linux-kernel - [PATCH v2 3/4] arm64: introduce rodata=noalias

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Message-Id: <20241126085647.4993-4-shijie@os.amperecomputing.com>
Date: Tue, 26 Nov 2024 16:56:46 +0800
From: Huang Shijie <shijie@...amperecomputing.com>
To: catalin.marinas@....com,
	will@...nel.org
Cc: patches@...erecomputing.com,
	paulmck@...nel.org,
	akpm@...ux-foundation.org,
	thuth@...hat.com,
	rostedt@...dmis.org,
	xiongwei.song@...driver.com,
	ardb@...nel.org,
	steven.price@....com,
	suzuki.poulose@....com,
	mark.rutland@....com,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	cl@...amperecomputing.com,
	Huang Shijie <shijie@...amperecomputing.com>
Subject: [PATCH v2 3/4] arm64: introduce rodata=noalias

The rodata=noalias is the original rodata=on.

The rodata=noalias can provide us more block mappings and contiguous hits
to map the linear region which minimize the TLB footprint. And the
linear aliases of pages belonging to read-only mappings in vmalloc
region are also marked as read-only.

Also update kernel-parameters.txt for it:
   change "full" to "noalias"

Signed-off-by: Huang Shijie <shijie@...amperecomputing.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 2 +-
 arch/arm64/include/asm/setup.h                  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index dc663c0ca670..54b4df42e631 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5894,7 +5894,7 @@
 	rodata=		[KNL,EARLY]
 		on	Mark read-only kernel memory as read-only (default).
 		off	Leave read-only kernel memory writable for debugging.
-		full	Mark read-only kernel memory and aliases as read-only
+		noalias	Use more block mappings,may have better performance.
 		        [arm64]
 
 	rockchip.usb_uart
diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h
index 5ded3bd11476..3d96dde4d214 100644
--- a/arch/arm64/include/asm/setup.h
+++ b/arch/arm64/include/asm/setup.h
@@ -31,7 +31,7 @@ static inline bool arch_parse_debug_rodata(char *arg)
 		return true;
 	}
 
-	if (!strcmp(arg, "full")) {
+	if (!strcmp(arg, "noalias")) {
 		rodata_enabled = true;
 		rodata_full = false;
 		return true;
-- 
2.40.1