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Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2023 ARM Limited.
4 */
5
6#ifndef GCS_UTIL_H
7#define GCS_UTIL_H
8
9#include <stdbool.h>
10
11#ifndef __NR_map_shadow_stack
12#define __NR_map_shadow_stack 453
13#endif
14
15#ifndef __NR_prctl
16#define __NR_prctl 167
17#endif
18
19#ifndef NT_ARM_GCS
20#define NT_ARM_GCS 0x410
21
22struct user_gcs {
23 __u64 features_enabled;
24 __u64 features_locked;
25 __u64 gcspr_el0;
26};
27#endif
28
29/* Shadow Stack/Guarded Control Stack interface */
30#define PR_GET_SHADOW_STACK_STATUS 74
31#define PR_SET_SHADOW_STACK_STATUS 75
32#define PR_LOCK_SHADOW_STACK_STATUS 76
33
34# define PR_SHADOW_STACK_ENABLE (1UL << 0)
35# define PR_SHADOW_STACK_WRITE (1UL << 1)
36# define PR_SHADOW_STACK_PUSH (1UL << 2)
37
38#define PR_SHADOW_STACK_ALL_MODES \
39 PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE | PR_SHADOW_STACK_PUSH
40
41#define SHADOW_STACK_SET_TOKEN (1ULL << 0) /* Set up a restore token in the shadow stack */
42#define SHADOW_STACK_SET_MARKER (1ULL << 1) /* Set up a top of stack merker in the shadow stack */
43
44#define GCS_CAP_ADDR_MASK (0xfffffffffffff000UL)
45#define GCS_CAP_TOKEN_MASK (0x0000000000000fffUL)
46#define GCS_CAP_VALID_TOKEN 1
47#define GCS_CAP_IN_PROGRESS_TOKEN 5
48
49#define GCS_CAP(x) (((unsigned long)(x) & GCS_CAP_ADDR_MASK) | \
50 GCS_CAP_VALID_TOKEN)
51
52static inline unsigned long *get_gcspr(void)
53{
54 unsigned long *gcspr;
55
56 asm volatile(
57 "mrs %0, S3_3_C2_C5_1"
58 : "=r" (gcspr)
59 :
60 : "cc");
61
62 return gcspr;
63}
64
65static inline void __attribute__((always_inline)) gcsss1(unsigned long *Xt)
66{
67 asm volatile (
68 "sys #3, C7, C7, #2, %0\n"
69 :
70 : "rZ" (Xt)
71 : "memory");
72}
73
74static inline unsigned long __attribute__((always_inline)) *gcsss2(void)
75{
76 unsigned long *Xt;
77
78 asm volatile(
79 "SYSL %0, #3, C7, C7, #3\n"
80 : "=r" (Xt)
81 :
82 : "memory");
83
84 return Xt;
85}
86
87static inline bool chkfeat_gcs(void)
88{
89 register long val __asm__ ("x16") = 1;
90
91 /* CHKFEAT x16 */
92 asm volatile(
93 "hint #0x28\n"
94 : "=r" (val)
95 : "r" (val));
96
97 return val != 1;
98}
99
100#endif