diff mbox series

[v3,07/23] arm64: mte: Tags-aware copy_page() implementation

Message ID 20200421142603.3894-8-catalin.marinas@arm.com (mailing list archive)
State New, archived
Headers show
Series arm64: Memory Tagging Extension user-space support | expand

Commit Message

Catalin Marinas April 21, 2020, 2:25 p.m. UTC 
From: Vincenzo Frascino <vincenzo.frascino@arm.com>

When the Memory Tagging Extension is enabled, the tags need to be
preserved across page copy (e.g. for copy-on-write).

Introduce MTE-aware copy_page() which preserves the tags across page
copy.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/lib/copy_page.S | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
diff mbox series

Patch

diff --git a/arch/arm64/lib/copy_page.S b/arch/arm64/lib/copy_page.S
index e7a793961408..c3234175efe0 100644
--- a/arch/arm64/lib/copy_page.S
+++ b/arch/arm64/lib/copy_page.S
@@ -25,6 +25,29 @@  alternative_if ARM64_HAS_NO_HW_PREFETCH
 	prfm	pldl1strm, [x1, #384]
 alternative_else_nop_endif
 
+#ifdef CONFIG_ARM64_MTE
+alternative_if_not ARM64_MTE
+	b	2f
+alternative_else_nop_endif
+	/*
+	 * Copy tags if MTE has been enabled.
+	 */
+	mov	x2, x0
+	mov	x3, x1
+
+	multitag_transfer_size x7, x5
+1:
+	ldgm	x4, [x3]
+	stgm	x4, [x2]
+
+	add	x2, x2, x7
+	add	x3, x3, x7
+
+	tst	x2, #(PAGE_SIZE - 1)
+	b.ne	1b
+2:
+#endif
+
 	ldp	x2, x3, [x1]
 	ldp	x4, x5, [x1, #16]
 	ldp	x6, x7, [x1, #32]