sigreturn.S

  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