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 | |
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; |
26 | unsigned long return_hooker = (unsigned long) |
27 | &return_to_handler; |
28 | |
29 | if (unlikely(ftrace_graph_is_dead())) |
30 | return; |
31 | |
32 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
33 | return; |
34 | |
35 | /* |
36 | * Protect against fault, even if it shouldn't |
37 | * happen. This tool is too much intrusive to |
38 | * ignore such a protection. |
39 | */ |
40 | asm volatile(" 1: lwi %0, %2, 0;" \ |
41 | "2: swi %3, %2, 0;" \ |
42 | " addik %1, r0, 0;" \ |
43 | "3:" \ |
44 | " .section .fixup, \"ax\";" \ |
45 | "4: brid 3b;" \ |
46 | " addik %1, r0, 1;" \ |
47 | " .previous;" \ |
48 | " .section __ex_table,\"a\";" \ |
49 | " .word 1b,4b;" \ |
50 | " .word 2b,4b;" \ |
51 | " .previous;" \ |
52 | : "=&r" (old), "=r" (faulted) |
53 | : "r" (parent), "r" (return_hooker) |
54 | ); |
55 | |
56 | flush_dcache_range((u32)parent, (u32)parent + 4); |
57 | flush_icache_range(start: (u32)parent, end: (u32)parent + 4); |
58 | |
59 | if (unlikely(faulted)) { |
60 | ftrace_graph_stop(); |
61 | WARN_ON(1); |
62 | return; |
63 | } |
64 | |
65 | if (function_graph_enter(ret: old, func: self_addr, frame_pointer: 0, NULL)) |
66 | *parent = old; |
67 | } |
68 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |
69 | |
70 | #ifdef CONFIG_DYNAMIC_FTRACE |
71 | /* save value to addr - it is save to do it in asm */ |
72 | static int ftrace_modify_code(unsigned long addr, unsigned int value) |
73 | { |
74 | int faulted = 0; |
75 | |
76 | __asm__ __volatile__(" 1: swi %2, %1, 0;" \ |
77 | " addik %0, r0, 0;" \ |
78 | "2:" \ |
79 | " .section .fixup, \"ax\";" \ |
80 | "3: brid 2b;" \ |
81 | " addik %0, r0, 1;" \ |
82 | " .previous;" \ |
83 | " .section __ex_table,\"a\";" \ |
84 | " .word 1b,3b;" \ |
85 | " .previous;" \ |
86 | : "=r" (faulted) |
87 | : "r" (addr), "r" (value) |
88 | ); |
89 | |
90 | if (unlikely(faulted)) |
91 | return -EFAULT; |
92 | |
93 | flush_dcache_range(addr, addr + 4); |
94 | flush_icache_range(start: addr, end: addr + 4); |
95 | |
96 | return 0; |
97 | } |
98 | |
99 | #define MICROBLAZE_NOP 0x80000000 |
100 | #define MICROBLAZE_BRI 0xb800000C |
101 | |
102 | static unsigned int recorded; /* if save was or not */ |
103 | static unsigned int imm; /* saving whole imm instruction */ |
104 | |
105 | /* There are two approaches howto solve ftrace_make nop function - look below */ |
106 | #undef USE_FTRACE_NOP |
107 | |
108 | #ifdef USE_FTRACE_NOP |
109 | static unsigned int bralid; /* saving whole bralid instruction */ |
110 | #endif |
111 | |
112 | int ftrace_make_nop(struct module *mod, |
113 | struct dyn_ftrace *rec, unsigned long addr) |
114 | { |
115 | /* we have this part of code which we are working with |
116 | * b000c000 imm -16384 |
117 | * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> |
118 | * 80000000 or r0, r0, r0 |
119 | * |
120 | * The first solution (!USE_FTRACE_NOP-could be called branch solution) |
121 | * b000c000 bri 12 (0xC - jump to any other instruction) |
122 | * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> |
123 | * 80000000 or r0, r0, r0 |
124 | * any other instruction |
125 | * |
126 | * The second solution (USE_FTRACE_NOP) - no jump just nops |
127 | * 80000000 or r0, r0, r0 |
128 | * 80000000 or r0, r0, r0 |
129 | * 80000000 or r0, r0, r0 |
130 | */ |
131 | int ret = 0; |
132 | |
133 | if (recorded == 0) { |
134 | recorded = 1; |
135 | imm = *(unsigned int *)rec->ip; |
136 | pr_debug("%s: imm:0x%x\n" , __func__, imm); |
137 | #ifdef USE_FTRACE_NOP |
138 | bralid = *(unsigned int *)(rec->ip + 4); |
139 | pr_debug("%s: bralid 0x%x\n" , __func__, bralid); |
140 | #endif /* USE_FTRACE_NOP */ |
141 | } |
142 | |
143 | #ifdef USE_FTRACE_NOP |
144 | ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP); |
145 | ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP); |
146 | #else /* USE_FTRACE_NOP */ |
147 | ret = ftrace_modify_code(addr: rec->ip, MICROBLAZE_BRI); |
148 | #endif /* USE_FTRACE_NOP */ |
149 | return ret; |
150 | } |
151 | |
152 | /* I believe that first is called ftrace_make_nop before this function */ |
153 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
154 | { |
155 | int ret; |
156 | pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n" , |
157 | __func__, (unsigned int)addr, (unsigned int)rec->ip, imm); |
158 | ret = ftrace_modify_code(addr: rec->ip, value: imm); |
159 | #ifdef USE_FTRACE_NOP |
160 | pr_debug("%s: bralid:0x%x\n" , __func__, bralid); |
161 | ret += ftrace_modify_code(rec->ip + 4, bralid); |
162 | #endif /* USE_FTRACE_NOP */ |
163 | return ret; |
164 | } |
165 | |
166 | int ftrace_update_ftrace_func(ftrace_func_t func) |
167 | { |
168 | unsigned long ip = (unsigned long)(&ftrace_call); |
169 | unsigned int upper = (unsigned int)func; |
170 | unsigned int lower = (unsigned int)func; |
171 | int ret = 0; |
172 | |
173 | /* create proper saving to ftrace_call poll */ |
174 | upper = 0xb0000000 + (upper >> 16); /* imm func_upper */ |
175 | lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */ |
176 | |
177 | pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n" , |
178 | __func__, (unsigned int)func, (unsigned int)ip, upper, lower); |
179 | |
180 | /* save upper and lower code */ |
181 | ret = ftrace_modify_code(addr: ip, value: upper); |
182 | ret += ftrace_modify_code(addr: ip + 4, value: lower); |
183 | |
184 | /* We just need to replace the rtsd r15, 8 with NOP */ |
185 | ret += ftrace_modify_code(addr: (unsigned long)&ftrace_caller, |
186 | MICROBLAZE_NOP); |
187 | |
188 | return ret; |
189 | } |
190 | |
191 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
192 | unsigned int old_jump; /* saving place for jump instruction */ |
193 | |
194 | int ftrace_enable_ftrace_graph_caller(void) |
195 | { |
196 | unsigned int ret; |
197 | unsigned long ip = (unsigned long)(&ftrace_call_graph); |
198 | |
199 | old_jump = *(unsigned int *)ip; /* save jump over instruction */ |
200 | ret = ftrace_modify_code(addr: ip, MICROBLAZE_NOP); |
201 | |
202 | pr_debug("%s: Replace instruction: 0x%x\n" , __func__, old_jump); |
203 | return ret; |
204 | } |
205 | |
206 | int ftrace_disable_ftrace_graph_caller(void) |
207 | { |
208 | unsigned int ret; |
209 | unsigned long ip = (unsigned long)(&ftrace_call_graph); |
210 | |
211 | ret = ftrace_modify_code(addr: ip, value: old_jump); |
212 | |
213 | pr_debug("%s\n" , __func__); |
214 | return ret; |
215 | } |
216 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |
217 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
218 | |