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

[Andrew Jones <ajones@ventanamicro.com>]

Add hwprobe test for Zicboz and its block size. Also, when Zicboz is
present, test that cbo.zero may be issued and works. Additionally
test that the Zicbom instructions cause SIGILL and also that cbo.zero
causes SIGILL when Zicboz is not present. 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@ventanamicro.com>
---
 tools/testing/selftests/riscv/Makefile        |   2 +-
 .../testing/selftests/riscv/hwprobe/Makefile  |   5 +-
 tools/testing/selftests/riscv/hwprobe/cbo.c   | 160 ++++++++++++++++++
 .../testing/selftests/riscv/hwprobe/hwprobe.c |  12 +-
 .../testing/selftests/riscv/hwprobe/hwprobe.h |  15 ++
 5 files changed, 181 insertions(+), 13 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/Makefile b/tools/testing/selftests/riscv/Makefile
index f4b3d5c9af5b..7bbeec48292d 100644
--- a/tools/testing/selftests/riscv/Makefile
+++ b/tools/testing/selftests/riscv/Makefile
@@ -16,7 +16,7 @@ CFLAGS := -Wall -O2 -g
 top_srcdir = $(realpath ../../../../)
 
 # Additional include paths needed by kselftest.h and local headers
-CFLAGS += -I$(top_srcdir)/tools/testing/selftests/
+CFLAGS += -I$(top_srcdir)/tools/testing/selftests/ -I$(top_srcdir)/tools/include
 
 CFLAGS += $(KHDR_INCLUDES)
 
diff --git a/tools/testing/selftests/riscv/hwprobe/Makefile b/tools/testing/selftests/riscv/hwprobe/Makefile
index 5f614c3ba598..56e54d66df7e 100644
--- a/tools/testing/selftests/riscv/hwprobe/Makefile
+++ b/tools/testing/selftests/riscv/hwprobe/Makefile
@@ -2,9 +2,12 @@
 # Copyright (C) 2021 ARM Limited
 # Originally tools/testing/arm64/abi/Makefile
 
-TEST_GEN_PROGS := hwprobe
+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..6fa01e4cec99
--- /dev/null
+++ b/tools/testing/selftests/riscv/hwprobe/cbo.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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 <sched.h>
+#include <signal.h>
+#include <assert.h>
+#include <linux/compiler.h>
+#include <asm/ucontext.h>
+
+#include "hwprobe.h"
+#include "../../kselftest.h"
+
+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 >> 20 == regs[11] &&
+	       (insn & ((1 << 20) - 1)) == (10 << 15 | 2 << 12 | 0 << 7 | 15));
+
+	illegal_insn = true;
+	regs[0] += 4;
+}
+
+static void cbo_insn(int fn, char *base)
+{
+	asm volatile(
+	"mv	a0, %0\n"
+	"li	a1, %1\n"
+	".4byte	%1 << 20 | 10 << 15 | 2 << 12 | 0 << 7 | 15\n"
+	: : "r" (base), "i" (fn) : "a0", "a1", "memory");
+}
+
+static void cbo_inval(char *base) { cbo_insn(0, base); }
+static void cbo_clean(char *base) { cbo_insn(1, base); }
+static void cbo_flush(char *base) { cbo_insn(2, base); }
+static void cbo_zero(char *base)  { cbo_insn(4, base); }
+
+static void test_no_zicbom(void)
+{
+	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)
+{
+	illegal_insn = false;
+	cbo_clean(&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(__u64 block_size)
+{
+	int i, j;
+
+	illegal_insn = false;
+	cbo_zero(&mem[block_size]);
+	ksft_test_result(!illegal_insn, "cbo.zero\n");
+
+	if (!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");
+}
+
+int main(int argc, char **argv)
+{
+	struct sigaction act = {
+		.sa_sigaction = &sigill_handler,
+		.sa_flags = SA_SIGINFO,
+	};
+	bool has_zicboz = false;
+	struct riscv_hwprobe pair;
+	cpu_set_t cpus;
+	size_t nr_cpus;
+	long rc;
+
+	rc = sigaction(SIGILL, &act, NULL);
+	assert(rc == 0);
+
+	rc = sched_getaffinity(0, sizeof(cpu_set_t), &cpus);
+	assert(rc == 0);
+	nr_cpus = CPU_COUNT(&cpus);
+
+	ksft_print_header();
+
+	pair.key = RISCV_HWPROBE_KEY_IMA_EXT_0;
+	rc = riscv_hwprobe(&pair, 1, nr_cpus, (unsigned long *)&cpus, 0);
+	if (rc < 0)
+		ksft_exit_fail_msg("hwprobe() failed with %d\n", rc);
+
+	if (pair.key != -1 && (pair.value & RISCV_HWPROBE_EXT_ZICBOZ)) {
+		has_zicboz = true;
+		ksft_set_plan(6);
+	} else {
+		ksft_print_msg("No Zicboz, testing cbo.zero remains privileged\n");
+		ksft_set_plan(4);
+	}
+
+	/* Ensure zicbom instructions remain privileged */
+	test_no_zicbom();
+
+	if (has_zicboz) {
+		pair.key = RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE;
+		rc = riscv_hwprobe(&pair, 1, nr_cpus, (unsigned long *)&cpus, 0);
+		ksft_test_result(rc == 0 && pair.key == RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE &&
+				 is_power_of_2(pair.value), "Zicboz block size\n");
+		ksft_print_msg("Zicboz block size: %ld\n", pair.value);
+		test_zicboz(pair.value);
+	} else {
+		test_no_zicboz();
+	}
+
+	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


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