2 * Kernel Probes (KProbes)
3 * arch/ia64/kernel/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) IBM Corporation, 2002, 2004
20 * Copyright (C) Intel Corporation, 2005
22 * 2005-Apr Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
23 * <anil.s.keshavamurthy@intel.com> adapted from i386
26 #include <linux/config.h>
27 #include <linux/kprobes.h>
28 #include <linux/ptrace.h>
29 #include <linux/spinlock.h>
30 #include <linux/string.h>
31 #include <linux/slab.h>
32 #include <linux/preempt.h>
33 #include <linux/moduleloader.h>
35 #include <asm/pgtable.h>
36 #include <asm/kdebug.h>
37 #include <asm/sections.h>
39 extern void jprobe_inst_return(void);
41 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
42 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
44 enum instruction_type {A, I, M, F, B, L, X, u};
45 static enum instruction_type bundle_encoding[32][3] = {
81 * In this function we check to see if the instruction
82 * is IP relative instruction and update the kprobe
83 * inst flag accordingly
85 static void __kprobes update_kprobe_inst_flag(uint template, uint slot,
87 unsigned long kprobe_inst,
90 p->ainsn.inst_flag = 0;
91 p->ainsn.target_br_reg = 0;
93 /* Check for Break instruction
94 * Bits 37:40 Major opcode to be zero
95 * Bits 27:32 X6 to be zero
96 * Bits 32:35 X3 to be zero
98 if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
99 /* is a break instruction */
100 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
104 if (bundle_encoding[template][slot] == B) {
105 switch (major_opcode) {
106 case INDIRECT_CALL_OPCODE:
107 p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
108 p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
110 case IP_RELATIVE_PREDICT_OPCODE:
111 case IP_RELATIVE_BRANCH_OPCODE:
112 p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
114 case IP_RELATIVE_CALL_OPCODE:
115 p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
116 p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
117 p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
120 } else if (bundle_encoding[template][slot] == X) {
121 switch (major_opcode) {
122 case LONG_CALL_OPCODE:
123 p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
124 p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
132 * In this function we check to see if the instruction
133 * on which we are inserting kprobe is supported.
134 * Returns 0 if supported
135 * Returns -EINVAL if unsupported
137 static int __kprobes unsupported_inst(uint template, uint slot,
139 unsigned long kprobe_inst,
142 unsigned long addr = (unsigned long)p->addr;
144 if (bundle_encoding[template][slot] == I) {
145 switch (major_opcode) {
146 case 0x0: //I_UNIT_MISC_OPCODE:
148 * Check for Integer speculation instruction
149 * - Bit 33-35 to be equal to 0x1
151 if (((kprobe_inst >> 33) & 0x7) == 1) {
153 "Kprobes on speculation inst at <0x%lx> not supported\n",
159 * IP relative mov instruction
160 * - Bit 27-35 to be equal to 0x30
162 if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
164 "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
176 * In this function we check to see if the instruction
177 * (qp) cmpx.crel.ctype p1,p2=r2,r3
178 * on which we are inserting kprobe is cmp instruction
181 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
183 unsigned long kprobe_inst)
188 if (!((bundle_encoding[template][slot] == I) ||
189 (bundle_encoding[template][slot] == M)))
192 if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
193 (major_opcode == 0xE)))
196 cmp_inst.l = kprobe_inst;
197 if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
198 /* Integere compare - Register Register (A6 type)*/
199 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
200 &&(cmp_inst.f.c == 1))
202 } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
203 /* Integere compare - Immediate Register (A8 type)*/
204 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
212 * In this function we override the bundle with
213 * the break instruction at the given slot.
215 static void __kprobes prepare_break_inst(uint template, uint slot,
217 unsigned long kprobe_inst,
220 unsigned long break_inst = BREAK_INST;
221 bundle_t *bundle = &p->ainsn.insn.bundle;
224 * Copy the original kprobe_inst qualifying predicate(qp)
225 * to the break instruction iff !is_cmp_ctype_unc_inst
226 * because for cmp instruction with ctype equal to unc,
227 * which is a special instruction always needs to be
228 * executed regradless of qp
230 if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
231 break_inst |= (0x3f & kprobe_inst);
235 bundle->quad0.slot0 = break_inst;
238 bundle->quad0.slot1_p0 = break_inst;
239 bundle->quad1.slot1_p1 = break_inst >> (64-46);
242 bundle->quad1.slot2 = break_inst;
247 * Update the instruction flag, so that we can
248 * emulate the instruction properly after we
249 * single step on original instruction
251 update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
254 static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
255 unsigned long *kprobe_inst, uint *major_opcode)
257 unsigned long kprobe_inst_p0, kprobe_inst_p1;
258 unsigned int template;
260 template = bundle->quad0.template;
264 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
265 *kprobe_inst = bundle->quad0.slot0;
268 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
269 kprobe_inst_p0 = bundle->quad0.slot1_p0;
270 kprobe_inst_p1 = bundle->quad1.slot1_p1;
271 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
274 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
275 *kprobe_inst = bundle->quad1.slot2;
280 /* Returns non-zero if the addr is in the Interrupt Vector Table */
281 static inline int in_ivt_functions(unsigned long addr)
283 return (addr >= (unsigned long)__start_ivt_text
284 && addr < (unsigned long)__end_ivt_text);
287 static int __kprobes valid_kprobe_addr(int template, int slot,
290 if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
291 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
296 if (in_ivt_functions(addr)) {
297 printk(KERN_WARNING "Kprobes can't be inserted inside "
298 "IVT functions at 0x%lx\n", addr);
302 if (slot == 1 && bundle_encoding[template][1] != L) {
303 printk(KERN_WARNING "Inserting kprobes on slot #1 "
304 "is not supported\n");
311 static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
313 kcb->prev_kprobe.kp = kprobe_running();
314 kcb->prev_kprobe.status = kcb->kprobe_status;
317 static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
319 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
320 kcb->kprobe_status = kcb->prev_kprobe.status;
323 static inline void set_current_kprobe(struct kprobe *p,
324 struct kprobe_ctlblk *kcb)
326 __get_cpu_var(current_kprobe) = p;
329 static void kretprobe_trampoline(void)
334 * At this point the target function has been tricked into
335 * returning into our trampoline. Lookup the associated instance
337 * - call the handler function
338 * - cleanup by marking the instance as unused
339 * - long jump back to the original return address
341 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
343 struct kretprobe_instance *ri = NULL;
344 struct hlist_head *head;
345 struct hlist_node *node, *tmp;
346 unsigned long orig_ret_address = 0;
347 unsigned long trampoline_address =
348 ((struct fnptr *)kretprobe_trampoline)->ip;
350 head = kretprobe_inst_table_head(current);
353 * It is possible to have multiple instances associated with a given
354 * task either because an multiple functions in the call path
355 * have a return probe installed on them, and/or more then one return
356 * return probe was registered for a target function.
358 * We can handle this because:
359 * - instances are always inserted at the head of the list
360 * - when multiple return probes are registered for the same
361 * function, the first instance's ret_addr will point to the
362 * real return address, and all the rest will point to
363 * kretprobe_trampoline
365 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
366 if (ri->task != current)
367 /* another task is sharing our hash bucket */
370 if (ri->rp && ri->rp->handler)
371 ri->rp->handler(ri, regs);
373 orig_ret_address = (unsigned long)ri->ret_addr;
376 if (orig_ret_address != trampoline_address)
378 * This is the real return address. Any other
379 * instances associated with this task are for
380 * other calls deeper on the call stack
385 BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
386 regs->cr_iip = orig_ret_address;
388 reset_current_kprobe();
390 preempt_enable_no_resched();
393 * By returning a non-zero value, we are telling
394 * kprobe_handler() that we have handled unlocking
395 * and re-enabling preemption
400 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
401 struct pt_regs *regs)
403 struct kretprobe_instance *ri;
405 if ((ri = get_free_rp_inst(rp)) != NULL) {
408 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
410 /* Replace the return addr with trampoline addr */
411 regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
419 int __kprobes arch_prepare_kprobe(struct kprobe *p)
421 unsigned long addr = (unsigned long) p->addr;
422 unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
423 unsigned long kprobe_inst=0;
424 unsigned int slot = addr & 0xf, template, major_opcode = 0;
425 bundle_t *bundle = &p->ainsn.insn.bundle;
427 memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
428 memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));
430 template = bundle->quad0.template;
432 if(valid_kprobe_addr(template, slot, addr))
435 /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
436 if (slot == 1 && bundle_encoding[template][1] == L)
439 /* Get kprobe_inst and major_opcode from the bundle */
440 get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
442 if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
445 prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
450 void __kprobes arch_arm_kprobe(struct kprobe *p)
452 unsigned long addr = (unsigned long)p->addr;
453 unsigned long arm_addr = addr & ~0xFULL;
455 memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
456 flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
459 void __kprobes arch_disarm_kprobe(struct kprobe *p)
461 unsigned long addr = (unsigned long)p->addr;
462 unsigned long arm_addr = addr & ~0xFULL;
464 /* p->opcode contains the original unaltered bundle */
465 memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
466 flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
469 void __kprobes arch_remove_kprobe(struct kprobe *p)
474 * We are resuming execution after a single step fault, so the pt_regs
475 * structure reflects the register state after we executed the instruction
476 * located in the kprobe (p->ainsn.insn.bundle). We still need to adjust
477 * the ip to point back to the original stack address. To set the IP address
478 * to original stack address, handle the case where we need to fixup the
479 * relative IP address and/or fixup branch register.
481 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
483 unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
484 unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
485 unsigned long template;
486 int slot = ((unsigned long)p->addr & 0xf);
488 template = p->opcode.bundle.quad0.template;
490 if (slot == 1 && bundle_encoding[template][1] == L)
493 if (p->ainsn.inst_flag) {
495 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
496 /* Fix relative IP address */
497 regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
500 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
502 * Fix target branch register, software convention is
503 * to use either b0 or b6 or b7, so just checking
504 * only those registers
506 switch (p->ainsn.target_br_reg) {
508 if ((regs->b0 == bundle_addr) ||
509 (regs->b0 == bundle_addr + 0x10)) {
510 regs->b0 = (regs->b0 - bundle_addr) +
515 if ((regs->b6 == bundle_addr) ||
516 (regs->b6 == bundle_addr + 0x10)) {
517 regs->b6 = (regs->b6 - bundle_addr) +
522 if ((regs->b7 == bundle_addr) ||
523 (regs->b7 == bundle_addr + 0x10)) {
524 regs->b7 = (regs->b7 - bundle_addr) +
534 if (regs->cr_iip == bundle_addr + 0x10) {
535 regs->cr_iip = resume_addr + 0x10;
538 if (regs->cr_iip == bundle_addr) {
539 regs->cr_iip = resume_addr;
544 /* Turn off Single Step bit */
545 ia64_psr(regs)->ss = 0;
548 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
550 unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
551 unsigned long slot = (unsigned long)p->addr & 0xf;
553 /* single step inline if break instruction */
554 if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
555 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
557 regs->cr_iip = bundle_addr & ~0xFULL;
562 ia64_psr(regs)->ri = slot;
564 /* turn on single stepping */
565 ia64_psr(regs)->ss = 1;
568 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
570 unsigned int slot = ia64_psr(regs)->ri;
571 unsigned int template, major_opcode;
572 unsigned long kprobe_inst;
573 unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
576 memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
577 template = bundle.quad0.template;
579 /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
580 if (slot == 1 && bundle_encoding[template][1] == L)
583 /* Get Kprobe probe instruction at given slot*/
584 get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
586 /* For break instruction,
587 * Bits 37:40 Major opcode to be zero
588 * Bits 27:32 X6 to be zero
589 * Bits 32:35 X3 to be zero
591 if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
592 /* Not a break instruction */
596 /* Is a break instruction */
600 static int __kprobes pre_kprobes_handler(struct die_args *args)
604 struct pt_regs *regs = args->regs;
605 kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
606 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
608 /* Handle recursion cases */
609 if (kprobe_running()) {
610 p = get_kprobe(addr);
612 if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
613 (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
614 ia64_psr(regs)->ss = 0;
618 /* We have reentered the pre_kprobe_handler(), since
619 * another probe was hit while within the handler.
620 * We here save the original kprobes variables and
621 * just single step on the instruction of the new probe
622 * without calling any user handlers.
624 save_previous_kprobe(kcb);
625 set_current_kprobe(p, kcb);
628 kcb->kprobe_status = KPROBE_REENTER;
630 } else if (args->err == __IA64_BREAK_JPROBE) {
632 * jprobe instrumented function just completed
634 p = __get_cpu_var(current_kprobe);
635 if (p->break_handler && p->break_handler(p, regs)) {
645 p = get_kprobe(addr);
648 if (!is_ia64_break_inst(regs)) {
650 * The breakpoint instruction was removed right
651 * after we hit it. Another cpu has removed
652 * either a probepoint or a debugger breakpoint
653 * at this address. In either case, no further
654 * handling of this interrupt is appropriate.
660 /* Not one of our break, let kernel handle it */
665 * This preempt_disable() matches the preempt_enable_no_resched()
666 * in post_kprobes_handler()
669 set_current_kprobe(p, kcb);
670 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
672 if (p->pre_handler && p->pre_handler(p, regs))
674 * Our pre-handler is specifically requesting that we just
675 * do a return. This is used for both the jprobe pre-handler
676 * and the kretprobe trampoline
682 kcb->kprobe_status = KPROBE_HIT_SS;
689 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
691 struct kprobe *cur = kprobe_running();
692 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
697 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
698 kcb->kprobe_status = KPROBE_HIT_SSDONE;
699 cur->post_handler(cur, regs, 0);
702 resume_execution(cur, regs);
704 /*Restore back the original saved kprobes variables and continue. */
705 if (kcb->kprobe_status == KPROBE_REENTER) {
706 restore_previous_kprobe(kcb);
709 reset_current_kprobe();
713 preempt_enable_no_resched();
717 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
719 struct kprobe *cur = kprobe_running();
720 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
725 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
728 if (kcb->kprobe_status & KPROBE_HIT_SS) {
729 resume_execution(cur, regs);
730 reset_current_kprobe();
732 preempt_enable_no_resched();
738 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
739 unsigned long val, void *data)
741 struct die_args *args = (struct die_args *)data;
742 int ret = NOTIFY_DONE;
747 if (pre_kprobes_handler(args))
751 if (post_kprobes_handler(args->regs))
755 if (kprobes_fault_handler(args->regs, args->trapnr))
764 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
766 struct jprobe *jp = container_of(p, struct jprobe, kp);
767 unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
768 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
770 /* save architectural state */
771 kcb->jprobe_saved_regs = *regs;
773 /* after rfi, execute the jprobe instrumented function */
774 regs->cr_iip = addr & ~0xFULL;
775 ia64_psr(regs)->ri = addr & 0xf;
776 regs->r1 = ((struct fnptr *)(jp->entry))->gp;
779 * fix the return address to our jprobe_inst_return() function
780 * in the jprobes.S file
782 regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
787 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
789 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
791 *regs = kcb->jprobe_saved_regs;
795 static struct kprobe trampoline_p = {
796 .pre_handler = trampoline_probe_handler
799 int __init arch_init_kprobes(void)
802 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
803 return register_kprobe(&trampoline_p);