Commit | Line | Data |
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538f1952 WZ |
1 | /* |
2 | * Code for replacing ftrace calls with jumps. | |
3 | * | |
4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> | |
e4240540 | 5 | * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China |
f7a904df | 6 | * Author: Wu Zhangjin <wuzhangjin@gmail.com> |
538f1952 WZ |
7 | * |
8 | * Thanks goes to Steven Rostedt for writing the original x86 version. | |
9 | */ | |
10 | ||
11 | #include <linux/uaccess.h> | |
12 | #include <linux/init.h> | |
13 | #include <linux/ftrace.h> | |
19e2e172 | 14 | #include <linux/syscalls.h> |
538f1952 | 15 | |
29c5d346 WZ |
16 | #include <asm/asm.h> |
17 | #include <asm/asm-offsets.h> | |
e4240540 | 18 | #include <asm/cacheflush.h> |
19e2e172 | 19 | #include <asm/syscall.h> |
e4240540 | 20 | #include <asm/uasm.h> |
19e2e172 | 21 | #include <asm/unistd.h> |
538f1952 | 22 | |
d9cdb2f1 | 23 | #include <asm-generic/sections.h> |
c9f84873 | 24 | |
49de830a TG |
25 | #if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT) |
26 | #define MCOUNT_OFFSET_INSNS 5 | |
27 | #else | |
28 | #define MCOUNT_OFFSET_INSNS 4 | |
29 | #endif | |
30 | ||
cb2f9938 MC |
31 | #ifdef CONFIG_DYNAMIC_FTRACE |
32 | ||
58b69401 AC |
33 | /* Arch override because MIPS doesn't need to run this from stop_machine() */ |
34 | void arch_ftrace_update_code(int command) | |
35 | { | |
36 | ftrace_modify_all_code(command); | |
37 | } | |
38 | ||
cb2f9938 MC |
39 | #endif |
40 | ||
49de830a TG |
41 | /* |
42 | * Check if the address is in kernel space | |
43 | * | |
44 | * Clone core_kernel_text() from kernel/extable.c, but doesn't call | |
45 | * init_kernel_text() for Ftrace doesn't trace functions in init sections. | |
46 | */ | |
47 | static inline int in_kernel_space(unsigned long ip) | |
48 | { | |
49 | if (ip >= (unsigned long)_stext && | |
50 | ip <= (unsigned long)_etext) | |
51 | return 1; | |
52 | return 0; | |
53 | } | |
54 | ||
538f1952 WZ |
55 | #ifdef CONFIG_DYNAMIC_FTRACE |
56 | ||
57 | #define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */ | |
58 | #define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */ | |
c54794d1 | 59 | #define JUMP_RANGE_MASK ((1UL << 28) - 1) |
538f1952 | 60 | |
4d6829f9 | 61 | #define INSN_NOP 0x00000000 /* nop */ |
e4240540 WZ |
62 | #define INSN_JAL(addr) \ |
63 | ((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK))) | |
64 | ||
65 | static unsigned int insn_jal_ftrace_caller __read_mostly; | |
66 | static unsigned int insn_lui_v1_hi16_mcount __read_mostly; | |
67 | static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly; | |
68 | ||
69 | static inline void ftrace_dyn_arch_init_insns(void) | |
70 | { | |
71 | u32 *buf; | |
72 | unsigned int v1; | |
73 | ||
74 | /* lui v1, hi16_mcount */ | |
75 | v1 = 3; | |
76 | buf = (u32 *)&insn_lui_v1_hi16_mcount; | |
77 | UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR); | |
78 | ||
79 | /* jal (ftrace_caller + 8), jump over the first two instruction */ | |
80 | buf = (u32 *)&insn_jal_ftrace_caller; | |
c54794d1 | 81 | uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK); |
e4240540 WZ |
82 | |
83 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
84 | /* j ftrace_graph_caller */ | |
85 | buf = (u32 *)&insn_j_ftrace_graph_caller; | |
c54794d1 | 86 | uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK); |
e4240540 WZ |
87 | #endif |
88 | } | |
538f1952 WZ |
89 | |
90 | static int ftrace_modify_code(unsigned long ip, unsigned int new_code) | |
91 | { | |
046199ca WZ |
92 | int faulted; |
93 | ||
94 | /* *(unsigned int *)ip = new_code; */ | |
95 | safe_store_code(new_code, ip, faulted); | |
96 | ||
97 | if (unlikely(faulted)) | |
98 | return -EFAULT; | |
538f1952 WZ |
99 | |
100 | flush_icache_range(ip, ip + 8); | |
101 | ||
102 | return 0; | |
103 | } | |
104 | ||
58b69401 AC |
105 | #ifndef CONFIG_64BIT |
106 | static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1, | |
107 | unsigned int new_code2) | |
108 | { | |
109 | int faulted; | |
110 | ||
111 | safe_store_code(new_code1, ip, faulted); | |
112 | if (unlikely(faulted)) | |
113 | return -EFAULT; | |
114 | ip += 4; | |
115 | safe_store_code(new_code2, ip, faulted); | |
116 | if (unlikely(faulted)) | |
117 | return -EFAULT; | |
118 | flush_icache_range(ip, ip + 8); /* original ip + 12 */ | |
119 | return 0; | |
120 | } | |
121 | #endif | |
122 | ||
7f21a609 WZ |
123 | /* |
124 | * The details about the calling site of mcount on MIPS | |
125 | * | |
126 | * 1. For kernel: | |
127 | * | |
128 | * move at, ra | |
129 | * jal _mcount --> nop | |
130 | * | |
131 | * 2. For modules: | |
132 | * | |
133 | * 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT | |
134 | * | |
70342287 | 135 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005) |
7f21a609 WZ |
136 | * addiu v1, v1, low_16bit_of_mcount |
137 | * move at, ra | |
138 | * move $12, ra_address | |
139 | * jalr v1 | |
140 | * sub sp, sp, 8 | |
70342287 | 141 | * 1: offset = 5 instructions |
7f21a609 WZ |
142 | * 2.2 For the Other situations |
143 | * | |
70342287 | 144 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004) |
7f21a609 WZ |
145 | * addiu v1, v1, low_16bit_of_mcount |
146 | * move at, ra | |
147 | * jalr v1 | |
148 | * nop | move $12, ra_address | sub sp, sp, 8 | |
70342287 | 149 | * 1: offset = 4 instructions |
7f21a609 WZ |
150 | */ |
151 | ||
7f21a609 WZ |
152 | #define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS) |
153 | ||
538f1952 WZ |
154 | int ftrace_make_nop(struct module *mod, |
155 | struct dyn_ftrace *rec, unsigned long addr) | |
156 | { | |
157 | unsigned int new; | |
158 | unsigned long ip = rec->ip; | |
159 | ||
e4240540 | 160 | /* |
d9cdb2f1 WZ |
161 | * If ip is in kernel space, no long call, otherwise, long call is |
162 | * needed. | |
e4240540 | 163 | */ |
7f21a609 | 164 | new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F; |
58b69401 | 165 | #ifdef CONFIG_64BIT |
538f1952 | 166 | return ftrace_modify_code(ip, new); |
58b69401 AC |
167 | #else |
168 | /* | |
169 | * On 32 bit MIPS platforms, gcc adds a stack adjust | |
170 | * instruction in the delay slot after the branch to | |
171 | * mcount and expects mcount to restore the sp on return. | |
172 | * This is based on a legacy API and does nothing but | |
173 | * waste instructions so it's being removed at runtime. | |
174 | */ | |
175 | return ftrace_modify_code_2(ip, new, INSN_NOP); | |
176 | #endif | |
538f1952 WZ |
177 | } |
178 | ||
538f1952 WZ |
179 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
180 | { | |
181 | unsigned int new; | |
182 | unsigned long ip = rec->ip; | |
183 | ||
d9cdb2f1 WZ |
184 | new = in_kernel_space(ip) ? insn_jal_ftrace_caller : |
185 | insn_lui_v1_hi16_mcount; | |
538f1952 WZ |
186 | |
187 | return ftrace_modify_code(ip, new); | |
188 | } | |
189 | ||
190 | #define FTRACE_CALL_IP ((unsigned long)(&ftrace_call)) | |
191 | ||
192 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
193 | { | |
194 | unsigned int new; | |
195 | ||
4d6829f9 | 196 | new = INSN_JAL((unsigned long)func); |
538f1952 WZ |
197 | |
198 | return ftrace_modify_code(FTRACE_CALL_IP, new); | |
199 | } | |
200 | ||
201 | int __init ftrace_dyn_arch_init(void *data) | |
202 | { | |
e4240540 WZ |
203 | /* Encode the instructions when booting */ |
204 | ftrace_dyn_arch_init_insns(); | |
205 | ||
206 | /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */ | |
207 | ftrace_modify_code(MCOUNT_ADDR, INSN_NOP); | |
208 | ||
538f1952 WZ |
209 | /* The return code is retured via data */ |
210 | *(unsigned long *)data = 0; | |
211 | ||
212 | return 0; | |
213 | } | |
68ccf752 | 214 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
29c5d346 WZ |
215 | |
216 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
217 | ||
e17ff5fe WZ |
218 | #ifdef CONFIG_DYNAMIC_FTRACE |
219 | ||
220 | extern void ftrace_graph_call(void); | |
e17ff5fe WZ |
221 | #define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call)) |
222 | ||
223 | int ftrace_enable_ftrace_graph_caller(void) | |
224 | { | |
225 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, | |
e4240540 | 226 | insn_j_ftrace_graph_caller); |
e17ff5fe WZ |
227 | } |
228 | ||
229 | int ftrace_disable_ftrace_graph_caller(void) | |
230 | { | |
4d6829f9 | 231 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP); |
e17ff5fe WZ |
232 | } |
233 | ||
68ccf752 | 234 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
e17ff5fe | 235 | |
7326c4e5 | 236 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
68ccf752 | 237 | |
70342287 RB |
238 | #define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */ |
239 | #define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */ | |
29c5d346 WZ |
240 | #define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */ |
241 | ||
2816e325 WZ |
242 | unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long |
243 | old_parent_ra, unsigned long parent_ra_addr, unsigned long fp) | |
29c5d346 | 244 | { |
2816e325 | 245 | unsigned long sp, ip, tmp; |
29c5d346 | 246 | unsigned int code; |
046199ca | 247 | int faulted; |
29c5d346 | 248 | |
68ccf752 | 249 | /* |
2816e325 | 250 | * For module, move the ip from the return address after the |
9a620a55 WZ |
251 | * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for |
252 | * kernel, move after the instruction "move ra, at"(offset is 16) | |
68ccf752 | 253 | */ |
2816e325 | 254 | ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24); |
29c5d346 | 255 | |
68ccf752 WZ |
256 | /* |
257 | * search the text until finding the non-store instruction or "s{d,w} | |
258 | * ra, offset(sp)" instruction | |
259 | */ | |
29c5d346 | 260 | do { |
046199ca WZ |
261 | /* get the code at "ip": code = *(unsigned int *)ip; */ |
262 | safe_load_code(code, ip, faulted); | |
263 | ||
264 | if (unlikely(faulted)) | |
265 | return 0; | |
68ccf752 WZ |
266 | /* |
267 | * If we hit the non-store instruction before finding where the | |
29c5d346 | 268 | * ra is stored, then this is a leaf function and it does not |
68ccf752 WZ |
269 | * store the ra on the stack |
270 | */ | |
29c5d346 | 271 | if ((code & S_R_SP) != S_R_SP) |
2816e325 | 272 | return parent_ra_addr; |
29c5d346 | 273 | |
9a620a55 WZ |
274 | /* Move to the next instruction */ |
275 | ip -= 4; | |
276 | } while ((code & S_RA_SP) != S_RA_SP); | |
29c5d346 WZ |
277 | |
278 | sp = fp + (code & OFFSET_MASK); | |
046199ca | 279 | |
2816e325 WZ |
280 | /* tmp = *(unsigned long *)sp; */ |
281 | safe_load_stack(tmp, sp, faulted); | |
046199ca WZ |
282 | if (unlikely(faulted)) |
283 | return 0; | |
29c5d346 | 284 | |
2816e325 | 285 | if (tmp == old_parent_ra) |
29c5d346 | 286 | return sp; |
29c5d346 WZ |
287 | return 0; |
288 | } | |
289 | ||
68ccf752 | 290 | #endif /* !KBUILD_MCOUNT_RA_ADDRESS */ |
7326c4e5 | 291 | |
29c5d346 WZ |
292 | /* |
293 | * Hook the return address and push it in the stack of return addrs | |
294 | * in current thread info. | |
295 | */ | |
2816e325 | 296 | void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, |
29c5d346 WZ |
297 | unsigned long fp) |
298 | { | |
2816e325 | 299 | unsigned long old_parent_ra; |
29c5d346 WZ |
300 | struct ftrace_graph_ent trace; |
301 | unsigned long return_hooker = (unsigned long) | |
302 | &return_to_handler; | |
b9f07eb2 | 303 | int faulted, insns; |
29c5d346 WZ |
304 | |
305 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) | |
306 | return; | |
307 | ||
68ccf752 | 308 | /* |
2816e325 WZ |
309 | * "parent_ra_addr" is the stack address saved the return address of |
310 | * the caller of _mcount. | |
7326c4e5 WZ |
311 | * |
312 | * if the gcc < 4.5, a leaf function does not save the return address | |
313 | * in the stack address, so, we "emulate" one in _mcount's stack space, | |
314 | * and hijack it directly, but for a non-leaf function, it save the | |
315 | * return address to the its own stack space, we can not hijack it | |
316 | * directly, but need to find the real stack address, | |
29c5d346 | 317 | * ftrace_get_parent_addr() does it! |
7326c4e5 WZ |
318 | * |
319 | * if gcc>= 4.5, with the new -mmcount-ra-address option, for a | |
320 | * non-leaf function, the location of the return address will be saved | |
321 | * to $12 for us, and for a leaf function, only put a zero into $12. we | |
322 | * do it in ftrace_graph_caller of mcount.S. | |
29c5d346 WZ |
323 | */ |
324 | ||
2816e325 WZ |
325 | /* old_parent_ra = *parent_ra_addr; */ |
326 | safe_load_stack(old_parent_ra, parent_ra_addr, faulted); | |
046199ca WZ |
327 | if (unlikely(faulted)) |
328 | goto out; | |
7326c4e5 | 329 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
2816e325 WZ |
330 | parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra, |
331 | old_parent_ra, (unsigned long)parent_ra_addr, fp); | |
68ccf752 WZ |
332 | /* |
333 | * If fails when getting the stack address of the non-leaf function's | |
334 | * ra, stop function graph tracer and return | |
335 | */ | |
2816e325 | 336 | if (parent_ra_addr == 0) |
046199ca | 337 | goto out; |
7326c4e5 | 338 | #endif |
2816e325 WZ |
339 | /* *parent_ra_addr = return_hooker; */ |
340 | safe_store_stack(return_hooker, parent_ra_addr, faulted); | |
046199ca WZ |
341 | if (unlikely(faulted)) |
342 | goto out; | |
29c5d346 | 343 | |
2816e325 WZ |
344 | if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp) |
345 | == -EBUSY) { | |
346 | *parent_ra_addr = old_parent_ra; | |
29c5d346 WZ |
347 | return; |
348 | } | |
349 | ||
b9f07eb2 WZ |
350 | /* |
351 | * Get the recorded ip of the current mcount calling site in the | |
352 | * __mcount_loc section, which will be used to filter the function | |
353 | * entries configured through the tracing/set_graph_function interface. | |
354 | */ | |
355 | ||
356 | insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1; | |
357 | trace.func = self_ra - (MCOUNT_INSN_SIZE * insns); | |
29c5d346 WZ |
358 | |
359 | /* Only trace if the calling function expects to */ | |
360 | if (!ftrace_graph_entry(&trace)) { | |
361 | current->curr_ret_stack--; | |
2816e325 | 362 | *parent_ra_addr = old_parent_ra; |
29c5d346 | 363 | } |
046199ca WZ |
364 | return; |
365 | out: | |
366 | ftrace_graph_stop(); | |
367 | WARN_ON(1); | |
29c5d346 | 368 | } |
68ccf752 | 369 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |
19e2e172 RB |
370 | |
371 | #ifdef CONFIG_FTRACE_SYSCALLS | |
372 | ||
373 | #ifdef CONFIG_32BIT | |
374 | unsigned long __init arch_syscall_addr(int nr) | |
375 | { | |
376 | return (unsigned long)sys_call_table[nr - __NR_O32_Linux]; | |
377 | } | |
378 | #endif | |
379 | ||
380 | #ifdef CONFIG_64BIT | |
381 | ||
382 | unsigned long __init arch_syscall_addr(int nr) | |
383 | { | |
384 | #ifdef CONFIG_MIPS32_N32 | |
385 | if (nr >= __NR_N32_Linux && nr <= __NR_N32_Linux + __NR_N32_Linux_syscalls) | |
46e12c07 | 386 | return (unsigned long)sysn32_call_table[nr - __NR_N32_Linux]; |
19e2e172 RB |
387 | #endif |
388 | if (nr >= __NR_64_Linux && nr <= __NR_64_Linux + __NR_64_Linux_syscalls) | |
389 | return (unsigned long)sys_call_table[nr - __NR_64_Linux]; | |
390 | #ifdef CONFIG_MIPS32_O32 | |
391 | if (nr >= __NR_O32_Linux && nr <= __NR_O32_Linux + __NR_O32_Linux_syscalls) | |
392 | return (unsigned long)sys32_call_table[nr - __NR_O32_Linux]; | |
393 | #endif | |
394 | ||
395 | return (unsigned long) &sys_ni_syscall; | |
396 | } | |
397 | #endif | |
398 | ||
399 | #endif /* CONFIG_FTRACE_SYSCALLS */ |