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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Kernel Probes (KProbes)
4 *
5 * Copyright IBM Corp. 2002, 2006
6 *
7 * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
8 */
9
10#define pr_fmt(fmt) "kprobes: " fmt
11
12#include <linux/kprobes.h>
13#include <linux/ptrace.h>
14#include <linux/preempt.h>
15#include <linux/stop_machine.h>
16#include <linux/kdebug.h>
17#include <linux/uaccess.h>
18#include <linux/extable.h>
19#include <linux/module.h>
20#include <linux/slab.h>
21#include <linux/hardirq.h>
22#include <linux/ftrace.h>
23#include <linux/execmem.h>
24#include <asm/text-patching.h>
25#include <asm/set_memory.h>
26#include <asm/sections.h>
27#include <asm/dis.h>
28#include "entry.h"
29
30DEFINE_PER_CPU(struct kprobe *, current_kprobe);
31DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
32
33struct kretprobe_blackpoint kretprobe_blacklist[] = { };
34
35void *alloc_insn_page(void)
36{
37 void *page;
38
39 page = execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE);
40 if (!page)
41 return NULL;
42 set_memory_rox((unsigned long)page, 1);
43 return page;
44}
45
46static void copy_instruction(struct kprobe *p)
47{
48 kprobe_opcode_t insn[MAX_INSN_SIZE];
49 s64 disp, new_disp;
50 u64 addr, new_addr;
51 unsigned int len;
52
53 len = insn_length(*p->addr >> 8);
54 memcpy(&insn, p->addr, len);
55 p->opcode = insn[0];
56 if (probe_is_insn_relative_long(&insn[0])) {
57 /*
58 * For pc-relative instructions in RIL-b or RIL-c format patch
59 * the RI2 displacement field. The insn slot for the to be
60 * patched instruction is within the same 4GB area like the
61 * original instruction. Therefore the new displacement will
62 * always fit.
63 */
64 disp = *(s32 *)&insn[1];
65 addr = (u64)(unsigned long)p->addr;
66 new_addr = (u64)(unsigned long)p->ainsn.insn;
67 new_disp = ((addr + (disp * 2)) - new_addr) / 2;
68 *(s32 *)&insn[1] = new_disp;
69 }
70 s390_kernel_write(p->ainsn.insn, &insn, len);
71}
72NOKPROBE_SYMBOL(copy_instruction);
73
74/* Check if paddr is at an instruction boundary */
75static bool can_probe(unsigned long paddr)
76{
77 unsigned long addr, offset = 0;
78 kprobe_opcode_t insn;
79 struct kprobe *kp;
80
81 if (paddr & 0x01)
82 return false;
83
84 if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))
85 return false;
86
87 /* Decode instructions */
88 addr = paddr - offset;
89 while (addr < paddr) {
90 if (copy_from_kernel_nofault(&insn, (void *)addr, sizeof(insn)))
91 return false;
92
93 if (insn >> 8 == 0) {
94 if (insn != BREAKPOINT_INSTRUCTION) {
95 /*
96 * Note that QEMU inserts opcode 0x0000 to implement
97 * software breakpoints for guests. Since the size of
98 * the original instruction is unknown, stop following
99 * instructions and prevent setting a kprobe.
100 */
101 return false;
102 }
103 /*
104 * Check if the instruction has been modified by another
105 * kprobe, in which case the original instruction is
106 * decoded.
107 */
108 kp = get_kprobe((void *)addr);
109 if (!kp) {
110 /* not a kprobe */
111 return false;
112 }
113 insn = kp->opcode;
114 }
115 addr += insn_length(insn >> 8);
116 }
117 return addr == paddr;
118}
119
120int arch_prepare_kprobe(struct kprobe *p)
121{
122 if (!can_probe((unsigned long)p->addr))
123 return -EINVAL;
124 /* Make sure the probe isn't going on a difficult instruction */
125 if (probe_is_prohibited_opcode(p->addr))
126 return -EINVAL;
127 p->ainsn.insn = get_insn_slot();
128 if (!p->ainsn.insn)
129 return -ENOMEM;
130 copy_instruction(p);
131 return 0;
132}
133NOKPROBE_SYMBOL(arch_prepare_kprobe);
134
135struct swap_insn_args {
136 struct kprobe *p;
137 unsigned int arm_kprobe : 1;
138};
139
140static int swap_instruction(void *data)
141{
142 struct swap_insn_args *args = data;
143 struct kprobe *p = args->p;
144 u16 opc;
145
146 opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;
147 s390_kernel_write(p->addr, &opc, sizeof(opc));
148 return 0;
149}
150NOKPROBE_SYMBOL(swap_instruction);
151
152void arch_arm_kprobe(struct kprobe *p)
153{
154 struct swap_insn_args args = {.p = p, .arm_kprobe = 1};
155
156 if (MACHINE_HAS_SEQ_INSN) {
157 swap_instruction(&args);
158 text_poke_sync();
159 } else {
160 stop_machine_cpuslocked(swap_instruction, &args, NULL);
161 }
162}
163NOKPROBE_SYMBOL(arch_arm_kprobe);
164
165void arch_disarm_kprobe(struct kprobe *p)
166{
167 struct swap_insn_args args = {.p = p, .arm_kprobe = 0};
168
169 if (MACHINE_HAS_SEQ_INSN) {
170 swap_instruction(&args);
171 text_poke_sync();
172 } else {
173 stop_machine_cpuslocked(swap_instruction, &args, NULL);
174 }
175}
176NOKPROBE_SYMBOL(arch_disarm_kprobe);
177
178void arch_remove_kprobe(struct kprobe *p)
179{
180 if (!p->ainsn.insn)
181 return;
182 free_insn_slot(p->ainsn.insn, 0);
183 p->ainsn.insn = NULL;
184}
185NOKPROBE_SYMBOL(arch_remove_kprobe);
186
187static void enable_singlestep(struct kprobe_ctlblk *kcb,
188 struct pt_regs *regs,
189 unsigned long ip)
190{
191 union {
192 struct ctlreg regs[3];
193 struct {
194 struct ctlreg control;
195 struct ctlreg start;
196 struct ctlreg end;
197 };
198 } per_kprobe;
199
200 /* Set up the PER control registers %cr9-%cr11 */
201 per_kprobe.control.val = PER_EVENT_IFETCH;
202 per_kprobe.start.val = ip;
203 per_kprobe.end.val = ip;
204
205 /* Save control regs and psw mask */
206 __local_ctl_store(9, 11, kcb->kprobe_saved_ctl);
207 kcb->kprobe_saved_imask = regs->psw.mask &
208 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
209
210 /* Set PER control regs, turns on single step for the given address */
211 __local_ctl_load(9, 11, per_kprobe.regs);
212 regs->psw.mask |= PSW_MASK_PER;
213 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
214 regs->psw.addr = ip;
215}
216NOKPROBE_SYMBOL(enable_singlestep);
217
218static void disable_singlestep(struct kprobe_ctlblk *kcb,
219 struct pt_regs *regs,
220 unsigned long ip)
221{
222 /* Restore control regs and psw mask, set new psw address */
223 __local_ctl_load(9, 11, kcb->kprobe_saved_ctl);
224 regs->psw.mask &= ~PSW_MASK_PER;
225 regs->psw.mask |= kcb->kprobe_saved_imask;
226 regs->psw.addr = ip;
227}
228NOKPROBE_SYMBOL(disable_singlestep);
229
230/*
231 * Activate a kprobe by storing its pointer to current_kprobe. The
232 * previous kprobe is stored in kcb->prev_kprobe. A stack of up to
233 * two kprobes can be active, see KPROBE_REENTER.
234 */
235static void push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
236{
237 kcb->prev_kprobe.kp = __this_cpu_read(current_kprobe);
238 kcb->prev_kprobe.status = kcb->kprobe_status;
239 __this_cpu_write(current_kprobe, p);
240}
241NOKPROBE_SYMBOL(push_kprobe);
242
243/*
244 * Deactivate a kprobe by backing up to the previous state. If the
245 * current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL,
246 * for any other state prev_kprobe.kp will be NULL.
247 */
248static void pop_kprobe(struct kprobe_ctlblk *kcb)
249{
250 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
251 kcb->kprobe_status = kcb->prev_kprobe.status;
252 kcb->prev_kprobe.kp = NULL;
253}
254NOKPROBE_SYMBOL(pop_kprobe);
255
256static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
257{
258 switch (kcb->kprobe_status) {
259 case KPROBE_HIT_SSDONE:
260 case KPROBE_HIT_ACTIVE:
261 kprobes_inc_nmissed_count(p);
262 break;
263 case KPROBE_HIT_SS:
264 case KPROBE_REENTER:
265 default:
266 /*
267 * A kprobe on the code path to single step an instruction
268 * is a BUG. The code path resides in the .kprobes.text
269 * section and is executed with interrupts disabled.
270 */
271 pr_err("Failed to recover from reentered kprobes.\n");
272 dump_kprobe(p);
273 BUG();
274 }
275}
276NOKPROBE_SYMBOL(kprobe_reenter_check);
277
278static int kprobe_handler(struct pt_regs *regs)
279{
280 struct kprobe_ctlblk *kcb;
281 struct kprobe *p;
282
283 /*
284 * We want to disable preemption for the entire duration of kprobe
285 * processing. That includes the calls to the pre/post handlers
286 * and single stepping the kprobe instruction.
287 */
288 preempt_disable();
289 kcb = get_kprobe_ctlblk();
290 p = get_kprobe((void *)(regs->psw.addr - 2));
291
292 if (p) {
293 if (kprobe_running()) {
294 /*
295 * We have hit a kprobe while another is still
296 * active. This can happen in the pre and post
297 * handler. Single step the instruction of the
298 * new probe but do not call any handler function
299 * of this secondary kprobe.
300 * push_kprobe and pop_kprobe saves and restores
301 * the currently active kprobe.
302 */
303 kprobe_reenter_check(kcb, p);
304 push_kprobe(kcb, p);
305 kcb->kprobe_status = KPROBE_REENTER;
306 } else {
307 /*
308 * If we have no pre-handler or it returned 0, we
309 * continue with single stepping. If we have a
310 * pre-handler and it returned non-zero, it prepped
311 * for changing execution path, so get out doing
312 * nothing more here.
313 */
314 push_kprobe(kcb, p);
315 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
316 if (p->pre_handler && p->pre_handler(p, regs)) {
317 pop_kprobe(kcb);
318 preempt_enable_no_resched();
319 return 1;
320 }
321 kcb->kprobe_status = KPROBE_HIT_SS;
322 }
323 enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
324 return 1;
325 } /* else:
326 * No kprobe at this address and no active kprobe. The trap has
327 * not been caused by a kprobe breakpoint. The race of breakpoint
328 * vs. kprobe remove does not exist because on s390 as we use
329 * stop_machine to arm/disarm the breakpoints.
330 */
331 preempt_enable_no_resched();
332 return 0;
333}
334NOKPROBE_SYMBOL(kprobe_handler);
335
336/*
337 * Called after single-stepping. p->addr is the address of the
338 * instruction whose first byte has been replaced by the "breakpoint"
339 * instruction. To avoid the SMP problems that can occur when we
340 * temporarily put back the original opcode to single-step, we
341 * single-stepped a copy of the instruction. The address of this
342 * copy is p->ainsn.insn.
343 */
344static void resume_execution(struct kprobe *p, struct pt_regs *regs)
345{
346 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
347 unsigned long ip = regs->psw.addr;
348 int fixup = probe_get_fixup_type(p->ainsn.insn);
349
350 if (fixup & FIXUP_PSW_NORMAL)
351 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
352
353 if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
354 int ilen = insn_length(p->ainsn.insn[0] >> 8);
355 if (ip - (unsigned long) p->ainsn.insn == ilen)
356 ip = (unsigned long) p->addr + ilen;
357 }
358
359 if (fixup & FIXUP_RETURN_REGISTER) {
360 int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
361 regs->gprs[reg] += (unsigned long) p->addr -
362 (unsigned long) p->ainsn.insn;
363 }
364
365 disable_singlestep(kcb, regs, ip);
366}
367NOKPROBE_SYMBOL(resume_execution);
368
369static int post_kprobe_handler(struct pt_regs *regs)
370{
371 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
372 struct kprobe *p = kprobe_running();
373
374 if (!p)
375 return 0;
376
377 resume_execution(p, regs);
378 if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) {
379 kcb->kprobe_status = KPROBE_HIT_SSDONE;
380 p->post_handler(p, regs, 0);
381 }
382 pop_kprobe(kcb);
383 preempt_enable_no_resched();
384
385 /*
386 * if somebody else is singlestepping across a probe point, psw mask
387 * will have PER set, in which case, continue the remaining processing
388 * of do_single_step, as if this is not a probe hit.
389 */
390 if (regs->psw.mask & PSW_MASK_PER)
391 return 0;
392
393 return 1;
394}
395NOKPROBE_SYMBOL(post_kprobe_handler);
396
397static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
398{
399 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
400 struct kprobe *p = kprobe_running();
401
402 switch(kcb->kprobe_status) {
403 case KPROBE_HIT_SS:
404 case KPROBE_REENTER:
405 /*
406 * We are here because the instruction being single
407 * stepped caused a page fault. We reset the current
408 * kprobe and the nip points back to the probe address
409 * and allow the page fault handler to continue as a
410 * normal page fault.
411 */
412 disable_singlestep(kcb, regs, (unsigned long) p->addr);
413 pop_kprobe(kcb);
414 preempt_enable_no_resched();
415 break;
416 case KPROBE_HIT_ACTIVE:
417 case KPROBE_HIT_SSDONE:
418 /*
419 * In case the user-specified fault handler returned
420 * zero, try to fix up.
421 */
422 if (fixup_exception(regs))
423 return 1;
424 /*
425 * fixup_exception() could not handle it,
426 * Let do_page_fault() fix it.
427 */
428 break;
429 default:
430 break;
431 }
432 return 0;
433}
434NOKPROBE_SYMBOL(kprobe_trap_handler);
435
436int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
437{
438 int ret;
439
440 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
441 local_irq_disable();
442 ret = kprobe_trap_handler(regs, trapnr);
443 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
444 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
445 return ret;
446}
447NOKPROBE_SYMBOL(kprobe_fault_handler);
448
449/*
450 * Wrapper routine to for handling exceptions.
451 */
452int kprobe_exceptions_notify(struct notifier_block *self,
453 unsigned long val, void *data)
454{
455 struct die_args *args = (struct die_args *) data;
456 struct pt_regs *regs = args->regs;
457 int ret = NOTIFY_DONE;
458
459 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
460 local_irq_disable();
461
462 switch (val) {
463 case DIE_BPT:
464 if (kprobe_handler(regs))
465 ret = NOTIFY_STOP;
466 break;
467 case DIE_SSTEP:
468 if (post_kprobe_handler(regs))
469 ret = NOTIFY_STOP;
470 break;
471 case DIE_TRAP:
472 if (!preemptible() && kprobe_running() &&
473 kprobe_trap_handler(regs, args->trapnr))
474 ret = NOTIFY_STOP;
475 break;
476 default:
477 break;
478 }
479
480 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
481 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
482
483 return ret;
484}
485NOKPROBE_SYMBOL(kprobe_exceptions_notify);
486
487int __init arch_init_kprobes(void)
488{
489 return 0;
490}
491
492int __init arch_populate_kprobe_blacklist(void)
493{
494 return kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
495 (unsigned long)__irqentry_text_end);
496}
497
498int arch_trampoline_kprobe(struct kprobe *p)
499{
500 return 0;
501}
502NOKPROBE_SYMBOL(arch_trampoline_kprobe);
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Kernel Probes (KProbes)
4 *
5 * Copyright IBM Corp. 2002, 2006
6 *
7 * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
8 */
9
10#define pr_fmt(fmt) "kprobes: " fmt
11
12#include <linux/moduleloader.h>
13#include <linux/kprobes.h>
14#include <linux/ptrace.h>
15#include <linux/preempt.h>
16#include <linux/stop_machine.h>
17#include <linux/kdebug.h>
18#include <linux/uaccess.h>
19#include <linux/extable.h>
20#include <linux/module.h>
21#include <linux/slab.h>
22#include <linux/hardirq.h>
23#include <linux/ftrace.h>
24#include <asm/set_memory.h>
25#include <asm/sections.h>
26#include <asm/dis.h>
27#include "kprobes.h"
28#include "entry.h"
29
30DEFINE_PER_CPU(struct kprobe *, current_kprobe);
31DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
32
33struct kretprobe_blackpoint kretprobe_blacklist[] = { };
34
35static int insn_page_in_use;
36
37void *alloc_insn_page(void)
38{
39 void *page;
40
41 page = module_alloc(PAGE_SIZE);
42 if (!page)
43 return NULL;
44 __set_memory((unsigned long) page, 1, SET_MEMORY_RO | SET_MEMORY_X);
45 return page;
46}
47
48static void *alloc_s390_insn_page(void)
49{
50 if (xchg(&insn_page_in_use, 1) == 1)
51 return NULL;
52 return &kprobes_insn_page;
53}
54
55static void free_s390_insn_page(void *page)
56{
57 xchg(&insn_page_in_use, 0);
58}
59
60struct kprobe_insn_cache kprobe_s390_insn_slots = {
61 .mutex = __MUTEX_INITIALIZER(kprobe_s390_insn_slots.mutex),
62 .alloc = alloc_s390_insn_page,
63 .free = free_s390_insn_page,
64 .pages = LIST_HEAD_INIT(kprobe_s390_insn_slots.pages),
65 .insn_size = MAX_INSN_SIZE,
66};
67
68static void copy_instruction(struct kprobe *p)
69{
70 kprobe_opcode_t insn[MAX_INSN_SIZE];
71 s64 disp, new_disp;
72 u64 addr, new_addr;
73 unsigned int len;
74
75 len = insn_length(*p->addr >> 8);
76 memcpy(&insn, p->addr, len);
77 p->opcode = insn[0];
78 if (probe_is_insn_relative_long(&insn[0])) {
79 /*
80 * For pc-relative instructions in RIL-b or RIL-c format patch
81 * the RI2 displacement field. We have already made sure that
82 * the insn slot for the patched instruction is within the same
83 * 2GB area as the original instruction (either kernel image or
84 * module area). Therefore the new displacement will always fit.
85 */
86 disp = *(s32 *)&insn[1];
87 addr = (u64)(unsigned long)p->addr;
88 new_addr = (u64)(unsigned long)p->ainsn.insn;
89 new_disp = ((addr + (disp * 2)) - new_addr) / 2;
90 *(s32 *)&insn[1] = new_disp;
91 }
92 s390_kernel_write(p->ainsn.insn, &insn, len);
93}
94NOKPROBE_SYMBOL(copy_instruction);
95
96static int s390_get_insn_slot(struct kprobe *p)
97{
98 /*
99 * Get an insn slot that is within the same 2GB area like the original
100 * instruction. That way instructions with a 32bit signed displacement
101 * field can be patched and executed within the insn slot.
102 */
103 p->ainsn.insn = NULL;
104 if (is_kernel((unsigned long)p->addr))
105 p->ainsn.insn = get_s390_insn_slot();
106 else if (is_module_addr(p->addr))
107 p->ainsn.insn = get_insn_slot();
108 return p->ainsn.insn ? 0 : -ENOMEM;
109}
110NOKPROBE_SYMBOL(s390_get_insn_slot);
111
112static void s390_free_insn_slot(struct kprobe *p)
113{
114 if (!p->ainsn.insn)
115 return;
116 if (is_kernel((unsigned long)p->addr))
117 free_s390_insn_slot(p->ainsn.insn, 0);
118 else
119 free_insn_slot(p->ainsn.insn, 0);
120 p->ainsn.insn = NULL;
121}
122NOKPROBE_SYMBOL(s390_free_insn_slot);
123
124/* Check if paddr is at an instruction boundary */
125static bool can_probe(unsigned long paddr)
126{
127 unsigned long addr, offset = 0;
128 kprobe_opcode_t insn;
129 struct kprobe *kp;
130
131 if (paddr & 0x01)
132 return false;
133
134 if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))
135 return false;
136
137 /* Decode instructions */
138 addr = paddr - offset;
139 while (addr < paddr) {
140 if (copy_from_kernel_nofault(&insn, (void *)addr, sizeof(insn)))
141 return false;
142
143 if (insn >> 8 == 0) {
144 if (insn != BREAKPOINT_INSTRUCTION) {
145 /*
146 * Note that QEMU inserts opcode 0x0000 to implement
147 * software breakpoints for guests. Since the size of
148 * the original instruction is unknown, stop following
149 * instructions and prevent setting a kprobe.
150 */
151 return false;
152 }
153 /*
154 * Check if the instruction has been modified by another
155 * kprobe, in which case the original instruction is
156 * decoded.
157 */
158 kp = get_kprobe((void *)addr);
159 if (!kp) {
160 /* not a kprobe */
161 return false;
162 }
163 insn = kp->opcode;
164 }
165 addr += insn_length(insn >> 8);
166 }
167 return addr == paddr;
168}
169
170int arch_prepare_kprobe(struct kprobe *p)
171{
172 if (!can_probe((unsigned long)p->addr))
173 return -EINVAL;
174 /* Make sure the probe isn't going on a difficult instruction */
175 if (probe_is_prohibited_opcode(p->addr))
176 return -EINVAL;
177 if (s390_get_insn_slot(p))
178 return -ENOMEM;
179 copy_instruction(p);
180 return 0;
181}
182NOKPROBE_SYMBOL(arch_prepare_kprobe);
183
184struct swap_insn_args {
185 struct kprobe *p;
186 unsigned int arm_kprobe : 1;
187};
188
189static int swap_instruction(void *data)
190{
191 struct swap_insn_args *args = data;
192 struct kprobe *p = args->p;
193 u16 opc;
194
195 opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;
196 s390_kernel_write(p->addr, &opc, sizeof(opc));
197 return 0;
198}
199NOKPROBE_SYMBOL(swap_instruction);
200
201void arch_arm_kprobe(struct kprobe *p)
202{
203 struct swap_insn_args args = {.p = p, .arm_kprobe = 1};
204
205 stop_machine_cpuslocked(swap_instruction, &args, NULL);
206}
207NOKPROBE_SYMBOL(arch_arm_kprobe);
208
209void arch_disarm_kprobe(struct kprobe *p)
210{
211 struct swap_insn_args args = {.p = p, .arm_kprobe = 0};
212
213 stop_machine_cpuslocked(swap_instruction, &args, NULL);
214}
215NOKPROBE_SYMBOL(arch_disarm_kprobe);
216
217void arch_remove_kprobe(struct kprobe *p)
218{
219 s390_free_insn_slot(p);
220}
221NOKPROBE_SYMBOL(arch_remove_kprobe);
222
223static void enable_singlestep(struct kprobe_ctlblk *kcb,
224 struct pt_regs *regs,
225 unsigned long ip)
226{
227 struct per_regs per_kprobe;
228
229 /* Set up the PER control registers %cr9-%cr11 */
230 per_kprobe.control = PER_EVENT_IFETCH;
231 per_kprobe.start = ip;
232 per_kprobe.end = ip;
233
234 /* Save control regs and psw mask */
235 __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
236 kcb->kprobe_saved_imask = regs->psw.mask &
237 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
238
239 /* Set PER control regs, turns on single step for the given address */
240 __ctl_load(per_kprobe, 9, 11);
241 regs->psw.mask |= PSW_MASK_PER;
242 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
243 regs->psw.addr = ip;
244}
245NOKPROBE_SYMBOL(enable_singlestep);
246
247static void disable_singlestep(struct kprobe_ctlblk *kcb,
248 struct pt_regs *regs,
249 unsigned long ip)
250{
251 /* Restore control regs and psw mask, set new psw address */
252 __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
253 regs->psw.mask &= ~PSW_MASK_PER;
254 regs->psw.mask |= kcb->kprobe_saved_imask;
255 regs->psw.addr = ip;
256}
257NOKPROBE_SYMBOL(disable_singlestep);
258
259/*
260 * Activate a kprobe by storing its pointer to current_kprobe. The
261 * previous kprobe is stored in kcb->prev_kprobe. A stack of up to
262 * two kprobes can be active, see KPROBE_REENTER.
263 */
264static void push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
265{
266 kcb->prev_kprobe.kp = __this_cpu_read(current_kprobe);
267 kcb->prev_kprobe.status = kcb->kprobe_status;
268 __this_cpu_write(current_kprobe, p);
269}
270NOKPROBE_SYMBOL(push_kprobe);
271
272/*
273 * Deactivate a kprobe by backing up to the previous state. If the
274 * current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL,
275 * for any other state prev_kprobe.kp will be NULL.
276 */
277static void pop_kprobe(struct kprobe_ctlblk *kcb)
278{
279 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
280 kcb->kprobe_status = kcb->prev_kprobe.status;
281}
282NOKPROBE_SYMBOL(pop_kprobe);
283
284void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
285{
286 ri->ret_addr = (kprobe_opcode_t *)regs->gprs[14];
287 ri->fp = (void *)regs->gprs[15];
288
289 /* Replace the return addr with trampoline addr */
290 regs->gprs[14] = (unsigned long)&__kretprobe_trampoline;
291}
292NOKPROBE_SYMBOL(arch_prepare_kretprobe);
293
294static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
295{
296 switch (kcb->kprobe_status) {
297 case KPROBE_HIT_SSDONE:
298 case KPROBE_HIT_ACTIVE:
299 kprobes_inc_nmissed_count(p);
300 break;
301 case KPROBE_HIT_SS:
302 case KPROBE_REENTER:
303 default:
304 /*
305 * A kprobe on the code path to single step an instruction
306 * is a BUG. The code path resides in the .kprobes.text
307 * section and is executed with interrupts disabled.
308 */
309 pr_err("Failed to recover from reentered kprobes.\n");
310 dump_kprobe(p);
311 BUG();
312 }
313}
314NOKPROBE_SYMBOL(kprobe_reenter_check);
315
316static int kprobe_handler(struct pt_regs *regs)
317{
318 struct kprobe_ctlblk *kcb;
319 struct kprobe *p;
320
321 /*
322 * We want to disable preemption for the entire duration of kprobe
323 * processing. That includes the calls to the pre/post handlers
324 * and single stepping the kprobe instruction.
325 */
326 preempt_disable();
327 kcb = get_kprobe_ctlblk();
328 p = get_kprobe((void *)(regs->psw.addr - 2));
329
330 if (p) {
331 if (kprobe_running()) {
332 /*
333 * We have hit a kprobe while another is still
334 * active. This can happen in the pre and post
335 * handler. Single step the instruction of the
336 * new probe but do not call any handler function
337 * of this secondary kprobe.
338 * push_kprobe and pop_kprobe saves and restores
339 * the currently active kprobe.
340 */
341 kprobe_reenter_check(kcb, p);
342 push_kprobe(kcb, p);
343 kcb->kprobe_status = KPROBE_REENTER;
344 } else {
345 /*
346 * If we have no pre-handler or it returned 0, we
347 * continue with single stepping. If we have a
348 * pre-handler and it returned non-zero, it prepped
349 * for changing execution path, so get out doing
350 * nothing more here.
351 */
352 push_kprobe(kcb, p);
353 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
354 if (p->pre_handler && p->pre_handler(p, regs)) {
355 pop_kprobe(kcb);
356 preempt_enable_no_resched();
357 return 1;
358 }
359 kcb->kprobe_status = KPROBE_HIT_SS;
360 }
361 enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
362 return 1;
363 } /* else:
364 * No kprobe at this address and no active kprobe. The trap has
365 * not been caused by a kprobe breakpoint. The race of breakpoint
366 * vs. kprobe remove does not exist because on s390 as we use
367 * stop_machine to arm/disarm the breakpoints.
368 */
369 preempt_enable_no_resched();
370 return 0;
371}
372NOKPROBE_SYMBOL(kprobe_handler);
373
374void arch_kretprobe_fixup_return(struct pt_regs *regs,
375 kprobe_opcode_t *correct_ret_addr)
376{
377 /* Replace fake return address with real one. */
378 regs->gprs[14] = (unsigned long)correct_ret_addr;
379}
380NOKPROBE_SYMBOL(arch_kretprobe_fixup_return);
381
382/*
383 * Called from __kretprobe_trampoline
384 */
385void trampoline_probe_handler(struct pt_regs *regs)
386{
387 kretprobe_trampoline_handler(regs, (void *)regs->gprs[15]);
388}
389NOKPROBE_SYMBOL(trampoline_probe_handler);
390
391/* assembler function that handles the kretprobes must not be probed itself */
392NOKPROBE_SYMBOL(__kretprobe_trampoline);
393
394/*
395 * Called after single-stepping. p->addr is the address of the
396 * instruction whose first byte has been replaced by the "breakpoint"
397 * instruction. To avoid the SMP problems that can occur when we
398 * temporarily put back the original opcode to single-step, we
399 * single-stepped a copy of the instruction. The address of this
400 * copy is p->ainsn.insn.
401 */
402static void resume_execution(struct kprobe *p, struct pt_regs *regs)
403{
404 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
405 unsigned long ip = regs->psw.addr;
406 int fixup = probe_get_fixup_type(p->ainsn.insn);
407
408 if (fixup & FIXUP_PSW_NORMAL)
409 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
410
411 if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
412 int ilen = insn_length(p->ainsn.insn[0] >> 8);
413 if (ip - (unsigned long) p->ainsn.insn == ilen)
414 ip = (unsigned long) p->addr + ilen;
415 }
416
417 if (fixup & FIXUP_RETURN_REGISTER) {
418 int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
419 regs->gprs[reg] += (unsigned long) p->addr -
420 (unsigned long) p->ainsn.insn;
421 }
422
423 disable_singlestep(kcb, regs, ip);
424}
425NOKPROBE_SYMBOL(resume_execution);
426
427static int post_kprobe_handler(struct pt_regs *regs)
428{
429 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
430 struct kprobe *p = kprobe_running();
431
432 if (!p)
433 return 0;
434
435 if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) {
436 kcb->kprobe_status = KPROBE_HIT_SSDONE;
437 p->post_handler(p, regs, 0);
438 }
439
440 resume_execution(p, regs);
441 pop_kprobe(kcb);
442 preempt_enable_no_resched();
443
444 /*
445 * if somebody else is singlestepping across a probe point, psw mask
446 * will have PER set, in which case, continue the remaining processing
447 * of do_single_step, as if this is not a probe hit.
448 */
449 if (regs->psw.mask & PSW_MASK_PER)
450 return 0;
451
452 return 1;
453}
454NOKPROBE_SYMBOL(post_kprobe_handler);
455
456static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
457{
458 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
459 struct kprobe *p = kprobe_running();
460
461 switch(kcb->kprobe_status) {
462 case KPROBE_HIT_SS:
463 case KPROBE_REENTER:
464 /*
465 * We are here because the instruction being single
466 * stepped caused a page fault. We reset the current
467 * kprobe and the nip points back to the probe address
468 * and allow the page fault handler to continue as a
469 * normal page fault.
470 */
471 disable_singlestep(kcb, regs, (unsigned long) p->addr);
472 pop_kprobe(kcb);
473 preempt_enable_no_resched();
474 break;
475 case KPROBE_HIT_ACTIVE:
476 case KPROBE_HIT_SSDONE:
477 /*
478 * In case the user-specified fault handler returned
479 * zero, try to fix up.
480 */
481 if (fixup_exception(regs))
482 return 1;
483 /*
484 * fixup_exception() could not handle it,
485 * Let do_page_fault() fix it.
486 */
487 break;
488 default:
489 break;
490 }
491 return 0;
492}
493NOKPROBE_SYMBOL(kprobe_trap_handler);
494
495int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
496{
497 int ret;
498
499 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
500 local_irq_disable();
501 ret = kprobe_trap_handler(regs, trapnr);
502 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
503 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
504 return ret;
505}
506NOKPROBE_SYMBOL(kprobe_fault_handler);
507
508/*
509 * Wrapper routine to for handling exceptions.
510 */
511int kprobe_exceptions_notify(struct notifier_block *self,
512 unsigned long val, void *data)
513{
514 struct die_args *args = (struct die_args *) data;
515 struct pt_regs *regs = args->regs;
516 int ret = NOTIFY_DONE;
517
518 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
519 local_irq_disable();
520
521 switch (val) {
522 case DIE_BPT:
523 if (kprobe_handler(regs))
524 ret = NOTIFY_STOP;
525 break;
526 case DIE_SSTEP:
527 if (post_kprobe_handler(regs))
528 ret = NOTIFY_STOP;
529 break;
530 case DIE_TRAP:
531 if (!preemptible() && kprobe_running() &&
532 kprobe_trap_handler(regs, args->trapnr))
533 ret = NOTIFY_STOP;
534 break;
535 default:
536 break;
537 }
538
539 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
540 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
541
542 return ret;
543}
544NOKPROBE_SYMBOL(kprobe_exceptions_notify);
545
546int __init arch_init_kprobes(void)
547{
548 return 0;
549}
550
551int arch_trampoline_kprobe(struct kprobe *p)
552{
553 return 0;
554}
555NOKPROBE_SYMBOL(arch_trampoline_kprobe);