Re: [PATCH v2 1/4] kselftest/arm64: Add test coverage for NT_ARM_TLS

[Luis Machado <luis.machado@arm.com>]

On 8/15/22 14:30, Mark Brown wrote:
> In preparation for extending support for NT_ARM_TLS to cover additional
> TPIDRs add some tests for the existing interface. Do this in a generic
> ptrace test program to provide a place to collect additional tests in
> the future.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>   tools/testing/selftests/arm64/abi/.gitignore |   1 +
>   tools/testing/selftests/arm64/abi/Makefile   |   2 +-
>   tools/testing/selftests/arm64/abi/ptrace.c   | 165 +++++++++++++++++++
>   3 files changed, 167 insertions(+), 1 deletion(-)
>   create mode 100644 tools/testing/selftests/arm64/abi/ptrace.c
> 
> diff --git a/tools/testing/selftests/arm64/abi/.gitignore b/tools/testing/selftests/arm64/abi/.gitignore
> index b9e54417250d..12607c4580c6 100644
> --- a/tools/testing/selftests/arm64/abi/.gitignore
> +++ b/tools/testing/selftests/arm64/abi/.gitignore
> @@ -1,2 +1,3 @@
> +ptrace
>   syscall-abi
>   tpidr2
> diff --git a/tools/testing/selftests/arm64/abi/Makefile b/tools/testing/selftests/arm64/abi/Makefile
> index c8d7f2495eb2..445ac2dac4ee 100644
> --- a/tools/testing/selftests/arm64/abi/Makefile
> +++ b/tools/testing/selftests/arm64/abi/Makefile
> @@ -1,7 +1,7 @@
>   # SPDX-License-Identifier: GPL-2.0
>   # Copyright (C) 2021 ARM Limited
>   
> -TEST_GEN_PROGS := syscall-abi tpidr2
> +TEST_GEN_PROGS := ptrace syscall-abi tpidr2
>   
>   include ../../lib.mk
>   
> diff --git a/tools/testing/selftests/arm64/abi/ptrace.c b/tools/testing/selftests/arm64/abi/ptrace.c
> new file mode 100644
> index 000000000000..4cc4d415b2e7
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/abi/ptrace.c
> @@ -0,0 +1,165 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2021 ARM Limited.

I suppose 2021 -> 2022?

> + */
> +#include <errno.h>
> +#include <stdbool.h>
> +#include <stddef.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/auxv.h>
> +#include <sys/prctl.h>
> +#include <sys/ptrace.h>
> +#include <sys/types.h>
> +#include <sys/uio.h>
> +#include <sys/wait.h>
> +#include <asm/sigcontext.h>
> +#include <asm/ptrace.h>
> +
> +#include "../../kselftest.h"
> +
> +#define EXPECTED_TESTS 3
> +
> +#define MAX_TPIDRS 1
> +
> +static bool have_sme(void)
> +{
> +	return getauxval(AT_HWCAP2) & HWCAP2_SME;
> +}
> +
> +static void test_tpidr(pid_t child)
> +{
> +	uint64_t read_val[MAX_TPIDRS];
> +	uint64_t write_val[MAX_TPIDRS];
> +	struct iovec read_iov, write_iov;
> +	int ret;
> +
> +	read_iov.iov_base = read_val;
> +	write_iov.iov_base = write_val;
> +
> +	/* Should be able to read a single TPIDR... */
> +	read_iov.iov_len = sizeof(uint64_t);
> +	ret = ptrace(PTRACE_GETREGSET, child, NT_ARM_TLS, &read_iov);
> +	ksft_test_result(ret == 0, "read_tpidr_one\n");
> +
> +	/* ...write a new value.. */
> +	write_iov.iov_len = sizeof(uint64_t);
> +	write_val[0] = read_val[0]++;
> +	ret = ptrace(PTRACE_SETREGSET, child, NT_ARM_TLS, &write_iov);
> +	ksft_test_result(ret == 0, "write_tpidr_one\n");
> +
> +	/* ...then read it back */
> +	ret = ptrace(PTRACE_GETREGSET, child, NT_ARM_TLS, &read_iov);
> +	ksft_test_result(ret == 0 && write_val[0] == read_val[0],
> +			 "verify_tpidr_one\n");
> +}
> +
> +static int do_child(void)
> +{
> +	if (ptrace(PTRACE_TRACEME, -1, NULL, NULL))
> +		ksft_exit_fail_msg("PTRACE_TRACEME", strerror(errno));
> +
> +	if (raise(SIGSTOP))
> +		ksft_exit_fail_msg("raise(SIGSTOP)", strerror(errno));
> +
> +	return EXIT_SUCCESS;
> +}
> +
> +static int do_parent(pid_t child)
> +{
> +	int ret = EXIT_FAILURE;
> +	pid_t pid;
> +	int status;
> +	siginfo_t si;
> +
> +	/* Attach to the child */
> +	while (1) {
> +		int sig;
> +
> +		pid = wait(&status);
> +		if (pid == -1) {
> +			perror("wait");
> +			goto error;
> +		}
> +
> +		/*
> +		 * This should never happen but it's hard to flag in
> +		 * the framework.
> +		 */
> +		if (pid != child)
> +			continue;
> +
> +		if (WIFEXITED(status) || WIFSIGNALED(status))
> +			ksft_exit_fail_msg("Child died unexpectedly\n");
> +
> +		if (!WIFSTOPPED(status))
> +			goto error;
> +
> +		sig = WSTOPSIG(status);
> +
> +		if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &si)) {
> +			if (errno == ESRCH)
> +				goto disappeared;
> +
> +			if (errno == EINVAL) {
> +				sig = 0; /* bust group-stop */
> +				goto cont;
> +			}
> +
> +			ksft_test_result_fail("PTRACE_GETSIGINFO: %s\n",
> +					      strerror(errno));
> +			goto error;
> +		}
> +
> +		if (sig == SIGSTOP && si.si_code == SI_TKILL &&
> +		    si.si_pid == pid)
> +			break;
> +
> +	cont:
> +		if (ptrace(PTRACE_CONT, pid, NULL, sig)) {
> +			if (errno == ESRCH)
> +				goto disappeared;
> +
> +			ksft_test_result_fail("PTRACE_CONT: %s\n",
> +					      strerror(errno));
> +			goto error;
> +		}
> +	}
> +
> +	ksft_print_msg("Parent is %d, child is %d\n", getpid(), child);
> +
> +	test_tpidr(child);
> +
> +	ret = EXIT_SUCCESS;
> +
> +error:
> +	kill(child, SIGKILL);
> +
> +disappeared:
> +	return ret;
> +}
> +
> +int main(void)
> +{
> +	int ret = EXIT_SUCCESS;
> +	pid_t child;
> +
> +	srandom(getpid());
> +
> +	ksft_print_header();
> +
> +	ksft_set_plan(EXPECTED_TESTS);
> +
> +	child = fork();
> +	if (!child)
> +		return do_child();
> +
> +	if (do_parent(child))
> +		ret = EXIT_FAILURE;
> +
> +	ksft_print_cnts();
> +
> +	return ret;
> +}