linux-kernel - Re: [PATCH 8/8] selftests: riscv: Add test for hardware breakpoints

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Message-ID: <CALSpo=bM8S2cKHRQ1Zn1ViDh9QfoKkWGVVeW50D1UQkXP_6rug@mail.gmail.com>
Date: Fri, 22 Aug 2025 10:58:12 -0700
From: Jesse Taube <jesse@...osinc.com>
To: Joel Stanley <joel@....id.au>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 8/8] selftests: riscv: Add test for hardware breakpoints

On Thu, Aug 14, 2025 at 10:42 PM Joel Stanley <joel@....id.au> wrote:
>
> Hi Jesse,
>
> We had a pretty huge cc list on the thread, I've trimmed it right
> back. Feel free to add some people back but keep it focused.
>
> On Wed, 6 Aug 2025 at 05:42, Jesse Taube <jesse@...osinc.com> wrote:
> >
> > Add riscv specific selftest for hardhardware breakpoints.
>
> nit: double hardware
>
> > These tests are based on:
> > tools/testing/selftests/breakpoints/breakpoint_test_arm64.c
>
> The sefltest didn't build for me. There's a few suggested fixes below.
>
> > Signed-off-by: Jesse Taube <jesse@...osinc.com>
> > ---
> > The selftest fails as register_user_hw_breakpoint seemingly does not
> > call arch_install_hw_breakpoint. The test also seems to fail on arm64
> > in the same way when I tested it.
>
> Is this still a problem with your patchset?

Yes

>
> Do you test in qemu? Can you share your version, command line, etc?

Yes. I used buildroot's `qemu_aarch64_virt_defconfig` config and set
`BR2_PACKAGE_LINUX_TOOLS_SELFTESTS` and tested with the example
command from the boards readme.

>
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/breakpoints/Makefile
> > @@ -0,0 +1,12 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (C) 2021 ARM Limited
> > +# Originally tools/testing/arm64/abi/Makefile
>
> CFLAGS += $(KHDR_INCLUDES)
>
> This adds -isystem to include local headers for the up to date
> ptrace.h and elf.h definitions.
>
>  $ make headers

oh that's why it wasn't building!

Thanks,
Jesse Taube
>  $ make -C tools/testing/selftests CROSS_COMPILE=riscv64-linux-gnu-
> ARCH=riscv TARGETS=riscv/breakpoints
>      make: Entering directory 'tools/testing/selftests'
>      riscv64-linux-gnu-gcc -static
> -otools/testing/selftests/riscv/breakpoints/breakpoint_test
>      -isystem usr/include -Itools/testing/selftests/../../../tools/include
>      -D_GNU_SOURCE=   breakpoint_test.c
>
> > +
> > +CFLAGS += -I$(top_srcdir)/tools/include
> > +
> > +TEST_GEN_PROGS := breakpoint_test
> > +
> > +include ../../lib.mk
> > +
> > +$(OUTPUT)/breakpoint_test: breakpoint_test.c
> > +       $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
> > diff --git a/tools/testing/selftests/riscv/breakpoints/breakpoint_test.c b/tools/testing/selftests/riscv/breakpoints/breakpoint_test.c
> > new file mode 100644
> > index 000000000000..faeecc72da12
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/breakpoints/breakpoint_test.c
> > @@ -0,0 +1,246 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2016 Google, Inc.
> > + *
> > + * Original Code by Pavel Labath <labath@...gle.com>
> > + *
> > + * Code modified by Pratyush Anand <panand@...hat.com>
> > + * for testing different byte select for each access size.
> > + * Originally tools/testing/selftests/breakpoints/breakpoint_test_arm64.c
> > + */
> > +
> > +#define _GNU_SOURCE
> > +
> > +#include <asm/ptrace.h>
> > +#include <sys/types.h>
> > +#include <sys/wait.h>
> > +#include <sys/ptrace.h>
> > +#include <sys/param.h>
> > +#include <sys/uio.h>
> > +#include <stdint.h>
> > +#include <stdbool.h>
> > +#include <stddef.h>
> > +#include <string.h>
> > +#include <stdio.h>
> > +#include <unistd.h>
> > +#include <elf.h>
>
> This is the wrong elf.h, we want the one with NT_RISCV_HW_BREAK.
>
> -#include <elf.h>
> +#include <linux/elf.h>
>
>
> > +#include <errno.h>
> > +#include <signal.h>
> > +
> > +#include "../../kselftest.h"
> > +
> > +#define MAX_BP_SIZE 8
> > +