root/arch/x86/entry/vdso/vdso32/sigreturn.S

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   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <linux/linkage.h>
   3 #include <asm/unistd_32.h>
   4 #include <asm/asm-offsets.h>
   5 
   6 #ifndef SYSCALL_ENTER_KERNEL
   7 #define SYSCALL_ENTER_KERNEL    int $0x80
   8 #endif
   9 
  10         .text
  11         .globl __kernel_sigreturn
  12         .type __kernel_sigreturn,@function
  13         nop /* this guy is needed for .LSTARTFDEDLSI1 below (watch for HACK) */
  14         ALIGN
  15 __kernel_sigreturn:
  16 .LSTART_sigreturn:
  17         popl %eax               /* XXX does this mean it needs unwind info? */
  18         movl $__NR_sigreturn, %eax
  19         SYSCALL_ENTER_KERNEL
  20 .LEND_sigreturn:
  21         nop
  22         .size __kernel_sigreturn,.-.LSTART_sigreturn
  23 
  24         .globl __kernel_rt_sigreturn
  25         .type __kernel_rt_sigreturn,@function
  26         ALIGN
  27 __kernel_rt_sigreturn:
  28 .LSTART_rt_sigreturn:
  29         movl $__NR_rt_sigreturn, %eax
  30         SYSCALL_ENTER_KERNEL
  31 .LEND_rt_sigreturn:
  32         nop
  33         .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
  34         .previous
  35 
  36         .section .eh_frame,"a",@progbits
  37 .LSTARTFRAMEDLSI1:
  38         .long .LENDCIEDLSI1-.LSTARTCIEDLSI1
  39 .LSTARTCIEDLSI1:
  40         .long 0                 /* CIE ID */
  41         .byte 1                 /* Version number */
  42         .string "zRS"           /* NUL-terminated augmentation string */
  43         .uleb128 1              /* Code alignment factor */
  44         .sleb128 -4             /* Data alignment factor */
  45         .byte 8                 /* Return address register column */
  46         .uleb128 1              /* Augmentation value length */
  47         .byte 0x1b              /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
  48         .byte 0                 /* DW_CFA_nop */
  49         .align 4
  50 .LENDCIEDLSI1:
  51         .long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
  52 .LSTARTFDEDLSI1:
  53         .long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
  54         /* HACK: The dwarf2 unwind routines will subtract 1 from the
  55            return address to get an address in the middle of the
  56            presumed call instruction.  Since we didn't get here via
  57            a call, we need to include the nop before the real start
  58            to make up for it.  */
  59         .long .LSTART_sigreturn-1-.     /* PC-relative start address */
  60         .long .LEND_sigreturn-.LSTART_sigreturn+1
  61         .uleb128 0                      /* Augmentation */
  62         /* What follows are the instructions for the table generation.
  63            We record the locations of each register saved.  This is
  64            complicated by the fact that the "CFA" is always assumed to
  65            be the value of the stack pointer in the caller.  This means
  66            that we must define the CFA of this body of code to be the
  67            saved value of the stack pointer in the sigcontext.  Which
  68            also means that there is no fixed relation to the other
  69            saved registers, which means that we must use DW_CFA_expression
  70            to compute their addresses.  It also means that when we
  71            adjust the stack with the popl, we have to do it all over again.  */
  72 
  73 #define do_cfa_expr(offset)                                             \
  74         .byte 0x0f;                     /* DW_CFA_def_cfa_expression */ \
  75         .uleb128 1f-0f;                 /*   length */                  \
  76 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  77         .sleb128 offset;                /*      offset */               \
  78         .byte 0x06;                     /*     DW_OP_deref */           \
  79 1:
  80 
  81 #define do_expr(regno, offset)                                          \
  82         .byte 0x10;                     /* DW_CFA_expression */         \
  83         .uleb128 regno;                 /*   regno */                   \
  84         .uleb128 1f-0f;                 /*   length */                  \
  85 0:      .byte 0x74;                     /*     DW_OP_breg4 */           \
  86         .sleb128 offset;                /*       offset */              \
  87 1:
  88 
  89         do_cfa_expr(IA32_SIGCONTEXT_sp+4)
  90         do_expr(0, IA32_SIGCONTEXT_ax+4)
  91         do_expr(1, IA32_SIGCONTEXT_cx+4)
  92         do_expr(2, IA32_SIGCONTEXT_dx+4)
  93         do_expr(3, IA32_SIGCONTEXT_bx+4)
  94         do_expr(5, IA32_SIGCONTEXT_bp+4)
  95         do_expr(6, IA32_SIGCONTEXT_si+4)
  96         do_expr(7, IA32_SIGCONTEXT_di+4)
  97         do_expr(8, IA32_SIGCONTEXT_ip+4)
  98 
  99         .byte 0x42      /* DW_CFA_advance_loc 2 -- nop; popl eax. */
 100 
 101         do_cfa_expr(IA32_SIGCONTEXT_sp)
 102         do_expr(0, IA32_SIGCONTEXT_ax)
 103         do_expr(1, IA32_SIGCONTEXT_cx)
 104         do_expr(2, IA32_SIGCONTEXT_dx)
 105         do_expr(3, IA32_SIGCONTEXT_bx)
 106         do_expr(5, IA32_SIGCONTEXT_bp)
 107         do_expr(6, IA32_SIGCONTEXT_si)
 108         do_expr(7, IA32_SIGCONTEXT_di)
 109         do_expr(8, IA32_SIGCONTEXT_ip)
 110 
 111         .align 4
 112 .LENDFDEDLSI1:
 113 
 114         .long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
 115 .LSTARTFDEDLSI2:
 116         .long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
 117         /* HACK: See above wrt unwind library assumptions.  */
 118         .long .LSTART_rt_sigreturn-1-.  /* PC-relative start address */
 119         .long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1
 120         .uleb128 0                      /* Augmentation */
 121         /* What follows are the instructions for the table generation.
 122            We record the locations of each register saved.  This is
 123            slightly less complicated than the above, since we don't
 124            modify the stack pointer in the process.  */
 125 
 126         do_cfa_expr(IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_sp)
 127         do_expr(0, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ax)
 128         do_expr(1, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_cx)
 129         do_expr(2, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_dx)
 130         do_expr(3, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bx)
 131         do_expr(5, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bp)
 132         do_expr(6, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_si)
 133         do_expr(7, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_di)
 134         do_expr(8, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ip)
 135 
 136         .align 4
 137 .LENDFDEDLSI2:
 138         .previous
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