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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/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);
1/*
2 * Kernel Probes (KProbes)
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright IBM Corp. 2002, 2006
19 *
20 * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
21 */
22
23#include <linux/kprobes.h>
24#include <linux/ptrace.h>
25#include <linux/preempt.h>
26#include <linux/stop_machine.h>
27#include <linux/kdebug.h>
28#include <linux/uaccess.h>
29#include <linux/module.h>
30#include <linux/slab.h>
31#include <linux/hardirq.h>
32#include <asm/cacheflush.h>
33#include <asm/sections.h>
34#include <asm/dis.h>
35
36DEFINE_PER_CPU(struct kprobe *, current_kprobe);
37DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
38
39struct kretprobe_blackpoint kretprobe_blacklist[] = { };
40
41DEFINE_INSN_CACHE_OPS(dmainsn);
42
43static void *alloc_dmainsn_page(void)
44{
45 return (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
46}
47
48static void free_dmainsn_page(void *page)
49{
50 free_page((unsigned long)page);
51}
52
53struct kprobe_insn_cache kprobe_dmainsn_slots = {
54 .mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex),
55 .alloc = alloc_dmainsn_page,
56 .free = free_dmainsn_page,
57 .pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages),
58 .insn_size = MAX_INSN_SIZE,
59};
60
61static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)
62{
63 if (!is_known_insn((unsigned char *)insn))
64 return -EINVAL;
65 switch (insn[0] >> 8) {
66 case 0x0c: /* bassm */
67 case 0x0b: /* bsm */
68 case 0x83: /* diag */
69 case 0x44: /* ex */
70 case 0xac: /* stnsm */
71 case 0xad: /* stosm */
72 return -EINVAL;
73 case 0xc6:
74 switch (insn[0] & 0x0f) {
75 case 0x00: /* exrl */
76 return -EINVAL;
77 }
78 }
79 switch (insn[0]) {
80 case 0x0101: /* pr */
81 case 0xb25a: /* bsa */
82 case 0xb240: /* bakr */
83 case 0xb258: /* bsg */
84 case 0xb218: /* pc */
85 case 0xb228: /* pt */
86 case 0xb98d: /* epsw */
87 return -EINVAL;
88 }
89 return 0;
90}
91
92static int __kprobes get_fixup_type(kprobe_opcode_t *insn)
93{
94 /* default fixup method */
95 int fixup = FIXUP_PSW_NORMAL;
96
97 switch (insn[0] >> 8) {
98 case 0x05: /* balr */
99 case 0x0d: /* basr */
100 fixup = FIXUP_RETURN_REGISTER;
101 /* if r2 = 0, no branch will be taken */
102 if ((insn[0] & 0x0f) == 0)
103 fixup |= FIXUP_BRANCH_NOT_TAKEN;
104 break;
105 case 0x06: /* bctr */
106 case 0x07: /* bcr */
107 fixup = FIXUP_BRANCH_NOT_TAKEN;
108 break;
109 case 0x45: /* bal */
110 case 0x4d: /* bas */
111 fixup = FIXUP_RETURN_REGISTER;
112 break;
113 case 0x47: /* bc */
114 case 0x46: /* bct */
115 case 0x86: /* bxh */
116 case 0x87: /* bxle */
117 fixup = FIXUP_BRANCH_NOT_TAKEN;
118 break;
119 case 0x82: /* lpsw */
120 fixup = FIXUP_NOT_REQUIRED;
121 break;
122 case 0xb2: /* lpswe */
123 if ((insn[0] & 0xff) == 0xb2)
124 fixup = FIXUP_NOT_REQUIRED;
125 break;
126 case 0xa7: /* bras */
127 if ((insn[0] & 0x0f) == 0x05)
128 fixup |= FIXUP_RETURN_REGISTER;
129 break;
130 case 0xc0:
131 if ((insn[0] & 0x0f) == 0x05) /* brasl */
132 fixup |= FIXUP_RETURN_REGISTER;
133 break;
134 case 0xeb:
135 switch (insn[2] & 0xff) {
136 case 0x44: /* bxhg */
137 case 0x45: /* bxleg */
138 fixup = FIXUP_BRANCH_NOT_TAKEN;
139 break;
140 }
141 break;
142 case 0xe3: /* bctg */
143 if ((insn[2] & 0xff) == 0x46)
144 fixup = FIXUP_BRANCH_NOT_TAKEN;
145 break;
146 case 0xec:
147 switch (insn[2] & 0xff) {
148 case 0xe5: /* clgrb */
149 case 0xe6: /* cgrb */
150 case 0xf6: /* crb */
151 case 0xf7: /* clrb */
152 case 0xfc: /* cgib */
153 case 0xfd: /* cglib */
154 case 0xfe: /* cib */
155 case 0xff: /* clib */
156 fixup = FIXUP_BRANCH_NOT_TAKEN;
157 break;
158 }
159 break;
160 }
161 return fixup;
162}
163
164static int __kprobes is_insn_relative_long(kprobe_opcode_t *insn)
165{
166 /* Check if we have a RIL-b or RIL-c format instruction which
167 * we need to modify in order to avoid instruction emulation. */
168 switch (insn[0] >> 8) {
169 case 0xc0:
170 if ((insn[0] & 0x0f) == 0x00) /* larl */
171 return true;
172 break;
173 case 0xc4:
174 switch (insn[0] & 0x0f) {
175 case 0x02: /* llhrl */
176 case 0x04: /* lghrl */
177 case 0x05: /* lhrl */
178 case 0x06: /* llghrl */
179 case 0x07: /* sthrl */
180 case 0x08: /* lgrl */
181 case 0x0b: /* stgrl */
182 case 0x0c: /* lgfrl */
183 case 0x0d: /* lrl */
184 case 0x0e: /* llgfrl */
185 case 0x0f: /* strl */
186 return true;
187 }
188 break;
189 case 0xc6:
190 switch (insn[0] & 0x0f) {
191 case 0x02: /* pfdrl */
192 case 0x04: /* cghrl */
193 case 0x05: /* chrl */
194 case 0x06: /* clghrl */
195 case 0x07: /* clhrl */
196 case 0x08: /* cgrl */
197 case 0x0a: /* clgrl */
198 case 0x0c: /* cgfrl */
199 case 0x0d: /* crl */
200 case 0x0e: /* clgfrl */
201 case 0x0f: /* clrl */
202 return true;
203 }
204 break;
205 }
206 return false;
207}
208
209static void __kprobes copy_instruction(struct kprobe *p)
210{
211 s64 disp, new_disp;
212 u64 addr, new_addr;
213
214 memcpy(p->ainsn.insn, p->addr, insn_length(p->opcode >> 8));
215 if (!is_insn_relative_long(p->ainsn.insn))
216 return;
217 /*
218 * For pc-relative instructions in RIL-b or RIL-c format patch the
219 * RI2 displacement field. We have already made sure that the insn
220 * slot for the patched instruction is within the same 2GB area
221 * as the original instruction (either kernel image or module area).
222 * Therefore the new displacement will always fit.
223 */
224 disp = *(s32 *)&p->ainsn.insn[1];
225 addr = (u64)(unsigned long)p->addr;
226 new_addr = (u64)(unsigned long)p->ainsn.insn;
227 new_disp = ((addr + (disp * 2)) - new_addr) / 2;
228 *(s32 *)&p->ainsn.insn[1] = new_disp;
229}
230
231static inline int is_kernel_addr(void *addr)
232{
233 return addr < (void *)_end;
234}
235
236static inline int is_module_addr(void *addr)
237{
238#ifdef CONFIG_64BIT
239 BUILD_BUG_ON(MODULES_LEN > (1UL << 31));
240 if (addr < (void *)MODULES_VADDR)
241 return 0;
242 if (addr > (void *)MODULES_END)
243 return 0;
244#endif
245 return 1;
246}
247
248static int __kprobes s390_get_insn_slot(struct kprobe *p)
249{
250 /*
251 * Get an insn slot that is within the same 2GB area like the original
252 * instruction. That way instructions with a 32bit signed displacement
253 * field can be patched and executed within the insn slot.
254 */
255 p->ainsn.insn = NULL;
256 if (is_kernel_addr(p->addr))
257 p->ainsn.insn = get_dmainsn_slot();
258 else if (is_module_addr(p->addr))
259 p->ainsn.insn = get_insn_slot();
260 return p->ainsn.insn ? 0 : -ENOMEM;
261}
262
263static void __kprobes s390_free_insn_slot(struct kprobe *p)
264{
265 if (!p->ainsn.insn)
266 return;
267 if (is_kernel_addr(p->addr))
268 free_dmainsn_slot(p->ainsn.insn, 0);
269 else
270 free_insn_slot(p->ainsn.insn, 0);
271 p->ainsn.insn = NULL;
272}
273
274int __kprobes arch_prepare_kprobe(struct kprobe *p)
275{
276 if ((unsigned long) p->addr & 0x01)
277 return -EINVAL;
278 /* Make sure the probe isn't going on a difficult instruction */
279 if (is_prohibited_opcode(p->addr))
280 return -EINVAL;
281 if (s390_get_insn_slot(p))
282 return -ENOMEM;
283 p->opcode = *p->addr;
284 copy_instruction(p);
285 return 0;
286}
287
288struct ins_replace_args {
289 kprobe_opcode_t *ptr;
290 kprobe_opcode_t opcode;
291};
292
293static int __kprobes swap_instruction(void *aref)
294{
295 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
296 unsigned long status = kcb->kprobe_status;
297 struct ins_replace_args *args = aref;
298
299 kcb->kprobe_status = KPROBE_SWAP_INST;
300 probe_kernel_write(args->ptr, &args->opcode, sizeof(args->opcode));
301 kcb->kprobe_status = status;
302 return 0;
303}
304
305void __kprobes arch_arm_kprobe(struct kprobe *p)
306{
307 struct ins_replace_args args;
308
309 args.ptr = p->addr;
310 args.opcode = BREAKPOINT_INSTRUCTION;
311 stop_machine(swap_instruction, &args, NULL);
312}
313
314void __kprobes arch_disarm_kprobe(struct kprobe *p)
315{
316 struct ins_replace_args args;
317
318 args.ptr = p->addr;
319 args.opcode = p->opcode;
320 stop_machine(swap_instruction, &args, NULL);
321}
322
323void __kprobes arch_remove_kprobe(struct kprobe *p)
324{
325 s390_free_insn_slot(p);
326}
327
328static void __kprobes enable_singlestep(struct kprobe_ctlblk *kcb,
329 struct pt_regs *regs,
330 unsigned long ip)
331{
332 struct per_regs per_kprobe;
333
334 /* Set up the PER control registers %cr9-%cr11 */
335 per_kprobe.control = PER_EVENT_IFETCH;
336 per_kprobe.start = ip;
337 per_kprobe.end = ip;
338
339 /* Save control regs and psw mask */
340 __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
341 kcb->kprobe_saved_imask = regs->psw.mask &
342 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
343
344 /* Set PER control regs, turns on single step for the given address */
345 __ctl_load(per_kprobe, 9, 11);
346 regs->psw.mask |= PSW_MASK_PER;
347 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
348 regs->psw.addr = ip | PSW_ADDR_AMODE;
349}
350
351static void __kprobes disable_singlestep(struct kprobe_ctlblk *kcb,
352 struct pt_regs *regs,
353 unsigned long ip)
354{
355 /* Restore control regs and psw mask, set new psw address */
356 __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
357 regs->psw.mask &= ~PSW_MASK_PER;
358 regs->psw.mask |= kcb->kprobe_saved_imask;
359 regs->psw.addr = ip | PSW_ADDR_AMODE;
360}
361
362/*
363 * Activate a kprobe by storing its pointer to current_kprobe. The
364 * previous kprobe is stored in kcb->prev_kprobe. A stack of up to
365 * two kprobes can be active, see KPROBE_REENTER.
366 */
367static void __kprobes push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
368{
369 kcb->prev_kprobe.kp = __get_cpu_var(current_kprobe);
370 kcb->prev_kprobe.status = kcb->kprobe_status;
371 __get_cpu_var(current_kprobe) = p;
372}
373
374/*
375 * Deactivate a kprobe by backing up to the previous state. If the
376 * current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL,
377 * for any other state prev_kprobe.kp will be NULL.
378 */
379static void __kprobes pop_kprobe(struct kprobe_ctlblk *kcb)
380{
381 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
382 kcb->kprobe_status = kcb->prev_kprobe.status;
383}
384
385void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
386 struct pt_regs *regs)
387{
388 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
389
390 /* Replace the return addr with trampoline addr */
391 regs->gprs[14] = (unsigned long) &kretprobe_trampoline;
392}
393
394static void __kprobes kprobe_reenter_check(struct kprobe_ctlblk *kcb,
395 struct kprobe *p)
396{
397 switch (kcb->kprobe_status) {
398 case KPROBE_HIT_SSDONE:
399 case KPROBE_HIT_ACTIVE:
400 kprobes_inc_nmissed_count(p);
401 break;
402 case KPROBE_HIT_SS:
403 case KPROBE_REENTER:
404 default:
405 /*
406 * A kprobe on the code path to single step an instruction
407 * is a BUG. The code path resides in the .kprobes.text
408 * section and is executed with interrupts disabled.
409 */
410 printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr);
411 dump_kprobe(p);
412 BUG();
413 }
414}
415
416static int __kprobes kprobe_handler(struct pt_regs *regs)
417{
418 struct kprobe_ctlblk *kcb;
419 struct kprobe *p;
420
421 /*
422 * We want to disable preemption for the entire duration of kprobe
423 * processing. That includes the calls to the pre/post handlers
424 * and single stepping the kprobe instruction.
425 */
426 preempt_disable();
427 kcb = get_kprobe_ctlblk();
428 p = get_kprobe((void *)((regs->psw.addr & PSW_ADDR_INSN) - 2));
429
430 if (p) {
431 if (kprobe_running()) {
432 /*
433 * We have hit a kprobe while another is still
434 * active. This can happen in the pre and post
435 * handler. Single step the instruction of the
436 * new probe but do not call any handler function
437 * of this secondary kprobe.
438 * push_kprobe and pop_kprobe saves and restores
439 * the currently active kprobe.
440 */
441 kprobe_reenter_check(kcb, p);
442 push_kprobe(kcb, p);
443 kcb->kprobe_status = KPROBE_REENTER;
444 } else {
445 /*
446 * If we have no pre-handler or it returned 0, we
447 * continue with single stepping. If we have a
448 * pre-handler and it returned non-zero, it prepped
449 * for calling the break_handler below on re-entry
450 * for jprobe processing, so get out doing nothing
451 * more here.
452 */
453 push_kprobe(kcb, p);
454 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
455 if (p->pre_handler && p->pre_handler(p, regs))
456 return 1;
457 kcb->kprobe_status = KPROBE_HIT_SS;
458 }
459 enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
460 return 1;
461 } else if (kprobe_running()) {
462 p = __get_cpu_var(current_kprobe);
463 if (p->break_handler && p->break_handler(p, regs)) {
464 /*
465 * Continuation after the jprobe completed and
466 * caused the jprobe_return trap. The jprobe
467 * break_handler "returns" to the original
468 * function that still has the kprobe breakpoint
469 * installed. We continue with single stepping.
470 */
471 kcb->kprobe_status = KPROBE_HIT_SS;
472 enable_singlestep(kcb, regs,
473 (unsigned long) p->ainsn.insn);
474 return 1;
475 } /* else:
476 * No kprobe at this address and the current kprobe
477 * has no break handler (no jprobe!). The kernel just
478 * exploded, let the standard trap handler pick up the
479 * pieces.
480 */
481 } /* else:
482 * No kprobe at this address and no active kprobe. The trap has
483 * not been caused by a kprobe breakpoint. The race of breakpoint
484 * vs. kprobe remove does not exist because on s390 as we use
485 * stop_machine to arm/disarm the breakpoints.
486 */
487 preempt_enable_no_resched();
488 return 0;
489}
490
491/*
492 * Function return probe trampoline:
493 * - init_kprobes() establishes a probepoint here
494 * - When the probed function returns, this probe
495 * causes the handlers to fire
496 */
497static void __used kretprobe_trampoline_holder(void)
498{
499 asm volatile(".global kretprobe_trampoline\n"
500 "kretprobe_trampoline: bcr 0,0\n");
501}
502
503/*
504 * Called when the probe at kretprobe trampoline is hit
505 */
506static int __kprobes trampoline_probe_handler(struct kprobe *p,
507 struct pt_regs *regs)
508{
509 struct kretprobe_instance *ri;
510 struct hlist_head *head, empty_rp;
511 struct hlist_node *tmp;
512 unsigned long flags, orig_ret_address;
513 unsigned long trampoline_address;
514 kprobe_opcode_t *correct_ret_addr;
515
516 INIT_HLIST_HEAD(&empty_rp);
517 kretprobe_hash_lock(current, &head, &flags);
518
519 /*
520 * It is possible to have multiple instances associated with a given
521 * task either because an multiple functions in the call path
522 * have a return probe installed on them, and/or more than one return
523 * return probe was registered for a target function.
524 *
525 * We can handle this because:
526 * - instances are always inserted at the head of the list
527 * - when multiple return probes are registered for the same
528 * function, the first instance's ret_addr will point to the
529 * real return address, and all the rest will point to
530 * kretprobe_trampoline
531 */
532 ri = NULL;
533 orig_ret_address = 0;
534 correct_ret_addr = NULL;
535 trampoline_address = (unsigned long) &kretprobe_trampoline;
536 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
537 if (ri->task != current)
538 /* another task is sharing our hash bucket */
539 continue;
540
541 orig_ret_address = (unsigned long) ri->ret_addr;
542
543 if (orig_ret_address != trampoline_address)
544 /*
545 * This is the real return address. Any other
546 * instances associated with this task are for
547 * other calls deeper on the call stack
548 */
549 break;
550 }
551
552 kretprobe_assert(ri, orig_ret_address, trampoline_address);
553
554 correct_ret_addr = ri->ret_addr;
555 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
556 if (ri->task != current)
557 /* another task is sharing our hash bucket */
558 continue;
559
560 orig_ret_address = (unsigned long) ri->ret_addr;
561
562 if (ri->rp && ri->rp->handler) {
563 ri->ret_addr = correct_ret_addr;
564 ri->rp->handler(ri, regs);
565 }
566
567 recycle_rp_inst(ri, &empty_rp);
568
569 if (orig_ret_address != trampoline_address)
570 /*
571 * This is the real return address. Any other
572 * instances associated with this task are for
573 * other calls deeper on the call stack
574 */
575 break;
576 }
577
578 regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
579
580 pop_kprobe(get_kprobe_ctlblk());
581 kretprobe_hash_unlock(current, &flags);
582 preempt_enable_no_resched();
583
584 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
585 hlist_del(&ri->hlist);
586 kfree(ri);
587 }
588 /*
589 * By returning a non-zero value, we are telling
590 * kprobe_handler() that we don't want the post_handler
591 * to run (and have re-enabled preemption)
592 */
593 return 1;
594}
595
596/*
597 * Called after single-stepping. p->addr is the address of the
598 * instruction whose first byte has been replaced by the "breakpoint"
599 * instruction. To avoid the SMP problems that can occur when we
600 * temporarily put back the original opcode to single-step, we
601 * single-stepped a copy of the instruction. The address of this
602 * copy is p->ainsn.insn.
603 */
604static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
605{
606 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
607 unsigned long ip = regs->psw.addr & PSW_ADDR_INSN;
608 int fixup = get_fixup_type(p->ainsn.insn);
609
610 if (fixup & FIXUP_PSW_NORMAL)
611 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
612
613 if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
614 int ilen = insn_length(p->ainsn.insn[0] >> 8);
615 if (ip - (unsigned long) p->ainsn.insn == ilen)
616 ip = (unsigned long) p->addr + ilen;
617 }
618
619 if (fixup & FIXUP_RETURN_REGISTER) {
620 int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
621 regs->gprs[reg] += (unsigned long) p->addr -
622 (unsigned long) p->ainsn.insn;
623 }
624
625 disable_singlestep(kcb, regs, ip);
626}
627
628static int __kprobes post_kprobe_handler(struct pt_regs *regs)
629{
630 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
631 struct kprobe *p = kprobe_running();
632
633 if (!p)
634 return 0;
635
636 if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) {
637 kcb->kprobe_status = KPROBE_HIT_SSDONE;
638 p->post_handler(p, regs, 0);
639 }
640
641 resume_execution(p, regs);
642 pop_kprobe(kcb);
643 preempt_enable_no_resched();
644
645 /*
646 * if somebody else is singlestepping across a probe point, psw mask
647 * will have PER set, in which case, continue the remaining processing
648 * of do_single_step, as if this is not a probe hit.
649 */
650 if (regs->psw.mask & PSW_MASK_PER)
651 return 0;
652
653 return 1;
654}
655
656static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr)
657{
658 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
659 struct kprobe *p = kprobe_running();
660 const struct exception_table_entry *entry;
661
662 switch(kcb->kprobe_status) {
663 case KPROBE_SWAP_INST:
664 /* We are here because the instruction replacement failed */
665 return 0;
666 case KPROBE_HIT_SS:
667 case KPROBE_REENTER:
668 /*
669 * We are here because the instruction being single
670 * stepped caused a page fault. We reset the current
671 * kprobe and the nip points back to the probe address
672 * and allow the page fault handler to continue as a
673 * normal page fault.
674 */
675 disable_singlestep(kcb, regs, (unsigned long) p->addr);
676 pop_kprobe(kcb);
677 preempt_enable_no_resched();
678 break;
679 case KPROBE_HIT_ACTIVE:
680 case KPROBE_HIT_SSDONE:
681 /*
682 * We increment the nmissed count for accounting,
683 * we can also use npre/npostfault count for accounting
684 * these specific fault cases.
685 */
686 kprobes_inc_nmissed_count(p);
687
688 /*
689 * We come here because instructions in the pre/post
690 * handler caused the page_fault, this could happen
691 * if handler tries to access user space by
692 * copy_from_user(), get_user() etc. Let the
693 * user-specified handler try to fix it first.
694 */
695 if (p->fault_handler && p->fault_handler(p, regs, trapnr))
696 return 1;
697
698 /*
699 * In case the user-specified fault handler returned
700 * zero, try to fix up.
701 */
702 entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
703 if (entry) {
704 regs->psw.addr = extable_fixup(entry) | PSW_ADDR_AMODE;
705 return 1;
706 }
707
708 /*
709 * fixup_exception() could not handle it,
710 * Let do_page_fault() fix it.
711 */
712 break;
713 default:
714 break;
715 }
716 return 0;
717}
718
719int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
720{
721 int ret;
722
723 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
724 local_irq_disable();
725 ret = kprobe_trap_handler(regs, trapnr);
726 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
727 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
728 return ret;
729}
730
731/*
732 * Wrapper routine to for handling exceptions.
733 */
734int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
735 unsigned long val, void *data)
736{
737 struct die_args *args = (struct die_args *) data;
738 struct pt_regs *regs = args->regs;
739 int ret = NOTIFY_DONE;
740
741 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
742 local_irq_disable();
743
744 switch (val) {
745 case DIE_BPT:
746 if (kprobe_handler(regs))
747 ret = NOTIFY_STOP;
748 break;
749 case DIE_SSTEP:
750 if (post_kprobe_handler(regs))
751 ret = NOTIFY_STOP;
752 break;
753 case DIE_TRAP:
754 if (!preemptible() && kprobe_running() &&
755 kprobe_trap_handler(regs, args->trapnr))
756 ret = NOTIFY_STOP;
757 break;
758 default:
759 break;
760 }
761
762 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
763 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
764
765 return ret;
766}
767
768int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
769{
770 struct jprobe *jp = container_of(p, struct jprobe, kp);
771 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
772 unsigned long stack;
773
774 memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
775
776 /* setup return addr to the jprobe handler routine */
777 regs->psw.addr = (unsigned long) jp->entry | PSW_ADDR_AMODE;
778 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
779
780 /* r15 is the stack pointer */
781 stack = (unsigned long) regs->gprs[15];
782
783 memcpy(kcb->jprobes_stack, (void *) stack, MIN_STACK_SIZE(stack));
784 return 1;
785}
786
787void __kprobes jprobe_return(void)
788{
789 asm volatile(".word 0x0002");
790}
791
792static void __used __kprobes jprobe_return_end(void)
793{
794 asm volatile("bcr 0,0");
795}
796
797int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
798{
799 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
800 unsigned long stack;
801
802 stack = (unsigned long) kcb->jprobe_saved_regs.gprs[15];
803
804 /* Put the regs back */
805 memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
806 /* put the stack back */
807 memcpy((void *) stack, kcb->jprobes_stack, MIN_STACK_SIZE(stack));
808 preempt_enable_no_resched();
809 return 1;
810}
811
812static struct kprobe trampoline = {
813 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
814 .pre_handler = trampoline_probe_handler
815};
816
817int __init arch_init_kprobes(void)
818{
819 return register_kprobe(&trampoline);
820}
821
822int __kprobes arch_trampoline_kprobe(struct kprobe *p)
823{
824 return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline;
825}