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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_POINTER_AUTH_H
#define __ASM_POINTER_AUTH_H
#include <linux/bitops.h>
#include <linux/random.h>
#include <asm/cpufeature.h>
#include <asm/memory.h>
#include <asm/sysreg.h>
#ifdef CONFIG_ARM64_PTR_AUTH
/*
* Each key is a 128-bit quantity which is split across a pair of 64-bit
* registers (Lo and Hi).
*/
struct ptrauth_key {
unsigned long lo, hi;
};
/*
* We give each process its own keys, which are shared by all threads. The keys
* are inherited upon fork(), and reinitialised upon exec*().
*/
struct ptrauth_keys {
struct ptrauth_key apia;
struct ptrauth_key apib;
struct ptrauth_key apda;
struct ptrauth_key apdb;
struct ptrauth_key apga;
};
static inline void ptrauth_keys_init(struct ptrauth_keys *keys)
{
if (system_supports_address_auth()) {
get_random_bytes(&keys->apia, sizeof(keys->apia));
get_random_bytes(&keys->apib, sizeof(keys->apib));
get_random_bytes(&keys->apda, sizeof(keys->apda));
get_random_bytes(&keys->apdb, sizeof(keys->apdb));
}
if (system_supports_generic_auth())
get_random_bytes(&keys->apga, sizeof(keys->apga));
}
#define __ptrauth_key_install(k, v) \
do { \
struct ptrauth_key __pki_v = (v); \
write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
} while (0)
static inline void ptrauth_keys_switch(struct ptrauth_keys *keys)
{
if (system_supports_address_auth()) {
__ptrauth_key_install(APIA, keys->apia);
__ptrauth_key_install(APIB, keys->apib);
__ptrauth_key_install(APDA, keys->apda);
__ptrauth_key_install(APDB, keys->apdb);
}
if (system_supports_generic_auth())
__ptrauth_key_install(APGA, keys->apga);
}
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
/*
* The EL0 pointer bits used by a pointer authentication code.
* This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
*/
#define ptrauth_user_pac_mask() GENMASK(54, vabits_actual)
/* Only valid for EL0 TTBR0 instruction pointers */
static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
{
return ptr & ~ptrauth_user_pac_mask();
}
#define ptrauth_thread_init_user(tsk) \
do { \
struct task_struct *__ptiu_tsk = (tsk); \
ptrauth_keys_init(&__ptiu_tsk->thread.keys_user); \
ptrauth_keys_switch(&__ptiu_tsk->thread.keys_user); \
} while (0)
#define ptrauth_thread_switch(tsk) \
ptrauth_keys_switch(&(tsk)->thread.keys_user)
#else /* CONFIG_ARM64_PTR_AUTH */
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
#define ptrauth_strip_insn_pac(lr) (lr)
#define ptrauth_thread_init_user(tsk)
#define ptrauth_thread_switch(tsk)
#endif /* CONFIG_ARM64_PTR_AUTH */
#endif /* __ASM_POINTER_AUTH_H */
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