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

[Andrew Jones <ajones@ventanamicro.com>]

On Fri, Sep 01, 2023 at 09:37:27AM +0000, Wang, Xiao W wrote:
> 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().

Nice catch, Xiao. Copy+paste mistake... Will fix for v3.

Thanks,
drew

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