| /* SPDX-License-Identifier: GPL-2.0 */ |
| /* |
| * Shadow Call Stack support. |
| * |
| * Copyright (C) 2019 Google LLC |
| */ |
| |
| #ifndef _LINUX_SCS_H |
| #define _LINUX_SCS_H |
| |
| #include <linux/gfp.h> |
| #include <linux/sched.h> |
| #include <asm/page.h> |
| |
| #ifdef CONFIG_SHADOW_CALL_STACK |
| |
| #ifdef CONFIG_SHADOW_CALL_STACK_VMAP |
| #define SCS_SIZE PAGE_SIZE |
| #else |
| /* |
| * In testing, 1 KiB shadow stack size (i.e. 128 stack frames on a 64-bit |
| * architecture) provided ~40% safety margin on stack usage while keeping |
| * memory allocation overhead reasonable. |
| */ |
| #define SCS_SIZE 1024UL |
| #endif |
| |
| #define GFP_SCS (GFP_KERNEL | __GFP_ZERO) |
| |
| /* |
| * A random number outside the kernel's virtual address space to mark the |
| * end of the shadow stack. |
| */ |
| #define SCS_END_MAGIC 0xaf0194819b1635f6UL |
| |
| #define task_scs(tsk) (task_thread_info(tsk)->shadow_call_stack) |
| |
| static inline void task_set_scs(struct task_struct *tsk, void *s) |
| { |
| task_scs(tsk) = s; |
| } |
| |
| extern void scs_init(void); |
| extern void scs_task_reset(struct task_struct *tsk); |
| extern int scs_prepare(struct task_struct *tsk, int node); |
| extern bool scs_corrupted(struct task_struct *tsk); |
| extern void scs_release(struct task_struct *tsk); |
| |
| #else /* CONFIG_SHADOW_CALL_STACK */ |
| |
| #define task_scs(tsk) NULL |
| |
| static inline void task_set_scs(struct task_struct *tsk, void *s) {} |
| static inline void scs_init(void) {} |
| static inline void scs_task_reset(struct task_struct *tsk) {} |
| static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; } |
| static inline bool scs_corrupted(struct task_struct *tsk) { return false; } |
| static inline void scs_release(struct task_struct *tsk) {} |
| |
| #endif /* CONFIG_SHADOW_CALL_STACK */ |
| |
| #endif /* _LINUX_SCS_H */ |
