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.
9 #include <linux/linkage.h>
10 #include <asm/unistd_32.h>
11 #include <asm/asm-offsets.h>
13 #ifndef SYSCALL_ENTER_KERNEL
14 #define SYSCALL_ENTER_KERNEL int $0x80
18 .globl __kernel_sigreturn
19 .type __kernel_sigreturn,@function
20 nop /* this guy is needed for .LSTARTFDEDLSI1 below (watch for HACK) */
24 popl %eax /* XXX does this mean it needs unwind info? */
25 movl $__NR_sigreturn, %eax
29 .size __kernel_sigreturn,.-.LSTART_sigreturn
31 .globl __kernel_rt_sigreturn
32 .type __kernel_rt_sigreturn,@function
34 __kernel_rt_sigreturn:
36 movl $__NR_rt_sigreturn, %eax
40 .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
43 .section .eh_frame,"a",@progbits
45 .long .LENDCIEDLSI1-.LSTARTCIEDLSI1
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 */
58 .long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
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
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. */
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 */ \
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 */ \
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)
106 .byte 0x42 /* DW_CFA_advance_loc 2 -- nop; popl eax. */
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)
121 .long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
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. */
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)