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
  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         .previous
  39
  40         .section .eh_frame,"a",@progbits
  41 .LSTARTFRAMEDLSI1:
  42         .long .LENDCIEDLSI1-.LSTARTCIEDLSI1
  43 .LSTARTCIEDLSI1:
  44         .long 0                 /* CIE ID */
  45         .byte 1                 /* Version number */
  46         .string "zR"            /* NUL-terminated augmentation string */
  47         .uleb128 1              /* Code alignment factor */
  48         .sleb128 -4             /* Data alignment factor */
  49         .byte 8                 /* Return address register column */
  50         .uleb128 1              /* Augmentation value length */
  51         .byte 0x1b              /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
  52         .byte 0                 /* DW_CFA_nop */
  53         .align 4
  54 .LENDCIEDLSI1:
  55         .long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
  56 .LSTARTFDEDLSI1:
  57         .long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
  58         /* HACK: The dwarf2 unwind routines will subtract 1 from the
  59            return address to get an address in the middle of the
  60            presumed call instruction.  Since we didn't get here via
  61            a call, we need to include the nop before the real start
  62            to make up for it.  */
  63         .long .LSTART_sigreturn-1-.     /* PC-relative start address */
  64         .long .LEND_sigreturn-.LSTART_sigreturn+1
  65         .uleb128 0                      /* Augmentation */
  66         /* What follows are the instructions for the table generation.
  67            We record the locations of each register saved.  This is
  68            complicated by the fact that the "CFA" is always assumed to
  69            be the value of the stack pointer in the caller.  This means
  70            that we must define the CFA of this body of code to be the
  71            saved value of the stack pointer in the sigcontext.  Which
  72            also means that there is no fixed relation to the other
  73            saved registers, which means that we must use DW_CFA_expression
  74            to compute their addresses.  It also means that when we
  75            adjust the stack with the popl, we have to do it all over again.  */
  76
  77 #define do_cfa_expr(offset)                                             \
  78         .byte 0x0f;                     /* DW_CFA_def_cfa_expression */ \
  79         .uleb128 1f-0f;                 /*   length */                  \
  80 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  81         .sleb128 offset;                /*      offset */               \
  82         .byte 0x06;                     /*     DW_OP_deref */           \
  83 1:
  84
  85 #define do_expr(regno, offset)                                          \
  86         .byte 0x10;                     /* DW_CFA_expression */         \
  87         .uleb128 regno;                 /*   regno */                   \
  88         .uleb128 1f-0f;                 /*   length */                  \
  89 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  90         .sleb128 offset;                /*       offset */              \
  91 1:
  92
  93         do_cfa_expr(SIGCONTEXT_esp+4)
  94         do_expr(0, SIGCONTEXT_eax+4)
  95         do_expr(1, SIGCONTEXT_ecx+4)
  96         do_expr(2, SIGCONTEXT_edx+4)
  97         do_expr(3, SIGCONTEXT_ebx+4)
  98         do_expr(5, SIGCONTEXT_ebp+4)
  99         do_expr(6, SIGCONTEXT_esi+4)
 100         do_expr(7, SIGCONTEXT_edi+4)
 101         do_expr(8, SIGCONTEXT_eip+4)
 102
 103         .byte 0x42      /* DW_CFA_advance_loc 2 -- nop; popl eax. */
 104
 105         do_cfa_expr(SIGCONTEXT_esp)
 106         do_expr(0, SIGCONTEXT_eax)
 107         do_expr(1, SIGCONTEXT_ecx)
 108         do_expr(2, SIGCONTEXT_edx)
 109         do_expr(3, SIGCONTEXT_ebx)
 110         do_expr(5, SIGCONTEXT_ebp)
 111         do_expr(6, SIGCONTEXT_esi)
 112         do_expr(7, SIGCONTEXT_edi)
 113         do_expr(8, SIGCONTEXT_eip)
 114
 115         .align 4
 116 .LENDFDEDLSI1:
 117
 118         .long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
 119 .LSTARTFDEDLSI2:
 120         .long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
 121         /* HACK: See above wrt unwind library assumptions.  */
 122         .long .LSTART_rt_sigreturn-1-.  /* PC-relative start address */
 123         .long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1
 124         .uleb128 0                      /* Augmentation */
 125         /* What follows are the instructions for the table generation.
 126            We record the locations of each register saved.  This is
 127            slightly less complicated than the above, since we don't
 128            modify the stack pointer in the process.  */
 129
 130         do_cfa_expr(RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_esp)
 131         do_expr(0, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_eax)
 132         do_expr(1, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ecx)
 133         do_expr(2, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_edx)
 134         do_expr(3, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ebx)
 135         do_expr(5, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ebp)
 136         do_expr(6, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_esi)
 137         do_expr(7, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_edi)
 138         do_expr(8, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_eip)
 139
 140         .align 4
 141 .LENDFDEDLSI2:
 142         .previous