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68 lines
1.8 KiB
68 lines
1.8 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* Shadow Call Stack support. |
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* |
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* Copyright (C) 2019 Google LLC |
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*/ |
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#ifndef _LINUX_SCS_H |
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#define _LINUX_SCS_H |
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#include <linux/gfp.h> |
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#include <linux/poison.h> |
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#include <linux/sched.h> |
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#include <linux/sizes.h> |
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#ifdef CONFIG_SHADOW_CALL_STACK |
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#define SCS_ORDER 0 |
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#define SCS_SIZE (PAGE_SIZE << SCS_ORDER) |
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#define GFP_SCS (GFP_KERNEL | __GFP_ZERO) |
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/* An illegal pointer value to mark the end of the shadow stack. */ |
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#define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA) |
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#define task_scs(tsk) (task_thread_info(tsk)->scs_base) |
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#define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp) |
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void *scs_alloc(int node); |
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void scs_free(void *s); |
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void scs_init(void); |
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int scs_prepare(struct task_struct *tsk, int node); |
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void scs_release(struct task_struct *tsk); |
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static inline void scs_task_reset(struct task_struct *tsk) |
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{ |
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/* |
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* Reset the shadow stack to the base address in case the task |
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* is reused. |
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*/ |
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task_scs_sp(tsk) = task_scs(tsk); |
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} |
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static inline unsigned long *__scs_magic(void *s) |
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{ |
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return (unsigned long *)(s + SCS_SIZE) - 1; |
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} |
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static inline bool task_scs_end_corrupted(struct task_struct *tsk) |
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{ |
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unsigned long *magic = __scs_magic(task_scs(tsk)); |
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unsigned long sz = task_scs_sp(tsk) - task_scs(tsk); |
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return sz >= SCS_SIZE - 1 || READ_ONCE_NOCHECK(*magic) != SCS_END_MAGIC; |
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} |
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#else /* CONFIG_SHADOW_CALL_STACK */ |
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static inline void *scs_alloc(int node) { return NULL; } |
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static inline void scs_free(void *s) {} |
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static inline void scs_init(void) {} |
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static inline void scs_task_reset(struct task_struct *tsk) {} |
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static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; } |
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static inline void scs_release(struct task_struct *tsk) {} |
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static inline bool task_scs_end_corrupted(struct task_struct *tsk) { return false; } |
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#endif /* CONFIG_SHADOW_CALL_STACK */ |
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#endif /* _LINUX_SCS_H */
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