1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Code for replacing ftrace calls with jumps.
4 *
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
6 *
7 * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
8 *
9 * Added function graph tracer code, taken from x86 that was written
10 * by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
11 *
12 */
13
14 #define pr_fmt(fmt) "ftrace-powerpc: " fmt
15
16 #include <linux/spinlock.h>
17 #include <linux/hardirq.h>
18 #include <linux/uaccess.h>
19 #include <linux/module.h>
20 #include <linux/ftrace.h>
21 #include <linux/percpu.h>
22 #include <linux/init.h>
23 #include <linux/list.h>
24
25 #include <asm/cacheflush.h>
26 #include <asm/code-patching.h>
27 #include <asm/ftrace.h>
28 #include <asm/syscall.h>
29 #include <asm/inst.h>
30 #include <asm/sections.h>
31
32 #define NUM_FTRACE_TRAMPS 2
33 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
34
35 unsigned long ftrace_call_adjust(unsigned long addr)
36 {
37 if (addr >= (unsigned long)__exittext_begin && addr < (unsigned long)__exittext_end)
38 return 0;
39
40 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY))
41 addr += MCOUNT_INSN_SIZE;
42
43 return addr;
44 }
45
46 static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link)
47 {
48 ppc_inst_t op;
49
50 WARN_ON(!is_offset_in_branch_range(addr - ip));
51 create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
52
53 return op;
54 }
55
56 static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
57 {
58 if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
59 pr_err("0x%lx: fetching instruction failed\n", ip);
60 return -EFAULT;
61 }
62
63 return 0;
64 }
65
66 static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
67 {
68 ppc_inst_t op;
69 int ret;
70
71 ret = ftrace_read_inst(ip, &op);
72 if (!ret && !ppc_inst_equal(op, inst)) {
73 pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
74 ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
75 ret = -EINVAL;
76 }
77
78 return ret;
79 }
80
81 static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
82 {
83 int ret = ftrace_validate_inst(ip, old);
84
85 if (!ret)
86 ret = patch_instruction((u32 *)ip, new);
87
88 return ret;
89 }
90
91 static int is_bl_op(ppc_inst_t op)
92 {
93 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
94 }
95
96 static unsigned long find_ftrace_tramp(unsigned long ip)
97 {
98 int i;
99
100 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
101 if (!ftrace_tramps[i])
102 continue;
103 else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
104 return ftrace_tramps[i];
105
106 return 0;
107 }
108
109 static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst)
110 {
111 unsigned long ip = rec->ip;
112 unsigned long stub;
113
114 if (is_offset_in_branch_range(addr - ip)) {
115 /* Within range */
116 stub = addr;
117 #ifdef CONFIG_MODULES
118 } else if (rec->arch.mod) {
119 /* Module code would be going to one of the module stubs */
120 stub = (addr == (unsigned long)ftrace_caller ? rec->arch.mod->arch.tramp :
121 rec->arch.mod->arch.tramp_regs);
122 #endif
123 } else if (core_kernel_text(ip)) {
124 /* We would be branching to one of our ftrace stubs */
125 stub = find_ftrace_tramp(ip);
126 if (!stub) {
127 pr_err("0x%lx: No ftrace stubs reachable\n", ip);
128 return -EINVAL;
129 }
130 } else {
131 return -EINVAL;
132 }
133
134 *call_inst = ftrace_create_branch_inst(ip, stub, 1);
135 return 0;
136 }
137
138 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
139 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
140 {
141 /* This should never be called since we override ftrace_replace_code() */
142 WARN_ON(1);
143 return -EINVAL;
144 }
145 #endif
146
147 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
148 {
149 ppc_inst_t old, new;
150 int ret;
151
152 /* This can only ever be called during module load */
153 if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(rec->ip)))
154 return -EINVAL;
155
156 old = ppc_inst(PPC_RAW_NOP());
157 ret = ftrace_get_call_inst(rec, addr, &new);
158 if (ret)
159 return ret;
160
161 return ftrace_modify_code(rec->ip, old, new);
162 }
163
164 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
165 {
166 /*
167 * This should never be called since we override ftrace_replace_code(),
168 * as well as ftrace_init_nop()
169 */
170 WARN_ON(1);
171 return -EINVAL;
172 }
173
174 void ftrace_replace_code(int enable)
175 {
176 ppc_inst_t old, new, call_inst, new_call_inst;
177 ppc_inst_t nop_inst = ppc_inst(PPC_RAW_NOP());
178 unsigned long ip, new_addr, addr;
179 struct ftrace_rec_iter *iter;
180 struct dyn_ftrace *rec;
181 int ret = 0, update;
182
183 for_ftrace_rec_iter(iter) {
184 rec = ftrace_rec_iter_record(iter);
185 ip = rec->ip;
186
187 if (rec->flags & FTRACE_FL_DISABLED && !(rec->flags & FTRACE_FL_ENABLED))
188 continue;
189
190 addr = ftrace_get_addr_curr(rec);
191 new_addr = ftrace_get_addr_new(rec);
192 update = ftrace_update_record(rec, enable);
193
194 switch (update) {
195 case FTRACE_UPDATE_IGNORE:
196 default:
197 continue;
198 case FTRACE_UPDATE_MODIFY_CALL:
199 ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
200 ret |= ftrace_get_call_inst(rec, addr, &call_inst);
201 old = call_inst;
202 new = new_call_inst;
203 break;
204 case FTRACE_UPDATE_MAKE_NOP:
205 ret = ftrace_get_call_inst(rec, addr, &call_inst);
206 old = call_inst;
207 new = nop_inst;
208 break;
209 case FTRACE_UPDATE_MAKE_CALL:
210 ret = ftrace_get_call_inst(rec, new_addr, &call_inst);
211 old = nop_inst;
212 new = call_inst;
213 break;
214 }
215
216 if (!ret)
217 ret = ftrace_modify_code(ip, old, new);
218 if (ret)
219 goto out;
220 }
221
222 out:
223 if (ret)
224 ftrace_bug(ret, rec);
225 return;
226 }
227
228 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
229 {
230 unsigned long addr, ip = rec->ip;
231 ppc_inst_t old, new;
232 int ret = 0;
233
234 /* Verify instructions surrounding the ftrace location */
235 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
236 /* Expect nops */
237 ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
238 if (!ret)
239 ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
240 } else if (IS_ENABLED(CONFIG_PPC32)) {
241 /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
242 ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
243 if (!ret)
244 ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)));
245 } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
246 /* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */
247 ret = ftrace_read_inst(ip - 4, &old);
248 if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) {
249 ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
250 ret |= ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16)));
251 }
252 } else {
253 return -EINVAL;
254 }
255
256 if (ret)
257 return ret;
258
259 if (!core_kernel_text(ip)) {
260 if (!mod) {
261 pr_err("0x%lx: No module provided for non-kernel address\n", ip);
262 return -EFAULT;
263 }
264 rec->arch.mod = mod;
265 }
266
267 /* Nop-out the ftrace location */
268 new = ppc_inst(PPC_RAW_NOP());
269 addr = MCOUNT_ADDR;
270 if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
271 /* we instead patch-in the 'mflr r0' */
272 old = ppc_inst(PPC_RAW_NOP());
273 new = ppc_inst(PPC_RAW_MFLR(_R0));
274 ret = ftrace_modify_code(ip - 4, old, new);
275 } else if (is_offset_in_branch_range(addr - ip)) {
276 /* Within range */
277 old = ftrace_create_branch_inst(ip, addr, 1);
278 ret = ftrace_modify_code(ip, old, new);
279 } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) {
280 /*
281 * We would be branching to a linker-generated stub, or to the module _mcount
282 * stub. Let's just confirm we have a 'bl' here.
283 */
284 ret = ftrace_read_inst(ip, &old);
285 if (ret)
286 return ret;
287 if (!is_bl_op(old)) {
288 pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
289 return -EINVAL;
290 }
291 ret = patch_instruction((u32 *)ip, new);
292 } else {
293 return -EINVAL;
294 }
295
296 return ret;
297 }
298
299 int ftrace_update_ftrace_func(ftrace_func_t func)
300 {
301 unsigned long ip = (unsigned long)(&ftrace_call);
302 ppc_inst_t old, new;
303 int ret;
304
305 old = ppc_inst_read((u32 *)&ftrace_call);
306 new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
307 ret = ftrace_modify_code(ip, old, new);
308
309 /* Also update the regs callback function */
310 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
311 ip = (unsigned long)(&ftrace_regs_call);
312 old = ppc_inst_read((u32 *)&ftrace_regs_call);
313 new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
314 ret = ftrace_modify_code(ip, old, new);
315 }
316
317 return ret;
318 }
319
320 /*
321 * Use the default ftrace_modify_all_code, but without
322 * stop_machine().
323 */
324 void arch_ftrace_update_code(int command)
325 {
326 ftrace_modify_all_code(command);
327 }
328
329 void ftrace_free_init_tramp(void)
330 {
331 int i;
332
333 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
334 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
335 ftrace_tramps[i] = 0;
336 return;
337 }
338 }
339
340 static void __init add_ftrace_tramp(unsigned long tramp)
341 {
342 int i;
343
344 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
345 if (!ftrace_tramps[i]) {
346 ftrace_tramps[i] = tramp;
347 return;
348 }
349 }
350
351 int __init ftrace_dyn_arch_init(void)
352 {
353 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
354 unsigned long addr = FTRACE_REGS_ADDR;
355 long reladdr;
356 int i;
357 u32 stub_insns[] = {
358 #ifdef CONFIG_PPC_KERNEL_PCREL
359 /* pla r12,addr */
360 PPC_PREFIX_MLS | __PPC_PRFX_R(1),
361 PPC_INST_PADDI | ___PPC_RT(_R12),
362 PPC_RAW_MTCTR(_R12),
363 PPC_RAW_BCTR()
364 #elif defined(CONFIG_PPC64)
365 PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
366 PPC_RAW_ADDIS(_R12, _R12, 0),
367 PPC_RAW_ADDI(_R12, _R12, 0),
368 PPC_RAW_MTCTR(_R12),
369 PPC_RAW_BCTR()
370 #else
371 PPC_RAW_LIS(_R12, 0),
372 PPC_RAW_ADDI(_R12, _R12, 0),
373 PPC_RAW_MTCTR(_R12),
374 PPC_RAW_BCTR()
375 #endif
376 };
377
378 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
379 for (i = 0; i < 2; i++) {
380 reladdr = addr - (unsigned long)tramp[i];
381
382 if (reladdr >= (long)SZ_8G || reladdr < -(long)SZ_8G) {
383 pr_err("Address of %ps out of range of pcrel address.\n",
384 (void *)addr);
385 return -1;
386 }
387
388 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
389 tramp[i][0] |= IMM_H18(reladdr);
390 tramp[i][1] |= IMM_L(reladdr);
391 add_ftrace_tramp((unsigned long)tramp[i]);
392 }
393 } else if (IS_ENABLED(CONFIG_PPC64)) {
394 reladdr = addr - kernel_toc_addr();
395
396 if (reladdr >= (long)SZ_2G || reladdr < -(long long)SZ_2G) {
397 pr_err("Address of %ps out of range of kernel_toc.\n",
398 (void *)addr);
399 return -1;
400 }
401
402 for (i = 0; i < 2; i++) {
403 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
404 tramp[i][1] |= PPC_HA(reladdr);
405 tramp[i][2] |= PPC_LO(reladdr);
406 add_ftrace_tramp((unsigned long)tramp[i]);
407 }
408 } else {
409 for (i = 0; i < 2; i++) {
410 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
411 tramp[i][0] |= PPC_HA(addr);
412 tramp[i][1] |= PPC_LO(addr);
413 add_ftrace_tramp((unsigned long)tramp[i]);
414 }
415 }
416
417 return 0;
418 }
419
420 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
421 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
422 struct ftrace_ops *op, struct ftrace_regs *fregs)
423 {
424 unsigned long sp = fregs->regs.gpr[1];
425 int bit;
426
427 if (unlikely(ftrace_graph_is_dead()))
428 goto out;
429
430 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
431 goto out;
432
433 bit = ftrace_test_recursion_trylock(ip, parent_ip);
434 if (bit < 0)
435 goto out;
436
437 if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
438 parent_ip = ppc_function_entry(return_to_handler);
439
440 ftrace_test_recursion_unlock(bit);
441 out:
442 fregs->regs.link = parent_ip;
443 }
444 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
445
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