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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Dynamic function tracer architecture backend.
4 *
5 * Copyright IBM Corp. 2009,2014
6 *
7 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
8 */
9
10#include <linux/moduleloader.h>
11#include <linux/hardirq.h>
12#include <linux/uaccess.h>
13#include <linux/ftrace.h>
14#include <linux/kernel.h>
15#include <linux/types.h>
16#include <linux/kprobes.h>
17#include <trace/syscall.h>
18#include <asm/asm-offsets.h>
19#include <asm/text-patching.h>
20#include <asm/cacheflush.h>
21#include <asm/ftrace.lds.h>
22#include <asm/nospec-branch.h>
23#include <asm/set_memory.h>
24#include "entry.h"
25#include "ftrace.h"
26
27/*
28 * To generate function prologue either gcc's hotpatch feature (since gcc 4.8)
29 * or a combination of -pg -mrecord-mcount -mnop-mcount -mfentry flags
30 * (since gcc 9 / clang 10) is used.
31 * In both cases the original and also the disabled function prologue contains
32 * only a single six byte instruction and looks like this:
33 * > brcl 0,0 # offset 0
34 * To enable ftrace the code gets patched like above and afterwards looks
35 * like this:
36 * > brasl %r0,ftrace_caller # offset 0
37 *
38 * The instruction will be patched by ftrace_make_call / ftrace_make_nop.
39 * The ftrace function gets called with a non-standard C function call ABI
40 * where r0 contains the return address. It is also expected that the called
41 * function only clobbers r0 and r1, but restores r2-r15.
42 * For module code we can't directly jump to ftrace caller, but need a
43 * trampoline (ftrace_plt), which clobbers also r1.
44 */
45
46void *ftrace_func __read_mostly = ftrace_stub;
47struct ftrace_insn {
48 u16 opc;
49 s32 disp;
50} __packed;
51
52#ifdef CONFIG_MODULES
53static char *ftrace_plt;
54#endif /* CONFIG_MODULES */
55
56static const char *ftrace_shared_hotpatch_trampoline(const char **end)
57{
58 const char *tstart, *tend;
59
60 tstart = ftrace_shared_hotpatch_trampoline_br;
61 tend = ftrace_shared_hotpatch_trampoline_br_end;
62#ifdef CONFIG_EXPOLINE
63 if (!nospec_disable) {
64 tstart = ftrace_shared_hotpatch_trampoline_exrl;
65 tend = ftrace_shared_hotpatch_trampoline_exrl_end;
66 }
67#endif /* CONFIG_EXPOLINE */
68 if (end)
69 *end = tend;
70 return tstart;
71}
72
73bool ftrace_need_init_nop(void)
74{
75 return true;
76}
77
78int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
79{
80 static struct ftrace_hotpatch_trampoline *next_vmlinux_trampoline =
81 __ftrace_hotpatch_trampolines_start;
82 static const char orig[6] = { 0xc0, 0x04, 0x00, 0x00, 0x00, 0x00 };
83 static struct ftrace_hotpatch_trampoline *trampoline;
84 struct ftrace_hotpatch_trampoline **next_trampoline;
85 struct ftrace_hotpatch_trampoline *trampolines_end;
86 struct ftrace_hotpatch_trampoline tmp;
87 struct ftrace_insn *insn;
88 const char *shared;
89 s32 disp;
90
91 BUILD_BUG_ON(sizeof(struct ftrace_hotpatch_trampoline) !=
92 SIZEOF_FTRACE_HOTPATCH_TRAMPOLINE);
93
94 next_trampoline = &next_vmlinux_trampoline;
95 trampolines_end = __ftrace_hotpatch_trampolines_end;
96 shared = ftrace_shared_hotpatch_trampoline(NULL);
97#ifdef CONFIG_MODULES
98 if (mod) {
99 next_trampoline = &mod->arch.next_trampoline;
100 trampolines_end = mod->arch.trampolines_end;
101 shared = ftrace_plt;
102 }
103#endif
104
105 if (WARN_ON_ONCE(*next_trampoline >= trampolines_end))
106 return -ENOMEM;
107 trampoline = (*next_trampoline)++;
108
109 /* Check for the compiler-generated fentry nop (brcl 0, .). */
110 if (WARN_ON_ONCE(memcmp((const void *)rec->ip, &orig, sizeof(orig))))
111 return -EINVAL;
112
113 /* Generate the trampoline. */
114 tmp.brasl_opc = 0xc015; /* brasl %r1, shared */
115 tmp.brasl_disp = (shared - (const char *)&trampoline->brasl_opc) / 2;
116 tmp.interceptor = FTRACE_ADDR;
117 tmp.rest_of_intercepted_function = rec->ip + sizeof(struct ftrace_insn);
118 s390_kernel_write(trampoline, &tmp, sizeof(tmp));
119
120 /* Generate a jump to the trampoline. */
121 disp = ((char *)trampoline - (char *)rec->ip) / 2;
122 insn = (struct ftrace_insn *)rec->ip;
123 s390_kernel_write(&insn->disp, &disp, sizeof(disp));
124
125 return 0;
126}
127
128static struct ftrace_hotpatch_trampoline *ftrace_get_trampoline(struct dyn_ftrace *rec)
129{
130 struct ftrace_hotpatch_trampoline *trampoline;
131 struct ftrace_insn insn;
132 s64 disp;
133 u16 opc;
134
135 if (copy_from_kernel_nofault(&insn, (void *)rec->ip, sizeof(insn)))
136 return ERR_PTR(-EFAULT);
137 disp = (s64)insn.disp * 2;
138 trampoline = (void *)(rec->ip + disp);
139 if (get_kernel_nofault(opc, &trampoline->brasl_opc))
140 return ERR_PTR(-EFAULT);
141 if (opc != 0xc015)
142 return ERR_PTR(-EINVAL);
143 return trampoline;
144}
145
146int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
147 unsigned long addr)
148{
149 struct ftrace_hotpatch_trampoline *trampoline;
150 u64 old;
151
152 trampoline = ftrace_get_trampoline(rec);
153 if (IS_ERR(trampoline))
154 return PTR_ERR(trampoline);
155 if (get_kernel_nofault(old, &trampoline->interceptor))
156 return -EFAULT;
157 if (old != old_addr)
158 return -EINVAL;
159 s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
160 return 0;
161}
162
163static int ftrace_patch_branch_mask(void *addr, u16 expected, bool enable)
164{
165 u16 old;
166 u8 op;
167
168 if (get_kernel_nofault(old, addr))
169 return -EFAULT;
170 if (old != expected)
171 return -EINVAL;
172 /* set mask field to all ones or zeroes */
173 op = enable ? 0xf4 : 0x04;
174 s390_kernel_write((char *)addr + 1, &op, sizeof(op));
175 return 0;
176}
177
178int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
179 unsigned long addr)
180{
181 /* Expect brcl 0xf,... */
182 return ftrace_patch_branch_mask((void *)rec->ip, 0xc0f4, false);
183}
184
185int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
186{
187 struct ftrace_hotpatch_trampoline *trampoline;
188
189 trampoline = ftrace_get_trampoline(rec);
190 if (IS_ERR(trampoline))
191 return PTR_ERR(trampoline);
192 s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
193 /* Expect brcl 0x0,... */
194 return ftrace_patch_branch_mask((void *)rec->ip, 0xc004, true);
195}
196
197int ftrace_update_ftrace_func(ftrace_func_t func)
198{
199 ftrace_func = func;
200 return 0;
201}
202
203void arch_ftrace_update_code(int command)
204{
205 ftrace_modify_all_code(command);
206}
207
208void ftrace_arch_code_modify_post_process(void)
209{
210 /*
211 * Flush any pre-fetched instructions on all
212 * CPUs to make the new code visible.
213 */
214 text_poke_sync_lock();
215}
216
217#ifdef CONFIG_MODULES
218
219static int __init ftrace_plt_init(void)
220{
221 const char *start, *end;
222
223 ftrace_plt = module_alloc(PAGE_SIZE);
224 if (!ftrace_plt)
225 panic("cannot allocate ftrace plt\n");
226
227 start = ftrace_shared_hotpatch_trampoline(&end);
228 memcpy(ftrace_plt, start, end - start);
229 set_memory_rox((unsigned long)ftrace_plt, 1);
230 return 0;
231}
232device_initcall(ftrace_plt_init);
233
234#endif /* CONFIG_MODULES */
235
236#ifdef CONFIG_FUNCTION_GRAPH_TRACER
237/*
238 * Hook the return address and push it in the stack of return addresses
239 * in current thread info.
240 */
241unsigned long prepare_ftrace_return(unsigned long ra, unsigned long sp,
242 unsigned long ip)
243{
244 if (unlikely(ftrace_graph_is_dead()))
245 goto out;
246 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
247 goto out;
248 ip -= MCOUNT_INSN_SIZE;
249 if (!function_graph_enter(ra, ip, 0, (void *) sp))
250 ra = (unsigned long) return_to_handler;
251out:
252 return ra;
253}
254NOKPROBE_SYMBOL(prepare_ftrace_return);
255
256/*
257 * Patch the kernel code at ftrace_graph_caller location. The instruction
258 * there is branch relative on condition. To enable the ftrace graph code
259 * block, we simply patch the mask field of the instruction to zero and
260 * turn the instruction into a nop.
261 * To disable the ftrace graph code the mask field will be patched to
262 * all ones, which turns the instruction into an unconditional branch.
263 */
264int ftrace_enable_ftrace_graph_caller(void)
265{
266 int rc;
267
268 /* Expect brc 0xf,... */
269 rc = ftrace_patch_branch_mask(ftrace_graph_caller, 0xa7f4, false);
270 if (rc)
271 return rc;
272 text_poke_sync_lock();
273 return 0;
274}
275
276int ftrace_disable_ftrace_graph_caller(void)
277{
278 int rc;
279
280 /* Expect brc 0x0,... */
281 rc = ftrace_patch_branch_mask(ftrace_graph_caller, 0xa704, true);
282 if (rc)
283 return rc;
284 text_poke_sync_lock();
285 return 0;
286}
287
288#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
289
290#ifdef CONFIG_KPROBES_ON_FTRACE
291void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
292 struct ftrace_ops *ops, struct ftrace_regs *fregs)
293{
294 struct kprobe_ctlblk *kcb;
295 struct pt_regs *regs;
296 struct kprobe *p;
297 int bit;
298
299 bit = ftrace_test_recursion_trylock(ip, parent_ip);
300 if (bit < 0)
301 return;
302
303 regs = ftrace_get_regs(fregs);
304 p = get_kprobe((kprobe_opcode_t *)ip);
305 if (!regs || unlikely(!p) || kprobe_disabled(p))
306 goto out;
307
308 if (kprobe_running()) {
309 kprobes_inc_nmissed_count(p);
310 goto out;
311 }
312
313 __this_cpu_write(current_kprobe, p);
314
315 kcb = get_kprobe_ctlblk();
316 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
317
318 instruction_pointer_set(regs, ip);
319
320 if (!p->pre_handler || !p->pre_handler(p, regs)) {
321
322 instruction_pointer_set(regs, ip + MCOUNT_INSN_SIZE);
323
324 if (unlikely(p->post_handler)) {
325 kcb->kprobe_status = KPROBE_HIT_SSDONE;
326 p->post_handler(p, regs, 0);
327 }
328 }
329 __this_cpu_write(current_kprobe, NULL);
330out:
331 ftrace_test_recursion_unlock(bit);
332}
333NOKPROBE_SYMBOL(kprobe_ftrace_handler);
334
335int arch_prepare_kprobe_ftrace(struct kprobe *p)
336{
337 p->ainsn.insn = NULL;
338 return 0;
339}
340#endif
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Dynamic function tracer architecture backend.
4 *
5 * Copyright IBM Corp. 2009,2014
6 *
7 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
8 */
9
10#include <linux/hardirq.h>
11#include <linux/uaccess.h>
12#include <linux/ftrace.h>
13#include <linux/kernel.h>
14#include <linux/types.h>
15#include <linux/kmsan-checks.h>
16#include <linux/kprobes.h>
17#include <linux/execmem.h>
18#include <trace/syscall.h>
19#include <asm/asm-offsets.h>
20#include <asm/text-patching.h>
21#include <asm/cacheflush.h>
22#include <asm/ftrace.lds.h>
23#include <asm/nospec-branch.h>
24#include <asm/set_memory.h>
25#include "entry.h"
26#include "ftrace.h"
27
28/*
29 * To generate function prologue either gcc's hotpatch feature (since gcc 4.8)
30 * or a combination of -pg -mrecord-mcount -mnop-mcount -mfentry flags
31 * (since gcc 9 / clang 10) is used.
32 * In both cases the original and also the disabled function prologue contains
33 * only a single six byte instruction and looks like this:
34 * > brcl 0,0 # offset 0
35 * To enable ftrace the code gets patched like above and afterwards looks
36 * like this:
37 * > brasl %r0,ftrace_caller # offset 0
38 *
39 * The instruction will be patched by ftrace_make_call / ftrace_make_nop.
40 * The ftrace function gets called with a non-standard C function call ABI
41 * where r0 contains the return address. It is also expected that the called
42 * function only clobbers r0 and r1, but restores r2-r15.
43 * For module code we can't directly jump to ftrace caller, but need a
44 * trampoline (ftrace_plt), which clobbers also r1.
45 */
46
47void *ftrace_func __read_mostly = ftrace_stub;
48struct ftrace_insn {
49 u16 opc;
50 s32 disp;
51} __packed;
52
53static const char *ftrace_shared_hotpatch_trampoline(const char **end)
54{
55 const char *tstart, *tend;
56
57 tstart = ftrace_shared_hotpatch_trampoline_br;
58 tend = ftrace_shared_hotpatch_trampoline_br_end;
59#ifdef CONFIG_EXPOLINE
60 if (!nospec_disable) {
61 tstart = ftrace_shared_hotpatch_trampoline_exrl;
62 tend = ftrace_shared_hotpatch_trampoline_exrl_end;
63 }
64#endif /* CONFIG_EXPOLINE */
65 if (end)
66 *end = tend;
67 return tstart;
68}
69
70bool ftrace_need_init_nop(void)
71{
72 return !MACHINE_HAS_SEQ_INSN;
73}
74
75int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
76{
77 static struct ftrace_hotpatch_trampoline *next_vmlinux_trampoline =
78 __ftrace_hotpatch_trampolines_start;
79 static const struct ftrace_insn orig = { .opc = 0xc004, .disp = 0 };
80 static struct ftrace_hotpatch_trampoline *trampoline;
81 struct ftrace_hotpatch_trampoline **next_trampoline;
82 struct ftrace_hotpatch_trampoline *trampolines_end;
83 struct ftrace_hotpatch_trampoline tmp;
84 struct ftrace_insn *insn;
85 struct ftrace_insn old;
86 const char *shared;
87 s32 disp;
88
89 BUILD_BUG_ON(sizeof(struct ftrace_hotpatch_trampoline) !=
90 SIZEOF_FTRACE_HOTPATCH_TRAMPOLINE);
91
92 next_trampoline = &next_vmlinux_trampoline;
93 trampolines_end = __ftrace_hotpatch_trampolines_end;
94 shared = ftrace_shared_hotpatch_trampoline(NULL);
95#ifdef CONFIG_MODULES
96 if (mod) {
97 next_trampoline = &mod->arch.next_trampoline;
98 trampolines_end = mod->arch.trampolines_end;
99 }
100#endif
101
102 if (WARN_ON_ONCE(*next_trampoline >= trampolines_end))
103 return -ENOMEM;
104 trampoline = (*next_trampoline)++;
105
106 if (copy_from_kernel_nofault(&old, (void *)rec->ip, sizeof(old)))
107 return -EFAULT;
108 /* Check for the compiler-generated fentry nop (brcl 0, .). */
109 if (WARN_ON_ONCE(memcmp(&orig, &old, sizeof(old))))
110 return -EINVAL;
111
112 /* Generate the trampoline. */
113 tmp.brasl_opc = 0xc015; /* brasl %r1, shared */
114 tmp.brasl_disp = (shared - (const char *)&trampoline->brasl_opc) / 2;
115 tmp.interceptor = FTRACE_ADDR;
116 tmp.rest_of_intercepted_function = rec->ip + sizeof(struct ftrace_insn);
117 s390_kernel_write(trampoline, &tmp, sizeof(tmp));
118
119 /* Generate a jump to the trampoline. */
120 disp = ((char *)trampoline - (char *)rec->ip) / 2;
121 insn = (struct ftrace_insn *)rec->ip;
122 s390_kernel_write(&insn->disp, &disp, sizeof(disp));
123
124 return 0;
125}
126
127static struct ftrace_hotpatch_trampoline *ftrace_get_trampoline(struct dyn_ftrace *rec)
128{
129 struct ftrace_hotpatch_trampoline *trampoline;
130 struct ftrace_insn insn;
131 s64 disp;
132 u16 opc;
133
134 if (copy_from_kernel_nofault(&insn, (void *)rec->ip, sizeof(insn)))
135 return ERR_PTR(-EFAULT);
136 disp = (s64)insn.disp * 2;
137 trampoline = (void *)(rec->ip + disp);
138 if (get_kernel_nofault(opc, &trampoline->brasl_opc))
139 return ERR_PTR(-EFAULT);
140 if (opc != 0xc015)
141 return ERR_PTR(-EINVAL);
142 return trampoline;
143}
144
145static inline struct ftrace_insn
146ftrace_generate_branch_insn(unsigned long ip, unsigned long target)
147{
148 /* brasl r0,target or brcl 0,0 */
149 return (struct ftrace_insn){ .opc = target ? 0xc005 : 0xc004,
150 .disp = target ? (target - ip) / 2 : 0 };
151}
152
153static int ftrace_patch_branch_insn(unsigned long ip, unsigned long old_target,
154 unsigned long target)
155{
156 struct ftrace_insn orig = ftrace_generate_branch_insn(ip, old_target);
157 struct ftrace_insn new = ftrace_generate_branch_insn(ip, target);
158 struct ftrace_insn old;
159
160 if (!IS_ALIGNED(ip, 8))
161 return -EINVAL;
162 if (copy_from_kernel_nofault(&old, (void *)ip, sizeof(old)))
163 return -EFAULT;
164 /* Verify that the to be replaced code matches what we expect. */
165 if (memcmp(&orig, &old, sizeof(old)))
166 return -EINVAL;
167 s390_kernel_write((void *)ip, &new, sizeof(new));
168 return 0;
169}
170
171static int ftrace_modify_trampoline_call(struct dyn_ftrace *rec,
172 unsigned long old_addr,
173 unsigned long addr)
174{
175 struct ftrace_hotpatch_trampoline *trampoline;
176 u64 old;
177
178 trampoline = ftrace_get_trampoline(rec);
179 if (IS_ERR(trampoline))
180 return PTR_ERR(trampoline);
181 if (get_kernel_nofault(old, &trampoline->interceptor))
182 return -EFAULT;
183 if (old != old_addr)
184 return -EINVAL;
185 s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
186 return 0;
187}
188
189int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
190 unsigned long addr)
191{
192 if (MACHINE_HAS_SEQ_INSN)
193 return ftrace_patch_branch_insn(rec->ip, old_addr, addr);
194 else
195 return ftrace_modify_trampoline_call(rec, old_addr, addr);
196}
197
198static int ftrace_patch_branch_mask(void *addr, u16 expected, bool enable)
199{
200 u16 old;
201 u8 op;
202
203 if (get_kernel_nofault(old, addr))
204 return -EFAULT;
205 if (old != expected)
206 return -EINVAL;
207 /* set mask field to all ones or zeroes */
208 op = enable ? 0xf4 : 0x04;
209 s390_kernel_write((char *)addr + 1, &op, sizeof(op));
210 return 0;
211}
212
213int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
214 unsigned long addr)
215{
216 /* Expect brcl 0xf,... for the !MACHINE_HAS_SEQ_INSN case */
217 if (MACHINE_HAS_SEQ_INSN)
218 return ftrace_patch_branch_insn(rec->ip, addr, 0);
219 else
220 return ftrace_patch_branch_mask((void *)rec->ip, 0xc0f4, false);
221}
222
223static int ftrace_make_trampoline_call(struct dyn_ftrace *rec, unsigned long addr)
224{
225 struct ftrace_hotpatch_trampoline *trampoline;
226
227 trampoline = ftrace_get_trampoline(rec);
228 if (IS_ERR(trampoline))
229 return PTR_ERR(trampoline);
230 s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
231 /* Expect brcl 0x0,... */
232 return ftrace_patch_branch_mask((void *)rec->ip, 0xc004, true);
233}
234
235int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
236{
237 if (MACHINE_HAS_SEQ_INSN)
238 return ftrace_patch_branch_insn(rec->ip, 0, addr);
239 else
240 return ftrace_make_trampoline_call(rec, addr);
241}
242
243int ftrace_update_ftrace_func(ftrace_func_t func)
244{
245 ftrace_func = func;
246 return 0;
247}
248
249void arch_ftrace_update_code(int command)
250{
251 ftrace_modify_all_code(command);
252}
253
254void ftrace_arch_code_modify_post_process(void)
255{
256 /*
257 * Flush any pre-fetched instructions on all
258 * CPUs to make the new code visible.
259 */
260 text_poke_sync_lock();
261}
262
263#ifdef CONFIG_FUNCTION_GRAPH_TRACER
264/*
265 * Hook the return address and push it in the stack of return addresses
266 * in current thread info.
267 */
268unsigned long prepare_ftrace_return(unsigned long ra, unsigned long sp,
269 unsigned long ip)
270{
271 if (unlikely(ftrace_graph_is_dead()))
272 goto out;
273 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
274 goto out;
275 ip -= MCOUNT_INSN_SIZE;
276 if (!function_graph_enter(ra, ip, 0, (void *) sp))
277 ra = (unsigned long) return_to_handler;
278out:
279 return ra;
280}
281NOKPROBE_SYMBOL(prepare_ftrace_return);
282
283/*
284 * Patch the kernel code at ftrace_graph_caller location. The instruction
285 * there is branch relative on condition. To enable the ftrace graph code
286 * block, we simply patch the mask field of the instruction to zero and
287 * turn the instruction into a nop.
288 * To disable the ftrace graph code the mask field will be patched to
289 * all ones, which turns the instruction into an unconditional branch.
290 */
291int ftrace_enable_ftrace_graph_caller(void)
292{
293 /* Expect brc 0xf,... */
294 return ftrace_patch_branch_mask(ftrace_graph_caller, 0xa7f4, false);
295}
296
297int ftrace_disable_ftrace_graph_caller(void)
298{
299 /* Expect brc 0x0,... */
300 return ftrace_patch_branch_mask(ftrace_graph_caller, 0xa704, true);
301}
302
303#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
304
305#ifdef CONFIG_KPROBES_ON_FTRACE
306void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
307 struct ftrace_ops *ops, struct ftrace_regs *fregs)
308{
309 struct kprobe_ctlblk *kcb;
310 struct pt_regs *regs;
311 struct kprobe *p;
312 int bit;
313
314 if (unlikely(kprobe_ftrace_disabled))
315 return;
316
317 bit = ftrace_test_recursion_trylock(ip, parent_ip);
318 if (bit < 0)
319 return;
320
321 kmsan_unpoison_memory(fregs, ftrace_regs_size());
322 regs = ftrace_get_regs(fregs);
323 p = get_kprobe((kprobe_opcode_t *)ip);
324 if (!regs || unlikely(!p) || kprobe_disabled(p))
325 goto out;
326
327 if (kprobe_running()) {
328 kprobes_inc_nmissed_count(p);
329 goto out;
330 }
331
332 __this_cpu_write(current_kprobe, p);
333
334 kcb = get_kprobe_ctlblk();
335 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
336
337 instruction_pointer_set(regs, ip);
338
339 if (!p->pre_handler || !p->pre_handler(p, regs)) {
340
341 instruction_pointer_set(regs, ip + MCOUNT_INSN_SIZE);
342
343 if (unlikely(p->post_handler)) {
344 kcb->kprobe_status = KPROBE_HIT_SSDONE;
345 p->post_handler(p, regs, 0);
346 }
347 }
348 __this_cpu_write(current_kprobe, NULL);
349out:
350 ftrace_test_recursion_unlock(bit);
351}
352NOKPROBE_SYMBOL(kprobe_ftrace_handler);
353
354int arch_prepare_kprobe_ftrace(struct kprobe *p)
355{
356 p->ainsn.insn = NULL;
357 return 0;
358}
359#endif