arch/x86/entry/vdso/vdso32/syscall.S

   1 /*
   2  * Code for the vDSO.  This version uses the syscall instruction.
   3  *
   4  * First get the common code for the sigreturn entry points.
   5  * This must come first.
   6  */
   7 #define SYSCALL_ENTER_KERNEL    syscall
   8 #include "sigreturn.S"
   9
  10 #include <asm/segment.h>
  11
  12         .text
  13         .globl __kernel_vsyscall
  14         .type __kernel_vsyscall,@function
  15         ALIGN
  16 __kernel_vsyscall:
  17 .LSTART_vsyscall:
  18         push    %ebp
  19 .Lpush_ebp:
  20         movl    %ecx, %ebp
  21         syscall
  22         movl    %ebp, %ecx
  23         popl    %ebp
  24 .Lpop_ebp:
  25         ret
  26 .LEND_vsyscall:
  27         .size __kernel_vsyscall,.-.LSTART_vsyscall
  28
  29         .section .eh_frame,"a",@progbits
  30 .LSTARTFRAME:
  31         .long .LENDCIE-.LSTARTCIE
  32 .LSTARTCIE:
  33         .long 0                 /* CIE ID */
  34         .byte 1                 /* Version number */
  35         .string "zR"            /* NUL-terminated augmentation string */
  36         .uleb128 1              /* Code alignment factor */
  37         .sleb128 -4             /* Data alignment factor */
  38         .byte 8                 /* Return address register column */
  39         .uleb128 1              /* Augmentation value length */
  40         .byte 0x1b              /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
  41         .byte 0x0c              /* DW_CFA_def_cfa */
  42         .uleb128 4
  43         .uleb128 4
  44         .byte 0x88              /* DW_CFA_offset, column 0x8 */
  45         .uleb128 1
  46         .align 4
  47 .LENDCIE:
  48
  49         .long .LENDFDE1-.LSTARTFDE1     /* Length FDE */
  50 .LSTARTFDE1:
  51         .long .LSTARTFDE1-.LSTARTFRAME  /* CIE pointer */
  52         .long .LSTART_vsyscall-.        /* PC-relative start address */
  53         .long .LEND_vsyscall-.LSTART_vsyscall
  54         .uleb128 0                      /* Augmentation length */
  55         /* What follows are the instructions for the table generation.
  56            We have to record all changes of the stack pointer.  */
  57         .byte 0x40 + .Lpush_ebp-.LSTART_vsyscall /* DW_CFA_advance_loc */
  58         .byte 0x0e              /* DW_CFA_def_cfa_offset */
  59         .uleb128 8
  60         .byte 0x85, 0x02        /* DW_CFA_offset %ebp -8 */
  61         .byte 0x40 + .Lpop_ebp-.Lpush_ebp /* DW_CFA_advance_loc */
  62         .byte 0xc5              /* DW_CFA_restore %ebp */
  63         .byte 0x0e              /* DW_CFA_def_cfa_offset */
  64         .uleb128 4
  65         .align 4
  66 .LENDFDE1:
  67         .previous
  68
  69         /*
  70          * Pad out the segment to match the size of the sysenter.S version.
  71          */
  72 VDSO32_vsyscall_eh_frame_size = 0x40
  73         .section .data,"aw",@progbits
  74         .space VDSO32_vsyscall_eh_frame_size-(.LENDFDE1-.LSTARTFRAME), 0
  75         .previous