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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
33static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
34
35unsigned 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
46static 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
56static 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
66static 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
81static 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
91static int is_bl_op(ppc_inst_t op)
92{
93 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
94}
95
96static 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
109static 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
139int 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
147int 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
164int 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
174void 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
222out:
223 if (ret)
224 ftrace_bug(ret, rec);
225 return;
226}
227
228int 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
299int 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 */
324void arch_ftrace_update_code(int command)
325{
326 ftrace_modify_all_code(command);
327}
328
329void 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
340static 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
351int __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
421void 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);
441out:
442 fregs->regs.link = parent_ip;
443}
444#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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/asm-prototypes.h>
26#include <asm/cacheflush.h>
27#include <asm/code-patching.h>
28#include <asm/ftrace.h>
29#include <asm/syscall.h>
30
31
32#ifdef CONFIG_DYNAMIC_FTRACE
33
34/*
35 * We generally only have a single long_branch tramp and at most 2 or 3 plt
36 * tramps generated. But, we don't use the plt tramps currently. We also allot
37 * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
38 * tramps in total. Set aside 8 just to be sure.
39 */
40#define NUM_FTRACE_TRAMPS 8
41static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
42
43static unsigned int
44ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
45{
46 unsigned int op;
47
48 addr = ppc_function_entry((void *)addr);
49
50 /* if (link) set op to 'bl' else 'b' */
51 op = create_branch((unsigned int *)ip, addr, link ? 1 : 0);
52
53 return op;
54}
55
56static int
57ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
58{
59 unsigned int replaced;
60
61 /*
62 * Note:
63 * We are paranoid about modifying text, as if a bug was to happen, it
64 * could cause us to read or write to someplace that could cause harm.
65 * Carefully read and modify the code with probe_kernel_*(), and make
66 * sure what we read is what we expected it to be before modifying it.
67 */
68
69 /* read the text we want to modify */
70 if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
71 return -EFAULT;
72
73 /* Make sure it is what we expect it to be */
74 if (replaced != old) {
75 pr_err("%p: replaced (%#x) != old (%#x)",
76 (void *)ip, replaced, old);
77 return -EINVAL;
78 }
79
80 /* replace the text with the new text */
81 if (patch_instruction((unsigned int *)ip, new))
82 return -EPERM;
83
84 return 0;
85}
86
87/*
88 * Helper functions that are the same for both PPC64 and PPC32.
89 */
90static int test_24bit_addr(unsigned long ip, unsigned long addr)
91{
92 addr = ppc_function_entry((void *)addr);
93
94 /* use the create_branch to verify that this offset can be branched */
95 return create_branch((unsigned int *)ip, addr, 0);
96}
97
98static int is_bl_op(unsigned int op)
99{
100 return (op & 0xfc000003) == 0x48000001;
101}
102
103static int is_b_op(unsigned int op)
104{
105 return (op & 0xfc000003) == 0x48000000;
106}
107
108static unsigned long find_bl_target(unsigned long ip, unsigned int op)
109{
110 int offset;
111
112 offset = (op & 0x03fffffc);
113 /* make it signed */
114 if (offset & 0x02000000)
115 offset |= 0xfe000000;
116
117 return ip + (long)offset;
118}
119
120#ifdef CONFIG_MODULES
121#ifdef CONFIG_PPC64
122static int
123__ftrace_make_nop(struct module *mod,
124 struct dyn_ftrace *rec, unsigned long addr)
125{
126 unsigned long entry, ptr, tramp;
127 unsigned long ip = rec->ip;
128 unsigned int op, pop;
129
130 /* read where this goes */
131 if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
132 pr_err("Fetching opcode failed.\n");
133 return -EFAULT;
134 }
135
136 /* Make sure that that this is still a 24bit jump */
137 if (!is_bl_op(op)) {
138 pr_err("Not expected bl: opcode is %x\n", op);
139 return -EINVAL;
140 }
141
142 /* lets find where the pointer goes */
143 tramp = find_bl_target(ip, op);
144
145 pr_devel("ip:%lx jumps to %lx", ip, tramp);
146
147 if (module_trampoline_target(mod, tramp, &ptr)) {
148 pr_err("Failed to get trampoline target\n");
149 return -EFAULT;
150 }
151
152 pr_devel("trampoline target %lx", ptr);
153
154 entry = ppc_global_function_entry((void *)addr);
155 /* This should match what was called */
156 if (ptr != entry) {
157 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
158 return -EINVAL;
159 }
160
161#ifdef CONFIG_MPROFILE_KERNEL
162 /* When using -mkernel_profile there is no load to jump over */
163 pop = PPC_INST_NOP;
164
165 if (probe_kernel_read(&op, (void *)(ip - 4), 4)) {
166 pr_err("Fetching instruction at %lx failed.\n", ip - 4);
167 return -EFAULT;
168 }
169
170 /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
171 if (op != PPC_INST_MFLR && op != PPC_INST_STD_LR) {
172 pr_err("Unexpected instruction %08x around bl _mcount\n", op);
173 return -EINVAL;
174 }
175#else
176 /*
177 * Our original call site looks like:
178 *
179 * bl <tramp>
180 * ld r2,XX(r1)
181 *
182 * Milton Miller pointed out that we can not simply nop the branch.
183 * If a task was preempted when calling a trace function, the nops
184 * will remove the way to restore the TOC in r2 and the r2 TOC will
185 * get corrupted.
186 *
187 * Use a b +8 to jump over the load.
188 */
189
190 pop = PPC_INST_BRANCH | 8; /* b +8 */
191
192 /*
193 * Check what is in the next instruction. We can see ld r2,40(r1), but
194 * on first pass after boot we will see mflr r0.
195 */
196 if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) {
197 pr_err("Fetching op failed.\n");
198 return -EFAULT;
199 }
200
201 if (op != PPC_INST_LD_TOC) {
202 pr_err("Expected %08x found %08x\n", PPC_INST_LD_TOC, op);
203 return -EINVAL;
204 }
205#endif /* CONFIG_MPROFILE_KERNEL */
206
207 if (patch_instruction((unsigned int *)ip, pop)) {
208 pr_err("Patching NOP failed.\n");
209 return -EPERM;
210 }
211
212 return 0;
213}
214
215#else /* !PPC64 */
216static int
217__ftrace_make_nop(struct module *mod,
218 struct dyn_ftrace *rec, unsigned long addr)
219{
220 unsigned int op;
221 unsigned int jmp[4];
222 unsigned long ip = rec->ip;
223 unsigned long tramp;
224
225 if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
226 return -EFAULT;
227
228 /* Make sure that that this is still a 24bit jump */
229 if (!is_bl_op(op)) {
230 pr_err("Not expected bl: opcode is %x\n", op);
231 return -EINVAL;
232 }
233
234 /* lets find where the pointer goes */
235 tramp = find_bl_target(ip, op);
236
237 /*
238 * On PPC32 the trampoline looks like:
239 * 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha
240 * 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l
241 * 0x7d, 0x89, 0x03, 0xa6 mtctr r12
242 * 0x4e, 0x80, 0x04, 0x20 bctr
243 */
244
245 pr_devel("ip:%lx jumps to %lx", ip, tramp);
246
247 /* Find where the trampoline jumps to */
248 if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
249 pr_err("Failed to read %lx\n", tramp);
250 return -EFAULT;
251 }
252
253 pr_devel(" %08x %08x ", jmp[0], jmp[1]);
254
255 /* verify that this is what we expect it to be */
256 if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
257 ((jmp[1] & 0xffff0000) != 0x398c0000) ||
258 (jmp[2] != 0x7d8903a6) ||
259 (jmp[3] != 0x4e800420)) {
260 pr_err("Not a trampoline\n");
261 return -EINVAL;
262 }
263
264 tramp = (jmp[1] & 0xffff) |
265 ((jmp[0] & 0xffff) << 16);
266 if (tramp & 0x8000)
267 tramp -= 0x10000;
268
269 pr_devel(" %lx ", tramp);
270
271 if (tramp != addr) {
272 pr_err("Trampoline location %08lx does not match addr\n",
273 tramp);
274 return -EINVAL;
275 }
276
277 op = PPC_INST_NOP;
278
279 if (patch_instruction((unsigned int *)ip, op))
280 return -EPERM;
281
282 return 0;
283}
284#endif /* PPC64 */
285#endif /* CONFIG_MODULES */
286
287static unsigned long find_ftrace_tramp(unsigned long ip)
288{
289 int i;
290
291 /*
292 * We have the compiler generated long_branch tramps at the end
293 * and we prefer those
294 */
295 for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
296 if (!ftrace_tramps[i])
297 continue;
298 else if (create_branch((void *)ip, ftrace_tramps[i], 0))
299 return ftrace_tramps[i];
300
301 return 0;
302}
303
304static int add_ftrace_tramp(unsigned long tramp)
305{
306 int i;
307
308 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
309 if (!ftrace_tramps[i]) {
310 ftrace_tramps[i] = tramp;
311 return 0;
312 }
313
314 return -1;
315}
316
317/*
318 * If this is a compiler generated long_branch trampoline (essentially, a
319 * trampoline that has a branch to _mcount()), we re-write the branch to
320 * instead go to ftrace_[regs_]caller() and note down the location of this
321 * trampoline.
322 */
323static int setup_mcount_compiler_tramp(unsigned long tramp)
324{
325 int i, op;
326 unsigned long ptr;
327 static unsigned long ftrace_plt_tramps[NUM_FTRACE_TRAMPS];
328
329 /* Is this a known long jump tramp? */
330 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
331 if (!ftrace_tramps[i])
332 break;
333 else if (ftrace_tramps[i] == tramp)
334 return 0;
335
336 /* Is this a known plt tramp? */
337 for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
338 if (!ftrace_plt_tramps[i])
339 break;
340 else if (ftrace_plt_tramps[i] == tramp)
341 return -1;
342
343 /* New trampoline -- read where this goes */
344 if (probe_kernel_read(&op, (void *)tramp, sizeof(int))) {
345 pr_debug("Fetching opcode failed.\n");
346 return -1;
347 }
348
349 /* Is this a 24 bit branch? */
350 if (!is_b_op(op)) {
351 pr_debug("Trampoline is not a long branch tramp.\n");
352 return -1;
353 }
354
355 /* lets find where the pointer goes */
356 ptr = find_bl_target(tramp, op);
357
358 if (ptr != ppc_global_function_entry((void *)_mcount)) {
359 pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
360 return -1;
361 }
362
363 /* Let's re-write the tramp to go to ftrace_[regs_]caller */
364#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
365 ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
366#else
367 ptr = ppc_global_function_entry((void *)ftrace_caller);
368#endif
369 if (!create_branch((void *)tramp, ptr, 0)) {
370 pr_debug("%ps is not reachable from existing mcount tramp\n",
371 (void *)ptr);
372 return -1;
373 }
374
375 if (patch_branch((unsigned int *)tramp, ptr, 0)) {
376 pr_debug("REL24 out of range!\n");
377 return -1;
378 }
379
380 if (add_ftrace_tramp(tramp)) {
381 pr_debug("No tramp locations left\n");
382 return -1;
383 }
384
385 return 0;
386}
387
388static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
389{
390 unsigned long tramp, ip = rec->ip;
391 unsigned int op;
392
393 /* Read where this goes */
394 if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
395 pr_err("Fetching opcode failed.\n");
396 return -EFAULT;
397 }
398
399 /* Make sure that that this is still a 24bit jump */
400 if (!is_bl_op(op)) {
401 pr_err("Not expected bl: opcode is %x\n", op);
402 return -EINVAL;
403 }
404
405 /* Let's find where the pointer goes */
406 tramp = find_bl_target(ip, op);
407
408 pr_devel("ip:%lx jumps to %lx", ip, tramp);
409
410 if (setup_mcount_compiler_tramp(tramp)) {
411 /* Are other trampolines reachable? */
412 if (!find_ftrace_tramp(ip)) {
413 pr_err("No ftrace trampolines reachable from %ps\n",
414 (void *)ip);
415 return -EINVAL;
416 }
417 }
418
419 if (patch_instruction((unsigned int *)ip, PPC_INST_NOP)) {
420 pr_err("Patching NOP failed.\n");
421 return -EPERM;
422 }
423
424 return 0;
425}
426
427int ftrace_make_nop(struct module *mod,
428 struct dyn_ftrace *rec, unsigned long addr)
429{
430 unsigned long ip = rec->ip;
431 unsigned int old, new;
432
433 /*
434 * If the calling address is more that 24 bits away,
435 * then we had to use a trampoline to make the call.
436 * Otherwise just update the call site.
437 */
438 if (test_24bit_addr(ip, addr)) {
439 /* within range */
440 old = ftrace_call_replace(ip, addr, 1);
441 new = PPC_INST_NOP;
442 return ftrace_modify_code(ip, old, new);
443 } else if (core_kernel_text(ip))
444 return __ftrace_make_nop_kernel(rec, addr);
445
446#ifdef CONFIG_MODULES
447 /*
448 * Out of range jumps are called from modules.
449 * We should either already have a pointer to the module
450 * or it has been passed in.
451 */
452 if (!rec->arch.mod) {
453 if (!mod) {
454 pr_err("No module loaded addr=%lx\n", addr);
455 return -EFAULT;
456 }
457 rec->arch.mod = mod;
458 } else if (mod) {
459 if (mod != rec->arch.mod) {
460 pr_err("Record mod %p not equal to passed in mod %p\n",
461 rec->arch.mod, mod);
462 return -EINVAL;
463 }
464 /* nothing to do if mod == rec->arch.mod */
465 } else
466 mod = rec->arch.mod;
467
468 return __ftrace_make_nop(mod, rec, addr);
469#else
470 /* We should not get here without modules */
471 return -EINVAL;
472#endif /* CONFIG_MODULES */
473}
474
475#ifdef CONFIG_MODULES
476#ifdef CONFIG_PPC64
477/*
478 * Examine the existing instructions for __ftrace_make_call.
479 * They should effectively be a NOP, and follow formal constraints,
480 * depending on the ABI. Return false if they don't.
481 */
482#ifndef CONFIG_MPROFILE_KERNEL
483static int
484expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1)
485{
486 /*
487 * We expect to see:
488 *
489 * b +8
490 * ld r2,XX(r1)
491 *
492 * The load offset is different depending on the ABI. For simplicity
493 * just mask it out when doing the compare.
494 */
495 if ((op0 != 0x48000008) || ((op1 & 0xffff0000) != 0xe8410000))
496 return 0;
497 return 1;
498}
499#else
500static int
501expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1)
502{
503 /* look for patched "NOP" on ppc64 with -mprofile-kernel */
504 if (op0 != PPC_INST_NOP)
505 return 0;
506 return 1;
507}
508#endif
509
510static int
511__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
512{
513 unsigned int op[2];
514 void *ip = (void *)rec->ip;
515 unsigned long entry, ptr, tramp;
516 struct module *mod = rec->arch.mod;
517
518 /* read where this goes */
519 if (probe_kernel_read(op, ip, sizeof(op)))
520 return -EFAULT;
521
522 if (!expected_nop_sequence(ip, op[0], op[1])) {
523 pr_err("Unexpected call sequence at %p: %x %x\n",
524 ip, op[0], op[1]);
525 return -EINVAL;
526 }
527
528 /* If we never set up ftrace trampoline(s), then bail */
529#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
530 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
531#else
532 if (!mod->arch.tramp) {
533#endif
534 pr_err("No ftrace trampoline\n");
535 return -EINVAL;
536 }
537
538#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
539 if (rec->flags & FTRACE_FL_REGS)
540 tramp = mod->arch.tramp_regs;
541 else
542#endif
543 tramp = mod->arch.tramp;
544
545 if (module_trampoline_target(mod, tramp, &ptr)) {
546 pr_err("Failed to get trampoline target\n");
547 return -EFAULT;
548 }
549
550 pr_devel("trampoline target %lx", ptr);
551
552 entry = ppc_global_function_entry((void *)addr);
553 /* This should match what was called */
554 if (ptr != entry) {
555 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
556 return -EINVAL;
557 }
558
559 /* Ensure branch is within 24 bits */
560 if (!create_branch(ip, tramp, BRANCH_SET_LINK)) {
561 pr_err("Branch out of range\n");
562 return -EINVAL;
563 }
564
565 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
566 pr_err("REL24 out of range!\n");
567 return -EINVAL;
568 }
569
570 return 0;
571}
572
573#else /* !CONFIG_PPC64: */
574static int
575__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
576{
577 unsigned int op;
578 unsigned long ip = rec->ip;
579
580 /* read where this goes */
581 if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
582 return -EFAULT;
583
584 /* It should be pointing to a nop */
585 if (op != PPC_INST_NOP) {
586 pr_err("Expected NOP but have %x\n", op);
587 return -EINVAL;
588 }
589
590 /* If we never set up a trampoline to ftrace_caller, then bail */
591 if (!rec->arch.mod->arch.tramp) {
592 pr_err("No ftrace trampoline\n");
593 return -EINVAL;
594 }
595
596 /* create the branch to the trampoline */
597 op = create_branch((unsigned int *)ip,
598 rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
599 if (!op) {
600 pr_err("REL24 out of range!\n");
601 return -EINVAL;
602 }
603
604 pr_devel("write to %lx\n", rec->ip);
605
606 if (patch_instruction((unsigned int *)ip, op))
607 return -EPERM;
608
609 return 0;
610}
611#endif /* CONFIG_PPC64 */
612#endif /* CONFIG_MODULES */
613
614static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
615{
616 unsigned int op;
617 void *ip = (void *)rec->ip;
618 unsigned long tramp, entry, ptr;
619
620 /* Make sure we're being asked to patch branch to a known ftrace addr */
621 entry = ppc_global_function_entry((void *)ftrace_caller);
622 ptr = ppc_global_function_entry((void *)addr);
623
624 if (ptr != entry) {
625#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
626 entry = ppc_global_function_entry((void *)ftrace_regs_caller);
627 if (ptr != entry) {
628#endif
629 pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
630 return -EINVAL;
631#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
632 }
633#endif
634 }
635
636 /* Make sure we have a nop */
637 if (probe_kernel_read(&op, ip, sizeof(op))) {
638 pr_err("Unable to read ftrace location %p\n", ip);
639 return -EFAULT;
640 }
641
642 if (op != PPC_INST_NOP) {
643 pr_err("Unexpected call sequence at %p: %x\n", ip, op);
644 return -EINVAL;
645 }
646
647 tramp = find_ftrace_tramp((unsigned long)ip);
648 if (!tramp) {
649 pr_err("No ftrace trampolines reachable from %ps\n", ip);
650 return -EINVAL;
651 }
652
653 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
654 pr_err("Error patching branch to ftrace tramp!\n");
655 return -EINVAL;
656 }
657
658 return 0;
659}
660
661int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
662{
663 unsigned long ip = rec->ip;
664 unsigned int old, new;
665
666 /*
667 * If the calling address is more that 24 bits away,
668 * then we had to use a trampoline to make the call.
669 * Otherwise just update the call site.
670 */
671 if (test_24bit_addr(ip, addr)) {
672 /* within range */
673 old = PPC_INST_NOP;
674 new = ftrace_call_replace(ip, addr, 1);
675 return ftrace_modify_code(ip, old, new);
676 } else if (core_kernel_text(ip))
677 return __ftrace_make_call_kernel(rec, addr);
678
679#ifdef CONFIG_MODULES
680 /*
681 * Out of range jumps are called from modules.
682 * Being that we are converting from nop, it had better
683 * already have a module defined.
684 */
685 if (!rec->arch.mod) {
686 pr_err("No module loaded\n");
687 return -EINVAL;
688 }
689
690 return __ftrace_make_call(rec, addr);
691#else
692 /* We should not get here without modules */
693 return -EINVAL;
694#endif /* CONFIG_MODULES */
695}
696
697#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
698#ifdef CONFIG_MODULES
699static int
700__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
701 unsigned long addr)
702{
703 unsigned int op;
704 unsigned long ip = rec->ip;
705 unsigned long entry, ptr, tramp;
706 struct module *mod = rec->arch.mod;
707
708 /* If we never set up ftrace trampolines, then bail */
709 if (!mod->arch.tramp || !mod->arch.tramp_regs) {
710 pr_err("No ftrace trampoline\n");
711 return -EINVAL;
712 }
713
714 /* read where this goes */
715 if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
716 pr_err("Fetching opcode failed.\n");
717 return -EFAULT;
718 }
719
720 /* Make sure that that this is still a 24bit jump */
721 if (!is_bl_op(op)) {
722 pr_err("Not expected bl: opcode is %x\n", op);
723 return -EINVAL;
724 }
725
726 /* lets find where the pointer goes */
727 tramp = find_bl_target(ip, op);
728 entry = ppc_global_function_entry((void *)old_addr);
729
730 pr_devel("ip:%lx jumps to %lx", ip, tramp);
731
732 if (tramp != entry) {
733 /* old_addr is not within range, so we must have used a trampoline */
734 if (module_trampoline_target(mod, tramp, &ptr)) {
735 pr_err("Failed to get trampoline target\n");
736 return -EFAULT;
737 }
738
739 pr_devel("trampoline target %lx", ptr);
740
741 /* This should match what was called */
742 if (ptr != entry) {
743 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
744 return -EINVAL;
745 }
746 }
747
748 /* The new target may be within range */
749 if (test_24bit_addr(ip, addr)) {
750 /* within range */
751 if (patch_branch((unsigned int *)ip, addr, BRANCH_SET_LINK)) {
752 pr_err("REL24 out of range!\n");
753 return -EINVAL;
754 }
755
756 return 0;
757 }
758
759 if (rec->flags & FTRACE_FL_REGS)
760 tramp = mod->arch.tramp_regs;
761 else
762 tramp = mod->arch.tramp;
763
764 if (module_trampoline_target(mod, tramp, &ptr)) {
765 pr_err("Failed to get trampoline target\n");
766 return -EFAULT;
767 }
768
769 pr_devel("trampoline target %lx", ptr);
770
771 entry = ppc_global_function_entry((void *)addr);
772 /* This should match what was called */
773 if (ptr != entry) {
774 pr_err("addr %lx does not match expected %lx\n", ptr, entry);
775 return -EINVAL;
776 }
777
778 /* Ensure branch is within 24 bits */
779 if (!create_branch((unsigned int *)ip, tramp, BRANCH_SET_LINK)) {
780 pr_err("Branch out of range\n");
781 return -EINVAL;
782 }
783
784 if (patch_branch((unsigned int *)ip, tramp, BRANCH_SET_LINK)) {
785 pr_err("REL24 out of range!\n");
786 return -EINVAL;
787 }
788
789 return 0;
790}
791#endif
792
793int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
794 unsigned long addr)
795{
796 unsigned long ip = rec->ip;
797 unsigned int old, new;
798
799 /*
800 * If the calling address is more that 24 bits away,
801 * then we had to use a trampoline to make the call.
802 * Otherwise just update the call site.
803 */
804 if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
805 /* within range */
806 old = ftrace_call_replace(ip, old_addr, 1);
807 new = ftrace_call_replace(ip, addr, 1);
808 return ftrace_modify_code(ip, old, new);
809 } else if (core_kernel_text(ip)) {
810 /*
811 * We always patch out of range locations to go to the regs
812 * variant, so there is nothing to do here
813 */
814 return 0;
815 }
816
817#ifdef CONFIG_MODULES
818 /*
819 * Out of range jumps are called from modules.
820 */
821 if (!rec->arch.mod) {
822 pr_err("No module loaded\n");
823 return -EINVAL;
824 }
825
826 return __ftrace_modify_call(rec, old_addr, addr);
827#else
828 /* We should not get here without modules */
829 return -EINVAL;
830#endif /* CONFIG_MODULES */
831}
832#endif
833
834int ftrace_update_ftrace_func(ftrace_func_t func)
835{
836 unsigned long ip = (unsigned long)(&ftrace_call);
837 unsigned int old, new;
838 int ret;
839
840 old = *(unsigned int *)&ftrace_call;
841 new = ftrace_call_replace(ip, (unsigned long)func, 1);
842 ret = ftrace_modify_code(ip, old, new);
843
844#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
845 /* Also update the regs callback function */
846 if (!ret) {
847 ip = (unsigned long)(&ftrace_regs_call);
848 old = *(unsigned int *)&ftrace_regs_call;
849 new = ftrace_call_replace(ip, (unsigned long)func, 1);
850 ret = ftrace_modify_code(ip, old, new);
851 }
852#endif
853
854 return ret;
855}
856
857/*
858 * Use the default ftrace_modify_all_code, but without
859 * stop_machine().
860 */
861void arch_ftrace_update_code(int command)
862{
863 ftrace_modify_all_code(command);
864}
865
866#ifdef CONFIG_PPC64
867#define PACATOC offsetof(struct paca_struct, kernel_toc)
868
869extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
870
871int __init ftrace_dyn_arch_init(void)
872{
873 int i;
874 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
875 u32 stub_insns[] = {
876 0xe98d0000 | PACATOC, /* ld r12,PACATOC(r13) */
877 0x3d8c0000, /* addis r12,r12,<high> */
878 0x398c0000, /* addi r12,r12,<low> */
879 0x7d8903a6, /* mtctr r12 */
880 0x4e800420, /* bctr */
881 };
882#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
883 unsigned long addr = ppc_global_function_entry((void *)ftrace_regs_caller);
884#else
885 unsigned long addr = ppc_global_function_entry((void *)ftrace_caller);
886#endif
887 long reladdr = addr - kernel_toc_addr();
888
889 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
890 pr_err("Address of %ps out of range of kernel_toc.\n",
891 (void *)addr);
892 return -1;
893 }
894
895 for (i = 0; i < 2; i++) {
896 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
897 tramp[i][1] |= PPC_HA(reladdr);
898 tramp[i][2] |= PPC_LO(reladdr);
899 add_ftrace_tramp((unsigned long)tramp[i]);
900 }
901
902 return 0;
903}
904#else
905int __init ftrace_dyn_arch_init(void)
906{
907 return 0;
908}
909#endif
910#endif /* CONFIG_DYNAMIC_FTRACE */
911
912#ifdef CONFIG_FUNCTION_GRAPH_TRACER
913
914extern void ftrace_graph_call(void);
915extern void ftrace_graph_stub(void);
916
917int ftrace_enable_ftrace_graph_caller(void)
918{
919 unsigned long ip = (unsigned long)(&ftrace_graph_call);
920 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
921 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
922 unsigned int old, new;
923
924 old = ftrace_call_replace(ip, stub, 0);
925 new = ftrace_call_replace(ip, addr, 0);
926
927 return ftrace_modify_code(ip, old, new);
928}
929
930int ftrace_disable_ftrace_graph_caller(void)
931{
932 unsigned long ip = (unsigned long)(&ftrace_graph_call);
933 unsigned long addr = (unsigned long)(&ftrace_graph_caller);
934 unsigned long stub = (unsigned long)(&ftrace_graph_stub);
935 unsigned int old, new;
936
937 old = ftrace_call_replace(ip, addr, 0);
938 new = ftrace_call_replace(ip, stub, 0);
939
940 return ftrace_modify_code(ip, old, new);
941}
942
943/*
944 * Hook the return address and push it in the stack of return addrs
945 * in current thread info. Return the address we want to divert to.
946 */
947unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
948 unsigned long sp)
949{
950 unsigned long return_hooker;
951
952 if (unlikely(ftrace_graph_is_dead()))
953 goto out;
954
955 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
956 goto out;
957
958 return_hooker = ppc_function_entry(return_to_handler);
959
960 if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
961 parent = return_hooker;
962out:
963 return parent;
964}
965#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
966
967#ifdef PPC64_ELF_ABI_v1
968char *arch_ftrace_match_adjust(char *str, const char *search)
969{
970 if (str[0] == '.' && search[0] != '.')
971 return str + 1;
972 else
973 return str;
974}
975#endif /* PPC64_ELF_ABI_v1 */