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 22 struct 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 52 static 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 65 static 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 74 static 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 87 static 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 101