Re: [PATCH v5 6/9] selftests: riscv: verify initial vector state with ptrace

Andy Chiu
2026-01-21T21:33:43Z

Hi Sergey,

On Sun, Dec 14, 2025 at 10:35 AM Sergey Matyukevich <geomatsi@gmail.com> wrote:
>
> Add a test case that attaches to a traced process immediately after its
> first executed vector instructions to verify the initial vector context.
>
> Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>

Reviewed-by: Andy Chiu <andybnac@gmail.com>

> ---
> .../riscv/vector/validate_v_ptrace.c | 135 ++++++++++++++++++
> 1 file changed, 135 insertions(+)
>
> diff --git a/tools/testing/selftests/riscv/vector/validate_v_ptrace.c b/tools/testing/selftests/riscv/vector/validate_v_ptrace.c
> index b64986b42270..a8d64d351edd 100644
> --- a/tools/testing/selftests/riscv/vector/validate_v_ptrace.c
> +++ b/tools/testing/selftests/riscv/vector/validate_v_ptrace.c
> @@ -13,6 +13,9 @@
> #include "kselftest_harness.h"
> #include "v_helpers.h"
>
> +#define SR_FS_DIRTY 0x00006000UL
> +#define CSR_VXRM_SHIFT 1
> +
> volatile unsigned long chld_lock;
>
> TEST(ptrace_v_not_enabled)
> @@ -77,4 +80,136 @@ TEST(ptrace_v_not_enabled)
> }
> }
>
> +TEST(ptrace_v_early_debug)
> +{
> + static volatile unsigned long vstart;
> + static volatile unsigned long vtype;
> + static volatile unsigned long vlenb;
> + static volatile unsigned long vcsr;
> + static volatile unsigned long vl;
> + bool xtheadvector;
> + pid_t pid;
> +
> + if (!(is_vector_supported() || is_xtheadvector_supported()))
> + SKIP(return, "Vector not supported");
> +
> + xtheadvector = is_xtheadvector_supported();
> +
> + chld_lock = 1;
> + pid = fork();
> + ASSERT_LE(0, pid)
> + TH_LOG("fork: %m");
> +
> + if (pid == 0) {
> + unsigned long vxsat, vxrm;
> +
> + vlenb = get_vr_len();
> +
> + while (chld_lock == 1)
> + asm volatile ("" : : "g"(chld_lock) : "memory");
> +
> + asm volatile (
> + "csrr %[vstart], vstart\n"
> + "csrr %[vtype], vtype\n"
> + "csrr %[vl], vl\n"
> + : [vtype] "=r"(vtype), [vstart] "=r"(vstart), [vl] "=r"(vl)
> + :
> + : "memory");
> +
> + /* no 'is_xtheadvector_supported()' here to avoid clobbering v-state by syscall */
> + if (xtheadvector) {
> + asm volatile (
> + "csrs sstatus, %[bit]\n"
> + "csrr %[vxsat], vxsat\n"
> + "csrr %[vxrm], vxrm\n"
> + : [vxsat] "=r"(vxsat), [vxrm] "=r"(vxrm)
> + : [bit] "r" (SR_FS_DIRTY)
> + : "memory");
> + vcsr = vxsat | vxrm << CSR_VXRM_SHIFT;
> + } else {
> + asm volatile (
> + "csrr %[vcsr], vcsr\n"
> + : [vcsr] "=r"(vcsr)
> + :
> + : "memory");
> + }
> +
> + asm volatile (
> + ".option push\n"
> + ".option norvc\n"
> + "ebreak\n"
> + ".option pop\n");
> + } else {
> + struct __riscv_v_regset_state *regset_data;
> + unsigned long vstart_csr;
> + unsigned long vlenb_csr;
> + unsigned long vtype_csr;
> + unsigned long vcsr_csr;
> + unsigned long vl_csr;
> + size_t regset_size;
> + struct iovec iov;
> + int status;
> +
> + /* attach */
> +
> + ASSERT_EQ(0, ptrace(PTRACE_ATTACH, pid, NULL, NULL));
> + ASSERT_EQ(pid, waitpid(pid, &status, 0));
> + ASSERT_TRUE(WIFSTOPPED(status));
> +
> + /* unlock */
> +
> + ASSERT_EQ(0, ptrace(PTRACE_POKEDATA, pid, &chld_lock, 0));
> +
> + /* resume and wait for ebreak */
> +
> + ASSERT_EQ(0, ptrace(PTRACE_CONT, pid, NULL, NULL));
> + ASSERT_EQ(pid, waitpid(pid, &status, 0));
> + ASSERT_TRUE(WIFSTOPPED(status));
> +
> + /* read tracee vector csr regs using ptrace PEEKDATA */
> +
> + errno = 0;
> + vstart_csr = ptrace(PTRACE_PEEKDATA, pid, &vstart, NULL);
> + ASSERT_FALSE((errno != 0) && (vstart_csr == -1));
> +
> + errno = 0;
> + vl_csr = ptrace(PTRACE_PEEKDATA, pid, &vl, NULL);
> + ASSERT_FALSE((errno != 0) && (vl_csr == -1));
> +
> + errno = 0;
> + vtype_csr = ptrace(PTRACE_PEEKDATA, pid, &vtype, NULL);
> + ASSERT_FALSE((errno != 0) && (vtype_csr == -1));
> +
> + errno = 0;
> + vcsr_csr = ptrace(PTRACE_PEEKDATA, pid, &vcsr, NULL);
> + ASSERT_FALSE((errno != 0) && (vcsr_csr == -1));
> +
> + errno = 0;
> + vlenb_csr = ptrace(PTRACE_PEEKDATA, pid, &vlenb, NULL);
> + ASSERT_FALSE((errno != 0) && (vlenb_csr == -1));
> +
> + /* read tracee csr regs using ptrace GETREGSET */
> +
> + regset_size = sizeof(*regset_data) + vlenb_csr * 32;
> + regset_data = calloc(1, regset_size);
> +
> + iov.iov_base = regset_data;
> + iov.iov_len = regset_size;
> +
> + ASSERT_EQ(0, ptrace(PTRACE_GETREGSET, pid, NT_RISCV_VECTOR, &iov));
> +
> + /* compare */
> +
> + EXPECT_EQ(vstart_csr, regset_data->vstart);
> + EXPECT_EQ(vtype_csr, regset_data->vtype);
> + EXPECT_EQ(vlenb_csr, regset_data->vlenb);
> + EXPECT_EQ(vcsr_csr, regset_data->vcsr);
> + EXPECT_EQ(vl_csr, regset_data->vl);
> +
> + /* cleanup */
> +
> + ASSERT_EQ(0, kill(pid, SIGKILL));
> + }
> +}
> +
> TEST_HARNESS_MAIN
> --
> 2.52.0
>