linux-kernel - Re: [PATCH v3 6/9] selftests/arm64: Split ptrace, use ifdeffery

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Date: Tue, 25 Jun 2024 19:13:37 +0100
From: Mark Brown <broonie@...nel.org>
To: Dev Jain <dev.jain@....com>
Cc: shuah@...nel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kselftest@...r.kernel.org, Catalin.Marinas@....com,
	will@...nel.org, ryan.roberts@....com, rob.herring@....com,
	mark.rutland@....com, linux@...linux.org.uk, suzuki.poulose@....com,
	Anshuman.Khandual@....com, aneesh.kumar@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 6/9] selftests/arm64: Split ptrace, use ifdeffery

On Tue, Jun 25, 2024 at 05:54:05PM +0530, Dev Jain wrote:

> --- /dev/null
> +++ b/tools/testing/selftests/arm64/abi/ptrace.h
> @@ -0,0 +1,135 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2024 ARM Limited.
> + */

> +#include "../../kselftest.h"
> +
> +static void run_tests(pid_t child);
> +
> +static int do_child(void);
> +
> +#ifdef __aarch64__
> +static bool have_sme(void)
> +{
> +	return getauxval(AT_HWCAP2) & HWCAP2_SME;
> +}

> +static void test_hw_debug(pid_t child, int type, const char *type_name)
> +{
> +	struct user_hwdebug_state state;
> +	struct iovec iov;
> +	int slots, arch, ret;
> +
> +	iov.iov_len = sizeof(state);
> +	iov.iov_base = &state;
> +
> +	/* Should be able to read the values */
> +	ret = ptrace(PTRACE_GETREGSET, child, type, &iov);
> +	ksft_test_result(ret == 0, "read_%s\n", type_name);

This feels like it's pulling way too much stuff out into the header.  I
think some of this needs to be a C file that gets built for both
architectures with some mechanism they can use to run tests, and a
library of any shared tests.

> +
> +	if (ret == 0) {
> +		/* Low 8 bits is the number of slots, next 4 bits the arch */
> +		slots = state.dbg_info & 0xff;
> +		arch = (state.dbg_info >> 8) & 0xf;
> +
> +		ksft_print_msg("%s version %d with %d slots\n", type_name,
> +			       arch, slots);
> +
> +		/* Zero is not currently architecturally valid */
> +		ksft_test_result(arch, "%s_arch_set\n", type_name);
> +	} else {
> +		ksft_test_result_skip("%s_arch_set\n", type_name);
> +	}
> +}
> +#endif
> +
> +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 (sig == SIGTRAP)
> +			ksft_print_msg("Child received SIGTRAP\n");
> +
> +		if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &si)) {
> +			if (errno == ESRCH)
> +				goto disappeared;
> +
> +			if (errno == EINVAL)
> +				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:
> +		/* bust group-stop */
> +		if (ptrace(PTRACE_CONT, pid, NULL, 0)) {
> +			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);
> +
> +	ret = EXIT_SUCCESS;
> +	run_tests(child);
> +
> +error:
> +	kill(child, SIGKILL);
> +
> +disappeared:
> +	return ret;
> +}
> -- 
> 2.39.2
> 

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