selftests: arm64: Add utility to set SVE vector lengths

// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright (C) 2015-2019 ARM Limited.

 * Original author: Dave Martin <Dave.Martin@arm.com>

 */

#define _GNU_SOURCE

#include <assert.h>

#include <errno.h>

#include <limits.h>

#include <stddef.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <getopt.h>

#include <unistd.h>

#include <sys/auxv.h>

#include <sys/prctl.h>

#include <asm/hwcap.h>

#include <asm/sigcontext.h>

static int inherit = 0;

static int no_inherit = 0;

static int force = 0;

static unsigned long vl;

static const struct option options[] = {

	{ "force",	no_argument, NULL, 'f' },

	{ "inherit",	no_argument, NULL, 'i' },

	{ "max",	no_argument, NULL, 'M' },

	{ "no-inherit",	no_argument, &no_inherit, 1 },

	{ "help",	no_argument, NULL, '?' },

	{}

};

static char const *program_name;

static int parse_options(int argc, char **argv)

{

	int c;

	char *rest;

	program_name = strrchr(argv[0], '/');

	if (program_name)

		++program_name;

	else

		program_name = argv[0];

	while ((c = getopt_long(argc, argv, "Mfhi", options, NULL)) != -1)

		switch (c) {

		case 'M':	vl = SVE_VL_MAX; break;

		case 'f':	force = 1; break;

		case 'i':	inherit = 1; break;

		case 0:		break;

		default:	goto error;

		}

	if (inherit && no_inherit)

		goto error;

	if (!vl) {

		/* vector length */

		if (optind >= argc)

			goto error;

		errno = 0;

		vl = strtoul(argv[optind], &rest, 0);

		if (*rest) {

			vl = ULONG_MAX;

			errno = EINVAL;

		}

		if (vl == ULONG_MAX && errno) {

			fprintf(stderr, "%s: %s: %s\n",

				program_name, argv[optind], strerror(errno));

			goto error;

		}

		++optind;

	}

	/* command */

	if (optind >= argc)

		goto error;

	return 0;

error:

	fprintf(stderr,

		"Usage: %s [-f | --force] "

		"[-i | --inherit | --no-inherit] "

		"{-M | --max | <vector length>} "

		"<command> [<arguments> ...]\n",

		program_name);

	return -1;

}

int main(int argc, char **argv)

{

	int ret = 126;	/* same as sh(1) command-not-executable error */

	long flags;

	char *path;

	int t, e;

	if (parse_options(argc, argv))

		return 2;	/* same as sh(1) builtin incorrect-usage */

	if (vl & ~(vl & PR_SVE_VL_LEN_MASK)) {

		fprintf(stderr, "%s: Invalid vector length %lu\n",

			program_name, vl);

		return 2;	/* same as sh(1) builtin incorrect-usage */

	}

	if (!(getauxval(AT_HWCAP) & HWCAP_SVE)) {

		fprintf(stderr, "%s: Scalable Vector Extension not present\n",

			program_name);

		if (!force)

			goto error;

		fputs("Going ahead anyway (--force):  "

		      "This is a debug option.  Don't rely on it.\n",

		      stderr);

	}

	flags = PR_SVE_SET_VL_ONEXEC;

	if (inherit)

		flags |= PR_SVE_VL_INHERIT;

	t = prctl(PR_SVE_SET_VL, vl | flags);

	if (t < 0) {

		fprintf(stderr, "%s: PR_SVE_SET_VL: %s\n",

			program_name, strerror(errno));

		goto error;

	}

	t = prctl(PR_SVE_GET_VL);

	if (t == -1) {

		fprintf(stderr, "%s: PR_SVE_GET_VL: %s\n",

			program_name, strerror(errno));

		goto error;

	}

	flags = PR_SVE_VL_LEN_MASK;

	flags = t & ~flags;

	assert(optind < argc);

	path = argv[optind];

	execvp(path, &argv[optind]);

	e = errno;

	if (errno == ENOENT)

		ret = 127;	/* same as sh(1) not-found error */

	fprintf(stderr, "%s: %s: %s\n", program_name, path, strerror(e));

error:

	return ret;		/* same as sh(1) not-executable error */

}