arch/i386/kernel/vsyscall-sigreturn.S

   1 /*
   2  * Common code for the sigreturn entry points on the vsyscall page.
   3  * So far this code is the same for both int80 and sysenter versions.
   4  * This file is #include'd by vsyscall-*.S to define them after the
   5  * vsyscall entry point.  The kernel assumes that the addresses of these
   6  * routines are constant for all vsyscall implementations.
   7  */
   8
   9 #include <asm/unistd.h>
  10 #include <asm/asm-offsets.h>
  11
  12
  13 /* XXX
  14    Should these be named "_sigtramp" or something?
  15 */
  16
  17         .text
  18         .org __kernel_vsyscall+32,0x90
  19         .globl __kernel_sigreturn
  20         .type __kernel_sigreturn,@function
  21 __kernel_sigreturn:
  22 .LSTART_sigreturn:
  23         popl %eax               /* XXX does this mean it needs unwind info? */
  24         movl $__NR_sigreturn, %eax
  25         int $0x80
  26 .LEND_sigreturn:
  27         .size __kernel_sigreturn,.-.LSTART_sigreturn
  28
  29         .balign 32
  30         .globl __kernel_rt_sigreturn
  31         .type __kernel_rt_sigreturn,@function
  32 __kernel_rt_sigreturn:
  33 .LSTART_rt_sigreturn:
  34         movl $__NR_rt_sigreturn, %eax
  35         int $0x80
  36 .LEND_rt_sigreturn:
  37         .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
  38         .balign 32
  39         .previous
  40
  41         .section .eh_frame,"a",@progbits
  42 .LSTARTFRAMEDLSI1:
  43         .long .LENDCIEDLSI1-.LSTARTCIEDLSI1
  44 .LSTARTCIEDLSI1:
  45         .long 0                 /* CIE ID */
  46         .byte 1                 /* Version number */
  47         .string "zRS"           /* NUL-terminated augmentation string */
  48         .uleb128 1              /* Code alignment factor */
  49         .sleb128 -4             /* Data alignment factor */
  50         .byte 8                 /* Return address register column */
  51         .uleb128 1              /* Augmentation value length */
  52         .byte 0x1b              /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
  53         .byte 0                 /* DW_CFA_nop */
  54         .align 4
  55 .LENDCIEDLSI1:
  56         .long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
  57 .LSTARTFDEDLSI1:
  58         .long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
  59         /* HACK: The dwarf2 unwind routines will subtract 1 from the
  60            return address to get an address in the middle of the
  61            presumed call instruction.  Since we didn't get here via
  62            a call, we need to include the nop before the real start
  63            to make up for it.  */
  64         .long .LSTART_sigreturn-1-.     /* PC-relative start address */
  65         .long .LEND_sigreturn-.LSTART_sigreturn+1
  66         .uleb128 0                      /* Augmentation */
  67         /* What follows are the instructions for the table generation.
  68            We record the locations of each register saved.  This is
  69            complicated by the fact that the "CFA" is always assumed to
  70            be the value of the stack pointer in the caller.  This means
  71            that we must define the CFA of this body of code to be the
  72            saved value of the stack pointer in the sigcontext.  Which
  73            also means that there is no fixed relation to the other
  74            saved registers, which means that we must use DW_CFA_expression
  75            to compute their addresses.  It also means that when we
  76            adjust the stack with the popl, we have to do it all over again.  */
  77
  78 #define do_cfa_expr(offset)                                             \
  79         .byte 0x0f;                     /* DW_CFA_def_cfa_expression */ \
  80         .uleb128 1f-0f;                 /*   length */                  \
  81 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  82         .sleb128 offset;                /*      offset */               \
  83         .byte 0x06;                     /*     DW_OP_deref */           \
  84 1:
  85
  86 #define do_expr(regno, offset)                                          \
  87         .byte 0x10;                     /* DW_CFA_expression */         \
  88         .uleb128 regno;                 /*   regno */                   \
  89         .uleb128 1f-0f;                 /*   length */                  \
  90 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  91         .sleb128 offset;                /*       offset */              \
  92 1:
  93
  94         do_cfa_expr(SIGCONTEXT_esp+4)
  95         do_expr(0, SIGCONTEXT_eax+4)
  96         do_expr(1, SIGCONTEXT_ecx+4)
  97         do_expr(2, SIGCONTEXT_edx+4)
  98         do_expr(3, SIGCONTEXT_ebx+4)
  99         do_expr(5, SIGCONTEXT_ebp+4)
 100         do_expr(6, SIGCONTEXT_esi+4)
 101         do_expr(7, SIGCONTEXT_edi+4)
 102         do_expr(8, SIGCONTEXT_eip+4)
 103
 104         .byte 0x42      /* DW_CFA_advance_loc 2 -- nop; popl eax. */
 105
 106         do_cfa_expr(SIGCONTEXT_esp)
 107         do_expr(0, SIGCONTEXT_eax)
 108         do_expr(1, SIGCONTEXT_ecx)
 109         do_expr(2, SIGCONTEXT_edx)
 110         do_expr(3, SIGCONTEXT_ebx)
 111         do_expr(5, SIGCONTEXT_ebp)
 112         do_expr(6, SIGCONTEXT_esi)
 113         do_expr(7, SIGCONTEXT_edi)
 114         do_expr(8, SIGCONTEXT_eip)
 115
 116         .align 4
 117 .LENDFDEDLSI1:
 118
 119         .long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
 120 .LSTARTFDEDLSI2:
 121         .long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
 122         /* HACK: See above wrt unwind library assumptions.  */
 123         .long .LSTART_rt_sigreturn-1-.  /* PC-relative start address */
 124         .long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1
 125         .uleb128 0                      /* Augmentation */
 126         /* What follows are the instructions for the table generation.
 127            We record the locations of each register saved.  This is
 128            slightly less complicated than the above, since we don't
 129            modify the stack pointer in the process.  */
 130
 131         do_cfa_expr(RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_esp)
 132         do_expr(0, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_eax)
 133         do_expr(1, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ecx)
 134         do_expr(2, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_edx)
 135         do_expr(3, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ebx)
 136         do_expr(5, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ebp)
 137         do_expr(6, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_esi)
 138         do_expr(7, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_edi)
 139         do_expr(8, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_eip)
 140
 141         .align 4
 142 .LENDFDEDLSI2:
 143         .previous