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[v3,06/23] arm64: mte: Tags-aware clear_page() implementation

Message ID 20200421142603.3894-7-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 set to
zero a page is cleared as they are visible to the user.

Introduce an MTE-aware clear_page() which clears the tags in addition to
data.

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/clear_page.S | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
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Patch

diff --git a/arch/arm64/lib/clear_page.S b/arch/arm64/lib/clear_page.S
index 073acbf02a7c..9f85a4cf9568 100644
--- a/arch/arm64/lib/clear_page.S
+++ b/arch/arm64/lib/clear_page.S
@@ -5,7 +5,9 @@ 
 
 #include <linux/linkage.h>
 #include <linux/const.h>
+#include <asm/alternative.h>
 #include <asm/assembler.h>
+#include <asm/cpufeature.h>
 #include <asm/page.h>
 
 /*
@@ -19,8 +21,9 @@  SYM_FUNC_START(clear_page)
 	and	w1, w1, #0xf
 	mov	x2, #4
 	lsl	x1, x2, x1
-
-1:	dc	zva, x0
+1:
+alternative_insn "dc zva, x0", "stzgm xzr, [x0]", \
+			 ARM64_MTE, IS_ENABLED(CONFIG_ARM64_MTE), 1
 	add	x0, x0, x1
 	tst	x0, #(PAGE_SIZE - 1)
 	b.ne	1b