[PATCH v2 1/6] selftests: riscv: test ptrace vector interface

[Sergey Matyukevich <geomatsi@gmail.com>]

Add a test case to check ptrace behavior in the case when vector
extension is supported by the system, but vector context is not
yet enabled for the traced process.

Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
---
 .../testing/selftests/riscv/vector/.gitignore |  1 +
 tools/testing/selftests/riscv/vector/Makefile |  5 +-
 .../testing/selftests/riscv/vector/v_ptrace.c | 87 +++++++++++++++++++
 3 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/riscv/vector/v_ptrace.c

diff --git a/tools/testing/selftests/riscv/vector/.gitignore b/tools/testing/selftests/riscv/vector/.gitignore
index 7d9c87cd0649..d21c03c3ee0e 100644
--- a/tools/testing/selftests/riscv/vector/.gitignore
+++ b/tools/testing/selftests/riscv/vector/.gitignore
@@ -2,3 +2,4 @@ vstate_exec_nolibc
 vstate_prctl
 v_initval
 v_exec_initval_nolibc
+v_ptrace
diff --git a/tools/testing/selftests/riscv/vector/Makefile b/tools/testing/selftests/riscv/vector/Makefile
index 6f7497f4e7b3..c14ad127e7fb 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 v_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)/v_ptrace: v_ptrace.c $(OUTPUT)/sys_hwprobe.o $(OUTPUT)/v_helpers.o
+	$(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
diff --git a/tools/testing/selftests/riscv/vector/v_ptrace.c b/tools/testing/selftests/riscv/vector/v_ptrace.c
new file mode 100644
index 000000000000..6a8d56a5c4f4
--- /dev/null
+++ b/tools/testing/selftests/riscv/vector/v_ptrace.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/wait.h>
+#include <sys/uio.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <linux/ptrace.h>
+#include <linux/elf.h>
+
+#include "../../kselftest_harness.h"
+#include "v_helpers.h"
+
+volatile unsigned long chld_lock;
+
+TEST(ptrace_rvv_not_enabled)
+{
+	pid_t pid;
+
+	if (!is_vector_supported())
+		SKIP(return, "Vector not supported");
+
+	chld_lock = 1;
+
+	pid = fork();
+
+	ASSERT_LE(0, pid)
+		TH_LOG("fork: %m");
+
+	if (pid == 0) {
+		while (chld_lock == 1)
+			asm volatile("" : : "g"(chld_lock) : "memory");
+
+		asm volatile ("ebreak" : : : );
+	} else {
+		struct __riscv_v_regset_state *regset_data;
+		unsigned long vlenb;
+		size_t regset_size;
+		struct iovec iov;
+		int status;
+		int ret;
+
+		asm volatile("csrr %[vlenb], vlenb" : [vlenb] "=r"(vlenb));
+
+		ASSERT_GT(vlenb, 0)
+			TH_LOG("vlenb is not valid: %lu\n", vlenb);
+
+		/* 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));
+
+		/* try to read vector registers from the tracee */
+
+		regset_size = sizeof(*regset_data) + vlenb * 32;
+		regset_data = calloc(1, regset_size);
+
+		iov.iov_base = regset_data;
+		iov.iov_len = regset_size;
+
+		/* V extension is available, but not yet enabled for the tracee */
+
+		errno = 0;
+		ret = ptrace(PTRACE_GETREGSET, pid, NT_RISCV_VECTOR, &iov);
+		ASSERT_EQ(ENODATA, errno);
+		ASSERT_EQ(-1, ret);
+
+		/* cleanup */
+
+		ASSERT_EQ(0, kill(pid, SIGKILL));
+	}
+}
+
+TEST_HARNESS_MAIN
-- 
2.51.0