1/*
2 * MIPS specific _mcount support
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive for
6 * more details.
7 *
8 * Copyright (C) 2009 Lemote Inc. & DSLab, Lanzhou University, China
9 * Copyright (C) 2010 DSLab, Lanzhou University, China
10 * Author: Wu Zhangjin <wuzhangjin@gmail.com>
11 */
12
13#include <linux/export.h>
14#include <asm/regdef.h>
15#include <asm/stackframe.h>
16#include <asm/ftrace.h>
17
18 .text
19 .set noreorder
20 .set noat
21
22 .macro MCOUNT_SAVE_REGS
23 PTR_SUBU sp, PT_SIZE
24 PTR_S ra, PT_R31(sp)
25 PTR_S AT, PT_R1(sp)
26 PTR_S a0, PT_R4(sp)
27 PTR_S a1, PT_R5(sp)
28 PTR_S a2, PT_R6(sp)
29 PTR_S a3, PT_R7(sp)
30#ifdef CONFIG_64BIT
31 PTR_S a4, PT_R8(sp)
32 PTR_S a5, PT_R9(sp)
33 PTR_S a6, PT_R10(sp)
34 PTR_S a7, PT_R11(sp)
35#endif
36 .endm
37
38 .macro MCOUNT_RESTORE_REGS
39 PTR_L ra, PT_R31(sp)
40 PTR_L AT, PT_R1(sp)
41 PTR_L a0, PT_R4(sp)
42 PTR_L a1, PT_R5(sp)
43 PTR_L a2, PT_R6(sp)
44 PTR_L a3, PT_R7(sp)
45#ifdef CONFIG_64BIT
46 PTR_L a4, PT_R8(sp)
47 PTR_L a5, PT_R9(sp)
48 PTR_L a6, PT_R10(sp)
49 PTR_L a7, PT_R11(sp)
50#endif
51 PTR_ADDIU sp, PT_SIZE
52 .endm
53
54 .macro RETURN_BACK
55 jr ra
56 move ra, AT
57 .endm
58
59/*
60 * The -mmcount-ra-address option of gcc 4.5 uses register $12 to pass
61 * the location of the parent's return address.
62 */
63#define MCOUNT_RA_ADDRESS_REG $12
64
65#ifdef CONFIG_DYNAMIC_FTRACE
66
67NESTED(ftrace_caller, PT_SIZE, ra)
68 .globl _mcount
69_mcount:
70EXPORT_SYMBOL(_mcount)
71 b ftrace_stub
72#ifdef CONFIG_32BIT
73 addiu sp,sp,8
74#else
75 nop
76#endif
77
78 /* When tracing is activated, it calls ftrace_caller+8 (aka here) */
79 MCOUNT_SAVE_REGS
80#ifdef KBUILD_MCOUNT_RA_ADDRESS
81 PTR_S MCOUNT_RA_ADDRESS_REG, PT_R12(sp)
82#endif
83
84 PTR_SUBU a0, ra, 8 /* arg1: self address */
85 PTR_LA t1, _stext
86 sltu t2, a0, t1 /* t2 = (a0 < _stext) */
87 PTR_LA t1, _etext
88 sltu t3, t1, a0 /* t3 = (a0 > _etext) */
89 or t1, t2, t3
90 beqz t1, ftrace_call
91 nop
92#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
93 PTR_SUBU a0, a0, 16 /* arg1: adjust to module's recorded callsite */
94#else
95 PTR_SUBU a0, a0, 12
96#endif
97
98 .globl ftrace_call
99ftrace_call:
100 nop /* a placeholder for the call to a real tracing function */
101 move a1, AT /* arg2: parent's return address */
102
103#ifdef CONFIG_FUNCTION_GRAPH_TRACER
104 .globl ftrace_graph_call
105ftrace_graph_call:
106 nop
107 nop
108#endif
109
110 MCOUNT_RESTORE_REGS
111 .globl ftrace_stub
112ftrace_stub:
113 RETURN_BACK
114 END(ftrace_caller)
115
116#else /* ! CONFIG_DYNAMIC_FTRACE */
117
118NESTED(_mcount, PT_SIZE, ra)
119EXPORT_SYMBOL(_mcount)
120 PTR_LA t1, ftrace_stub
121 PTR_L t2, ftrace_trace_function /* Prepare t2 for (1) */
122 beq t1, t2, fgraph_trace
123 nop
124
125 MCOUNT_SAVE_REGS
126
127 move a0, ra /* arg1: self return address */
128 jalr t2 /* (1) call *ftrace_trace_function */
129 move a1, AT /* arg2: parent's return address */
130
131 MCOUNT_RESTORE_REGS
132
133fgraph_trace:
134#ifdef CONFIG_FUNCTION_GRAPH_TRACER
135 PTR_LA t1, ftrace_stub
136 PTR_L t3, ftrace_graph_return
137 bne t1, t3, ftrace_graph_caller
138 nop
139 PTR_LA t1, ftrace_graph_entry_stub
140 PTR_L t3, ftrace_graph_entry
141 bne t1, t3, ftrace_graph_caller
142 nop
143#endif
144
145#ifdef CONFIG_32BIT
146 addiu sp, sp, 8
147#endif
148
149 .globl ftrace_stub
150ftrace_stub:
151 RETURN_BACK
152 END(_mcount)
153
154#endif /* ! CONFIG_DYNAMIC_FTRACE */
155
156#ifdef CONFIG_FUNCTION_GRAPH_TRACER
157
158NESTED(ftrace_graph_caller, PT_SIZE, ra)
159#ifndef CONFIG_DYNAMIC_FTRACE
160 MCOUNT_SAVE_REGS
161#endif
162
163 /* arg1: Get the location of the parent's return address */
164#ifdef KBUILD_MCOUNT_RA_ADDRESS
165#ifdef CONFIG_DYNAMIC_FTRACE
166 PTR_L a0, PT_R12(sp)
167#else
168 move a0, MCOUNT_RA_ADDRESS_REG
169#endif
170 bnez a0, 1f /* non-leaf func: stored in MCOUNT_RA_ADDRESS_REG */
171 nop
172#endif
173 PTR_LA a0, PT_R1(sp) /* leaf func: the location in current stack */
1741:
175
176 /* arg2: Get self return address */
177#ifdef CONFIG_DYNAMIC_FTRACE
178 PTR_L a1, PT_R31(sp)
179#else
180 move a1, ra
181#endif
182
183 /* arg3: Get frame pointer of current stack */
184#ifdef CONFIG_64BIT
185 PTR_LA a2, PT_SIZE(sp)
186#else
187 PTR_LA a2, (PT_SIZE+8)(sp)
188#endif
189
190 jal prepare_ftrace_return
191 nop
192 MCOUNT_RESTORE_REGS
193#ifndef CONFIG_DYNAMIC_FTRACE
194#ifdef CONFIG_32BIT
195 addiu sp, sp, 8
196#endif
197#endif
198 RETURN_BACK
199 END(ftrace_graph_caller)
200
201 .align 2
202 .globl return_to_handler
203return_to_handler:
204 PTR_SUBU sp, PT_SIZE
205 PTR_S v0, PT_R2(sp)
206
207 jal ftrace_return_to_handler
208 PTR_S v1, PT_R3(sp)
209
210 /* restore the real parent address: v0 -> ra */
211 move ra, v0
212
213 PTR_L v0, PT_R2(sp)
214 PTR_L v1, PT_R3(sp)
215 jr ra
216 PTR_ADDIU sp, PT_SIZE
217#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
218
219 .set at
220 .set reorder
221

source code of linux/arch/mips/kernel/mcount.S