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:
21SYM_INNER_LABEL(vdso32_sigreturn_landing_pad, SYM_L_GLOBAL)
22 nop
23 .size __kernel_sigreturn,.-.LSTART_sigreturn
24
25 .globl __kernel_rt_sigreturn
26 .type __kernel_rt_sigreturn,@function
27 ALIGN
28__kernel_rt_sigreturn:
29.LSTART_rt_sigreturn:
30 movl $__NR_rt_sigreturn, %eax
31 SYSCALL_ENTER_KERNEL
32.LEND_rt_sigreturn:
33SYM_INNER_LABEL(vdso32_rt_sigreturn_landing_pad, SYM_L_GLOBAL)
34 nop
35 .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
36 .previous
37
38 .section .eh_frame,"a",@progbits
39.LSTARTFRAMEDLSI1:
40 .long .LENDCIEDLSI1-.LSTARTCIEDLSI1
41.LSTARTCIEDLSI1:
42 .long 0 /* CIE ID */
43 .byte 1 /* Version number */
44 .string "zRS" /* NUL-terminated augmentation string */
45 .uleb128 1 /* Code alignment factor */
46 .sleb128 -4 /* Data alignment factor */
47 .byte 8 /* Return address register column */
48 .uleb128 1 /* Augmentation value length */
49 .byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
50 .byte 0 /* DW_CFA_nop */
51 .align 4
52.LENDCIEDLSI1:
53 .long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
54.LSTARTFDEDLSI1:
55 .long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
56 /* HACK: The dwarf2 unwind routines will subtract 1 from the
57 return address to get an address in the middle of the
58 presumed call instruction. Since we didn't get here via
59 a call, we need to include the nop before the real start
60 to make up for it. */
61 .long .LSTART_sigreturn-1-. /* PC-relative start address */
62 .long .LEND_sigreturn-.LSTART_sigreturn+1
63 .uleb128 0 /* Augmentation */
64 /* What follows are the instructions for the table generation.
65 We record the locations of each register saved. This is
66 complicated by the fact that the "CFA" is always assumed to
67 be the value of the stack pointer in the caller. This means
68 that we must define the CFA of this body of code to be the
69 saved value of the stack pointer in the sigcontext. Which
70 also means that there is no fixed relation to the other
71 saved registers, which means that we must use DW_CFA_expression
72 to compute their addresses. It also means that when we
73 adjust the stack with the popl, we have to do it all over again. */
74
75#define do_cfa_expr(offset) \
76 .byte 0x0f; /* DW_CFA_def_cfa_expression */ \
77 .uleb128 1f-0f; /* length */ \
780: .byte 0x74; /* DW_OP_breg4 */ \
79 .sleb128 offset; /* offset */ \
80 .byte 0x06; /* DW_OP_deref */ \
811:
82
83#define do_expr(regno, offset) \
84 .byte 0x10; /* DW_CFA_expression */ \
85 .uleb128 regno; /* regno */ \
86 .uleb128 1f-0f; /* length */ \
870: .byte 0x74; /* DW_OP_breg4 */ \
88 .sleb128 offset; /* offset */ \
891:
90
91 do_cfa_expr(IA32_SIGCONTEXT_sp+4)
92 do_expr(0, IA32_SIGCONTEXT_ax+4)
93 do_expr(1, IA32_SIGCONTEXT_cx+4)
94 do_expr(2, IA32_SIGCONTEXT_dx+4)
95 do_expr(3, IA32_SIGCONTEXT_bx+4)
96 do_expr(5, IA32_SIGCONTEXT_bp+4)
97 do_expr(6, IA32_SIGCONTEXT_si+4)
98 do_expr(7, IA32_SIGCONTEXT_di+4)
99 do_expr(8, IA32_SIGCONTEXT_ip+4)
100
101 .byte 0x42 /* DW_CFA_advance_loc 2 -- nop; popl eax. */
102
103 do_cfa_expr(IA32_SIGCONTEXT_sp)
104 do_expr(0, IA32_SIGCONTEXT_ax)
105 do_expr(1, IA32_SIGCONTEXT_cx)
106 do_expr(2, IA32_SIGCONTEXT_dx)
107 do_expr(3, IA32_SIGCONTEXT_bx)
108 do_expr(5, IA32_SIGCONTEXT_bp)
109 do_expr(6, IA32_SIGCONTEXT_si)
110 do_expr(7, IA32_SIGCONTEXT_di)
111 do_expr(8, IA32_SIGCONTEXT_ip)
112
113 .align 4
114.LENDFDEDLSI1:
115
116 .long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
117.LSTARTFDEDLSI2:
118 .long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
119 /* HACK: See above wrt unwind library assumptions. */
120 .long .LSTART_rt_sigreturn-1-. /* PC-relative start address */
121 .long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1
122 .uleb128 0 /* Augmentation */
123 /* What follows are the instructions for the table generation.
124 We record the locations of each register saved. This is
125 slightly less complicated than the above, since we don't
126 modify the stack pointer in the process. */
127
128 do_cfa_expr(IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_sp)
129 do_expr(0, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ax)
130 do_expr(1, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_cx)
131 do_expr(2, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_dx)
132 do_expr(3, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bx)
133 do_expr(5, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bp)
134 do_expr(6, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_si)
135 do_expr(7, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_di)
136 do_expr(8, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ip)
137
138 .align 4
139.LENDFDEDLSI2:
140 .previous
141

source code of linux/arch/x86/entry/vdso/vdso32/sigreturn.S