gcs-util.h

  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