Commit | Line | Data |
---|---|---|
4e491d14 SR |
1 | /* |
2 | * Code for replacing ftrace calls with jumps. | |
3 | * | |
4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> | |
5 | * | |
6 | * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. | |
7 | * | |
6794c782 SR |
8 | * Added function graph tracer code, taken from x86 that was written |
9 | * by Frederic Weisbecker, and ported to PPC by Steven Rostedt. | |
10 | * | |
4e491d14 SR |
11 | */ |
12 | ||
13 | #include <linux/spinlock.h> | |
14 | #include <linux/hardirq.h> | |
e4486fe3 | 15 | #include <linux/uaccess.h> |
f48cb8b4 | 16 | #include <linux/module.h> |
4e491d14 SR |
17 | #include <linux/ftrace.h> |
18 | #include <linux/percpu.h> | |
19 | #include <linux/init.h> | |
20 | #include <linux/list.h> | |
21 | ||
22 | #include <asm/cacheflush.h> | |
f48cb8b4 | 23 | #include <asm/code-patching.h> |
395a59d0 | 24 | #include <asm/ftrace.h> |
4e491d14 | 25 | |
4e491d14 | 26 | |
6794c782 | 27 | #ifdef CONFIG_DYNAMIC_FTRACE |
b54dcfe1 | 28 | static unsigned int |
46542888 | 29 | ftrace_call_replace(unsigned long ip, unsigned long addr, int link) |
4e491d14 | 30 | { |
b54dcfe1 | 31 | unsigned int op; |
4e491d14 | 32 | |
4a9e3f8e | 33 | addr = ppc_function_entry((void *)addr); |
4e491d14 | 34 | |
46542888 | 35 | /* if (link) set op to 'bl' else 'b' */ |
bb9b9035 | 36 | op = create_branch((unsigned int *)ip, addr, link ? 1 : 0); |
4e491d14 | 37 | |
b54dcfe1 | 38 | return op; |
4e491d14 SR |
39 | } |
40 | ||
8fd6e5a8 | 41 | static int |
b54dcfe1 | 42 | ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) |
4e491d14 | 43 | { |
b54dcfe1 | 44 | unsigned int replaced; |
4e491d14 | 45 | |
4e491d14 SR |
46 | /* |
47 | * Note: Due to modules and __init, code can | |
48 | * disappear and change, we need to protect against faulting | |
e4486fe3 SR |
49 | * as well as code changing. We do this by using the |
50 | * probe_kernel_* functions. | |
4e491d14 SR |
51 | * |
52 | * No real locking needed, this code is run through | |
e4486fe3 | 53 | * kstop_machine, or before SMP starts. |
4e491d14 | 54 | */ |
e4486fe3 SR |
55 | |
56 | /* read the text we want to modify */ | |
b54dcfe1 | 57 | if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE)) |
e4486fe3 SR |
58 | return -EFAULT; |
59 | ||
60 | /* Make sure it is what we expect it to be */ | |
b54dcfe1 | 61 | if (replaced != old) |
e4486fe3 SR |
62 | return -EINVAL; |
63 | ||
64 | /* replace the text with the new text */ | |
b54dcfe1 | 65 | if (probe_kernel_write((void *)ip, &new, MCOUNT_INSN_SIZE)) |
e4486fe3 SR |
66 | return -EPERM; |
67 | ||
68 | flush_icache_range(ip, ip + 8); | |
69 | ||
70 | return 0; | |
4e491d14 SR |
71 | } |
72 | ||
f48cb8b4 SR |
73 | /* |
74 | * Helper functions that are the same for both PPC64 and PPC32. | |
75 | */ | |
8fd6e5a8 SR |
76 | static int test_24bit_addr(unsigned long ip, unsigned long addr) |
77 | { | |
8fd6e5a8 | 78 | |
0029ff87 SR |
79 | /* use the create_branch to verify that this offset can be branched */ |
80 | return create_branch((unsigned int *)ip, addr, 0); | |
8fd6e5a8 SR |
81 | } |
82 | ||
17be5b3d SR |
83 | #ifdef CONFIG_MODULES |
84 | ||
f48cb8b4 SR |
85 | static int is_bl_op(unsigned int op) |
86 | { | |
87 | return (op & 0xfc000003) == 0x48000001; | |
88 | } | |
89 | ||
f48cb8b4 SR |
90 | static unsigned long find_bl_target(unsigned long ip, unsigned int op) |
91 | { | |
92 | static int offset; | |
93 | ||
94 | offset = (op & 0x03fffffc); | |
95 | /* make it signed */ | |
96 | if (offset & 0x02000000) | |
97 | offset |= 0xfe000000; | |
98 | ||
99 | return ip + (long)offset; | |
100 | } | |
101 | ||
f48cb8b4 SR |
102 | #ifdef CONFIG_PPC64 |
103 | static int | |
104 | __ftrace_make_nop(struct module *mod, | |
105 | struct dyn_ftrace *rec, unsigned long addr) | |
106 | { | |
d9af12b7 SR |
107 | unsigned int op; |
108 | unsigned int jmp[5]; | |
109 | unsigned long ptr; | |
f48cb8b4 SR |
110 | unsigned long ip = rec->ip; |
111 | unsigned long tramp; | |
112 | int offset; | |
113 | ||
114 | /* read where this goes */ | |
d9af12b7 | 115 | if (probe_kernel_read(&op, (void *)ip, sizeof(int))) |
f48cb8b4 SR |
116 | return -EFAULT; |
117 | ||
118 | /* Make sure that that this is still a 24bit jump */ | |
d9af12b7 SR |
119 | if (!is_bl_op(op)) { |
120 | printk(KERN_ERR "Not expected bl: opcode is %x\n", op); | |
f48cb8b4 SR |
121 | return -EINVAL; |
122 | } | |
123 | ||
124 | /* lets find where the pointer goes */ | |
d9af12b7 | 125 | tramp = find_bl_target(ip, op); |
f48cb8b4 SR |
126 | |
127 | /* | |
128 | * On PPC64 the trampoline looks like: | |
129 | * 0x3d, 0x82, 0x00, 0x00, addis r12,r2, <high> | |
130 | * 0x39, 0x8c, 0x00, 0x00, addi r12,r12, <low> | |
131 | * Where the bytes 2,3,6 and 7 make up the 32bit offset | |
132 | * to the TOC that holds the pointer. | |
133 | * to jump to. | |
134 | * 0xf8, 0x41, 0x00, 0x28, std r2,40(r1) | |
135 | * 0xe9, 0x6c, 0x00, 0x20, ld r11,32(r12) | |
136 | * The actually address is 32 bytes from the offset | |
137 | * into the TOC. | |
138 | * 0xe8, 0x4c, 0x00, 0x28, ld r2,40(r12) | |
139 | */ | |
140 | ||
021376a3 | 141 | pr_devel("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc); |
f48cb8b4 SR |
142 | |
143 | /* Find where the trampoline jumps to */ | |
d9af12b7 | 144 | if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) { |
f48cb8b4 SR |
145 | printk(KERN_ERR "Failed to read %lx\n", tramp); |
146 | return -EFAULT; | |
147 | } | |
148 | ||
021376a3 | 149 | pr_devel(" %08x %08x", jmp[0], jmp[1]); |
d9af12b7 SR |
150 | |
151 | /* verify that this is what we expect it to be */ | |
152 | if (((jmp[0] & 0xffff0000) != 0x3d820000) || | |
153 | ((jmp[1] & 0xffff0000) != 0x398c0000) || | |
154 | (jmp[2] != 0xf8410028) || | |
155 | (jmp[3] != 0xe96c0020) || | |
156 | (jmp[4] != 0xe84c0028)) { | |
157 | printk(KERN_ERR "Not a trampoline\n"); | |
158 | return -EINVAL; | |
159 | } | |
f48cb8b4 | 160 | |
f25f9074 SR |
161 | /* The bottom half is signed extended */ |
162 | offset = ((unsigned)((unsigned short)jmp[0]) << 16) + | |
163 | (int)((short)jmp[1]); | |
f48cb8b4 | 164 | |
021376a3 | 165 | pr_devel(" %x ", offset); |
f48cb8b4 SR |
166 | |
167 | /* get the address this jumps too */ | |
168 | tramp = mod->arch.toc + offset + 32; | |
021376a3 | 169 | pr_devel("toc: %lx", tramp); |
f48cb8b4 SR |
170 | |
171 | if (probe_kernel_read(jmp, (void *)tramp, 8)) { | |
172 | printk(KERN_ERR "Failed to read %lx\n", tramp); | |
173 | return -EFAULT; | |
174 | } | |
175 | ||
021376a3 | 176 | pr_devel(" %08x %08x\n", jmp[0], jmp[1]); |
d9af12b7 SR |
177 | |
178 | ptr = ((unsigned long)jmp[0] << 32) + jmp[1]; | |
f48cb8b4 SR |
179 | |
180 | /* This should match what was called */ | |
4a9e3f8e | 181 | if (ptr != ppc_function_entry((void *)addr)) { |
d9af12b7 | 182 | printk(KERN_ERR "addr does not match %lx\n", ptr); |
f48cb8b4 SR |
183 | return -EINVAL; |
184 | } | |
185 | ||
186 | /* | |
187 | * We want to nop the line, but the next line is | |
188 | * 0xe8, 0x41, 0x00, 0x28 ld r2,40(r1) | |
189 | * This needs to be turned to a nop too. | |
190 | */ | |
d9af12b7 | 191 | if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) |
f48cb8b4 SR |
192 | return -EFAULT; |
193 | ||
d9af12b7 SR |
194 | if (op != 0xe8410028) { |
195 | printk(KERN_ERR "Next line is not ld! (%08x)\n", op); | |
f48cb8b4 SR |
196 | return -EINVAL; |
197 | } | |
198 | ||
199 | /* | |
200 | * Milton Miller pointed out that we can not blindly do nops. | |
201 | * If a task was preempted when calling a trace function, | |
202 | * the nops will remove the way to restore the TOC in r2 | |
203 | * and the r2 TOC will get corrupted. | |
204 | */ | |
205 | ||
206 | /* | |
207 | * Replace: | |
208 | * bl <tramp> <==== will be replaced with "b 1f" | |
209 | * ld r2,40(r1) | |
210 | * 1: | |
211 | */ | |
d9af12b7 | 212 | op = 0x48000008; /* b +8 */ |
f48cb8b4 | 213 | |
d9af12b7 | 214 | if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) |
f48cb8b4 SR |
215 | return -EPERM; |
216 | ||
ec682cef SR |
217 | |
218 | flush_icache_range(ip, ip + 8); | |
219 | ||
f48cb8b4 SR |
220 | return 0; |
221 | } | |
222 | ||
223 | #else /* !PPC64 */ | |
224 | static int | |
225 | __ftrace_make_nop(struct module *mod, | |
226 | struct dyn_ftrace *rec, unsigned long addr) | |
227 | { | |
d9af12b7 SR |
228 | unsigned int op; |
229 | unsigned int jmp[4]; | |
7cc45e64 SR |
230 | unsigned long ip = rec->ip; |
231 | unsigned long tramp; | |
7cc45e64 | 232 | |
d9af12b7 | 233 | if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
234 | return -EFAULT; |
235 | ||
236 | /* Make sure that that this is still a 24bit jump */ | |
d9af12b7 SR |
237 | if (!is_bl_op(op)) { |
238 | printk(KERN_ERR "Not expected bl: opcode is %x\n", op); | |
7cc45e64 SR |
239 | return -EINVAL; |
240 | } | |
241 | ||
242 | /* lets find where the pointer goes */ | |
d9af12b7 | 243 | tramp = find_bl_target(ip, op); |
7cc45e64 SR |
244 | |
245 | /* | |
246 | * On PPC32 the trampoline looks like: | |
d9af12b7 SR |
247 | * 0x3d, 0x60, 0x00, 0x00 lis r11,sym@ha |
248 | * 0x39, 0x6b, 0x00, 0x00 addi r11,r11,sym@l | |
249 | * 0x7d, 0x69, 0x03, 0xa6 mtctr r11 | |
250 | * 0x4e, 0x80, 0x04, 0x20 bctr | |
7cc45e64 SR |
251 | */ |
252 | ||
021376a3 | 253 | pr_devel("ip:%lx jumps to %lx", ip, tramp); |
7cc45e64 SR |
254 | |
255 | /* Find where the trampoline jumps to */ | |
d9af12b7 | 256 | if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) { |
7cc45e64 SR |
257 | printk(KERN_ERR "Failed to read %lx\n", tramp); |
258 | return -EFAULT; | |
259 | } | |
260 | ||
021376a3 | 261 | pr_devel(" %08x %08x ", jmp[0], jmp[1]); |
d9af12b7 SR |
262 | |
263 | /* verify that this is what we expect it to be */ | |
264 | if (((jmp[0] & 0xffff0000) != 0x3d600000) || | |
265 | ((jmp[1] & 0xffff0000) != 0x396b0000) || | |
266 | (jmp[2] != 0x7d6903a6) || | |
267 | (jmp[3] != 0x4e800420)) { | |
268 | printk(KERN_ERR "Not a trampoline\n"); | |
269 | return -EINVAL; | |
270 | } | |
7cc45e64 | 271 | |
d9af12b7 SR |
272 | tramp = (jmp[1] & 0xffff) | |
273 | ((jmp[0] & 0xffff) << 16); | |
7cc45e64 SR |
274 | if (tramp & 0x8000) |
275 | tramp -= 0x10000; | |
276 | ||
021376a3 | 277 | pr_devel(" %lx ", tramp); |
7cc45e64 SR |
278 | |
279 | if (tramp != addr) { | |
280 | printk(KERN_ERR | |
281 | "Trampoline location %08lx does not match addr\n", | |
282 | tramp); | |
283 | return -EINVAL; | |
284 | } | |
285 | ||
16c57b36 | 286 | op = PPC_INST_NOP; |
7cc45e64 | 287 | |
d9af12b7 | 288 | if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
289 | return -EPERM; |
290 | ||
ec682cef SR |
291 | flush_icache_range(ip, ip + 8); |
292 | ||
f48cb8b4 SR |
293 | return 0; |
294 | } | |
295 | #endif /* PPC64 */ | |
17be5b3d | 296 | #endif /* CONFIG_MODULES */ |
f48cb8b4 | 297 | |
8fd6e5a8 SR |
298 | int ftrace_make_nop(struct module *mod, |
299 | struct dyn_ftrace *rec, unsigned long addr) | |
300 | { | |
f48cb8b4 | 301 | unsigned long ip = rec->ip; |
b54dcfe1 | 302 | unsigned int old, new; |
8fd6e5a8 SR |
303 | |
304 | /* | |
305 | * If the calling address is more that 24 bits away, | |
306 | * then we had to use a trampoline to make the call. | |
307 | * Otherwise just update the call site. | |
308 | */ | |
f48cb8b4 | 309 | if (test_24bit_addr(ip, addr)) { |
8fd6e5a8 | 310 | /* within range */ |
46542888 | 311 | old = ftrace_call_replace(ip, addr, 1); |
92e02a51 | 312 | new = PPC_INST_NOP; |
f48cb8b4 SR |
313 | return ftrace_modify_code(ip, old, new); |
314 | } | |
315 | ||
17be5b3d | 316 | #ifdef CONFIG_MODULES |
f48cb8b4 SR |
317 | /* |
318 | * Out of range jumps are called from modules. | |
319 | * We should either already have a pointer to the module | |
320 | * or it has been passed in. | |
321 | */ | |
322 | if (!rec->arch.mod) { | |
323 | if (!mod) { | |
324 | printk(KERN_ERR "No module loaded addr=%lx\n", | |
325 | addr); | |
326 | return -EFAULT; | |
327 | } | |
328 | rec->arch.mod = mod; | |
329 | } else if (mod) { | |
330 | if (mod != rec->arch.mod) { | |
331 | printk(KERN_ERR | |
332 | "Record mod %p not equal to passed in mod %p\n", | |
333 | rec->arch.mod, mod); | |
334 | return -EINVAL; | |
335 | } | |
336 | /* nothing to do if mod == rec->arch.mod */ | |
337 | } else | |
338 | mod = rec->arch.mod; | |
f48cb8b4 SR |
339 | |
340 | return __ftrace_make_nop(mod, rec, addr); | |
17be5b3d SR |
341 | #else |
342 | /* We should not get here without modules */ | |
343 | return -EINVAL; | |
344 | #endif /* CONFIG_MODULES */ | |
f48cb8b4 SR |
345 | } |
346 | ||
17be5b3d | 347 | #ifdef CONFIG_MODULES |
f48cb8b4 SR |
348 | #ifdef CONFIG_PPC64 |
349 | static int | |
350 | __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
351 | { | |
d9af12b7 | 352 | unsigned int op[2]; |
f48cb8b4 | 353 | unsigned long ip = rec->ip; |
f48cb8b4 SR |
354 | |
355 | /* read where this goes */ | |
d9af12b7 | 356 | if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2)) |
f48cb8b4 SR |
357 | return -EFAULT; |
358 | ||
359 | /* | |
360 | * It should be pointing to two nops or | |
361 | * b +8; ld r2,40(r1) | |
362 | */ | |
363 | if (((op[0] != 0x48000008) || (op[1] != 0xe8410028)) && | |
16c57b36 | 364 | ((op[0] != PPC_INST_NOP) || (op[1] != PPC_INST_NOP))) { |
f48cb8b4 SR |
365 | printk(KERN_ERR "Expected NOPs but have %x %x\n", op[0], op[1]); |
366 | return -EINVAL; | |
367 | } | |
368 | ||
369 | /* If we never set up a trampoline to ftrace_caller, then bail */ | |
370 | if (!rec->arch.mod->arch.tramp) { | |
371 | printk(KERN_ERR "No ftrace trampoline\n"); | |
372 | return -EINVAL; | |
373 | } | |
374 | ||
0029ff87 SR |
375 | /* create the branch to the trampoline */ |
376 | op[0] = create_branch((unsigned int *)ip, | |
377 | rec->arch.mod->arch.tramp, BRANCH_SET_LINK); | |
378 | if (!op[0]) { | |
379 | printk(KERN_ERR "REL24 out of range!\n"); | |
f48cb8b4 | 380 | return -EINVAL; |
8fd6e5a8 SR |
381 | } |
382 | ||
f48cb8b4 SR |
383 | /* ld r2,40(r1) */ |
384 | op[1] = 0xe8410028; | |
385 | ||
021376a3 | 386 | pr_devel("write to %lx\n", rec->ip); |
f48cb8b4 | 387 | |
d9af12b7 | 388 | if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2)) |
f48cb8b4 SR |
389 | return -EPERM; |
390 | ||
ec682cef SR |
391 | flush_icache_range(ip, ip + 8); |
392 | ||
8fd6e5a8 SR |
393 | return 0; |
394 | } | |
f48cb8b4 SR |
395 | #else |
396 | static int | |
397 | __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
398 | { | |
d9af12b7 | 399 | unsigned int op; |
7cc45e64 | 400 | unsigned long ip = rec->ip; |
7cc45e64 SR |
401 | |
402 | /* read where this goes */ | |
d9af12b7 | 403 | if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
404 | return -EFAULT; |
405 | ||
406 | /* It should be pointing to a nop */ | |
16c57b36 | 407 | if (op != PPC_INST_NOP) { |
d9af12b7 | 408 | printk(KERN_ERR "Expected NOP but have %x\n", op); |
7cc45e64 SR |
409 | return -EINVAL; |
410 | } | |
411 | ||
412 | /* If we never set up a trampoline to ftrace_caller, then bail */ | |
413 | if (!rec->arch.mod->arch.tramp) { | |
414 | printk(KERN_ERR "No ftrace trampoline\n"); | |
415 | return -EINVAL; | |
416 | } | |
417 | ||
0029ff87 SR |
418 | /* create the branch to the trampoline */ |
419 | op = create_branch((unsigned int *)ip, | |
420 | rec->arch.mod->arch.tramp, BRANCH_SET_LINK); | |
421 | if (!op) { | |
422 | printk(KERN_ERR "REL24 out of range!\n"); | |
7cc45e64 SR |
423 | return -EINVAL; |
424 | } | |
425 | ||
021376a3 | 426 | pr_devel("write to %lx\n", rec->ip); |
7cc45e64 | 427 | |
d9af12b7 | 428 | if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
429 | return -EPERM; |
430 | ||
ec682cef SR |
431 | flush_icache_range(ip, ip + 8); |
432 | ||
f48cb8b4 SR |
433 | return 0; |
434 | } | |
435 | #endif /* CONFIG_PPC64 */ | |
17be5b3d | 436 | #endif /* CONFIG_MODULES */ |
8fd6e5a8 SR |
437 | |
438 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
439 | { | |
f48cb8b4 | 440 | unsigned long ip = rec->ip; |
b54dcfe1 | 441 | unsigned int old, new; |
8fd6e5a8 SR |
442 | |
443 | /* | |
444 | * If the calling address is more that 24 bits away, | |
445 | * then we had to use a trampoline to make the call. | |
446 | * Otherwise just update the call site. | |
447 | */ | |
f48cb8b4 | 448 | if (test_24bit_addr(ip, addr)) { |
8fd6e5a8 | 449 | /* within range */ |
92e02a51 | 450 | old = PPC_INST_NOP; |
46542888 | 451 | new = ftrace_call_replace(ip, addr, 1); |
f48cb8b4 | 452 | return ftrace_modify_code(ip, old, new); |
8fd6e5a8 SR |
453 | } |
454 | ||
17be5b3d | 455 | #ifdef CONFIG_MODULES |
f48cb8b4 SR |
456 | /* |
457 | * Out of range jumps are called from modules. | |
458 | * Being that we are converting from nop, it had better | |
459 | * already have a module defined. | |
460 | */ | |
461 | if (!rec->arch.mod) { | |
462 | printk(KERN_ERR "No module loaded\n"); | |
463 | return -EINVAL; | |
464 | } | |
f48cb8b4 SR |
465 | |
466 | return __ftrace_make_call(rec, addr); | |
17be5b3d SR |
467 | #else |
468 | /* We should not get here without modules */ | |
469 | return -EINVAL; | |
470 | #endif /* CONFIG_MODULES */ | |
8fd6e5a8 SR |
471 | } |
472 | ||
15adc048 | 473 | int ftrace_update_ftrace_func(ftrace_func_t func) |
4e491d14 SR |
474 | { |
475 | unsigned long ip = (unsigned long)(&ftrace_call); | |
b54dcfe1 | 476 | unsigned int old, new; |
4e491d14 SR |
477 | int ret; |
478 | ||
b54dcfe1 | 479 | old = *(unsigned int *)&ftrace_call; |
46542888 | 480 | new = ftrace_call_replace(ip, (unsigned long)func, 1); |
4e491d14 SR |
481 | ret = ftrace_modify_code(ip, old, new); |
482 | ||
483 | return ret; | |
484 | } | |
485 | ||
4e491d14 SR |
486 | int __init ftrace_dyn_arch_init(void *data) |
487 | { | |
8fd6e5a8 SR |
488 | /* caller expects data to be zero */ |
489 | unsigned long *p = data; | |
4e491d14 | 490 | |
8fd6e5a8 | 491 | *p = 0; |
4e491d14 SR |
492 | |
493 | return 0; | |
494 | } | |
6794c782 SR |
495 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
496 | ||
497 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
498 | ||
46542888 SR |
499 | #ifdef CONFIG_DYNAMIC_FTRACE |
500 | extern void ftrace_graph_call(void); | |
501 | extern void ftrace_graph_stub(void); | |
502 | ||
503 | int ftrace_enable_ftrace_graph_caller(void) | |
504 | { | |
505 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
506 | unsigned long addr = (unsigned long)(&ftrace_graph_caller); | |
507 | unsigned long stub = (unsigned long)(&ftrace_graph_stub); | |
b54dcfe1 | 508 | unsigned int old, new; |
46542888 | 509 | |
b54dcfe1 | 510 | old = ftrace_call_replace(ip, stub, 0); |
46542888 SR |
511 | new = ftrace_call_replace(ip, addr, 0); |
512 | ||
513 | return ftrace_modify_code(ip, old, new); | |
514 | } | |
515 | ||
516 | int ftrace_disable_ftrace_graph_caller(void) | |
517 | { | |
518 | unsigned long ip = (unsigned long)(&ftrace_graph_call); | |
519 | unsigned long addr = (unsigned long)(&ftrace_graph_caller); | |
520 | unsigned long stub = (unsigned long)(&ftrace_graph_stub); | |
b54dcfe1 | 521 | unsigned int old, new; |
46542888 | 522 | |
b54dcfe1 | 523 | old = ftrace_call_replace(ip, addr, 0); |
46542888 SR |
524 | new = ftrace_call_replace(ip, stub, 0); |
525 | ||
526 | return ftrace_modify_code(ip, old, new); | |
527 | } | |
528 | #endif /* CONFIG_DYNAMIC_FTRACE */ | |
529 | ||
bb725340 SR |
530 | #ifdef CONFIG_PPC64 |
531 | extern void mod_return_to_handler(void); | |
532 | #endif | |
533 | ||
6794c782 SR |
534 | /* |
535 | * Hook the return address and push it in the stack of return addrs | |
536 | * in current thread info. | |
537 | */ | |
538 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) | |
539 | { | |
540 | unsigned long old; | |
6794c782 SR |
541 | int faulted; |
542 | struct ftrace_graph_ent trace; | |
bb725340 | 543 | unsigned long return_hooker = (unsigned long)&return_to_handler; |
6794c782 SR |
544 | |
545 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) | |
546 | return; | |
547 | ||
f4952f6c | 548 | #ifdef CONFIG_PPC64 |
bb725340 SR |
549 | /* non core kernel code needs to save and restore the TOC */ |
550 | if (REGION_ID(self_addr) != KERNEL_REGION_ID) | |
551 | return_hooker = (unsigned long)&mod_return_to_handler; | |
552 | #endif | |
553 | ||
4a9e3f8e | 554 | return_hooker = ppc_function_entry((void *)return_hooker); |
6794c782 SR |
555 | |
556 | /* | |
557 | * Protect against fault, even if it shouldn't | |
558 | * happen. This tool is too much intrusive to | |
559 | * ignore such a protection. | |
560 | */ | |
561 | asm volatile( | |
562 | "1: " PPC_LL "%[old], 0(%[parent])\n" | |
563 | "2: " PPC_STL "%[return_hooker], 0(%[parent])\n" | |
564 | " li %[faulted], 0\n" | |
fad4f47c | 565 | "3:\n" |
6794c782 SR |
566 | |
567 | ".section .fixup, \"ax\"\n" | |
568 | "4: li %[faulted], 1\n" | |
569 | " b 3b\n" | |
570 | ".previous\n" | |
571 | ||
572 | ".section __ex_table,\"a\"\n" | |
573 | PPC_LONG_ALIGN "\n" | |
574 | PPC_LONG "1b,4b\n" | |
575 | PPC_LONG "2b,4b\n" | |
576 | ".previous" | |
577 | ||
c3cf8667 | 578 | : [old] "=&r" (old), [faulted] "=r" (faulted) |
6794c782 SR |
579 | : [parent] "r" (parent), [return_hooker] "r" (return_hooker) |
580 | : "memory" | |
581 | ); | |
582 | ||
583 | if (unlikely(faulted)) { | |
584 | ftrace_graph_stop(); | |
585 | WARN_ON(1); | |
586 | return; | |
587 | } | |
588 | ||
71e308a2 | 589 | if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY) { |
6794c782 SR |
590 | *parent = old; |
591 | return; | |
592 | } | |
593 | ||
594 | trace.func = self_addr; | |
595 | ||
596 | /* Only trace if the calling function expects to */ | |
597 | if (!ftrace_graph_entry(&trace)) { | |
598 | current->curr_ret_stack--; | |
599 | *parent = old; | |
600 | } | |
601 | } | |
602 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |