| /* 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/poison.h> |
| #include <linux/sched.h> |
| #include <linux/sizes.h> |
| |
| #ifdef CONFIG_SHADOW_CALL_STACK |
| |
| #define SCS_ORDER 0 |
| #define SCS_SIZE (PAGE_SIZE << SCS_ORDER) |
| #define GFP_SCS (GFP_KERNEL | __GFP_ZERO) |
| |
| /* An illegal pointer value to mark the end of the shadow stack. */ |
| #define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA) |
| |
| #define task_scs(tsk) (task_thread_info(tsk)->scs_base) |
| #define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp) |
| |
| void *scs_alloc(int node); |
| void scs_free(void *s); |
| void scs_init(void); |
| int scs_prepare(struct task_struct *tsk, int node); |
| void scs_release(struct task_struct *tsk); |
| |
| static inline void scs_task_reset(struct task_struct *tsk) |
| { |
| /* |
| * Reset the shadow stack to the base address in case the task |
| * is reused. |
| */ |
| task_scs_sp(tsk) = task_scs(tsk); |
| } |
| |
| static inline unsigned long *__scs_magic(void *s) |
| { |
| return (unsigned long *)(s + SCS_SIZE) - 1; |
| } |
| |
| static inline bool task_scs_end_corrupted(struct task_struct *tsk) |
| { |
| unsigned long *magic = __scs_magic(task_scs(tsk)); |
| unsigned long sz = task_scs_sp(tsk) - task_scs(tsk); |
| |
| return sz >= SCS_SIZE - 1 || READ_ONCE_NOCHECK(*magic) != SCS_END_MAGIC; |
| } |
| |
| #else /* CONFIG_SHADOW_CALL_STACK */ |
| |
| static inline void *scs_alloc(int node) { return NULL; } |
| static inline void scs_free(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 void scs_release(struct task_struct *tsk) {} |
| static inline bool task_scs_end_corrupted(struct task_struct *tsk) { return false; } |
| |
| #endif /* CONFIG_SHADOW_CALL_STACK */ |
| |
| #endif /* _LINUX_SCS_H */ |