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arm64/mm: Add uffd write-protect support

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Let's use the newly-free PTE SW bit (58) to add support for uffd-wp.

The standard handlers are implemented for set/test/clear for both pte
and pmd. Additionally we must also track the uffd-wp state as a pte swp
bit, so use a free swap pte bit (3).

Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/r/20240503144604.151095-5-ryan.roberts@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ryan Roberts 2024-05-03 15:46:02 +01:00 committed by Will Deacon
parent 55564814a8
commit 5b32510af7
3 changed files with 53 additions and 0 deletions
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1
arch/arm64/Kconfig
View File

@ -255,6 +255,7 @@ config ARM64
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD
select HAVE_ARCH_USERFAULTFD_WP if USERFAULTFD
select TRACE_IRQFLAGS_SUPPORT
select TRACE_IRQFLAGS_NMI_SUPPORT
select HAVE_SOFTIRQ_ON_OWN_STACK

8
arch/arm64/include/asm/pgtable-prot.h
View File

@ -26,6 +26,14 @@
*/
#define PTE_PRESENT_INVALID (PTE_NG) /* only when !PTE_VALID */
#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP
#define PTE_UFFD_WP (_AT(pteval_t, 1) << 58) /* uffd-wp tracking */
#define PTE_SWP_UFFD_WP (_AT(pteval_t, 1) << 3) /* only for swp ptes */
#else
#define PTE_UFFD_WP (_AT(pteval_t, 0))
#define PTE_SWP_UFFD_WP (_AT(pteval_t, 0))
#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */
#define _PROT_DEFAULT (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
#define _PROT_SECT_DEFAULT (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)

44
arch/arm64/include/asm/pgtable.h
View File

@ -280,6 +280,23 @@ static inline pte_t pte_mkdevmap(pte_t pte)
return set_pte_bit(pte, __pgprot(PTE_DEVMAP | PTE_SPECIAL));
}
#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP
static inline int pte_uffd_wp(pte_t pte)
{
return !!(pte_val(pte) & PTE_UFFD_WP);
}
static inline pte_t pte_mkuffd_wp(pte_t pte)
{
return pte_wrprotect(set_pte_bit(pte, __pgprot(PTE_UFFD_WP)));
}
static inline pte_t pte_clear_uffd_wp(pte_t pte)
{
return clear_pte_bit(pte, __pgprot(PTE_UFFD_WP));
}
#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */
static inline void __set_pte_nosync(pte_t *ptep, pte_t pte)
{
WRITE_ONCE(*ptep, pte);
@ -477,6 +494,23 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
return clear_pte_bit(pte, __pgprot(PTE_SWP_EXCLUSIVE));
}
#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP
static inline pte_t pte_swp_mkuffd_wp(pte_t pte)
{
return set_pte_bit(pte, __pgprot(PTE_SWP_UFFD_WP));
}
static inline int pte_swp_uffd_wp(pte_t pte)
{
return !!(pte_val(pte) & PTE_SWP_UFFD_WP);
}
static inline pte_t pte_swp_clear_uffd_wp(pte_t pte)
{
return clear_pte_bit(pte, __pgprot(PTE_SWP_UFFD_WP));
}
#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */
#ifdef CONFIG_NUMA_BALANCING
/*
* See the comment in include/linux/pgtable.h
@ -527,6 +561,15 @@ static inline int pmd_trans_huge(pmd_t pmd)
#define pmd_mkdirty(pmd) pte_pmd(pte_mkdirty(pmd_pte(pmd)))
#define pmd_mkyoung(pmd) pte_pmd(pte_mkyoung(pmd_pte(pmd)))
#define pmd_mkinvalid(pmd) pte_pmd(pte_mkinvalid(pmd_pte(pmd)))
#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP
#define pmd_uffd_wp(pmd) pte_uffd_wp(pmd_pte(pmd))
#define pmd_mkuffd_wp(pmd) pte_pmd(pte_mkuffd_wp(pmd_pte(pmd)))
#define pmd_clear_uffd_wp(pmd) pte_pmd(pte_clear_uffd_wp(pmd_pte(pmd)))
#define pmd_swp_uffd_wp(pmd) pte_swp_uffd_wp(pmd_pte(pmd))
#define pmd_swp_mkuffd_wp(pmd) pte_pmd(pte_swp_mkuffd_wp(pmd_pte(pmd)))
#define pmd_swp_clear_uffd_wp(pmd) \
pte_pmd(pte_swp_clear_uffd_wp(pmd_pte(pmd)))
#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */
#define pmd_thp_or_huge(pmd) (pmd_huge(pmd) || pmd_trans_huge(pmd))
@ -1261,6 +1304,7 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
* Encode and decode a swap entry:
* bits 0-1: present (must be zero)
* bits 2: remember PG_anon_exclusive
* bit 3: remember uffd-wp state
* bits 6-10: swap type
* bit 11: PTE_PRESENT_INVALID (must be zero)
* bits 12-61: swap offset