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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2020 ARM Ltd.
*/
#ifndef __ASM_MTE_H
#define __ASM_MTE_H
#include <asm/compiler.h>
#include <asm/mte-def.h>
#ifndef __ASSEMBLY__
#include <linux/bitfield.h>
#include <linux/kasan-enabled.h>
#include <linux/page-flags.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <asm/pgtable-types.h>
void mte_clear_page_tags(void *addr);
unsigned long mte_copy_tags_from_user(void *to, const void __user *from,
unsigned long n);
unsigned long mte_copy_tags_to_user(void __user *to, void *from,
unsigned long n);
int mte_save_tags(struct page *page);
void mte_save_page_tags(const void *page_addr, void *tag_storage);
void mte_restore_tags(swp_entry_t entry, struct page *page);
void mte_restore_page_tags(void *page_addr, const void *tag_storage);
void mte_invalidate_tags(int type, pgoff_t offset);
void mte_invalidate_tags_area(int type);
void *mte_allocate_tag_storage(void);
void mte_free_tag_storage(char *storage);
#ifdef CONFIG_ARM64_MTE
/* track which pages have valid allocation tags */
#define PG_mte_tagged PG_arch_2
/* simple lock to avoid multiple threads tagging the same page */
#define PG_mte_lock PG_arch_3
static inline void set_page_mte_tagged(struct page *page)
{
/*
* Ensure that the tags written prior to this function are visible
* before the page flags update.
*/
smp_wmb();
set_bit(PG_mte_tagged, &page->flags);
}
static inline bool page_mte_tagged(struct page *page)
{
bool ret = test_bit(PG_mte_tagged, &page->flags);
/*
* If the page is tagged, ensure ordering with a likely subsequent
* read of the tags.
*/
if (ret)
smp_rmb();
return ret;
}
/*
* Lock the page for tagging and return 'true' if the page can be tagged,
* 'false' if already tagged. PG_mte_tagged is never cleared and therefore the
* locking only happens once for page initialisation.
*
* The page MTE lock state:
*
* Locked: PG_mte_lock && !PG_mte_tagged
* Unlocked: !PG_mte_lock || PG_mte_tagged
*
* Acquire semantics only if the page is tagged (returning 'false').
*/
static inline bool try_page_mte_tagging(struct page *page)
{
if (!test_and_set_bit(PG_mte_lock, &page->flags))
return true;
/*
* The tags are either being initialised or may have been initialised
* already. Check if the PG_mte_tagged flag has been set or wait
* otherwise.
*/
smp_cond_load_acquire(&page->flags, VAL & (1UL << PG_mte_tagged));
return false;
}
void mte_zero_clear_page_tags(void *addr);
void mte_sync_tags(pte_t pte, unsigned int nr_pages);
void mte_copy_page_tags(void *kto, const void *kfrom);
void mte_thread_init_user(void);
void mte_thread_switch(struct task_struct *next);
void mte_cpu_setup(void);
void mte_suspend_enter(void);
void mte_suspend_exit(void);
long set_mte_ctrl(struct task_struct *task, unsigned long arg);
long get_mte_ctrl(struct task_struct *task);
int mte_ptrace_copy_tags(struct task_struct *child, long request,
unsigned long addr, unsigned long data);
size_t mte_probe_user_range(const char __user *uaddr, size_t size);
#else /* CONFIG_ARM64_MTE */
/* unused if !CONFIG_ARM64_MTE, silence the compiler */
#define PG_mte_tagged 0
static inline void set_page_mte_tagged(struct page *page)
{
}
static inline bool page_mte_tagged(struct page *page)
{
return false;
}
static inline bool try_page_mte_tagging(struct page *page)
{
return false;
}
static inline void mte_zero_clear_page_tags(void *addr)
{
}
static inline void mte_sync_tags(pte_t pte, unsigned int nr_pages)
{
}
static inline void mte_copy_page_tags(void *kto, const void *kfrom)
{
}
static inline void mte_thread_init_user(void)
{
}
static inline void mte_thread_switch(struct task_struct *next)
{
}
static inline void mte_suspend_enter(void)
{
}
static inline void mte_suspend_exit(void)
{
}
static inline long set_mte_ctrl(struct task_struct *task, unsigned long arg)
{
return 0;
}
static inline long get_mte_ctrl(struct task_struct *task)
{
return 0;
}
static inline int mte_ptrace_copy_tags(struct task_struct *child,
long request, unsigned long addr,
unsigned long data)
{
return -EIO;
}
#endif /* CONFIG_ARM64_MTE */
static inline void mte_disable_tco_entry(struct task_struct *task)
{
if (!system_supports_mte())
return;
/*
* Re-enable tag checking (TCO set on exception entry). This is only
* necessary if MTE is enabled in either the kernel or the userspace
* task in synchronous or asymmetric mode (SCTLR_EL1.TCF0 bit 0 is set
* for both). With MTE disabled in the kernel and disabled or
* asynchronous in userspace, tag check faults (including in uaccesses)
* are not reported, therefore there is no need to re-enable checking.
* This is beneficial on microarchitectures where re-enabling TCO is
* expensive.
*/
if (kasan_hw_tags_enabled() ||
(task->thread.sctlr_user & (1UL << SCTLR_EL1_TCF0_SHIFT)))
asm volatile(SET_PSTATE_TCO(0));
}
#ifdef CONFIG_KASAN_HW_TAGS
void mte_check_tfsr_el1(void);
static inline void mte_check_tfsr_entry(void)
{
if (!system_supports_mte())
return;
mte_check_tfsr_el1();
}
static inline void mte_check_tfsr_exit(void)
{
if (!system_supports_mte())
return;
/*
* The asynchronous faults are sync'ed automatically with
* TFSR_EL1 on kernel entry but for exit an explicit dsb()
* is required.
*/
dsb(nsh);
isb();
mte_check_tfsr_el1();
}
#else
static inline void mte_check_tfsr_el1(void)
{
}
static inline void mte_check_tfsr_entry(void)
{
}
static inline void mte_check_tfsr_exit(void)
{
}
#endif /* CONFIG_KASAN_HW_TAGS */
#endif /* __ASSEMBLY__ */
#endif /* __ASM_MTE_H */
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