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Message-ID: <CAFTtA3MSxexbb8b063rfST1QDtj8Urhg9VCuDSCnpezW9_BAqQ@mail.gmail.com>
Date: Wed, 1 Oct 2025 10:12:50 -0500
From: Andy Chiu <andybnac@...il.com>
To: Yong-Xuan Wang <yongxuan.wang@...ive.com>
Cc: linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
greentime.hu@...ive.com, vincent.chen@...ive.com,
Shuah Khan <shuah@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
Alexandre Ghiti <alex@...ti.fr>, Charlie Jenkins <charlie@...osinc.com>, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v 2/2] selftests: riscv: Add test for the Vector ptrace interface
Hi Yong-Xuan,
On Wed, Oct 1, 2025 at 6:15 AM Yong-Xuan Wang <yongxuan.wang@...ive.com> wrote:
>
> Add a test case that does some basic verification of the Vector ptrace
> interface. This forks a child process then using ptrace to inspect and
> manipulate the v31 register of the child.
>
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@...ive.com>
> ---
> tools/testing/selftests/riscv/vector/Makefile | 5 +-
> .../selftests/riscv/vector/vstate_ptrace.c | 132 ++++++++++++++++++
> 2 files changed, 136 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/riscv/vector/vstate_ptrace.c
>
> diff --git a/tools/testing/selftests/riscv/vector/Makefile b/tools/testing/selftests/riscv/vector/Makefile
> index 6f7497f4e7b3..45f25e9dd264 100644
> --- a/tools/testing/selftests/riscv/vector/Makefile
> +++ b/tools/testing/selftests/riscv/vector/Makefile
> @@ -2,7 +2,7 @@
> # Copyright (C) 2021 ARM Limited
> # Originally tools/testing/arm64/abi/Makefile
>
> -TEST_GEN_PROGS := v_initval vstate_prctl
> +TEST_GEN_PROGS := v_initval vstate_prctl vsate_ptrace
> TEST_GEN_PROGS_EXTENDED := vstate_exec_nolibc v_exec_initval_nolibc
>
> include ../../lib.mk
> @@ -26,3 +26,6 @@ $(OUTPUT)/v_initval: v_initval.c $(OUTPUT)/sys_hwprobe.o $(OUTPUT)/v_helpers.o
> $(OUTPUT)/v_exec_initval_nolibc: v_exec_initval_nolibc.c
> $(CC) -nostdlib -static -include ../../../../include/nolibc/nolibc.h \
> -Wall $(CFLAGS) $(LDFLAGS) $^ -o $@ -lgcc
> +
> +$(OUTPUT)/vstate_ptrace: vstate_ptrace.c $(OUTPUT)/sys_hwprobe.o $(OUTPUT)/v_helpers.o
> + $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
> diff --git a/tools/testing/selftests/riscv/vector/vstate_ptrace.c b/tools/testing/selftests/riscv/vector/vstate_ptrace.c
> new file mode 100644
> index 000000000000..8a7bcf318e59
> --- /dev/null
> +++ b/tools/testing/selftests/riscv/vector/vstate_ptrace.c
> @@ -0,0 +1,132 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <asm/ptrace.h>
> +#include <linux/elf.h>
> +#include <sys/ptrace.h>
> +#include <sys/uio.h>
> +#include <sys/wait.h>
> +#include "../../kselftest.h"
> +#include "v_helpers.h"
> +
> +int parent_set_val, child_set_val;
> +
> +static long do_ptrace(enum __ptrace_request op, pid_t pid, long type, size_t size, void *data)
> +{
> + struct iovec v_iovec = {
> + .iov_len = size,
> + .iov_base = data
> + };
> +
> + return ptrace(op, pid, type, &v_iovec);
> +}
> +
> +static int do_child(void)
> +{
> + int out;
> +
> + if (ptrace(PTRACE_TRACEME, -1, NULL, NULL)) {
> + ksft_perror("PTRACE_TRACEME failed\n");
> + return EXIT_FAILURE;
> + }
> +
> + asm volatile (".option push\n\t"
> + ".option arch, +v\n\t"
> + "vsetivli x0, 1, e32, m1, ta, ma\n\t"
> + "vmv.s.x v31, %[in]\n\t"
> + "ebreak\n\t"
> + "vmv.x.s %[out], v31\n\t"
> + ".option pop\n\t"
> + : [out] "=r" (out)
> + : [in] "r" (child_set_val));
> +
> + if (out != parent_set_val)
> + return EXIT_FAILURE;
> +
> + return EXIT_SUCCESS;
> +}
> +
> +static void do_parent(pid_t child)
> +{
> + int status;
> + void *data = NULL;
> +
> + /* Attach to the child */
> + while (waitpid(child, &status, 0)) {
> + if (WIFEXITED(status)) {
> + ksft_test_result(WEXITSTATUS(status) == 0, "SETREGSET vector\n");
> + goto out;
> + } else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) {
> + size_t size, t;
> + void *data, *v31;
> + struct __riscv_v_regset_state *v_regset_hdr;
> + struct user_regs_struct *gpreg;
> +
> + size = sizeof(*v_regset_hdr);
> + data = malloc(size);
> + if (!data)
> + goto out;
> + v_regset_hdr = (struct __riscv_v_regset_state *)data;
> +
> + if (do_ptrace(PTRACE_GETREGSET, child, NT_RISCV_VECTOR, size, data))
> + goto out;
> +
> + ksft_print_msg("vlenb %ld\n", v_regset_hdr->vlenb);
> + data = realloc(data, size + v_regset_hdr->vlenb * 32);
> + if (!data)
> + goto out;
> + v31 = (void *)(data + size + v_regset_hdr->vlenb * 31);
> + size += v_regset_hdr->vlenb * 32;
> +
> + if (do_ptrace(PTRACE_GETREGSET, child, NT_RISCV_VECTOR, size, data))
> + goto out;
> +
> + ksft_test_result(*(int *)v31 == child_set_val, "GETREGSET vector\n");
> +
> + *(int *)v31 = parent_set_val;
> + if (do_ptrace(PTRACE_SETREGSET, child, NT_RISCV_VECTOR, size, data))
> + goto out;
> +
> + /* move the pc forward */
> + size = sizeof(*gpreg);
> + data = realloc(data, size);
> + gpreg = (struct user_regs_struct *)data;
> +
> + if (do_ptrace(PTRACE_GETREGSET, child, NT_PRSTATUS, size, data))
> + goto out;
> +
> + gpreg->pc += 2;
Just nitpicking here, simply adding 2 may fail if the program is not
compiled with C. You may either +=4 and use ".option norvc" in the asm
or determine the size of ebreak by decoding it.
with or without the fix,
Reviewed-by: Andy Chiu <andybnac@...il.com>
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