[RFC PATCH 03/11] arm64: pgtable: Implement p[mu]d_valid() and check in set_p[mu]d()

Will Deacon
2018-08-24T15:53:27Z

Now that our walk-cache invalidation routines imply a DSB before the
invalidation, we no longer need one when we are clearing an entry during
unmap.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/pgtable.h | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 1bdeca8918a6..2ab2031b778c 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -360,6 +360,7 @@ static inline int pmd_protnone(pmd_t pmd)
#define pmd_present(pmd) pte_present(pmd_pte(pmd))
#define pmd_dirty(pmd) pte_dirty(pmd_pte(pmd))
#define pmd_young(pmd) pte_young(pmd_pte(pmd))
+#define pmd_valid(pmd) pte_valid(pmd_pte(pmd))
#define pmd_wrprotect(pmd) pte_pmd(pte_wrprotect(pmd_pte(pmd)))
#define pmd_mkold(pmd) pte_pmd(pte_mkold(pmd_pte(pmd)))
#define pmd_mkwrite(pmd) pte_pmd(pte_mkwrite(pmd_pte(pmd)))
@@ -431,7 +432,9 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
{
WRITE_ONCE(*pmdp, pmd);
- dsb(ishst);
+
+ if (pmd_valid(pmd))
+ dsb(ishst);
}

static inline void pmd_clear(pmd_t *pmdp)
@@ -477,11 +480,14 @@ static inline phys_addr_t pmd_page_paddr(pmd_t pmd)
#define pud_none(pud) (!pud_val(pud))
#define pud_bad(pud) (!(pud_val(pud) & PUD_TABLE_BIT))
#define pud_present(pud) pte_present(pud_pte(pud))
+#define pud_valid(pud) pte_valid(pud_pte(pud))

static inline void set_pud(pud_t *pudp, pud_t pud)
{
WRITE_ONCE(*pudp, pud);
- dsb(ishst);
+
+ if (pud_valid(pud))
+ dsb(ishst);
}

static inline void pud_clear(pud_t *pudp)
--
2.1.4