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Commit 69d0627a authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

x86 vDSO: reorder vdso32 code 



This reorders the code in the 32-bit vDSO images to put the signal
trampolines first and __kernel_vsyscall after them.  The order does
not matter to userland, it just uses what AT_SYSINFO or e_entry
says.  Since the signal trampolines are the same size in both
versions of the vDSO, putting them first is the simplest way to get
the addresses to line up.  This makes it work to use a more compact
layout for the vDSO.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 16f4bc73

arch/x86/vdso/vdso32/int80.S

+12 −9
Original line number Diff line number Diff line 
/*

 * Code for the vsyscall page.  This version uses the old int $0x80 method.

 * Code for the vDSO.  This version uses the old int $0x80 method.

 *

 * NOTE:

 * 1) __kernel_vsyscall _must_ be first in this page.

 * 2) there are alignment constraints on this stub, see vsyscall-sigreturn.S

 *    for details.

 * 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

	ALIGN

__kernel_vsyscall:

.LSTART_vsyscall:

	int $0x80
@@ -48,6 +48,9 @@ __kernel_vsyscall: 
	.previous



	/*

 * Get the common code for the sigreturn entry points.

	 * Pad out the segment to match the size of the sysenter.S version.

	 */

#include "sigreturn.S"
 
VDSO32_vsyscall_eh_frame_size = 0x44

	.section .data,"aw",@progbits

	.space VDSO32_vsyscall_eh_frame_size-(.LENDFDEDLSI-.LSTARTFRAMEDLSI), 0

	.previous

arch/x86/vdso/vdso32/sigreturn.S

+9 −11
Original line number Diff line number Diff line 
/*

 * Common code for the sigreturn entry points on the vsyscall page.

 * 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 vsyscall-*.S to define them after the

 * vsyscall entry point.  The kernel assumes that the addresses of these

 * routines are constant for all vsyscall implementations.

 * 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>
@@ -13,32 +14,29 @@ 
#define	SYSCALL_ENTER_KERNEL	int $0x80

#endif



/* XXX

   Should these be named "_sigtramp" or something?

*/



	.text

	.org __kernel_vsyscall+32,0x90

	.globl __kernel_sigreturn

	.type __kernel_sigreturn,@function

	ALIGN

__kernel_sigreturn:

.LSTART_sigreturn:

	popl %eax		/* XXX does this mean it needs unwind info? */

	movl $__NR_sigreturn, %eax

	SYSCALL_ENTER_KERNEL

.LEND_sigreturn:

	nop

	.size __kernel_sigreturn,.-.LSTART_sigreturn



	.balign 32

	.globl __kernel_rt_sigreturn

	.type __kernel_rt_sigreturn,@function

	ALIGN

__kernel_rt_sigreturn:

.LSTART_rt_sigreturn:

	movl $__NR_rt_sigreturn, %eax

	SYSCALL_ENTER_KERNEL

.LEND_rt_sigreturn:

	nop

	.size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn

	.balign 32

	.previous



	.section .eh_frame,"a",@progbits

arch/x86/vdso/vdso32/syscall.S

+15 −7
Original line number Diff line number Diff line 
/*

 * Code for the vsyscall page.  This version uses the syscall instruction.

 * Code for the vDSO.  This version uses the syscall instruction.

 *

 * First get the common code for the sigreturn entry points.

 * This must come first.

 */

#define SYSCALL_ENTER_KERNEL	syscall

#include "sigreturn.S"



#include <asm/asm-offsets.h>

#include <asm/segment.h>



	.text

	.globl __kernel_vsyscall

	.type __kernel_vsyscall,@function

	ALIGN

__kernel_vsyscall:

.LSTART_vsyscall:

	push	%ebp
@@ -61,9 +66,12 @@ __kernel_vsyscall: 
	.uleb128 4

	.align 4

.LENDFDE1:

	.previous



	/*

 * Get the common code for the sigreturn entry points.

	 * Pad out the segment to match the size of the sysenter.S version.

	 */

#define SYSCALL_ENTER_KERNEL	syscall

#include "sigreturn.S"
 
VDSO32_vsyscall_eh_frame_size = 0x44

	.section .data,"aw",@progbits

	.space VDSO32_vsyscall_eh_frame_size-(.LENDFDE1-.LSTARTFRAME), 0

	.previous

arch/x86/vdso/vdso32/sysenter.S

+11 −10
Original line number Diff line number Diff line 
/*

 * Code for the vsyscall page.  This version uses the sysenter instruction.

 * Code for the vDSO.  This version uses the sysenter instruction.

 *

 * NOTE:

 * 1) __kernel_vsyscall _must_ be first in this page.

 * 2) there are alignment constraints on this stub, see vsyscall-sigreturn.S

 *    for details.

 * First get the common code for the sigreturn entry points.

 * This must come first.

 */

#include "sigreturn.S"



/*

 * The caller puts arg2 in %ecx, which gets pushed. The kernel will use
@@ -23,11 +22,12 @@ 
 * arg6 from the stack.

 *

 * You can not use this vsyscall for the clone() syscall because the

 * three dwords on the parent stack do not get copied to the child.

 * three words on the parent stack do not get copied to the child.

 */

	.text

	.globl __kernel_vsyscall

	.type __kernel_vsyscall,@function

	ALIGN

__kernel_vsyscall:

.LSTART_vsyscall:

	push %ecx
@@ -116,6 +116,7 @@ VDSO32_SYSENTER_RETURN: /* Symbol used by sysenter.c via vdso32-syms.h */ 
	.previous



	/*

 * Get the common code for the sigreturn entry points.

	 * Emit a symbol with the size of this .eh_frame data,

	 * to verify it matches the other versions.

	 */

#include "sigreturn.S"
 
VDSO32_vsyscall_eh_frame_size = (.LENDFDEDLSI-.LSTARTFRAMEDLSI)