diff options
| -rw-r--r-- | arch/arm64/include/asm/pgtable.h | 5 | ||||
| -rw-r--r-- | arch/arm64/mm/fault.c | 50 |
2 files changed, 55 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 3c91b179089a..3eefc181d00b 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -535,6 +535,11 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) } #ifdef CONFIG_ARM64_HW_AFDBM +#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS +extern int ptep_set_access_flags(struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, + pte_t entry, int dirty); + /* * Atomic pte/pmd modifications. */ diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index c12e96753de9..d24a5e05a3f2 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -81,6 +81,56 @@ void show_pte(struct mm_struct *mm, unsigned long addr) printk("\n"); } +#ifdef CONFIG_ARM64_HW_AFDBM +/* + * This function sets the access flags (dirty, accessed), as well as write + * permission, and only to a more permissive setting. + * + * It needs to cope with hardware update of the accessed/dirty state by other + * agents in the system and can safely skip the __sync_icache_dcache() call as, + * like set_pte_at(), the PTE is never changed from no-exec to exec here. + * + * Returns whether or not the PTE actually changed. + */ +int ptep_set_access_flags(struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, + pte_t entry, int dirty) +{ + pteval_t old_pteval; + unsigned int tmp; + + if (pte_same(*ptep, entry)) + return 0; + + /* only preserve the access flags and write permission */ + pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY; + + /* + * PTE_RDONLY is cleared by default in the asm below, so set it in + * back if necessary (read-only or clean PTE). + */ + if (!pte_write(entry) || !dirty) + pte_val(entry) |= PTE_RDONLY; + + /* + * Setting the flags must be done atomically to avoid racing with the + * hardware update of the access/dirty state. + */ + asm volatile("// ptep_set_access_flags\n" + " prfm pstl1strm, %2\n" + "1: ldxr %0, %2\n" + " and %0, %0, %3 // clear PTE_RDONLY\n" + " orr %0, %0, %4 // set flags\n" + " stxr %w1, %0, %2\n" + " cbnz %w1, 1b\n" + : "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep)) + : "L" (~PTE_RDONLY), "r" (pte_val(entry))); + + flush_tlb_fix_spurious_fault(vma, address); + return 1; +} +#endif + /* * The kernel tried to access some page that wasn't present. */ |
