linux-kernel - [tip: timers/vdso] ARM: vdso: Remove assembly for datapage access

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Message-ID: <173054822675.3137.4490550265684382864.tip-bot2@tip-bot2>
Date: Sat, 02 Nov 2024 11:50:26 -0000
From:
 tip-bot2 for Thomas Weißschuh <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: thomas.weissschuh@...utronix.de, Thomas Gleixner <tglx@...utronix.de>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: timers/vdso] ARM: vdso: Remove assembly for datapage access

The following commit has been merged into the timers/vdso branch of tip:

Commit-ID:     2bb79470e5c87f211d05f0dd1c7a4291c9b7e1a4
Gitweb:        https://git.kernel.org/tip/2bb79470e5c87f211d05f0dd1c7a4291c9b7e1a4
Author:        Thomas Weißschuh <thomas.weissschuh@...utronix.de>
AuthorDate:    Thu, 10 Oct 2024 09:01:09 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Sat, 02 Nov 2024 12:37:33 +01:00

ARM: vdso: Remove assembly for datapage access

vdso/datapage.h provides a hidden declaration for _vdso_data.
When using it the compiler will automatically generate PC-relative
accesses which avoids the need for a custom assembly-based accessor.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/all/20241010-vdso-generic-base-v1-7-b64f0842d512@linutronix.de

---
 arch/arm/include/asm/vdso/gettimeofday.h |  4 +---
 arch/arm/vdso/Makefile                   |  2 +-
 arch/arm/vdso/datapage.S                 | 16 ----------------
 arch/arm/vdso/vdso.lds.S                 |  3 ++-
 4 files changed, 4 insertions(+), 21 deletions(-)
 delete mode 100644 arch/arm/vdso/datapage.S

diff --git a/arch/arm/include/asm/vdso/gettimeofday.h b/arch/arm/include/asm/vdso/gettimeofday.h
index 2134cbd..592d3d0 100644
--- a/arch/arm/include/asm/vdso/gettimeofday.h
+++ b/arch/arm/include/asm/vdso/gettimeofday.h
@@ -15,8 +15,6 @@
 
 #define VDSO_HAS_CLOCK_GETRES		1
 
-extern struct vdso_data *__get_datapage(void);
-
 static __always_inline int gettimeofday_fallback(
 				struct __kernel_old_timeval *_tv,
 				struct timezone *_tz)
@@ -139,7 +137,7 @@ static __always_inline u64 __arch_get_hw_counter(int clock_mode,
 
 static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
 {
-	return __get_datapage();
+	return _vdso_data;
 }
 
 #endif /* !__ASSEMBLY__ */
diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
index 01067a2..8a306bb 100644
--- a/arch/arm/vdso/Makefile
+++ b/arch/arm/vdso/Makefile
@@ -5,7 +5,7 @@ include $(srctree)/lib/vdso/Makefile
 
 hostprogs := vdsomunge
 
-obj-vdso := vgettimeofday.o datapage.o note.o
+obj-vdso := vgettimeofday.o note.o
 
 # Build rules
 targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.so.raw vdso.lds
diff --git a/arch/arm/vdso/datapage.S b/arch/arm/vdso/datapage.S
deleted file mode 100644
index 9cd73b7..0000000
--- a/arch/arm/vdso/datapage.S
+++ /dev/null
@@ -1,16 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <linux/linkage.h>
-#include <asm/asm-offsets.h>
-
-	.align 2
-.L_vdso_data_ptr:
-	.long	_start - . - VDSO_DATA_SIZE
-
-ENTRY(__get_datapage)
-	.fnstart
-	adr	r0, .L_vdso_data_ptr
-	ldr	r1, [r0]
-	add	r0, r0, r1
-	bx	lr
-	.fnend
-ENDPROC(__get_datapage)
diff --git a/arch/arm/vdso/vdso.lds.S b/arch/arm/vdso/vdso.lds.S
index 165d1d2..9bfa0f5 100644
--- a/arch/arm/vdso/vdso.lds.S
+++ b/arch/arm/vdso/vdso.lds.S
@@ -11,6 +11,7 @@
  */
 
 #include <linux/const.h>
+#include <asm/asm-offsets.h>
 #include <asm/page.h>
 #include <asm/vdso.h>
 
@@ -19,7 +20,7 @@ OUTPUT_ARCH(arm)
 
 SECTIONS
 {
-	PROVIDE(_start = .);
+	PROVIDE(_vdso_data = . - VDSO_DATA_SIZE);
 
 	. = SIZEOF_HEADERS;