Re: [PATCH V2 02/14] arm64/mm: Route all pgtable reads via ptval_get()

Define arm64 platform specific implementations for new pxdp_get() helpers.
These resolve into READ_ONCE(), thus ensuring required single copy atomic
semantics for the page table entry reads.

In future this infrastructure can be used for D128 to maintain single copy
atomicity semantics with inline asm blocks.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <redacted>
---
 arch/arm64/include/asm/pgtable.h | 38 +++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 83087b70f192..f764132ca34e 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h

@@ -84,6 +84,32 @@ static inline void arch_leave_lazy_mmu_mode(void)
 	arch_flush_lazy_mmu_mode();
 }
 
+#define ptval_get(x)		READ_ONCE(x)
+
+#define pmdp_get pmdp_get
+static inline pmd_t pmdp_get(pmd_t *pmdp)
+{
+	return ptval_get(*pmdp);
+}