linux-stable/include/linux/scs.h
Sami Tolvanen ac20ffbb02 arm64: scs: use vmapped IRQ and SDEI shadow stacks
Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of
using statically allocated stacks.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201130233442.2562064-3-samitolvanen@google.com
[will: Move CONFIG_SHADOW_CALL_STACK check into init_irq_scs()]
Signed-off-by: Will Deacon <will@kernel.org>
2020-12-01 11:23:34 +00:00

68 lines
1.8 KiB
C

/* 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 */