RE: [PATCH v2 6/6] RISC-V: selftests: Add CBO tests

["Wang, Xiao W" <xiao.w.wang@intel.com>]

Hi,

> -----Original Message-----
> From: linux-riscv <linux-riscv-bounces@lists.infradead.org> On Behalf Of
> Andrew Jones
> Sent: Thursday, August 31, 2023 12:50 AM
> To: linux-riscv@lists.infradead.org
> Cc: paul.walmsley@sifive.com; palmer@dabbelt.com;
> aou@eecs.berkeley.edu; evan@rivosinc.com; conor.dooley@microchip.com;
> apatel@ventanamicro.com
> Subject: [PATCH v2 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
> 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>
> ---
>  .../testing/selftests/riscv/hwprobe/Makefile  |   7 +-
>  tools/testing/selftests/riscv/hwprobe/cbo.c   | 162 ++++++++++++++++++
>  .../testing/selftests/riscv/hwprobe/hwprobe.c |  12 +-
>  .../testing/selftests/riscv/hwprobe/hwprobe.h |  15 ++
>  4 files changed, 184 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..920abfaa10c2
> --- /dev/null
> +++ b/tools/testing/selftests/riscv/hwprobe/cbo.c
> @@ -0,0 +1,162 @@
> +// 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 <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]);

Seems we need to call cbo_zero() instead of cbo_clean().

BRs,
Xiao

> +	ksft_test_result(illegal_insn, "No cbo.zero\n");
> +}
> +
[...]
> 
> 
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