selftests: arm64: Add utility to set SVE vector lengths

vlset is a small utility for use in conjunction with tests like the sve-test
stress test which allows another executable to be invoked with a configured
SVE vector length.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-5-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/tools/testing/selftests/arm64/fp/vlset.c b/tools/testing/selftests/arm64/fp/vlset.c
new file mode 100644 (file)
index 0000000..308d27a
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/vlset.c
@@ -0,0 +1,155 @@
+// 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 */
+}