2 * Dynamic Binary Instrumentation Module based on KProbes
3 * modules/kprobe/arch/asm-arm/dbi_kprobes.c
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 * Copyright (C) Samsung Electronics, 2006-2010
21 * 2006-2007 Ekaterina Gorelkina <e.gorelkina@samsung.com>: initial implementation for ARM/MIPS
22 * 2008-2009 Alexey Gerenkov <a.gerenkov@samsung.com> User-Space
23 * Probes initial implementation; Support x86.
24 * 2010 Ekaterina Gorelkina <e.gorelkina@samsung.com>: redesign module for separating core and arch parts
25 * 2010-2011 Alexander Shirshikov <a.shirshikov@samsung.com>: initial implementation for Thumb
26 * 2012 Stanislav Andreev <s.andreev@samsung.com>: added time debug profiling support; BUG() message fix
27 * 2012 Stanislav Andreev <s.andreev@samsung.com>: redesign of kprobe functionality -
28 * kprobe_handler() now called via undefined instruction hooks
29 * 2012 Stanislav Andreev <s.andreev@samsung.com>: hash tables search implemented for uprobes
32 #include <linux/module.h>
35 #include "dbi_kprobes.h"
36 #include "trampoline_arm.h"
37 #include <kprobe/dbi_kprobes.h>
39 #include <kprobe/dbi_kdebug.h>
40 #include <kprobe/dbi_insn_slots.h>
41 #include <kprobe/dbi_kprobes_deps.h>
42 #include <ksyms/ksyms.h>
44 #include <asm/cacheflush.h>
45 #include <asm/traps.h>
46 #include <asm/ptrace.h>
47 #include <linux/list.h>
48 #include <linux/hash.h>
50 #define SUPRESS_BUG_MESSAGES
52 #define sign_extend(x, signbit) ((x) | (0 - ((x) & (1 << (signbit)))))
53 #define branch_displacement(insn) sign_extend(((insn) & 0xffffff) << 2, 25)
55 extern struct kprobe * per_cpu__current_kprobe;
56 extern struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
58 static void (*__swap_register_undef_hook)(struct undef_hook *hook);
59 static void (*__swap_unregister_undef_hook)(struct undef_hook *hook);
61 static unsigned long get_addr_b(unsigned long insn, unsigned long addr)
63 /* real position less then PC by 8 */
64 return (kprobe_opcode_t)((long)addr + 8 + branch_displacement(insn));
67 static int prep_pc_dep_insn_execbuf(kprobe_opcode_t *insns,
68 kprobe_opcode_t insn, int uregs)
75 for (i = 0; i < 13; i++, reg_mask <<= 1) {
76 if (!(insn & reg_mask))
80 for (i = 0; i < 13; i++) {
81 if ((uregs & 0x1) && (ARM_INSN_REG_RN(insn) == i))
83 if ((uregs & 0x2) && (ARM_INSN_REG_RD(insn) == i))
85 if ((uregs & 0x4) && (ARM_INSN_REG_RS(insn) == i))
87 if ((uregs & 0x8) && (ARM_INSN_REG_RM(insn) == i))
94 DBPRINTF ("there are no free register %x in insn %lx!", uregs, insn);
97 DBPRINTF ("prep_pc_dep_insn_execbuf: using R%d, changing regs %x", i, uregs);
99 // set register to save
100 ARM_INSN_REG_SET_RD(insns[0], i);
101 // set register to load address to
102 ARM_INSN_REG_SET_RD(insns[1], i);
103 // set instruction to execute and patch it
105 ARM_INSN_REG_CLEAR_MR(insn, 15);
106 ARM_INSN_REG_SET_MR(insn, i);
108 if ((uregs & 0x1) && (ARM_INSN_REG_RN(insn) == 15))
109 ARM_INSN_REG_SET_RN(insn, i);
110 if ((uregs & 0x2) && (ARM_INSN_REG_RD(insn) == 15))
111 ARM_INSN_REG_SET_RD(insn, i);
112 if ((uregs & 0x4) && (ARM_INSN_REG_RS(insn) == 15))
113 ARM_INSN_REG_SET_RS(insn, i);
114 if ((uregs & 0x8) && (ARM_INSN_REG_RM(insn) == 15))
115 ARM_INSN_REG_SET_RM(insn, i);
118 insns[UPROBES_TRAMP_INSN_IDX] = insn;
119 // set register to restore
120 ARM_INSN_REG_SET_RD(insns[3], i);
125 static int arch_check_insn_arm(unsigned long insn)
127 /* check instructions that can change PC by nature */
129 /* ARM_INSN_MATCH(UNDEF, insn) || */
130 ARM_INSN_MATCH(AUNDEF, insn) ||
131 ARM_INSN_MATCH(SWI, insn) ||
132 ARM_INSN_MATCH(BREAK, insn) ||
133 ARM_INSN_MATCH(BXJ, insn)) {
135 #ifndef CONFIG_CPU_V7
136 /* check instructions that can write result to PC */
137 } else if ((ARM_INSN_MATCH(DPIS, insn) ||
138 ARM_INSN_MATCH(DPRS, insn) ||
139 ARM_INSN_MATCH(DPI, insn) ||
140 ARM_INSN_MATCH(LIO, insn) ||
141 ARM_INSN_MATCH(LRO, insn)) &&
142 (ARM_INSN_REG_RD(insn) == 15)) {
144 #endif /* CONFIG_CPU_V7 */
145 /* check special instruction loads store multiple registers */
146 } else if ((ARM_INSN_MATCH(LM, insn) || ARM_INSN_MATCH(SM, insn)) &&
147 /* store PC or load to PC */
148 (ARM_INSN_REG_MR(insn, 15) ||
149 /* store/load with PC update */
150 ((ARM_INSN_REG_RN(insn) == 15) && (insn & 0x200000)))) {
157 printk("Bad insn arch_check_insn_arm: %lx\n", insn);
161 static int make_branch_tarmpoline(unsigned long addr, unsigned long insn,
162 unsigned long *tramp)
167 if (ARM_INSN_MATCH(B, insn) &&
168 !ARM_INSN_MATCH(BLX1, insn)) {
169 /* B check can be false positive on BLX1 instruction */
170 memcpy(tramp, b_cond_insn_execbuf, KPROBES_TRAMP_LEN);
171 tramp[KPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
172 tramp[0] |= insn & 0xf0000000;
173 tramp[6] = get_addr_b(insn, addr);
177 } else if (ARM_INSN_MATCH(BX, insn) ||
178 ARM_INSN_MATCH(BLX2, insn)) {
179 memcpy(tramp, b_r_insn_execbuf, KPROBES_TRAMP_LEN);
181 tramp[KPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
185 } else if (ARM_INSN_MATCH(BLX1, insn)) {
186 memcpy(tramp, blx_off_insn_execbuf, KPROBES_TRAMP_LEN);
187 tramp[0] |= 0xe0000000;
188 tramp[1] |= 0xe0000000;
189 tramp[KPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
190 tramp[6] = get_addr_b(insn, addr) +
191 2 * (insn & 01000000) + 1; /* jump to thumb */
195 } else if (ARM_INSN_MATCH(BL, insn)) {
196 memcpy(tramp, blx_off_insn_execbuf, KPROBES_TRAMP_LEN);
197 tramp[0] |= insn & 0xf0000000;
198 tramp[1] |= insn & 0xf0000000;
199 tramp[KPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
200 tramp[6] = get_addr_b(insn, addr);
208 int arch_make_trampoline_arm(unsigned long addr, unsigned long insn,
209 unsigned long *tramp)
211 int ret, uregs, pc_dep;
214 printk("Error in %s at %d: attempt to register uprobe "
215 "at an unaligned address\n", __FILE__, __LINE__);
219 ret = arch_check_insn_arm(insn);
223 if (make_branch_tarmpoline(addr, insn, tramp))
228 if (ARM_INSN_MATCH(CLZ, insn)) {
230 if (ARM_INSN_REG_RM(insn) == 15)
233 } else if (ARM_INSN_MATCH(DPIS, insn) || ARM_INSN_MATCH(LRO, insn) ||
234 ARM_INSN_MATCH(SRO, insn)) {
236 if ((ARM_INSN_REG_RN(insn) == 15) ||
237 (ARM_INSN_REG_RM(insn) == 15) ||
238 (ARM_INSN_MATCH(SRO, insn) &&
239 (ARM_INSN_REG_RD(insn) == 15))) {
243 } else if (ARM_INSN_MATCH(DPI, insn) || ARM_INSN_MATCH(LIO, insn) ||
244 ARM_INSN_MATCH(SIO, insn)) {
246 if ((ARM_INSN_REG_RN(insn) == 15) ||
247 (ARM_INSN_MATCH(SIO, insn) &&
248 (ARM_INSN_REG_RD(insn) == 15))) {
252 } else if (ARM_INSN_MATCH(DPRS, insn)) {
254 if ((ARM_INSN_REG_RN(insn) == 15) ||
255 (ARM_INSN_REG_RM(insn) == 15) ||
256 (ARM_INSN_REG_RS(insn) == 15)) {
260 } else if (ARM_INSN_MATCH(SM, insn)) {
262 if (ARM_INSN_REG_MR(insn, 15)) {
267 /* check instructions that can write result to SP and uses PC */
268 if (pc_dep && (ARM_INSN_REG_RD(insn) == 13)) {
269 printk("Error in %s at %d: instruction check failed (arm)\n",
274 if (unlikely(uregs && pc_dep)) {
275 memcpy(tramp, pc_dep_insn_execbuf, KPROBES_TRAMP_LEN);
276 if (prep_pc_dep_insn_execbuf(tramp, insn, uregs) != 0) {
277 printk("Error in %s at %d: failed "
278 "to prepare exec buffer for insn %lx!",
279 __FILE__, __LINE__, insn);
285 memcpy(tramp, gen_insn_execbuf, KPROBES_TRAMP_LEN);
286 tramp[KPROBES_TRAMP_INSN_IDX] = insn;
289 /* TODO: remove for kprobe */
290 tramp[KPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
295 EXPORT_SYMBOL_GPL(arch_make_trampoline_arm);
297 int arch_prepare_kprobe(struct kprobe *p, struct slot_manager *sm)
299 unsigned long addr = (unsigned long)p->addr;
300 unsigned long insn = p->opcode = *p->addr;
301 unsigned long *tramp;
304 tramp = alloc_insn_slot(sm);
308 ret = arch_make_trampoline_arm(addr, insn, tramp);
310 free_insn_slot(sm, tramp);
314 flush_icache_range((unsigned long)tramp,
315 (unsigned long)tramp + KPROBES_TRAMP_LEN);
317 p->ainsn.insn = tramp;
322 void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
325 regs->ARM_pc = (unsigned long)p->ss_addr;
328 regs->ARM_pc = (unsigned long)p->ainsn.insn;
331 EXPORT_SYMBOL_GPL(prepare_singlestep);
333 void save_previous_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p_run)
335 kcb->prev_kprobe.kp = kprobe_running();
336 kcb->prev_kprobe.status = kcb->kprobe_status;
339 void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
341 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
342 kcb->kprobe_status = kcb->prev_kprobe.status;
345 void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
347 __get_cpu_var(current_kprobe) = p;
348 DBPRINTF ("set_current_kprobe: p=%p addr=%p\n", p, p->addr);
351 static int kprobe_handler(struct pt_regs *regs)
353 struct kprobe *p, *cur;
354 struct kprobe_ctlblk *kcb;
356 kcb = get_kprobe_ctlblk();
357 cur = kprobe_running();
358 p = get_kprobe((void *)regs->ARM_pc);
362 /* Kprobe is pending, so we're recursing. */
363 switch (kcb->kprobe_status) {
364 case KPROBE_HIT_ACTIVE:
365 case KPROBE_HIT_SSDONE:
366 /* A pre- or post-handler probe got us here. */
367 kprobes_inc_nmissed_count(p);
368 save_previous_kprobe(kcb, NULL);
369 set_current_kprobe(p, 0, 0);
370 kcb->kprobe_status = KPROBE_REENTER;
371 prepare_singlestep(p, regs);
372 restore_previous_kprobe(kcb);
375 /* impossible cases */
379 set_current_kprobe(p, 0, 0);
380 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
382 if (!p->pre_handler || !p->pre_handler(p, regs)) {
383 kcb->kprobe_status = KPROBE_HIT_SS;
384 prepare_singlestep(p, regs);
385 reset_current_kprobe();
395 printk("no_kprobe: Not one of ours: let kernel handle it %p\n",
396 (unsigned long *)regs->ARM_pc);
400 int kprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
405 #ifdef SUPRESS_BUG_MESSAGES
406 int swap_oops_in_progress;
407 /* oops_in_progress used to avoid BUG() messages
408 * that slow down kprobe_handler() execution */
409 swap_oops_in_progress = oops_in_progress;
410 oops_in_progress = 1;
413 local_irq_save(flags);
415 ret = kprobe_handler(regs);
416 preempt_enable_no_resched();
417 local_irq_restore(flags);
419 #ifdef SUPRESS_BUG_MESSAGES
420 oops_in_progress = swap_oops_in_progress;
426 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
428 struct jprobe *jp = container_of(p, struct jprobe, kp);
429 kprobe_pre_entry_handler_t pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
430 entry_point_t entry = (entry_point_t)jp->entry;
431 pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
434 p->ss_addr = (void *)pre_entry (jp->priv_arg, regs);
438 entry(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2,
439 regs->ARM_r3, regs->ARM_r4, regs->ARM_r5);
447 void dbi_jprobe_return (void)
451 int longjmp_break_handler (struct kprobe *p, struct pt_regs *regs)
455 EXPORT_SYMBOL_GPL(longjmp_break_handler);
457 #ifdef CONFIG_STRICT_MEMORY_RWX
458 extern void mem_text_write_kernel_word(unsigned long *addr, unsigned long word);
461 void arch_arm_kprobe(struct kprobe *p)
463 #ifdef CONFIG_STRICT_MEMORY_RWX
464 mem_text_write_kernel_word(p->addr, BREAKPOINT_INSTRUCTION);
466 *p->addr = BREAKPOINT_INSTRUCTION;
467 flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t));
471 void arch_disarm_kprobe(struct kprobe *p)
473 #ifdef CONFIG_STRICT_MEMORY_RWX
474 mem_text_write_kernel_word(p->addr, p->opcode);
476 *p->addr = p->opcode;
477 flush_icache_range((unsigned long)p->addr, (unsigned long)p->addr + sizeof(kprobe_opcode_t));
481 void __naked kretprobe_trampoline(void)
483 __asm__ __volatile__ (
484 "stmdb sp!, {r0 - r11} \n\t"
487 "bl trampoline_probe_handler\n\t"
489 "ldmia sp!, {r0 - r11} \n\t"
494 void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
496 unsigned long *ptr_ret_addr;
498 /* for __switch_to probe */
499 if ((unsigned long)ri->rp->kp.addr == sched_addr) {
500 struct thread_info *tinfo = (struct thread_info *)regs->ARM_r2;
502 ptr_ret_addr = (unsigned long *)&tinfo->cpu_context.pc;
504 ri->task = tinfo->task;
506 ptr_ret_addr = (unsigned long *)®s->ARM_lr;
507 ri->sp = (unsigned long *)regs->ARM_sp;
510 /* Save the return address */
511 ri->ret_addr = (unsigned long *)*ptr_ret_addr;
513 /* Replace the return addr with trampoline addr */
514 *ptr_ret_addr = (unsigned long)&kretprobe_trampoline;
517 void swap_register_undef_hook(struct undef_hook *hook)
519 __swap_register_undef_hook(hook);
521 EXPORT_SYMBOL_GPL(swap_register_undef_hook);
523 void swap_unregister_undef_hook(struct undef_hook *hook)
525 __swap_unregister_undef_hook(hook);
527 EXPORT_SYMBOL_GPL(swap_unregister_undef_hook);
529 // kernel probes hook
530 static struct undef_hook undef_ho_k = {
531 .instr_mask = 0xffffffff,
532 .instr_val = BREAKPOINT_INSTRUCTION,
533 .cpsr_mask = MODE_MASK,
534 .cpsr_val = SVC_MODE,
535 .fn = kprobe_trap_handler
538 int arch_init_kprobes(void)
540 // Register hooks (kprobe_handler)
541 __swap_register_undef_hook = (void *)swap_ksyms("register_undef_hook");
542 if (__swap_register_undef_hook == NULL) {
543 printk("no register_undef_hook symbol found!\n");
547 // Unregister hooks (kprobe_handler)
548 __swap_unregister_undef_hook = (void *)swap_ksyms("unregister_undef_hook");
549 if (__swap_unregister_undef_hook == NULL) {
550 printk("no unregister_undef_hook symbol found!\n");
554 swap_register_undef_hook(&undef_ho_k);
559 void arch_exit_kprobes(void)
561 swap_unregister_undef_hook(&undef_ho_k);
564 /* export symbol for trampoline_arm.h */
565 EXPORT_SYMBOL_GPL(gen_insn_execbuf);
566 EXPORT_SYMBOL_GPL(pc_dep_insn_execbuf);
567 EXPORT_SYMBOL_GPL(b_r_insn_execbuf);
568 EXPORT_SYMBOL_GPL(b_cond_insn_execbuf);
569 EXPORT_SYMBOL_GPL(blx_off_insn_execbuf);