UPSTREAM: arm64: pgtable: implement pte_accessible()

This patch implements the pte_accessible() macro, which can be used to
test whether or not a given pte is a candidate for allocation in the
TLB.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Bug: 30369029

(cherry picked from commit 76c714be0e5e60c935a53b31be58939510ba1d0f)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: I249e2d15665870149dd17d1cdb3850008f5a56fd

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 63f52b5..824416a 100644 (file)
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -167,6 +167,16 @@ extern struct page *empty_zero_page;
        ((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))
 #define pte_valid_not_user(pte) \
        ((pte_val(pte) & (PTE_VALID | PTE_USER)) == PTE_VALID)
+#define pte_valid_young(pte) \
+       ((pte_val(pte) & (PTE_VALID | PTE_AF)) == (PTE_VALID | PTE_AF))
+
+/*
+ * Could the pte be present in the TLB? We must check mm_tlb_flush_pending
+ * so that we don't erroneously return false for pages that have been
+ * remapped as PROT_NONE but are yet to be flushed from the TLB.
+ */
+#define pte_accessible(mm, pte)        \
+       (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid_young(pte))
 
 static inline pte_t clear_pte_bit(pte_t pte, pgprot_t prot)
 {