vlset.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2015-2019 ARM Limited.
  4 * Original author: Dave Martin <Dave.Martin@arm.com>
  5 */
  6#define _GNU_SOURCE
  7#include <assert.h>
  8#include <errno.h>
  9#include <limits.h>
 10#include <stddef.h>
 11#include <stdio.h>
 12#include <stdlib.h>
 13#include <string.h>
 14#include <getopt.h>
 15#include <unistd.h>
 16#include <sys/auxv.h>
 17#include <sys/prctl.h>
 18#include <asm/hwcap.h>
 19#include <asm/sigcontext.h>
 20
 21static int inherit = 0;
 22static int no_inherit = 0;
 23static int force = 0;
 24static unsigned long vl;
 25static int set_ctl = PR_SVE_SET_VL;
 26static int get_ctl = PR_SVE_GET_VL;
 27
 28static const struct option options[] = {
 29	{ "force",	no_argument, NULL, 'f' },
 30	{ "inherit",	no_argument, NULL, 'i' },
 31	{ "max",	no_argument, NULL, 'M' },
 32	{ "no-inherit",	no_argument, &no_inherit, 1 },
 33	{ "sme",	no_argument, NULL, 's' },
 34	{ "help",	no_argument, NULL, '?' },
 35	{}
 36};
 37
 38static char const *program_name;
 39
 40static int parse_options(int argc, char **argv)
 41{
 42	int c;
 43	char *rest;
 44
 45	program_name = strrchr(argv[0], '/');
 46	if (program_name)
 47		++program_name;
 48	else
 49		program_name = argv[0];
 50
 51	while ((c = getopt_long(argc, argv, "Mfhi", options, NULL)) != -1)
 52		switch (c) {
 53		case 'M':	vl = SVE_VL_MAX; break;
 54		case 'f':	force = 1; break;
 55		case 'i':	inherit = 1; break;
 56		case 's':	set_ctl = PR_SME_SET_VL;
 57				get_ctl = PR_SME_GET_VL;
 58				break;
 59		case 0:		break;
 60		default:	goto error;
 61		}
 62
 63	if (inherit && no_inherit)
 64		goto error;
 65
 66	if (!vl) {
 67		/* vector length */
 68		if (optind >= argc)
 69			goto error;
 70
 71		errno = 0;
 72		vl = strtoul(argv[optind], &rest, 0);
 73		if (*rest) {
 74			vl = ULONG_MAX;
 75			errno = EINVAL;
 76		}
 77		if (vl == ULONG_MAX && errno) {
 78			fprintf(stderr, "%s: %s: %s\n",
 79				program_name, argv[optind], strerror(errno));
 80			goto error;
 81		}
 82
 83		++optind;
 84	}
 85
 86	/* command */
 87	if (optind >= argc)
 88		goto error;
 89
 90	return 0;
 91
 92error:
 93	fprintf(stderr,
 94		"Usage: %s [-f | --force] "
 95		"[-i | --inherit | --no-inherit] "
 96		"{-M | --max | <vector length>} "
 97		"<command> [<arguments> ...]\n",
 98		program_name);
 99	return -1;
100}
101
102int main(int argc, char **argv)
103{
104	int ret = 126;	/* same as sh(1) command-not-executable error */
105	long flags;
106	char *path;
107	int t, e;
108
109	if (parse_options(argc, argv))
110		return 2;	/* same as sh(1) builtin incorrect-usage */
111
112	if (vl & ~(vl & PR_SVE_VL_LEN_MASK)) {
113		fprintf(stderr, "%s: Invalid vector length %lu\n",
114			program_name, vl);
115		return 2;	/* same as sh(1) builtin incorrect-usage */
116	}
117
118	if (!(getauxval(AT_HWCAP) & HWCAP_SVE)) {
119		fprintf(stderr, "%s: Scalable Vector Extension not present\n",
120			program_name);
121
122		if (!force)
123			goto error;
124
125		fputs("Going ahead anyway (--force):  "
126		      "This is a debug option.  Don't rely on it.\n",
127		      stderr);
128	}
129
130	flags = PR_SVE_SET_VL_ONEXEC;
131	if (inherit)
132		flags |= PR_SVE_VL_INHERIT;
133
134	t = prctl(set_ctl, vl | flags);
135	if (t < 0) {
136		fprintf(stderr, "%s: PR_SVE_SET_VL: %s\n",
137			program_name, strerror(errno));
138		goto error;
139	}
140
141	t = prctl(get_ctl);
142	if (t == -1) {
143		fprintf(stderr, "%s: PR_SVE_GET_VL: %s\n",
144			program_name, strerror(errno));
145		goto error;
146	}
147	flags = PR_SVE_VL_LEN_MASK;
148	flags = t & ~flags;
149
150	assert(optind < argc);
151	path = argv[optind];
152
153	execvp(path, &argv[optind]);
154	e = errno;
155	if (errno == ENOENT)
156		ret = 127;	/* same as sh(1) not-found error */
157	fprintf(stderr, "%s: %s: %s\n", program_name, path, strerror(e));
158
159error:
160	return ret;		/* same as sh(1) not-executable error */
161}