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selftests: arm64: Add test for the SVE ptrace interface
Add a test case that does some basic verification of the SVE ptrace interface, forking off a child with known values in the registers and then using ptrace to inspect and manipulate the SVE registers of the child, including in FPSIMD mode to account for sharing between the SVE and FPSIMD registers. This program was written by Dave Martin and modified for kselftest by me. Signed-off-by: Mark Brown <broonie@kernel.org> Acked-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Shuah Khan <skhan@linuxfoundation.org> Link: https://lore.kernel.org/r/20200819114837.51466-3-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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‎tools/testing/selftests/arm64/fp/sve-ptrace-asm.S‎

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// SPDX-License-Identifier: GPL-2.0-only
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// Copyright (C) 2015-2019 ARM Limited.
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// Original author: Dave Martin <Dave.Martin@arm.com>
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#include <asm/unistd.h>
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.arch_extension sve
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.globl sve_store_patterns
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sve_store_patterns:
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mov x1, x0
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index z0.b, #0, #1
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str q0, [x1]
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mov w8, #__NR_getpid
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svc #0
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str q0, [x1, #0x10]
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mov z1.d, z0.d
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str q0, [x1, #0x20]
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mov w8, #__NR_getpid
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svc #0
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str q0, [x1, #0x30]
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mov z1.d, z0.d
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str q0, [x1, #0x40]
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ret
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.size sve_store_patterns, . - sve_store_patterns
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.type sve_store_patterns, @function

‎tools/testing/selftests/arm64/fp/sve-ptrace.c‎

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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2015-2020 ARM Limited.
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* Original author: Dave Martin <Dave.Martin@arm.com>
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*/
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#include <errno.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/auxv.h>
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#include <sys/ptrace.h>
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#include <sys/types.h>
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#include <sys/uio.h>
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#include <sys/wait.h>
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#include <asm/sigcontext.h>
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#include <asm/ptrace.h>
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#include "../../kselftest.h"
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/* <linux/elf.h> and <sys/auxv.h> don't like each other, so: */
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#ifndef NT_ARM_SVE
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#define NT_ARM_SVE 0x405
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#endif
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/* Number of registers filled in by sve_store_patterns */
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#define NR_VREGS 5
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void sve_store_patterns(__uint128_t v[NR_VREGS]);
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static void dump(const void *buf, size_t size)
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{
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size_t i;
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const unsigned char *p = buf;
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for (i = 0; i < size; ++i)
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printf(" %.2x", *p++);
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}
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static int check_vregs(const __uint128_t vregs[NR_VREGS])
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{
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int i;
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int ok = 1;
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for (i = 0; i < NR_VREGS; ++i) {
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printf("# v[%d]:", i);
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dump(&vregs[i], sizeof vregs[i]);
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putchar('\n');
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if (vregs[i] != vregs[0])
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ok = 0;
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}
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return ok;
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}
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static int do_child(void)
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{
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if (ptrace(PTRACE_TRACEME, -1, NULL, NULL))
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ksft_exit_fail_msg("PTRACE_TRACEME", strerror(errno));
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if (raise(SIGSTOP))
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ksft_exit_fail_msg("raise(SIGSTOP)", strerror(errno));
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return EXIT_SUCCESS;
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}
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static struct user_sve_header *get_sve(pid_t pid, void **buf, size_t *size)
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{
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struct user_sve_header *sve;
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void *p;
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size_t sz = sizeof *sve;
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struct iovec iov;
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while (1) {
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if (*size < sz) {
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p = realloc(*buf, sz);
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if (!p) {
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errno = ENOMEM;
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goto error;
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}
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*buf = p;
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*size = sz;
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}
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iov.iov_base = *buf;
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iov.iov_len = sz;
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if (ptrace(PTRACE_GETREGSET, pid, NT_ARM_SVE, &iov))
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goto error;
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sve = *buf;
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if (sve->size <= sz)
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break;
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sz = sve->size;
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}
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return sve;
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error:
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return NULL;
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}
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static int set_sve(pid_t pid, const struct user_sve_header *sve)
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{
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struct iovec iov;
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iov.iov_base = (void *)sve;
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iov.iov_len = sve->size;
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return ptrace(PTRACE_SETREGSET, pid, NT_ARM_SVE, &iov);
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}
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static void dump_sve_regs(const struct user_sve_header *sve, unsigned int num,
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unsigned int vlmax)
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{
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unsigned int vq;
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unsigned int i;
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if ((sve->flags & SVE_PT_REGS_MASK) != SVE_PT_REGS_SVE)
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ksft_exit_fail_msg("Dumping non-SVE register\n");
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if (vlmax > sve->vl)
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vlmax = sve->vl;
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vq = sve_vq_from_vl(sve->vl);
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for (i = 0; i < num; ++i) {
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printf("# z%u:", i);
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dump((const char *)sve + SVE_PT_SVE_ZREG_OFFSET(vq, i),
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vlmax);
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printf("%s\n", vlmax == sve->vl ? "" : " ...");
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}
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}
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static int do_parent(pid_t child)
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{
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int ret = EXIT_FAILURE;
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pid_t pid;
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int status;
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siginfo_t si;
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void *svebuf = NULL, *newsvebuf;
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size_t svebufsz = 0, newsvebufsz;
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struct user_sve_header *sve, *new_sve;
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struct user_fpsimd_state *fpsimd;
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unsigned int i, j;
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unsigned char *p;
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unsigned int vq;
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/* Attach to the child */
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while (1) {
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int sig;
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pid = wait(&status);
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if (pid == -1) {
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perror("wait");
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goto error;
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}
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/*
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* This should never happen but it's hard to flag in
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* the framework.
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*/
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if (pid != child)
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continue;
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if (WIFEXITED(status) || WIFSIGNALED(status))
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ksft_exit_fail_msg("Child died unexpectedly\n");
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ksft_test_result(WIFSTOPPED(status), "WIFSTOPPED(%d)\n",
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status);
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if (!WIFSTOPPED(status))
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goto error;
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sig = WSTOPSIG(status);
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if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &si)) {
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if (errno == ESRCH)
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goto disappeared;
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if (errno == EINVAL) {
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sig = 0; /* bust group-stop */
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goto cont;
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}
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ksft_test_result_fail("PTRACE_GETSIGINFO: %s\n",
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strerror(errno));
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goto error;
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}
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if (sig == SIGSTOP && si.si_code == SI_TKILL &&
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si.si_pid == pid)
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break;
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cont:
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if (ptrace(PTRACE_CONT, pid, NULL, sig)) {
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if (errno == ESRCH)
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goto disappeared;
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ksft_test_result_fail("PTRACE_CONT: %s\n",
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strerror(errno));
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goto error;
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}
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}
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sve = get_sve(pid, &svebuf, &svebufsz);
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if (!sve) {
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int e = errno;
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ksft_test_result_fail("get_sve: %s\n", strerror(errno));
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if (e == ESRCH)
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goto disappeared;
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goto error;
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} else {
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ksft_test_result_pass("get_sve\n");
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}
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ksft_test_result((sve->flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD,
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"FPSIMD registers\n");
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if ((sve->flags & SVE_PT_REGS_MASK) != SVE_PT_REGS_FPSIMD)
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goto error;
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fpsimd = (struct user_fpsimd_state *)((char *)sve +
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SVE_PT_FPSIMD_OFFSET);
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for (i = 0; i < 32; ++i) {
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p = (unsigned char *)&fpsimd->vregs[i];
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for (j = 0; j < sizeof fpsimd->vregs[i]; ++j)
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p[j] = j;
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}
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if (set_sve(pid, sve)) {
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int e = errno;
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ksft_test_result_fail("set_sve(FPSIMD): %s\n",
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strerror(errno));
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if (e == ESRCH)
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goto disappeared;
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goto error;
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}
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vq = sve_vq_from_vl(sve->vl);
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newsvebufsz = SVE_PT_SVE_ZREG_OFFSET(vq, 1);
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new_sve = newsvebuf = malloc(newsvebufsz);
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if (!new_sve) {
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errno = ENOMEM;
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perror(NULL);
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goto error;
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}
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*new_sve = *sve;
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new_sve->flags &= ~SVE_PT_REGS_MASK;
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new_sve->flags |= SVE_PT_REGS_SVE;
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memset((char *)new_sve + SVE_PT_SVE_ZREG_OFFSET(vq, 0),
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0, SVE_PT_SVE_ZREG_SIZE(vq));
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new_sve->size = SVE_PT_SVE_ZREG_OFFSET(vq, 1);
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if (set_sve(pid, new_sve)) {
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int e = errno;
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ksft_test_result_fail("set_sve(ZREG): %s\n", strerror(errno));
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if (e == ESRCH)
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goto disappeared;
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goto error;
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}
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new_sve = get_sve(pid, &newsvebuf, &newsvebufsz);
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if (!new_sve) {
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int e = errno;
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ksft_test_result_fail("get_sve(ZREG): %s\n", strerror(errno));
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if (e == ESRCH)
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goto disappeared;
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goto error;
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}
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ksft_test_result((new_sve->flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_SVE,
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"SVE registers\n");
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if ((new_sve->flags & SVE_PT_REGS_MASK) != SVE_PT_REGS_SVE)
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goto error;
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dump_sve_regs(new_sve, 3, sizeof fpsimd->vregs[0]);
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p = (unsigned char *)new_sve + SVE_PT_SVE_ZREG_OFFSET(vq, 1);
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for (i = 0; i < sizeof fpsimd->vregs[0]; ++i) {
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unsigned char expected = i;
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if (__BYTE_ORDER == __BIG_ENDIAN)
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expected = sizeof fpsimd->vregs[0] - 1 - expected;
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ksft_test_result(p[i] == expected, "p[%d] == expected\n", i);
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if (p[i] != expected)
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goto error;
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}
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ret = EXIT_SUCCESS;
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error:
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kill(child, SIGKILL);
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disappeared:
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return ret;
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}
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int main(void)
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{
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int ret = EXIT_SUCCESS;
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__uint128_t v[NR_VREGS];
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pid_t child;
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ksft_print_header();
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ksft_set_plan(20);
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if (!(getauxval(AT_HWCAP) & HWCAP_SVE))
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ksft_exit_skip("SVE not available\n");
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sve_store_patterns(v);
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if (!check_vregs(v))
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ksft_exit_fail_msg("Initial check_vregs() failed\n");
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child = fork();
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if (!child)
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return do_child();
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if (do_parent(child))
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ret = EXIT_FAILURE;
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ksft_print_cnts();
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return 0;
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}

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