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7d241ff0 MS |
1 | /* |
2 | * Ftrace support for Microblaze. | |
3 | * | |
4 | * Copyright (C) 2009 Michal Simek <monstr@monstr.eu> | |
5 | * Copyright (C) 2009 PetaLogix | |
6 | * | |
7 | * Based on MIPS and PowerPC ftrace code | |
8 | * | |
9 | * This file is subject to the terms and conditions of the GNU General Public | |
10 | * License. See the file "COPYING" in the main directory of this archive | |
11 | * for more details. | |
12 | */ | |
13 | ||
14 | #include <asm/cacheflush.h> | |
15 | #include <linux/ftrace.h> | |
16 | ||
a0d3e665 MS |
17 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
18 | /* | |
19 | * Hook the return address and push it in the stack of return addrs | |
20 | * in current thread info. | |
21 | */ | |
22 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) | |
23 | { | |
24 | unsigned long old; | |
25 | int faulted, err; | |
26 | struct ftrace_graph_ent trace; | |
27 | unsigned long return_hooker = (unsigned long) | |
28 | &return_to_handler; | |
29 | ||
30 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) | |
31 | return; | |
32 | ||
33 | /* | |
34 | * Protect against fault, even if it shouldn't | |
35 | * happen. This tool is too much intrusive to | |
36 | * ignore such a protection. | |
37 | */ | |
38 | asm volatile(" 1: lwi %0, %2, 0; \ | |
39 | 2: swi %3, %2, 0; \ | |
40 | addik %1, r0, 0; \ | |
41 | 3: \ | |
42 | .section .fixup, \"ax\"; \ | |
43 | 4: brid 3b; \ | |
44 | addik %1, r0, 1; \ | |
45 | .previous; \ | |
46 | .section __ex_table,\"a\"; \ | |
47 | .word 1b,4b; \ | |
48 | .word 2b,4b; \ | |
49 | .previous;" \ | |
50 | : "=&r" (old), "=r" (faulted) | |
51 | : "r" (parent), "r" (return_hooker) | |
52 | ); | |
53 | ||
54 | if (unlikely(faulted)) { | |
55 | ftrace_graph_stop(); | |
56 | WARN_ON(1); | |
57 | return; | |
58 | } | |
59 | ||
60 | err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0); | |
61 | if (err == -EBUSY) { | |
62 | *parent = old; | |
63 | return; | |
64 | } | |
65 | ||
66 | trace.func = self_addr; | |
67 | /* Only trace if the calling function expects to */ | |
68 | if (!ftrace_graph_entry(&trace)) { | |
69 | current->curr_ret_stack--; | |
70 | *parent = old; | |
71 | } | |
72 | } | |
73 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ | |
74 | ||
7d241ff0 MS |
75 | #ifdef CONFIG_DYNAMIC_FTRACE |
76 | /* save value to addr - it is save to do it in asm */ | |
77 | static int ftrace_modify_code(unsigned long addr, unsigned int value) | |
78 | { | |
79 | int faulted = 0; | |
80 | ||
81 | __asm__ __volatile__(" 1: swi %2, %1, 0; \ | |
82 | addik %0, r0, 0; \ | |
83 | 2: \ | |
84 | .section .fixup, \"ax\"; \ | |
85 | 3: brid 2b; \ | |
86 | addik %0, r0, 1; \ | |
87 | .previous; \ | |
88 | .section __ex_table,\"a\"; \ | |
89 | .word 1b,3b; \ | |
90 | .previous;" \ | |
91 | : "=r" (faulted) | |
92 | : "r" (addr), "r" (value) | |
93 | ); | |
94 | ||
95 | if (unlikely(faulted)) | |
96 | return -EFAULT; | |
97 | ||
98 | return 0; | |
99 | } | |
100 | ||
101 | #define MICROBLAZE_NOP 0x80000000 | |
102 | #define MICROBLAZE_BRI 0xb800000C | |
103 | ||
104 | static unsigned int recorded; /* if save was or not */ | |
105 | static unsigned int imm; /* saving whole imm instruction */ | |
106 | ||
107 | /* There are two approaches howto solve ftrace_make nop function - look below */ | |
108 | #undef USE_FTRACE_NOP | |
109 | ||
110 | #ifdef USE_FTRACE_NOP | |
111 | static unsigned int bralid; /* saving whole bralid instruction */ | |
112 | #endif | |
113 | ||
114 | int ftrace_make_nop(struct module *mod, | |
115 | struct dyn_ftrace *rec, unsigned long addr) | |
116 | { | |
117 | /* we have this part of code which we are working with | |
118 | * b000c000 imm -16384 | |
119 | * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> | |
120 | * 80000000 or r0, r0, r0 | |
121 | * | |
122 | * The first solution (!USE_FTRACE_NOP-could be called branch solution) | |
123 | * b000c000 bri 12 (0xC - jump to any other instruction) | |
124 | * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> | |
125 | * 80000000 or r0, r0, r0 | |
126 | * any other instruction | |
127 | * | |
128 | * The second solution (USE_FTRACE_NOP) - no jump just nops | |
129 | * 80000000 or r0, r0, r0 | |
130 | * 80000000 or r0, r0, r0 | |
131 | * 80000000 or r0, r0, r0 | |
132 | */ | |
133 | int ret = 0; | |
134 | ||
135 | if (recorded == 0) { | |
136 | recorded = 1; | |
137 | imm = *(unsigned int *)rec->ip; | |
138 | pr_debug("%s: imm:0x%x\n", __func__, imm); | |
139 | #ifdef USE_FTRACE_NOP | |
140 | bralid = *(unsigned int *)(rec->ip + 4); | |
141 | pr_debug("%s: bralid 0x%x\n", __func__, bralid); | |
142 | #endif /* USE_FTRACE_NOP */ | |
143 | } | |
144 | ||
145 | #ifdef USE_FTRACE_NOP | |
146 | ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP); | |
147 | ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP); | |
148 | #else /* USE_FTRACE_NOP */ | |
149 | ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI); | |
150 | #endif /* USE_FTRACE_NOP */ | |
151 | return ret; | |
152 | } | |
153 | ||
7d241ff0 MS |
154 | /* I believe that first is called ftrace_make_nop before this function */ |
155 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
156 | { | |
157 | int ret; | |
7d241ff0 MS |
158 | pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n", |
159 | __func__, (unsigned int)addr, (unsigned int)rec->ip, imm); | |
160 | ret = ftrace_modify_code(rec->ip, imm); | |
161 | #ifdef USE_FTRACE_NOP | |
162 | pr_debug("%s: bralid:0x%x\n", __func__, bralid); | |
163 | ret += ftrace_modify_code(rec->ip + 4, bralid); | |
164 | #endif /* USE_FTRACE_NOP */ | |
165 | return ret; | |
166 | } | |
167 | ||
168 | int __init ftrace_dyn_arch_init(void *data) | |
169 | { | |
170 | /* The return code is retured via data */ | |
171 | *(unsigned long *)data = 0; | |
172 | ||
173 | return 0; | |
174 | } | |
175 | ||
176 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
177 | { | |
178 | unsigned long ip = (unsigned long)(&ftrace_call); | |
179 | unsigned int upper = (unsigned int)func; | |
180 | unsigned int lower = (unsigned int)func; | |
181 | int ret = 0; | |
182 | ||
183 | /* create proper saving to ftrace_call poll */ | |
184 | upper = 0xb0000000 + (upper >> 16); /* imm func_upper */ | |
185 | lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */ | |
186 | ||
187 | pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n", | |
188 | __func__, (unsigned int)func, (unsigned int)ip, upper, lower); | |
189 | ||
190 | /* save upper and lower code */ | |
191 | ret = ftrace_modify_code(ip, upper); | |
192 | ret += ftrace_modify_code(ip + 4, lower); | |
193 | ||
d2bf98e6 SM |
194 | /* We just need to replace the rtsd r15, 8 with NOP */ |
195 | ret += ftrace_modify_code((unsigned long)&ftrace_caller, | |
196 | MICROBLAZE_NOP); | |
7d241ff0 MS |
197 | |
198 | /* All changes are done - lets do caches consistent */ | |
199 | flush_icache(); | |
200 | return ret; | |
201 | } | |
202 | ||
4f911b0d MS |
203 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
204 | unsigned int old_jump; /* saving place for jump instruction */ | |
205 | ||
206 | int ftrace_enable_ftrace_graph_caller(void) | |
207 | { | |
208 | unsigned int ret; | |
209 | unsigned long ip = (unsigned long)(&ftrace_call_graph); | |
210 | ||
211 | old_jump = *(unsigned int *)ip; /* save jump over instruction */ | |
212 | ret = ftrace_modify_code(ip, MICROBLAZE_NOP); | |
213 | flush_icache(); | |
214 | ||
215 | pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump); | |
216 | return ret; | |
217 | } | |
218 | ||
219 | int ftrace_disable_ftrace_graph_caller(void) | |
220 | { | |
221 | unsigned int ret; | |
222 | unsigned long ip = (unsigned long)(&ftrace_call_graph); | |
223 | ||
224 | ret = ftrace_modify_code(ip, old_jump); | |
225 | flush_icache(); | |
226 | ||
227 | pr_debug("%s\n", __func__); | |
228 | return ret; | |
229 | } | |
230 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ | |
7d241ff0 | 231 | #endif /* CONFIG_DYNAMIC_FTRACE */ |