selftests: riscv: Add test for the Vector ptrace interface

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@sifive.com>
Reviewed-by: Andy Chiu <andybnac@gmail.com>
Tested-by: Andy Chiu <andybnac@gmail.com>
Link: https://patch.msgid.link/20251013091318.467864-3-yongxuan.wang@sifive.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>

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 vstate_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) $^

tools/testing/selftests/riscv/vector/vstate_ptrace.c

@@ -0,0 +1,134 @@
+// 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"
+		".option	norvc\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;
+			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;
+			v_regset_hdr = (struct __riscv_v_regset_state *)data;
+			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 += 4;
+			if (do_ptrace(PTRACE_SETREGSET, child, NT_PRSTATUS, size, data))
+				goto out;
+		}
+
+		ptrace(PTRACE_CONT, child, NULL, NULL);
+	}
+
+out:
+	free(data);
+}
+
+int main(void)
+{
+	pid_t child;
+
+	ksft_set_plan(2);
+	if (!is_vector_supported() && !is_xtheadvector_supported())
+		ksft_exit_skip("Vector not supported\n");
+
+	srandom(getpid());
+	parent_set_val = rand();
+	child_set_val = rand();
+
+	child = fork();
+	if (child < 0)
+		ksft_exit_fail_msg("Fork failed %d\n", child);
+
+	if (!child)
+		return do_child();
+
+	do_parent(child);
+
+	ksft_finished();
+}