linux-kernel - [PATCH] x86/vdso/32: Assemble sigreturn.S separately

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Message-Id: <d7b6dfde3c7397aa26977320da90448363b5a7e9.1465505753.git.luto@kernel.org>
Date:	Thu,  9 Jun 2016 13:57:04 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	x86@...nel.org
Cc:	Borislav Petkov <bp@...en8.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...nel.org>
Subject: [PATCH] x86/vdso/32: Assemble sigreturn.S separately

sigreturn.S was historically included by the various
__kernel_vsyscall implementations due to assumptions about all the
32-bit vDSO images having the sigreturn symbols at the same address.
Thsoe assumptions were removed in 3.16, and as of 4.4, there is only
a single 32-bit vDSO.

Simplify the build process by assembling sigreturn.S into a normal
object file.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/entry/vdso/Makefile             | 5 +++--
 arch/x86/entry/vdso/vdso32/sigreturn.S   | 8 --------
 arch/x86/entry/vdso/vdso32/system_call.S | 7 +------
 3 files changed, 4 insertions(+), 16 deletions(-)

diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 253b72eaade6..68b63fddc209 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -134,7 +134,7 @@ VDSO_LDFLAGS_vdso32.lds = -m32 -Wl,-m,elf_i386 -Wl,-soname=linux-gate.so.1
 override obj-dirs = $(dir $(obj)) $(obj)/vdso32/
 
 targets += vdso32/vdso32.lds
-targets += vdso32/note.o vdso32/vclock_gettime.o vdso32/system_call.o
+targets += vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
 targets += vdso32/vclock_gettime.o
 
 KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS)) -DBUILD_VDSO
@@ -156,7 +156,8 @@ $(obj)/vdso32.so.dbg: FORCE \
 		      $(obj)/vdso32/vdso32.lds \
 		      $(obj)/vdso32/vclock_gettime.o \
 		      $(obj)/vdso32/note.o \
-		      $(obj)/vdso32/system_call.o
+		      $(obj)/vdso32/system_call.o \
+		      $(obj)/vdso32/sigreturn.o
 	$(call if_changed,vdso)
 
 #
diff --git a/arch/x86/entry/vdso/vdso32/sigreturn.S b/arch/x86/entry/vdso/vdso32/sigreturn.S
index d7ec4e251c0a..20633e026e82 100644
--- a/arch/x86/entry/vdso/vdso32/sigreturn.S
+++ b/arch/x86/entry/vdso/vdso32/sigreturn.S
@@ -1,11 +1,3 @@
-/*
- * Common code for the sigreturn entry points in vDSO images.
- * So far this code is the same for both int80 and sysenter versions.
- * This file is #include'd by int80.S et al to define them first thing.
- * The kernel assumes that the addresses of these routines are constant
- * for all vDSO implementations.
- */
-
 #include <linux/linkage.h>
 #include <asm/unistd_32.h>
 #include <asm/asm-offsets.h>
diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vdso/vdso32/system_call.S
index 0109ac6cb79c..ed4bc9731cbb 100644
--- a/arch/x86/entry/vdso/vdso32/system_call.S
+++ b/arch/x86/entry/vdso/vdso32/system_call.S
@@ -2,16 +2,11 @@
  * AT_SYSINFO entry point
 */
 
+#include <linux/linkage.h>
 #include <asm/dwarf2.h>
 #include <asm/cpufeatures.h>
 #include <asm/alternative-asm.h>
 
-/*
- * First get the common code for the sigreturn entry points.
- * This must come first.
- */
-#include "sigreturn.S"
-
 	.text
 	.globl __kernel_vsyscall
 	.type __kernel_vsyscall,@function
-- 
2.5.5