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 static struct uprobe_ctlblk *current_ucb(void)
59 /* FIXME hardcoded offset */
60 return (struct uprobe_ctlblk *)(end_of_stack(current) + 20);
63 static struct kprobe *get_current_probe(void)
65 return current_ucb()->p;
68 static void set_current_probe(struct kprobe *p)
73 static void save_current_flags(struct pt_regs *regs)
75 current_ucb()->flags = regs->flags;
78 static void restore_current_flags(struct pt_regs *regs, unsigned long flags)
80 regs->flags &= ~IF_MASK;
81 regs->flags |= flags & IF_MASK;
85 * @brief Prepares uprobe for x86.
87 * @param up Pointer to the uprobe.
88 * @return 0 on success,\n
91 int arch_prepare_uprobe(struct uprobe *up)
93 struct kprobe *p = up2kp(up);
94 struct task_struct *task = up->task;
95 u8 *tramp = up->atramp.tramp;
96 enum { call_relative_opcode = 0xe8 };
98 if (!read_proc_vm_atomic(task, (unsigned long)p->addr,
99 tramp, MAX_INSN_SIZE)) {
100 printk(KERN_ERR "failed to read memory %p!\n", p->addr);
103 /* TODO: this is a workaround */
104 if (tramp[0] == call_relative_opcode) {
105 printk(KERN_INFO "cannot install probe: 1st instruction is call\n");
109 tramp[UPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
111 /* TODO: remove dual info */
112 p->opcode = tramp[0];
114 p->ainsn.boostable = swap_can_boost(tramp) ? 0 : -1;
116 p->ainsn.insn = swap_slot_alloc(up->sm);
117 if (p->ainsn.insn == NULL) {
118 printk(KERN_ERR "trampoline out of memory\n");
122 if (!write_proc_vm_atomic(task, (unsigned long)p->ainsn.insn,
123 tramp, sizeof(up->atramp.tramp))) {
124 swap_slot_free(up->sm, p->ainsn.insn);
125 printk(KERN_INFO "failed to write memory %p!\n", tramp);
133 * @brief Jump pre-handler.
135 * @param p Pointer to the uprobe's kprobe.
136 * @param regs Pointer to CPU register data.
139 int setjmp_upre_handler(struct kprobe *p, struct pt_regs *regs)
141 struct uprobe *up = container_of(p, struct uprobe, kp);
142 struct ujprobe *jp = container_of(up, struct ujprobe, up);
143 kprobe_pre_entry_handler_t pre_entry =
144 (kprobe_pre_entry_handler_t)jp->pre_entry;
145 entry_point_t entry = (entry_point_t)jp->entry;
146 unsigned long args[6];
148 /* FIXME some user space apps crash if we clean interrupt bit */
149 /* regs->EREG(flags) &= ~IF_MASK; */
150 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 18)
151 trace_hardirqs_off();
154 /* read first 6 args from stack */
155 if (!read_proc_vm_atomic(current, regs->EREG(sp) + 4,
158 "failed to read user space func arguments %lx!\n",
162 p->ss_addr[smp_processor_id()] = (kprobe_opcode_t *)
163 pre_entry(jp->priv_arg, regs);
166 entry(args[0], args[1], args[2], args[3], args[4], args[5]);
168 arch_ujprobe_return();
174 * @brief Prepares uretprobe for x86.
176 * @param ri Pointer to the uretprobe instance.
177 * @param regs Pointer to CPU register data.
180 int arch_prepare_uretprobe(struct uretprobe_instance *ri, struct pt_regs *regs)
182 /* Replace the return addr with trampoline addr */
183 unsigned long ra = trampoline_addr(&ri->rp->up);
184 ri->sp = (kprobe_opcode_t *)regs->sp;
186 if (!read_proc_vm_atomic(current, regs->EREG(sp), &(ri->ret_addr),
187 sizeof(ri->ret_addr))) {
188 printk(KERN_ERR "failed to read user space func ra %lx addr=%p!\n",
189 regs->EREG(sp), ri->rp->up.kp.addr);
193 if (!write_proc_vm_atomic(current, regs->EREG(sp), &ra, sizeof(ra))) {
194 printk(KERN_ERR "failed to write user space func ra %lx!\n",
199 add_uprobe_table(&ri->rp->up.kp);
205 * @brief Disarms uretprobe on x86 arch.
207 * @param ri Pointer to the uretprobe instance.
208 * @param task Pointer to the task for which the probe.
209 * @return 0 on success,\n
210 * negative error code on error.
212 int arch_disarm_urp_inst(struct uretprobe_instance *ri,
213 struct task_struct *task)
216 unsigned long ret_addr;
217 unsigned long sp = (unsigned long)ri->sp;
218 unsigned long tramp_addr = trampoline_addr(&ri->rp->up);
219 len = read_proc_vm_atomic(task, sp, &ret_addr, sizeof(ret_addr));
220 if (len != sizeof(ret_addr)) {
221 printk(KERN_INFO "---> %s (%d/%d): failed to read stack from %08lx\n",
222 task->comm, task->tgid, task->pid, sp);
226 if (tramp_addr == ret_addr) {
227 len = write_proc_vm_atomic(task, sp, &ri->ret_addr,
228 sizeof(ri->ret_addr));
229 if (len != sizeof(ri->ret_addr)) {
230 printk(KERN_INFO "---> %s (%d/%d): failed to write "
231 "orig_ret_addr to %08lx",
232 task->comm, task->tgid, task->pid, sp);
236 printk(KERN_INFO "---> %s (%d/%d): trampoline NOT found at sp = %08lx\n",
237 task->comm, task->tgid, task->pid, sp);
245 * @brief Gets trampoline address.
247 * @param p Pointer to the uprobe's kprobe.
248 * @param regs Pointer to CPU register data.
249 * @return Trampoline address.
251 unsigned long arch_get_trampoline_addr(struct kprobe *p, struct pt_regs *regs)
253 return trampoline_addr(kp2up(p));
257 * @brief Restores return address.
259 * @param orig_ret_addr Original return address.
260 * @param regs Pointer to CPU register data.
263 void arch_set_orig_ret_addr(unsigned long orig_ret_addr, struct pt_regs *regs)
265 regs->EREG(ip) = orig_ret_addr;
269 * @brief Removes uprobe.
271 * @param up Pointer to the target uprobe.
274 void arch_remove_uprobe(struct uprobe *up)
276 struct kprobe *p = up2kp(up);
278 swap_slot_free(up->sm, p->ainsn.insn);
281 static void set_user_jmp_op(void *from, void *to)
283 struct __arch_jmp_op {
288 jop.raddr = (long)(to) - ((long)(from) + 5);
289 jop.op = RELATIVEJUMP_INSTRUCTION;
291 if (!write_proc_vm_atomic(current, (unsigned long)from, &jop,
294 "failed to write jump opcode to user space %p\n", from);
297 static void resume_execution(struct kprobe *p,
298 struct pt_regs *regs,
301 unsigned long *tos, tos_dword = 0;
302 unsigned long copy_eip = (unsigned long)p->ainsn.insn;
303 unsigned long orig_eip = (unsigned long)p->addr;
304 kprobe_opcode_t insns[2];
306 regs->EREG(flags) &= ~TF_MASK;
308 tos = (unsigned long *)&tos_dword;
309 if (!read_proc_vm_atomic(current, regs->EREG(sp), &tos_dword,
310 sizeof(tos_dword))) {
312 "failed to read dword from top of the user space stack %lx!\n",
317 if (!read_proc_vm_atomic(current, (unsigned long)p->ainsn.insn, insns,
318 2 * sizeof(kprobe_opcode_t))) {
320 "failed to read first 2 opcodes of instruction copy from user space %p!\n",
326 case 0x9c: /* pushfl */
327 *tos &= ~(TF_MASK | IF_MASK);
328 *tos |= flags & (TF_MASK | IF_MASK);
330 case 0xc2: /* iret/ret/lret */
335 case 0xea: /* jmp absolute -- eip is correct */
336 /* eip is already adjusted, no more changes required */
337 p->ainsn.boostable = 1;
339 case 0xe8: /* call relative - Fix return addr */
340 *tos = orig_eip + (*tos - copy_eip);
342 case 0x9a: /* call absolute -- same as call absolute, indirect */
343 *tos = orig_eip + (*tos - copy_eip);
345 if (!write_proc_vm_atomic(current,
348 sizeof(tos_dword))) {
350 "failed to write dword to top of the user space stack %lx!\n",
357 if ((insns[1] & 0x30) == 0x10) {
359 * call absolute, indirect
360 * Fix return addr; eip is correct.
361 * But this is not boostable
363 *tos = orig_eip + (*tos - copy_eip);
365 if (!write_proc_vm_atomic(current, regs->EREG(sp),
367 sizeof(tos_dword))) {
369 "failed to write dword to top of the user space stack %lx!\n",
375 } else if (((insns[1] & 0x31) == 0x20) || /* jmp near, absolute
377 ((insns[1] & 0x31) == 0x21)) {
378 /* jmp far, absolute indirect */
379 /* eip is correct. And this is boostable */
380 p->ainsn.boostable = 1;
384 if (insns[1] == 0xc3)
385 /* repz ret special handling: no more changes */
392 if (!write_proc_vm_atomic(current, regs->EREG(sp), &tos_dword,
393 sizeof(tos_dword))) {
395 "failed to write dword to top of the user space stack %lx!\n",
400 if (p->ainsn.boostable == 0) {
401 if ((regs->EREG(ip) > copy_eip) && (regs->EREG(ip) - copy_eip) +
404 * These instructions can be executed directly if it
405 * jumps back to correct address.
407 set_user_jmp_op((void *) regs->EREG(ip),
409 (regs->EREG(ip) - copy_eip));
410 p->ainsn.boostable = 1;
412 p->ainsn.boostable = -1;
416 regs->EREG(ip) = orig_eip + (regs->EREG(ip) - copy_eip);
422 static bool prepare_ss_addr(struct kprobe *p, struct pt_regs *regs)
424 unsigned long *ss_addr = (long *)&p->ss_addr[smp_processor_id()];
431 regs->ip = (unsigned long)p->ainsn.insn;
436 static void prepare_ss(struct pt_regs *regs)
438 /* set single step mode */
439 regs->flags |= TF_MASK;
440 regs->flags &= ~IF_MASK;
443 static int uprobe_handler(struct pt_regs *regs)
446 kprobe_opcode_t *addr;
447 struct task_struct *task = current;
448 pid_t tgid = task->tgid;
450 save_current_flags(regs);
452 addr = (kprobe_opcode_t *)(regs->EREG(ip) - sizeof(kprobe_opcode_t));
453 p = get_ukprobe(addr, tgid);
456 void *tramp_addr = (void *)addr - UPROBES_TRAMP_RET_BREAK_IDX;
458 p = get_ukprobe_by_insn_slot(tramp_addr, tgid, regs);
460 printk(KERN_INFO "no_uprobe\n");
464 trampoline_uprobe_handler(p, regs);
467 if (!p->pre_handler || !p->pre_handler(p, regs)) {
468 if (p->ainsn.boostable == 1 && !p->post_handler) {
469 prepare_ss_addr(p, regs);
473 if (prepare_ss_addr(p, regs) == false) {
474 set_current_probe(p);
483 static int post_uprobe_handler(struct pt_regs *regs)
485 struct kprobe *p = get_current_probe();
486 unsigned long flags = current_ucb()->flags;
489 printk("task[%u %u %s] current uprobe is not found\n",
490 current->tgid, current->pid, current->comm);
494 resume_execution(p, regs, flags);
495 restore_current_flags(regs, flags);
498 current_ucb()->p = 0;
499 current_ucb()->flags = 0;
504 static int uprobe_exceptions_notify(struct notifier_block *self,
505 unsigned long val, void *data)
507 struct die_args *args = (struct die_args *)data;
508 int ret = NOTIFY_DONE;
510 if (args->regs == NULL || !user_mode_vm(args->regs))
514 #ifdef CONFIG_KPROBES
519 if (uprobe_handler(args->regs))
523 if (post_uprobe_handler(args->regs))
533 static struct notifier_block uprobe_exceptions_nb = {
534 .notifier_call = uprobe_exceptions_notify,
539 * @brief Registers notify.
541 * @return register_die_notifier result.
543 int swap_arch_init_uprobes(void)
545 return register_die_notifier(&uprobe_exceptions_nb);
549 * @brief Unregisters notify.
553 void swap_arch_exit_uprobes(void)
555 unregister_die_notifier(&uprobe_exceptions_nb);