gcs_frame.c

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (C) 2023 ARM Limited
 4 */
 5
 6#include <signal.h>
 7#include <ucontext.h>
 8#include <sys/prctl.h>
 9
10#include "test_signals_utils.h"
11#include "testcases.h"
12
13static union {
14	ucontext_t uc;
15	char buf[1024 * 64];
16} context;
17
18static int gcs_regs(struct tdescr *td, siginfo_t *si, ucontext_t *uc)
19{
20	size_t offset;
21	struct _aarch64_ctx *head = GET_BUF_RESV_HEAD(context);
22	struct gcs_context *gcs;
23	unsigned long expected, gcspr;
24	uint64_t *u64_val;
25	int ret;
26
27	ret = prctl(PR_GET_SHADOW_STACK_STATUS, &expected, 0, 0, 0);
28	if (ret != 0) {
29		fprintf(stderr, "Unable to query GCS status\n");
30		return 1;
31	}
32
33	/* We expect a cap to be added to the GCS in the signal frame */
34	gcspr = get_gcspr_el0();
35	gcspr -= 8;
36	fprintf(stderr, "Expecting GCSPR_EL0 %lx\n", gcspr);
37
38	if (!get_current_context(td, &context.uc, sizeof(context))) {
39		fprintf(stderr, "Failed getting context\n");
40		return 1;
41	}
42
43	/* Ensure that the signal restore token was consumed */
44	u64_val = (uint64_t *)get_gcspr_el0() + 1;
45	if (*u64_val) {
46		fprintf(stderr, "GCS value at %p is %lx not 0\n",
47			u64_val, *u64_val);
48		return 1;
49	}
50
51	fprintf(stderr, "Got context\n");
52
53	head = get_header(head, GCS_MAGIC, GET_BUF_RESV_SIZE(context),
54			  &offset);
55	if (!head) {
56		fprintf(stderr, "No GCS context\n");
57		return 1;
58	}
59
60	gcs = (struct gcs_context *)head;
61
62	/* Basic size validation is done in get_current_context() */
63
64	if (gcs->features_enabled != expected) {
65		fprintf(stderr, "Features enabled %llx but expected %lx\n",
66			gcs->features_enabled, expected);
67		return 1;
68	}
69
70	if (gcs->gcspr != gcspr) {
71		fprintf(stderr, "Got GCSPR %llx but expected %lx\n",
72			gcs->gcspr, gcspr);
73		return 1;
74	}
75
76	fprintf(stderr, "GCS context validated\n");
77	td->pass = 1;
78
79	return 0;
80}
81
82struct tdescr tde = {
83	.name = "GCS basics",
84	.descr = "Validate a GCS signal context",
85	.feats_required = FEAT_GCS,
86	.timeout = 3,
87	.run = gcs_regs,
88};