1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __ASM_POINTER_AUTH_H
3#define __ASM_POINTER_AUTH_H
4
5#include <linux/bitops.h>
6#include <linux/random.h>
7
8#include <asm/cpufeature.h>
9#include <asm/memory.h>
10#include <asm/sysreg.h>
11
12#ifdef CONFIG_ARM64_PTR_AUTH
13/*
14 * Each key is a 128-bit quantity which is split across a pair of 64-bit
15 * registers (Lo and Hi).
16 */
17struct ptrauth_key {
18	unsigned long lo, hi;
19};
20
21/*
22 * We give each process its own keys, which are shared by all threads. The keys
23 * are inherited upon fork(), and reinitialised upon exec*().
24 */
25struct ptrauth_keys_user {
26	struct ptrauth_key apia;
27	struct ptrauth_key apib;
28	struct ptrauth_key apda;
29	struct ptrauth_key apdb;
30	struct ptrauth_key apga;
31};
32
33struct ptrauth_keys_kernel {
34	struct ptrauth_key apia;
35};
36
37static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
38{
39	if (system_supports_address_auth()) {
40		get_random_bytes(&keys->apia, sizeof(keys->apia));
41		get_random_bytes(&keys->apib, sizeof(keys->apib));
42		get_random_bytes(&keys->apda, sizeof(keys->apda));
43		get_random_bytes(&keys->apdb, sizeof(keys->apdb));
44	}
45
46	if (system_supports_generic_auth())
47		get_random_bytes(&keys->apga, sizeof(keys->apga));
48}
49
50#define __ptrauth_key_install_nosync(k, v)			\
51do {								\
52	struct ptrauth_key __pki_v = (v);			\
53	write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);	\
54	write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);	\
55} while (0)
56
57static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
58{
59	if (system_supports_address_auth())
60		get_random_bytes(&keys->apia, sizeof(keys->apia));
61}
62
63static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
64{
65	if (!system_supports_address_auth())
66		return;
67
68	__ptrauth_key_install_nosync(APIA, keys->apia);
69	isb();
70}
71
72extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
73
74static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
75{
76	return ptrauth_clear_pac(ptr);
77}
78
79#define ptrauth_thread_init_user(tsk)					\
80	ptrauth_keys_init_user(&(tsk)->thread.keys_user)
81#define ptrauth_thread_init_kernel(tsk)					\
82	ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
83#define ptrauth_thread_switch_kernel(tsk)				\
84	ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
85
86#else /* CONFIG_ARM64_PTR_AUTH */
87#define ptrauth_prctl_reset_keys(tsk, arg)	(-EINVAL)
88#define ptrauth_strip_insn_pac(lr)	(lr)
89#define ptrauth_thread_init_user(tsk)
90#define ptrauth_thread_init_kernel(tsk)
91#define ptrauth_thread_switch_kernel(tsk)
92#endif /* CONFIG_ARM64_PTR_AUTH */
93
94#endif /* __ASM_POINTER_AUTH_H */
95