static int check_fpr(struct syscall_cfg *cfg, int sve_vl)
+static int check_fpr(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		     uint64_t svcr)
  {
  	int errors = 0;
  	int i;
@@ -109,13 +116,15 @@ static uint8_t z_zero[__SVE_ZREG_SIZE(SVE_VQ_MAX)];
  uint8_t z_in[SVE_NUM_PREGS * __SVE_ZREG_SIZE(SVE_VQ_MAX)];
  uint8_t z_out[SVE_NUM_PREGS * __SVE_ZREG_SIZE(SVE_VQ_MAX)];
-static void setup_z(struct syscall_cfg *cfg, int sve_vl)
+static void setup_z(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		    uint64_t svcr)
  {
  	fill_random(z_in, sizeof(z_in));
  	fill_random(z_out, sizeof(z_out));
  }
-static int check_z(struct syscall_cfg *cfg, int sve_vl)
+static int check_z(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		   uint64_t svcr)
  {
  	size_t reg_size = sve_vl;
  	int errors = 0;
@@ -126,13 +135,17 @@ static int check_z(struct syscall_cfg *cfg, int sve_vl)
/*
  	 * After a syscall the low 128 bits of the Z registers should
-	 * be preserved and the rest be zeroed or preserved.
+	 * be preserved and the rest be zeroed or preserved, except if
+	 * we were in streaming mode in which case the low 128 bits may
+	 * also be cleared by the transition out of streaming mode.
  	 */
  	for (i = 0; i < SVE_NUM_ZREGS; i++) {
  		void *in = &z_in[reg_size * i];
  		void *out = &z_out[reg_size * i];
- if (memcmp(in, out, SVE_VQ_BYTES) != 0) {
+		if ((memcmp(in, out, SVE_VQ_BYTES) != 0) &&
+		    !((svcr & SVCR_SM_MASK) &&
+		      memcmp(z_zero, out, SVE_VQ_BYTES) == 0)) {
  			ksft_print_msg("%s SVE VL %d Z%d low 128 bits changed\n",
  				       cfg->name, sve_vl, i);
  			errors++;
@@ -145,13 +158,15 @@ static int check_z(struct syscall_cfg *cfg, int sve_vl)
  uint8_t p_in[SVE_NUM_PREGS * __SVE_PREG_SIZE(SVE_VQ_MAX)];
  uint8_t p_out[SVE_NUM_PREGS * __SVE_PREG_SIZE(SVE_VQ_MAX)];
-static void setup_p(struct syscall_cfg *cfg, int sve_vl)
+static void setup_p(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		    uint64_t svcr)
  {
  	fill_random(p_in, sizeof(p_in));
  	fill_random(p_out, sizeof(p_out));
  }
-static int check_p(struct syscall_cfg *cfg, int sve_vl)
+static int check_p(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		   uint64_t svcr)
  {
  	size_t reg_size = sve_vq_from_vl(sve_vl) * 2; /* 1 bit per VL byte */
@@ -175,8 +190,19 @@ static int check_p(struct syscall_cfg *cfg, int sve_vl)
  uint8_t ffr_in[__SVE_PREG_SIZE(SVE_VQ_MAX)];
  uint8_t ffr_out[__SVE_PREG_SIZE(SVE_VQ_MAX)];
-static void setup_ffr(struct syscall_cfg *cfg, int sve_vl)
+static void setup_ffr(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		      uint64_t svcr)
  {
+	/*
+	 * If we are in streaming mode and do not have FA64 then FFR
+	 * is unavailable.
+	 */
+	if ((svcr & SVCR_SM_MASK) &&
+	    !(getauxval(AT_HWCAP2) & HWCAP2_SME_FA64)) {
+		memset(&ffr_in, 0, sizeof(ffr_in));
+		return;
+	}
+
  	/*
  	 * It is only valid to set a contiguous set of bits starting
  	 * at 0.  For now since we're expecting this to be cleared by
@@ -186,7 +212,8 @@ static void setup_ffr(struct syscall_cfg *cfg, int sve_vl)
  	fill_random(ffr_out, sizeof(ffr_out));
  }
-static int check_ffr(struct syscall_cfg *cfg, int sve_vl)
+static int check_ffr(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		     uint64_t svcr)
  {
  	size_t reg_size = sve_vq_from_vl(sve_vl) * 2;  /* 1 bit per VL byte */
  	int errors = 0;
@@ -195,6 +222,10 @@ static int check_ffr(struct syscall_cfg *cfg, int sve_vl)
  	if (!sve_vl)
  		return 0;
+ if ((svcr & SVCR_SM_MASK) &&
+	    !(getauxval(AT_HWCAP2) & HWCAP2_SME_FA64))
+		return 0;
+
  	/* After a syscall the P registers should be preserved or zeroed */
  	for (i = 0; i < reg_size; i++)
  		if (ffr_out[i] && (ffr_in[i] != ffr_out[i]))
@@ -206,8 +237,65 @@ static int check_ffr(struct syscall_cfg *cfg, int sve_vl)
  	return errors;
  }
-typedef void (*setup_fn)(struct syscall_cfg *cfg, int sve_vl);
-typedef int (*check_fn)(struct syscall_cfg *cfg, int sve_vl);
+uint64_t svcr_in, svcr_out;
+
+static void setup_svcr(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		    uint64_t svcr)
+{
+	svcr_in = svcr;
+}
+
+static int check_svcr(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		      uint64_t svcr)
+{
+	int errors = 0;
+
+	if (svcr_out & SVCR_SM_MASK) {
+		ksft_print_msg("%s Still in SM, SVCR %llx\n",
+			       cfg->name, svcr_out);
+		errors++;
+	}
+
+	if ((svcr_in & SVCR_ZA_MASK) != (svcr_out & SVCR_ZA_MASK)) {
+		ksft_print_msg("%s PSTATE.ZA changed, SVCR %llx != %llx\n",
+			       cfg->name, svcr_in, svcr_out);
+		errors++;
+	}
+
+	return errors;
+}
+
+uint8_t za_in[SVE_NUM_PREGS * __SVE_ZREG_SIZE(SVE_VQ_MAX)];
+uint8_t za_out[SVE_NUM_PREGS * __SVE_ZREG_SIZE(SVE_VQ_MAX)];
+
+static void setup_za(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		     uint64_t svcr)
+{
+	fill_random(za_in, sizeof(za_in));
+	memset(za_out, 0, sizeof(za_out));
+}
+
+static int check_za(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		    uint64_t svcr)
+{
+	size_t reg_size = sme_vl * sme_vl;

Is there possibilty of size_t overfolow here?

+	int errors = 0;
+
+	if (!(svcr & SVCR_ZA_MASK))
+		return 0;
+
+	if (memcmp(za_in, za_out, reg_size) != 0) {
+		ksft_print_msg("SME VL %d ZA does not match\n", sme_vl);

Print the expected value in addition to the sme_val.

+		errors++;
+	}
+
+	return errors;
+}
+
+typedef void (*setup_fn)(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+			 uint64_t svcr);
+typedef int (*check_fn)(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+			uint64_t svcr);
/*
   * Each set of registers has a setup function which is called before
@@ -225,20 +313,23 @@ static struct {
  	{ setup_z, check_z },
  	{ setup_p, check_p },
  	{ setup_ffr, check_ffr },
+	{ setup_svcr, check_svcr },
+	{ setup_za, check_za },
  };
-static bool do_test(struct syscall_cfg *cfg, int sve_vl)
+static bool do_test(struct syscall_cfg *cfg, int sve_vl, int sme_vl,
+		    uint64_t svcr)
  {
  	int errors = 0;
  	int i;
for (i = 0; i < ARRAY_SIZE(regset); i++)
-		regset[i].setup(cfg, sve_vl);
+		regset[i].setup(cfg, sve_vl, sme_vl, svcr);
- do_syscall(sve_vl);
+	do_syscall(sve_vl, sme_vl);
for (i = 0; i < ARRAY_SIZE(regset); i++)
-		errors += regset[i].check(cfg, sve_vl);
+		errors += regset[i].check(cfg, sve_vl, sme_vl, svcr);
return errors == 0;
  }
@@ -246,9 +337,10 @@ static bool do_test(struct syscall_cfg *cfg, int sve_vl)
  static void test_one_syscall(struct syscall_cfg *cfg)
  {
  	int sve_vq, sve_vl;
+	int sme_vq, sme_vl;
/* FPSIMD only case */
-	ksft_test_result(do_test(cfg, 0),
+	ksft_test_result(do_test(cfg, 0, default_sme_vl, 0),
  			 "%s FPSIMD\n", cfg->name);
if (!(getauxval(AT_HWCAP) & HWCAP_SVE))
@@ -265,8 +357,36 @@ static void test_one_syscall(struct syscall_cfg *cfg)
  		if (sve_vq != sve_vq_from_vl(sve_vl))
  			sve_vq = sve_vq_from_vl(sve_vl);
- ksft_test_result(do_test(cfg, sve_vl),
+		ksft_test_result(do_test(cfg, sve_vl, default_sme_vl, 0),
  				 "%s SVE VL %d\n", cfg->name, sve_vl);

Print default_sme_vl as well.

+
+		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)
+				ksft_exit_fail_msg("PR_SME_SET_VL failed: %s (%d)\n",
+						   strerror(errno), errno);
+
+			sme_vl &= PR_SME_VL_LEN_MASK;
+
+			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,
+						 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),
+					 "%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),
+					 "%s SVE VL %d/SME VL %d ZA\n",
+					 cfg->name, sve_vl, sme_vl);
+		}
  	}
  }
@@ -299,14 +419,54 @@ int sve_count_vls(void)
  	return vl_count;
  }
+int 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;
+
+	/*
+	 * Enumerate up to SVE_VQ_MAX vector lengths
+	 */
+	for (vq = SVE_VQ_MAX; vq > 0; --vq) {
+		vl = prctl(PR_SME_SET_VL, vq * 16);
+		if (vl == -1)
+			ksft_exit_fail_msg("PR_SME_SET_VL failed: %s (%d)\n",
+					   strerror(errno), errno);
+
+		vl &= PR_SME_VL_LEN_MASK;
+
+		if (vq != sve_vq_from_vl(vl))
+			vq = sve_vq_from_vl(vl);
+
+		vl_count++;
+	}
+
+	return vl_count;
+}
+
  int main(void)
  {
  	int i;
+	int tests = 1;  /* FPSIMD */
srandom(getpid()); ksft_print_header();
-	ksft_set_plan(ARRAY_SIZE(syscalls) * (sve_count_vls() + 1));
+	tests += sve_count_vls();
+	tests += (sve_count_vls() * sme_count_vls()) * 3;
+	ksft_set_plan(ARRAY_SIZE(syscalls) * tests);
+
+	if (getauxval(AT_HWCAP2) & HWCAP2_SME_FA64)
+		ksft_print_msg("SME with FA64\n");
+	else if (getauxval(AT_HWCAP2) & HWCAP2_SME)
+		ksft_print_msg("SME without FA64\n");
for (i = 0; i < ARRAY_SIZE(syscalls); i++)
  		test_one_syscall(&syscalls[i]);
diff --git a/tools/testing/selftests/arm64/abi/syscall-abi.h b/tools/testing/selftests/arm64/abi/syscall-abi.h
new file mode 100644
index 000000000000..bda5a87ad381
--- /dev/null
+++ b/tools/testing/selftests/arm64/abi/syscall-abi.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 ARM Limited.
+ */
+
+#ifndef SYSCALL_ABI_H
+#define SYSCALL_ABI_H
+
+#define SVCR_ZA_MASK		2
+#define SVCR_SM_MASK		1
+
+#define SVCR_ZA_SHIFT		1
+#define SVCR_SM_SHIFT		0
+
+#endif


With these fixed or explained

Reviewed-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>

thanks,
-- Shuah
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