arch/arm64/include/asm/mte.h

Source file repositories/reference/linux-study-clean/arch/arm64/include/asm/mte.h

File Facts

System
Linux kernel
Corpus path
arch/arm64/include/asm/mte.h
Extension
.h
Size
7283 bytes
Lines
293
Domain
Architecture Layer
Bucket
arch/arm64
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __ASM_MTE_H
#define __ASM_MTE_H

#include <asm/compiler.h>
#include <asm/mte-def.h>

#ifndef __ASSEMBLER__

#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)
{
	VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(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.f);
}

static inline bool page_mte_tagged(struct page *page)
{
	bool ret = test_bit(PG_mte_tagged, &page->flags.f);

	VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(page)));

	/*
	 * 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)
{
	VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(page)));

	if (!test_and_set_bit(PG_mte_lock, &page->flags.f))
		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.f, VAL & (1UL << PG_mte_tagged));

Annotation

Implementation Notes