xref: /linux/tools/testing/selftests/arm64/signal/testcases/gcs_frame.c (revision 9208c05f9fdfd927ea160b97dfef3c379049fff2)
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 
13 static union {
14 	ucontext_t uc;
15 	char buf[1024 * 64];
16 } context;
17 
18 static 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 
82 struct 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 };
89