On Thu, Oct 09, 2025 at 09:41:54PM +0800, Yao Zihong wrote:
Add a new selftest under hwprobe/ to verify Zicbop extension behavior.
The test checks:
- That hwprobe correctly reports Zicbop presence and block size.
- That prefetch instructions execute without exception on valid and NULL addresses when Zicbop is present.
- That prefetch.{i,r,w} do not trigger SIGILL even when Zicbop is absent, since Zicbop instructions are defined as hints.
The test is based on cbo.c but adapted for Zicbop prefetch instructions.
Signed-off-by: Yao Zihong zihong.plct@isrc.iscas.ac.cn
.../testing/selftests/riscv/hwprobe/Makefile | 5 +- .../selftests/riscv/hwprobe/prefetch.c | 236 ++++++++++++++++++ 2 files changed, 240 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/riscv/hwprobe/prefetch.c
diff --git a/tools/testing/selftests/riscv/hwprobe/Makefile b/tools/testing/selftests/riscv/hwprobe/Makefile index cec81610a5f2..3c8b8ba7629c 100644 --- a/tools/testing/selftests/riscv/hwprobe/Makefile +++ b/tools/testing/selftests/riscv/hwprobe/Makefile @@ -4,7 +4,7 @@ CFLAGS += -I$(top_srcdir)/tools/include -TEST_GEN_PROGS := hwprobe cbo which-cpus +TEST_GEN_PROGS := hwprobe cbo which-cpus prefetch include ../../lib.mk @@ -16,3 +16,6 @@ $(OUTPUT)/cbo: cbo.c sys_hwprobe.S $(OUTPUT)/which-cpus: which-cpus.c sys_hwprobe.S $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
+$(OUTPUT)/prefetch: prefetch.c sys_hwprobe.S
- $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
diff --git a/tools/testing/selftests/riscv/hwprobe/prefetch.c b/tools/testing/selftests/riscv/hwprobe/prefetch.c new file mode 100644 index 000000000000..d9ea048325fb --- /dev/null +++ b/tools/testing/selftests/riscv/hwprobe/prefetch.c @@ -0,0 +1,236 @@ +// SPDX-License-Identifier: GPL-2.0-only +/*
- Copyright (c) 2023 Ventana Micro Systems Inc.
- Copyright (c) 2025 PLCT Lab, ISCAS
- Based on tools/testing/selftests/riscv/hwprobe/cbo.c with modifications
- for Zicbop prefetch testing.
- Run with 'taskset -c <cpu-list> prefetch' 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_PREFETCH(fn) \
- le32_bswap(0 << 25 | (uint32_t)(fn) << 20 | 10 << 15 | 6 << 12 | 0 << 7 | 19)
+static char mem[4096] __aligned(4096) = { [0 ... 4095] = 0xa5 };
+static bool illegal;
+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_PREFETCH(regs[11]));
- illegal = true;
- regs[0] += 4;
+}
+#define prefetch_insn(base, fn) \ +({ \
- asm volatile( \
- "mv a0, %0\n" \
- "li a1, %1\n" \
- ".4byte %2\n" \
- : : "r" (base), "i" (fn), "i" (MK_PREFETCH(fn)) : "a0", "a1", "memory");\
+})
+static void prefetch_i(char *base) { prefetch_insn(base, 0); }
+static void prefetch_r(char *base) { prefetch_insn(base, 1); }
+static void prefetch_w(char *base) { prefetch_insn(base, 3); }
Please remove the unnecessary blank lines between function definitions.
+static bool is_power_of_2(__u64 n) +{
- return n != 0 && (n & (n - 1)) == 0;
+}
+static void test_no_zicbop(void *arg) +{
- // Zicbop prefetch.* are HINT instructions.
No C++ comments. Run checkpatch.
- ksft_print_msg("Testing Zicbop instructions\n");
- illegal = false;
- prefetch_i(&mem[0]);
- ksft_test_result(!illegal, "No prefetch.i\n");
- illegal = false;
- prefetch_r(&mem[0]);
- ksft_test_result(!illegal, "No prefetch.r\n");
- illegal = false;
- prefetch_w(&mem[0]);
- ksft_test_result(!illegal, "No prefetch.w\n");
+}
+static void test_zicbop(void *arg) +{
- struct riscv_hwprobe pair = {
.key = RISCV_HWPROBE_KEY_ZICBOP_BLOCK_SIZE,- };
- cpu_set_t *cpus = (cpu_set_t *)arg;
- __u64 block_size;
- 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_ZICBOP_BLOCK_SIZE &&
is_power_of_2(block_size), "Zicbop block size\n");- ksft_print_msg("Zicbop block size: %llu\n", block_size);
- illegal = false;
- prefetch_i(&mem[0]);
- prefetch_r(&mem[0]);
- prefetch_w(&mem[0]);
- ksft_test_result(!illegal, "Zicbop prefetch.* on valid address\n");
- illegal = false;
- prefetch_i(NULL);
- prefetch_r(NULL);
- prefetch_w(NULL);
- ksft_test_result(!illegal, "Zicbop prefetch.* on NULL\n");
+}
+static void check_no_zicbop_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_ZICBOP)ksft_exit_fail_msg("zicbop is only present on a subset of harts.\n""Use taskset to select a set of harts where zicbop\n""presence (present or not) is consistent for each hart\n");++c;- }
+}
+enum {
- TEST_ZICBOP,
- TEST_NO_ZICBOP,
+};
+enum {
- HANDLER_SIGILL,
- HANDLER_SIGSEGV,
- HANDLER_SIGBUS,
+};
Why create this enum?
+static struct test_info {
- bool enabled;
- unsigned int nr_tests;
- void (*test_fn)(void *arg);
+} tests[] = {
- [TEST_ZICBOP] = { .nr_tests = 3, test_zicbop },
- [TEST_NO_ZICBOP] = { .nr_tests = 3, test_no_zicbop },
+};
+static struct sighandler_info {
- const char *flag;
- int sig;
+} handlers[] = {
- [HANDLER_SIGILL] = { .flag = "--sigill", .sig = SIGILL },
- [HANDLER_SIGSEGV] = { .flag = "--sigsegv", .sig = SIGSEGV },
- [HANDLER_SIGBUS] = { .flag = "--sigbus", .sig = SIGBUS },
+};
+static bool search_flag(int argc, char **argv, const char *flag) +{
- int i;
- for (i = 1; i < argc; i++) {
if (!strcmp(argv[i], flag))return true;- }
- return false;
+}
Instead of this search function just use getopt()
+static void install_sigaction(int argc, char **argv) +{
- int i, rc;
- struct sigaction act = {
.sa_sigaction = &sigill_handler,.sa_flags = SA_SIGINFO,- };
- for (i = 0; i < ARRAY_SIZE(handlers); ++i) {
if (search_flag(argc, argv, handlers[i].flag)) {rc = sigaction(handlers[i].sig, &act, NULL);assert(rc == 0);}- }
- if (search_flag(argc, argv, handlers[HANDLER_SIGILL].flag))
tests[TEST_NO_ZICBOP].enabled = true;+}
+int main(int argc, char **argv) +{
- struct riscv_hwprobe pair;
- unsigned int plan = 0;
- cpu_set_t cpus;
- long rc;
- int i;
- install_sigaction(argc, argv);
- 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 %ld\n", rc);- assert(rc == 0 && pair.key == RISCV_HWPROBE_KEY_IMA_EXT_0);
- if (pair.value & RISCV_HWPROBE_EXT_ZICBOP)
tests[TEST_ZICBOP].enabled = true;- else
check_no_zicbop_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();
+}
2.47.2
There's no reason to duplicate cbo.c. Just parameterize check_no_zicboz_cpus() (and rename it to check_no_zicbo_cpus()) in order to share it with zicbop and then add your new tests.
drew