2 * uprobe/arch/asm-x86/swap_uprobes.c
3 * @author Alexey Gerenkov <a.gerenkov@samsung.com> User-Space Probes initial
4 * implementation; Support x86/ARM/MIPS for both user and kernel spaces.
5 * @author Ekaterina Gorelkina <e.gorelkina@samsung.com>: redesign module for
6 * separating core and arch parts
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
26 * Copyright (C) Samsung Electronics, 2006-2010
28 * @section DESCRIPTION
30 * Arch-dependent uprobe interface implementation for x86.
34 #include <linux/kdebug.h>
36 #include <kprobe/swap_slots.h>
37 #include <uprobe/swap_uprobes.h>
39 #include "swap_uprobes.h"
43 * @struct uprobe_ctlblk
44 * @brief Uprobe control block
46 struct uprobe_ctlblk {
47 unsigned long flags; /**< Flags */
48 struct kprobe *p; /**< Pointer to the uprobe's kprobe */
51 static unsigned long trampoline_addr(struct uprobe *up)
53 return (unsigned long)(up->kp.ainsn.insn +
54 UPROBES_TRAMP_RET_BREAK_IDX);
57 unsigned long arch_tramp_by_ri(struct uretprobe_instance *ri)
59 return trampoline_addr(&ri->rp->up);
62 static struct uprobe_ctlblk *current_ucb(void)
64 /* FIXME hardcoded offset */
65 return (struct uprobe_ctlblk *)(end_of_stack(current) + 20);
68 static struct kprobe *get_current_probe(void)
70 return current_ucb()->p;
73 static void set_current_probe(struct kprobe *p)
78 static void save_current_flags(struct pt_regs *regs)
80 current_ucb()->flags = regs->flags;
83 static void restore_current_flags(struct pt_regs *regs, unsigned long flags)
85 regs->flags &= ~IF_MASK;
86 regs->flags |= flags & IF_MASK;
90 * @brief Prepares uprobe for x86.
92 * @param up Pointer to the uprobe.
93 * @return 0 on success,\n
96 int arch_prepare_uprobe(struct uprobe *up)
98 struct kprobe *p = up2kp(up);
99 struct task_struct *task = up->task;
100 u8 *tramp = up->atramp.tramp;
101 enum { call_relative_opcode = 0xe8 };
103 if (!read_proc_vm_atomic(task, (unsigned long)p->addr,
104 tramp, MAX_INSN_SIZE)) {
105 printk(KERN_ERR "failed to read memory %p!\n", p->addr);
108 /* TODO: this is a workaround */
109 if (tramp[0] == call_relative_opcode) {
110 printk(KERN_INFO "cannot install probe: 1st instruction is call\n");
114 tramp[UPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
116 /* TODO: remove dual info */
117 p->opcode = tramp[0];
119 p->ainsn.boostable = swap_can_boost(tramp) ? 0 : -1;
121 p->ainsn.insn = swap_slot_alloc(up->sm);
122 if (p->ainsn.insn == NULL) {
123 printk(KERN_ERR "trampoline out of memory\n");
127 if (!write_proc_vm_atomic(task, (unsigned long)p->ainsn.insn,
128 tramp, sizeof(up->atramp.tramp))) {
129 swap_slot_free(up->sm, p->ainsn.insn);
130 printk(KERN_INFO "failed to write memory %p!\n", tramp);
141 * @brief Jump pre-handler.
143 * @param p Pointer to the uprobe's kprobe.
144 * @param regs Pointer to CPU register data.
147 int setjmp_upre_handler(struct kprobe *p, struct pt_regs *regs)
149 struct uprobe *up = container_of(p, struct uprobe, kp);
150 struct ujprobe *jp = container_of(up, struct ujprobe, up);
151 kprobe_pre_entry_handler_t pre_entry =
152 (kprobe_pre_entry_handler_t)jp->pre_entry;
153 entry_point_t entry = (entry_point_t)jp->entry;
154 unsigned long args[6];
156 /* FIXME some user space apps crash if we clean interrupt bit */
157 /* regs->EREG(flags) &= ~IF_MASK; */
158 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 18)
159 trace_hardirqs_off();
162 /* read first 6 args from stack */
163 if (!read_proc_vm_atomic(current, regs->EREG(sp) + 4,
166 "failed to read user space func arguments %lx!\n",
170 p->ss_addr[smp_processor_id()] = (kprobe_opcode_t *)
171 pre_entry(jp->priv_arg, regs);
174 entry(args[0], args[1], args[2], args[3], args[4], args[5]);
176 arch_ujprobe_return();
182 * @brief Prepares uretprobe for x86.
184 * @param ri Pointer to the uretprobe instance.
185 * @param regs Pointer to CPU register data.
188 int arch_prepare_uretprobe(struct uretprobe_instance *ri, struct pt_regs *regs)
190 /* Replace the return addr with trampoline addr */
191 unsigned long ra = trampoline_addr(&ri->rp->up);
192 ri->sp = (kprobe_opcode_t *)regs->sp;
194 if (!read_proc_vm_atomic(current, regs->EREG(sp), &(ri->ret_addr),
195 sizeof(ri->ret_addr))) {
196 printk(KERN_ERR "failed to read user space func ra %lx addr=%p!\n",
197 regs->EREG(sp), ri->rp->up.kp.addr);
201 if (!write_proc_vm_atomic(current, regs->EREG(sp), &ra, sizeof(ra))) {
202 printk(KERN_ERR "failed to write user space func ra %lx!\n",
211 * @brief Disarms uretprobe on x86 arch.
213 * @param ri Pointer to the uretprobe instance.
214 * @param task Pointer to the task for which the probe.
215 * @return 0 on success,\n
216 * negative error code on error.
218 int arch_disarm_urp_inst(struct uretprobe_instance *ri,
219 struct task_struct *task, unsigned long tr)
222 unsigned long ret_addr;
223 unsigned long sp = (unsigned long)ri->sp;
224 unsigned long tramp_addr;
227 tramp_addr = arch_tramp_by_ri(ri);
229 tramp_addr = tr; /* ri - invalid */
231 len = read_proc_vm_atomic(task, sp, &ret_addr, sizeof(ret_addr));
232 if (len != sizeof(ret_addr)) {
233 printk(KERN_INFO "---> %s (%d/%d): failed to read stack from %08lx\n",
234 task->comm, task->tgid, task->pid, sp);
238 if (tramp_addr == ret_addr) {
239 len = write_proc_vm_atomic(task, sp, &ri->ret_addr,
240 sizeof(ri->ret_addr));
241 if (len != sizeof(ri->ret_addr)) {
242 printk(KERN_INFO "---> %s (%d/%d): failed to write "
243 "orig_ret_addr to %08lx",
244 task->comm, task->tgid, task->pid, sp);
248 printk(KERN_INFO "---> %s (%d/%d): trampoline NOT found at sp = %08lx\n",
249 task->comm, task->tgid, task->pid, sp);
257 * @brief Gets trampoline address.
259 * @param p Pointer to the uprobe's kprobe.
260 * @param regs Pointer to CPU register data.
261 * @return Trampoline address.
263 unsigned long arch_get_trampoline_addr(struct kprobe *p, struct pt_regs *regs)
265 return trampoline_addr(kp2up(p));
269 * @brief Restores return address.
271 * @param orig_ret_addr Original return address.
272 * @param regs Pointer to CPU register data.
275 void arch_set_orig_ret_addr(unsigned long orig_ret_addr, struct pt_regs *regs)
277 regs->EREG(ip) = orig_ret_addr;
281 * @brief Removes uprobe.
283 * @param up Pointer to the target uprobe.
286 void arch_remove_uprobe(struct uprobe *up)
288 struct kprobe *p = up2kp(up);
290 swap_slot_free(up->sm, p->ainsn.insn);
293 int arch_arm_uprobe(struct uprobe *p)
296 kprobe_opcode_t insn = BREAKPOINT_INSTRUCTION;
297 unsigned long vaddr = (unsigned long)p->kp.addr;
299 ret = write_proc_vm_atomic(p->task, vaddr, &insn, sizeof(insn));
301 pr_err("arch_arm_uprobe: failed to write memory tgid=%u vaddr=%08lx\n",
302 p->task->tgid, vaddr);
310 void arch_disarm_uprobe(struct kprobe *p, struct task_struct *task)
313 unsigned long vaddr = (unsigned long)p->addr;
315 ret = write_proc_vm_atomic(task, vaddr, &p->opcode, sizeof(p->opcode));
317 pr_err("arch_disarm_uprobe: failed to write memory tgid=%u, vaddr=%08lx\n",
322 static void set_user_jmp_op(void *from, void *to)
324 struct __arch_jmp_op {
329 jop.raddr = (long)(to) - ((long)(from) + 5);
330 jop.op = RELATIVEJUMP_INSTRUCTION;
332 if (!write_proc_vm_atomic(current, (unsigned long)from, &jop,
335 "failed to write jump opcode to user space %p\n", from);
338 static void resume_execution(struct kprobe *p,
339 struct pt_regs *regs,
342 unsigned long *tos, tos_dword = 0;
343 unsigned long copy_eip = (unsigned long)p->ainsn.insn;
344 unsigned long orig_eip = (unsigned long)p->addr;
345 kprobe_opcode_t insns[2];
347 regs->EREG(flags) &= ~TF_MASK;
349 tos = (unsigned long *)&tos_dword;
350 if (!read_proc_vm_atomic(current, regs->EREG(sp), &tos_dword,
351 sizeof(tos_dword))) {
353 "failed to read dword from top of the user space stack %lx!\n",
358 if (!read_proc_vm_atomic(current, (unsigned long)p->ainsn.insn, insns,
359 2 * sizeof(kprobe_opcode_t))) {
361 "failed to read first 2 opcodes of instruction copy from user space %p!\n",
367 case 0x9c: /* pushfl */
368 *tos &= ~(TF_MASK | IF_MASK);
369 *tos |= flags & (TF_MASK | IF_MASK);
371 case 0xc2: /* iret/ret/lret */
376 case 0xea: /* jmp absolute -- eip is correct */
377 /* eip is already adjusted, no more changes required */
378 p->ainsn.boostable = 1;
380 case 0xe8: /* call relative - Fix return addr */
381 *tos = orig_eip + (*tos - copy_eip);
383 case 0x9a: /* call absolute -- same as call absolute, indirect */
384 *tos = orig_eip + (*tos - copy_eip);
386 if (!write_proc_vm_atomic(current,
389 sizeof(tos_dword))) {
391 "failed to write dword to top of the user space stack %lx!\n",
398 if ((insns[1] & 0x30) == 0x10) {
400 * call absolute, indirect
401 * Fix return addr; eip is correct.
402 * But this is not boostable
404 *tos = orig_eip + (*tos - copy_eip);
406 if (!write_proc_vm_atomic(current, regs->EREG(sp),
408 sizeof(tos_dword))) {
410 "failed to write dword to top of the user space stack %lx!\n",
416 } else if (((insns[1] & 0x31) == 0x20) || /* jmp near, absolute
418 ((insns[1] & 0x31) == 0x21)) {
419 /* jmp far, absolute indirect */
420 /* eip is correct. And this is boostable */
421 p->ainsn.boostable = 1;
425 if (insns[1] == 0xc3)
426 /* repz ret special handling: no more changes */
433 if (!write_proc_vm_atomic(current, regs->EREG(sp), &tos_dword,
434 sizeof(tos_dword))) {
436 "failed to write dword to top of the user space stack %lx!\n",
441 if (p->ainsn.boostable == 0) {
442 if ((regs->EREG(ip) > copy_eip) && (regs->EREG(ip) - copy_eip) +
445 * These instructions can be executed directly if it
446 * jumps back to correct address.
448 set_user_jmp_op((void *) regs->EREG(ip),
450 (regs->EREG(ip) - copy_eip));
451 p->ainsn.boostable = 1;
453 p->ainsn.boostable = -1;
457 regs->EREG(ip) = orig_eip + (regs->EREG(ip) - copy_eip);
463 static bool prepare_ss_addr(struct kprobe *p, struct pt_regs *regs)
465 unsigned long *ss_addr = (long *)&p->ss_addr[smp_processor_id()];
472 regs->ip = (unsigned long)p->ainsn.insn;
477 static void prepare_ss(struct pt_regs *regs)
479 /* set single step mode */
480 regs->flags |= TF_MASK;
481 regs->flags &= ~IF_MASK;
484 static int uprobe_handler(struct pt_regs *regs)
487 kprobe_opcode_t *addr;
488 struct task_struct *task = current;
489 pid_t tgid = task->tgid;
491 save_current_flags(regs);
493 addr = (kprobe_opcode_t *)(regs->EREG(ip) - sizeof(kprobe_opcode_t));
494 p = get_ukprobe(addr, tgid);
497 void *tramp_addr = (void *)addr - UPROBES_TRAMP_RET_BREAK_IDX;
499 p = get_ukprobe_by_insn_slot(tramp_addr, tgid, regs);
501 printk(KERN_INFO "no_uprobe\n");
505 trampoline_uprobe_handler(p, regs);
508 if (!p->pre_handler || !p->pre_handler(p, regs)) {
509 if (p->ainsn.boostable == 1 && !p->post_handler) {
510 prepare_ss_addr(p, regs);
514 if (prepare_ss_addr(p, regs) == false) {
515 set_current_probe(p);
524 static int post_uprobe_handler(struct pt_regs *regs)
526 struct kprobe *p = get_current_probe();
527 unsigned long flags = current_ucb()->flags;
530 printk("task[%u %u %s] current uprobe is not found\n",
531 current->tgid, current->pid, current->comm);
535 resume_execution(p, regs, flags);
536 restore_current_flags(regs, flags);
539 current_ucb()->p = 0;
540 current_ucb()->flags = 0;
545 static int uprobe_exceptions_notify(struct notifier_block *self,
546 unsigned long val, void *data)
548 struct die_args *args = (struct die_args *)data;
549 int ret = NOTIFY_DONE;
551 if (args->regs == NULL || !user_mode_vm(args->regs))
555 #ifdef CONFIG_KPROBES
560 if (uprobe_handler(args->regs))
564 if (post_uprobe_handler(args->regs))
574 static struct notifier_block uprobe_exceptions_nb = {
575 .notifier_call = uprobe_exceptions_notify,
580 * @brief Registers notify.
582 * @return register_die_notifier result.
584 int swap_arch_init_uprobes(void)
586 return register_die_notifier(&uprobe_exceptions_nb);
590 * @brief Unregisters notify.
594 void swap_arch_exit_uprobes(void)
596 unregister_die_notifier(&uprobe_exceptions_nb);