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linux-next/arch/x86/vdso/vdso32/syscall.S
Roland McGrath cadd516422 x86 vDSO: canonicalize sysenter .eh_frame
Some assembler versions automagically optimize .eh_frame contents,
changing their size.  The CFI in sysenter.S was not using optimal
formatting, so it would be changed by newer/smarter assemblers.
This ran afoul of the wired constant for padding out the other vDSO
images to match its size.  This changes the original hand-coded
source to use the optimal format encoding for its operations.  That
leaves nothing more for a fancy assembler to do, so the sizes will
match the wired-in expected size regardless of the assembler version.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:44 +01:00

78 lines
2.0 KiB
ArmAsm

/*
* 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/segment.h>
.text
.globl __kernel_vsyscall
.type __kernel_vsyscall,@function
ALIGN
__kernel_vsyscall:
.LSTART_vsyscall:
push %ebp
.Lpush_ebp:
movl %ecx, %ebp
syscall
movl $__USER32_DS, %ecx
movl %ecx, %ss
movl %ebp, %ecx
popl %ebp
.Lpop_ebp:
ret
.LEND_vsyscall:
.size __kernel_vsyscall,.-.LSTART_vsyscall
.section .eh_frame,"a",@progbits
.LSTARTFRAME:
.long .LENDCIE-.LSTARTCIE
.LSTARTCIE:
.long 0 /* CIE ID */
.byte 1 /* Version number */
.string "zR" /* NUL-terminated augmentation string */
.uleb128 1 /* Code alignment factor */
.sleb128 -4 /* Data alignment factor */
.byte 8 /* Return address register column */
.uleb128 1 /* Augmentation value length */
.byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
.byte 0x0c /* DW_CFA_def_cfa */
.uleb128 4
.uleb128 4
.byte 0x88 /* DW_CFA_offset, column 0x8 */
.uleb128 1
.align 4
.LENDCIE:
.long .LENDFDE1-.LSTARTFDE1 /* Length FDE */
.LSTARTFDE1:
.long .LSTARTFDE1-.LSTARTFRAME /* CIE pointer */
.long .LSTART_vsyscall-. /* PC-relative start address */
.long .LEND_vsyscall-.LSTART_vsyscall
.uleb128 0 /* Augmentation length */
/* What follows are the instructions for the table generation.
We have to record all changes of the stack pointer. */
.byte 0x40 + .Lpush_ebp-.LSTART_vsyscall /* DW_CFA_advance_loc */
.byte 0x0e /* DW_CFA_def_cfa_offset */
.uleb128 8
.byte 0x85, 0x02 /* DW_CFA_offset %ebp -8 */
.byte 0x40 + .Lpop_ebp-.Lpush_ebp /* DW_CFA_advance_loc */
.byte 0xc5 /* DW_CFA_restore %ebp */
.byte 0x0e /* DW_CFA_def_cfa_offset */
.uleb128 4
.align 4
.LENDFDE1:
.previous
/*
* Pad out the segment to match the size of the sysenter.S version.
*/
VDSO32_vsyscall_eh_frame_size = 0x40
.section .data,"aw",@progbits
.space VDSO32_vsyscall_eh_frame_size-(.LENDFDE1-.LSTARTFRAME), 0
.previous