[PATCH v4 6/6] RISC-V: selftests: Add CBO tests

Wang, Xiao W xiao.w.wang at intel.com
Tue Sep 19 22:41:55 PDT 2023



> -----Original Message-----
> From: linux-riscv <linux-riscv-bounces at lists.infradead.org> On Behalf Of
> Andrew Jones
> Sent: Monday, September 18, 2023 9:15 PM
> To: linux-riscv at lists.infradead.org
> Cc: paul.walmsley at sifive.com; palmer at dabbelt.com;
> aou at eecs.berkeley.edu; evan at rivosinc.com; conor.dooley at microchip.com;
> apatel at ventanamicro.com; Wang, Xiao W <xiao.w.wang at intel.com>
> Subject: [PATCH v4 6/6] RISC-V: selftests: Add CBO tests
> 
> Add hwprobe test for Zicboz and its block size. Also, when Zicboz is
> present, test that cbo.zero may be issued and works. Additionally
> provide a command line option that enables testing that the Zicbom
> instructions cause SIGILL and also that cbo.zero causes SIGILL when
> Zicboz it's not present. The SIGILL tests require "opt-in" with a
> command line option because the RISC-V ISA does not require
> unimplemented standard opcodes to issue illegal-instruction
> exceptions (but hopefully most platforms do).
> 
> Pinning the test to a subset of cpus with taskset will also restrict
> the hwprobe calls to that set.
> 
> Signed-off-by: Andrew Jones <ajones at ventanamicro.com>
> ---
>  .../testing/selftests/riscv/hwprobe/Makefile  |   7 +-
>  tools/testing/selftests/riscv/hwprobe/cbo.c   | 228 ++++++++++++++++++
>  .../testing/selftests/riscv/hwprobe/hwprobe.c |  12 +-
>  .../testing/selftests/riscv/hwprobe/hwprobe.h |  15 ++
>  4 files changed, 250 insertions(+), 12 deletions(-)
>  create mode 100644 tools/testing/selftests/riscv/hwprobe/cbo.c
>  create mode 100644 tools/testing/selftests/riscv/hwprobe/hwprobe.h
> 
> diff --git a/tools/testing/selftests/riscv/hwprobe/Makefile
> b/tools/testing/selftests/riscv/hwprobe/Makefile
> index 5f614c3ba598..f224b84591fb 100644
> --- a/tools/testing/selftests/riscv/hwprobe/Makefile
> +++ b/tools/testing/selftests/riscv/hwprobe/Makefile
> @@ -2,9 +2,14 @@
>  # Copyright (C) 2021 ARM Limited
>  # Originally tools/testing/arm64/abi/Makefile
> 
> -TEST_GEN_PROGS := hwprobe
> +CFLAGS += -I$(top_srcdir)/tools/include
> +
> +TEST_GEN_PROGS := hwprobe cbo
> 
>  include ../../lib.mk
> 
>  $(OUTPUT)/hwprobe: hwprobe.c sys_hwprobe.S
>  	$(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
> +
> +$(OUTPUT)/cbo: cbo.c sys_hwprobe.S
> +	$(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
> diff --git a/tools/testing/selftests/riscv/hwprobe/cbo.c
> b/tools/testing/selftests/riscv/hwprobe/cbo.c
> new file mode 100644
> index 000000000000..50a2cc8aef38
> --- /dev/null
> +++ b/tools/testing/selftests/riscv/hwprobe/cbo.c
> @@ -0,0 +1,228 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2023 Ventana Micro Systems Inc.
> + *
> + * Run with 'taskset -c <cpu-list> cbo' to only execute hwprobe on a
> + * subset of cpus, as well as only executing the tests on those cpus.
> + */
> +#define _GNU_SOURCE
> +#include <stdbool.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <sched.h>
> +#include <signal.h>
> +#include <assert.h>
> +#include <linux/compiler.h>
> +#include <linux/kernel.h>
> +#include <asm/ucontext.h>
> +
> +#include "hwprobe.h"
> +#include "../../kselftest.h"
> +
> +#define MK_CBO(fn) cpu_to_le32((fn) << 20 | 10 << 15 | 2 << 12 | 0 << 7 |
> 15)
> +
> +static char mem[4096] __aligned(4096) = { [0 ... 4095] = 0xa5 };
> +
> +static bool illegal_insn;
> +
> +static void sigill_handler(int sig, siginfo_t *info, void *context)
> +{
> +	unsigned long *regs = (unsigned long *)&((ucontext_t *)context)-
> >uc_mcontext;
> +	uint32_t insn = *(uint32_t *)regs[0];
> +
> +	assert(insn == MK_CBO(regs[11]));
> +
> +	illegal_insn = true;
> +	regs[0] += 4;
> +}
> +
> +static void cbo_insn(char *base, int fn)
> +{
> +	uint32_t insn = MK_CBO(fn);
> +
> +	asm volatile(
> +	"mv	a0, %0\n"
> +	"li	a1, %1\n"
> +	".4byte	%2\n"
> +	: : "r" (base), "i" (fn), "i" (insn) : "a0", "a1", "memory");
> +}
> +
> +static void cbo_inval(char *base) { cbo_insn(base, 0); }
> +static void cbo_clean(char *base) { cbo_insn(base, 1); }
> +static void cbo_flush(char *base) { cbo_insn(base, 2); }
> +static void cbo_zero(char *base)  { cbo_insn(base, 4); }
> +
> +static void test_no_zicbom(void *arg)
> +{
> +	ksft_print_msg("Testing Zicbom instructions remain privileged\n");
> +
> +	illegal_insn = false;
> +	cbo_clean(&mem[0]);
> +	ksft_test_result(illegal_insn, "No cbo.clean\n");
> +
> +	illegal_insn = false;
> +	cbo_flush(&mem[0]);
> +	ksft_test_result(illegal_insn, "No cbo.flush\n");
> +
> +	illegal_insn = false;
> +	cbo_inval(&mem[0]);
> +	ksft_test_result(illegal_insn, "No cbo.inval\n");
> +}
> +
> +static void test_no_zicboz(void *arg)
> +{
> +	ksft_print_msg("No Zicboz, testing cbo.zero remains privileged\n");
> +
> +	illegal_insn = false;
> +	cbo_zero(&mem[0]);
> +	ksft_test_result(illegal_insn, "No cbo.zero\n");
> +}
> +
> +static bool is_power_of_2(__u64 n)
> +{
> +	return n != 0 && (n & (n - 1)) == 0;
> +}
> +
> +static void test_zicboz(void *arg)
> +{
> +	struct riscv_hwprobe pair = {
> +		.key = RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE,
> +	};
> +	cpu_set_t *cpus = (cpu_set_t *)arg;
> +	__u64 block_size;
> +	int i, j;
> +	long rc;
> +
> +	rc = riscv_hwprobe(&pair, 1, sizeof(cpu_set_t), (unsigned long *)cpus,
> 0);
> +	block_size = pair.value;
> +	ksft_test_result(rc == 0 && pair.key ==
> RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE &&
> +			 is_power_of_2(block_size), "Zicboz block size\n");
> +	ksft_print_msg("Zicboz block size: %ld\n", block_size);
> +
> +	illegal_insn = false;
> +	cbo_zero(&mem[block_size]);
> +	ksft_test_result(!illegal_insn, "cbo.zero\n");
> +
> +	if (illegal_insn || !is_power_of_2(block_size)) {
> +		ksft_test_result_skip("cbo.zero check\n");
> +		return;
> +	}
> +
> +	assert(block_size <= 1024);
> +
> +	for (i = 0; i < 4096 / block_size; ++i) {
> +		if (i % 2)
> +			cbo_zero(&mem[i * block_size]);
> +	}
> +
> +	for (i = 0; i < 4096 / block_size; ++i) {
> +		char expected = i % 2 ? 0x0 : 0xa5;
> +
> +		for (j = 0; j < block_size; ++j) {
> +			if (mem[i * block_size + j] != expected) {
> +				ksft_test_result_fail("cbo.zero check\n");
> +				ksft_print_msg("cbo.zero check: mem[%d] !=
> 0x%x\n",
> +					       i * block_size + j, expected);
> +				return;
> +			}
> +		}
> +	}
> +
> +	ksft_test_result_pass("cbo.zero check\n");
> +}
> +
> +static void check_no_zicboz_cpus(cpu_set_t *cpus)
> +{
> +	struct riscv_hwprobe pair = {
> +		.key = RISCV_HWPROBE_KEY_IMA_EXT_0,
> +	};
> +	cpu_set_t one_cpu;
> +	int i = 0, c = 0;
> +	long rc;
> +
> +	while (i++ < CPU_COUNT(cpus)) {
> +		while (!CPU_ISSET(c, cpus))
> +			++c;
> +
> +		CPU_ZERO(&one_cpu);
> +		CPU_SET(c, &one_cpu);
> +
> +		rc = riscv_hwprobe(&pair, 1, sizeof(cpu_set_t), (unsigned long
> *)&one_cpu, 0);
> +		assert(rc == 0 && pair.key ==
> RISCV_HWPROBE_KEY_IMA_EXT_0);
> +
> +		if (pair.value & RISCV_HWPROBE_EXT_ZICBOZ)
> +			ksft_exit_fail_msg("Zicboz is only present on a subset
> of harts.\n"
> +					   "Use taskset to select a set of harts
> where Zicboz\n"
> +					   "presence (present or not) is
> consistent for each hart\n");
> +		++c;
> +	}
> +}
> +
> +enum {
> +	TEST_ZICBOZ,
> +	TEST_NO_ZICBOZ,
> +	TEST_NO_ZICBOM,
> +};
> +
> +static struct test_info {
> +	bool enabled;
> +	unsigned int nr_tests;
> +	void (*test_fn)(void *arg);
> +} tests[] = {
> +	[TEST_ZICBOZ]		= { .nr_tests = 3, test_zicboz },
> +	[TEST_NO_ZICBOZ]	= { .nr_tests = 1, test_no_zicboz },
> +	[TEST_NO_ZICBOM]	= { .nr_tests = 3, test_no_zicbom },
> +};
> +
> +int main(int argc, char **argv)
> +{
> +	struct sigaction act = {
> +		.sa_sigaction = &sigill_handler,
> +		.sa_flags = SA_SIGINFO,
> +	};
> +	struct riscv_hwprobe pair;
> +	unsigned int plan = 0;
> +	cpu_set_t cpus;
> +	long rc;
> +	int i;
> +
> +	if (argc > 1 && !strcmp(argv[1], "--sigill")) {
> +		rc = sigaction(SIGILL, &act, NULL);
> +		assert(rc == 0);
> +		tests[TEST_NO_ZICBOZ].enabled = true;
> +		tests[TEST_NO_ZICBOM].enabled = true;
> +	}
> +
> +	rc = sched_getaffinity(0, sizeof(cpu_set_t), &cpus);
> +	assert(rc == 0);
> +
> +	ksft_print_header();
> +
> +	pair.key = RISCV_HWPROBE_KEY_IMA_EXT_0;
> +	rc = riscv_hwprobe(&pair, 1, sizeof(cpu_set_t), (unsigned long
> *)&cpus, 0);
> +	if (rc < 0)
> +		ksft_exit_fail_msg("hwprobe() failed with %d\n", rc);
> +	assert(rc == 0 && pair.key == RISCV_HWPROBE_KEY_IMA_EXT_0);
> +
> +	if (pair.value & RISCV_HWPROBE_EXT_ZICBOZ) {
> +		tests[TEST_ZICBOZ].enabled = true;
> +		tests[TEST_NO_ZICBOZ].enabled = false;
> +	} else {
> +		check_no_zicboz_cpus(&cpus);
> +	}
> +
> +	for (i = 0; i < ARRAY_SIZE(tests); ++i)
> +		plan += tests[i].enabled ? tests[i].nr_tests : 0;
> +
> +	if (plan == 0)
> +		ksft_print_msg("No tests enabled.\n");
> +	else
> +		ksft_set_plan(plan);
> +
> +	for (i = 0; i < ARRAY_SIZE(tests); ++i) {
> +		if (tests[i].enabled)
> +			tests[i].test_fn(&cpus);
> +	}
> +
> +	ksft_finished();
> +}
> diff --git a/tools/testing/selftests/riscv/hwprobe/hwprobe.c
> b/tools/testing/selftests/riscv/hwprobe/hwprobe.c
> index 4f15f1f3b4c3..c474891df307 100644
> --- a/tools/testing/selftests/riscv/hwprobe/hwprobe.c
> +++ b/tools/testing/selftests/riscv/hwprobe/hwprobe.c
> @@ -1,17 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0-only
> -#include <stddef.h>
> -#include <asm/hwprobe.h>
> -
> +#include "hwprobe.h"
>  #include "../../kselftest.h"
> 
> -/*
> - * Rather than relying on having a new enough libc to define this, just do it
> - * ourselves.  This way we don't need to be coupled to a new-enough libc to
> - * contain the call.
> - */
> -long riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
> -		   size_t cpu_count, unsigned long *cpus, unsigned int flags);
> -
>  int main(int argc, char **argv)
>  {
>  	struct riscv_hwprobe pairs[8];
> diff --git a/tools/testing/selftests/riscv/hwprobe/hwprobe.h
> b/tools/testing/selftests/riscv/hwprobe/hwprobe.h
> new file mode 100644
> index 000000000000..721b0ce73a56
> --- /dev/null
> +++ b/tools/testing/selftests/riscv/hwprobe/hwprobe.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef SELFTEST_RISCV_HWPROBE_H
> +#define SELFTEST_RISCV_HWPROBE_H
> +#include <stddef.h>
> +#include <asm/hwprobe.h>
> +
> +/*
> + * Rather than relying on having a new enough libc to define this, just do it
> + * ourselves.  This way we don't need to be coupled to a new-enough libc to
> + * contain the call.
> + */
> +long riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
> +		   size_t cpu_count, unsigned long *cpus, unsigned int flags);
> +
> +#endif
> --
> 2.41.0
> 

Reviewed-by: Xiao Wang <xiao.w.wang at intel.com>

> 
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