arch/x86/vdso/vdso32/sigreturn.S

   1 /*
   2  * Common code for the sigreturn entry points in vDSO images.
   3  * So far this code is the same for both int80 and sysenter versions.
   4  * This file is #include'd by int80.S et al to define them first thing.
   5  * The kernel assumes that the addresses of these routines are constant
   6  * for all vDSO implementations.
   7  */
   8
   9 #include <linux/linkage.h>
  10 #include <asm/unistd_32.h>
  11 #include <asm/asm-offsets.h>
  12
  13 #ifndef SYSCALL_ENTER_KERNEL
  14 #define SYSCALL_ENTER_KERNEL    int $0x80
  15 #endif
  16
  17         .text
  18         .globl __kernel_sigreturn
  19         .type __kernel_sigreturn,@function
  20         nop /* this guy is needed for .LSTARTFDEDLSI1 below (watch for HACK) */
  21         ALIGN
  22 __kernel_sigreturn:
  23 .LSTART_sigreturn:
  24         popl %eax               /* XXX does this mean it needs unwind info? */
  25         movl $__NR_sigreturn, %eax
  26         SYSCALL_ENTER_KERNEL
  27 .LEND_sigreturn:
  28         nop
  29         .size __kernel_sigreturn,.-.LSTART_sigreturn
  30
  31         .globl __kernel_rt_sigreturn
  32         .type __kernel_rt_sigreturn,@function
  33         ALIGN
  34 __kernel_rt_sigreturn:
  35 .LSTART_rt_sigreturn:
  36         movl $__NR_rt_sigreturn, %eax
  37         SYSCALL_ENTER_KERNEL
  38 .LEND_rt_sigreturn:
  39         nop
  40         .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
  41         .previous
  42
  43         .section .eh_frame,"a",@progbits
  44 .LSTARTFRAMEDLSI1:
  45         .long .LENDCIEDLSI1-.LSTARTCIEDLSI1
  46 .LSTARTCIEDLSI1:
  47         .long 0                 /* CIE ID */
  48         .byte 1                 /* Version number */
  49         .string "zRS"           /* NUL-terminated augmentation string */
  50         .uleb128 1              /* Code alignment factor */
  51         .sleb128 -4             /* Data alignment factor */
  52         .byte 8                 /* Return address register column */
  53         .uleb128 1              /* Augmentation value length */
  54         .byte 0x1b              /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
  55         .byte 0                 /* DW_CFA_nop */
  56         .align 4
  57 .LENDCIEDLSI1:
  58         .long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
  59 .LSTARTFDEDLSI1:
  60         .long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
  61         /* HACK: The dwarf2 unwind routines will subtract 1 from the
  62            return address to get an address in the middle of the
  63            presumed call instruction.  Since we didn't get here via
  64            a call, we need to include the nop before the real start
  65            to make up for it.  */
  66         .long .LSTART_sigreturn-1-.     /* PC-relative start address */
  67         .long .LEND_sigreturn-.LSTART_sigreturn+1
  68         .uleb128 0                      /* Augmentation */
  69         /* What follows are the instructions for the table generation.
  70            We record the locations of each register saved.  This is
  71            complicated by the fact that the "CFA" is always assumed to
  72            be the value of the stack pointer in the caller.  This means
  73            that we must define the CFA of this body of code to be the
  74            saved value of the stack pointer in the sigcontext.  Which
  75            also means that there is no fixed relation to the other
  76            saved registers, which means that we must use DW_CFA_expression
  77            to compute their addresses.  It also means that when we
  78            adjust the stack with the popl, we have to do it all over again.  */
  79
  80 #define do_cfa_expr(offset)                                             \
  81         .byte 0x0f;                     /* DW_CFA_def_cfa_expression */ \
  82         .uleb128 1f-0f;                 /*   length */                  \
  83 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  84         .sleb128 offset;                /*      offset */               \
  85         .byte 0x06;                     /*     DW_OP_deref */           \
  86 1:
  87
  88 #define do_expr(regno, offset)                                          \
  89         .byte 0x10;                     /* DW_CFA_expression */         \
  90         .uleb128 regno;                 /*   regno */                   \
  91         .uleb128 1f-0f;                 /*   length */                  \
  92 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  93         .sleb128 offset;                /*       offset */              \
  94 1:
  95
  96         do_cfa_expr(IA32_SIGCONTEXT_sp+4)
  97         do_expr(0, IA32_SIGCONTEXT_ax+4)
  98         do_expr(1, IA32_SIGCONTEXT_cx+4)
  99         do_expr(2, IA32_SIGCONTEXT_dx+4)
 100         do_expr(3, IA32_SIGCONTEXT_bx+4)
 101         do_expr(5, IA32_SIGCONTEXT_bp+4)
 102         do_expr(6, IA32_SIGCONTEXT_si+4)
 103         do_expr(7, IA32_SIGCONTEXT_di+4)
 104         do_expr(8, IA32_SIGCONTEXT_ip+4)
 105
 106         .byte 0x42      /* DW_CFA_advance_loc 2 -- nop; popl eax. */
 107
 108         do_cfa_expr(IA32_SIGCONTEXT_sp)
 109         do_expr(0, IA32_SIGCONTEXT_ax)
 110         do_expr(1, IA32_SIGCONTEXT_cx)
 111         do_expr(2, IA32_SIGCONTEXT_dx)
 112         do_expr(3, IA32_SIGCONTEXT_bx)
 113         do_expr(5, IA32_SIGCONTEXT_bp)
 114         do_expr(6, IA32_SIGCONTEXT_si)
 115         do_expr(7, IA32_SIGCONTEXT_di)
 116         do_expr(8, IA32_SIGCONTEXT_ip)
 117
 118         .align 4
 119 .LENDFDEDLSI1:
 120
 121         .long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
 122 .LSTARTFDEDLSI2:
 123         .long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
 124         /* HACK: See above wrt unwind library assumptions.  */
 125         .long .LSTART_rt_sigreturn-1-.  /* PC-relative start address */
 126         .long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1
 127         .uleb128 0                      /* Augmentation */
 128         /* What follows are the instructions for the table generation.
 129            We record the locations of each register saved.  This is
 130            slightly less complicated than the above, since we don't
 131            modify the stack pointer in the process.  */
 132
 133         do_cfa_expr(IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_sp)
 134         do_expr(0, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ax)
 135         do_expr(1, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_cx)
 136         do_expr(2, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_dx)
 137         do_expr(3, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bx)
 138         do_expr(5, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bp)
 139         do_expr(6, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_si)
 140         do_expr(7, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_di)
 141         do_expr(8, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ip)
 142
 143         .align 4
 144 .LENDFDEDLSI2:
 145         .previous