summaryrefslogtreecommitdiffstats
path: root/arch/x86/include/asm/pgtable-invert.h
blob: 44b1203ece12abb31f0b782b7219f61eb8045ae6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_PGTABLE_INVERT_H
#define _ASM_PGTABLE_INVERT_H 1

#ifndef __ASSEMBLY__

static inline bool __pte_needs_invert(u64 val)
{
	return !(val & _PAGE_PRESENT);
}

/* Get a mask to xor with the page table entry to get the correct pfn. */
static inline u64 protnone_mask(u64 val)
{
	return __pte_needs_invert(val) ?  ~0ull : 0;
}

static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask)
{
	/*
	 * When a PTE transitions from NONE to !NONE or vice-versa
	 * invert the PFN part to stop speculation.
	 * pte_pfn undoes this when needed.
	 */
	if (__pte_needs_invert(oldval) != __pte_needs_invert(val))
		val = (val & ~mask) | (~val & mask);
	return val;
}

#endif /* __ASSEMBLY__ */

#endif