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 DEFINE_PER_CPU(struct uprobe_ctlblk, ucb) = { 0, NULL };
59 static struct kprobe *get_current_probe(void)
61 return __get_cpu_var(ucb).p;
64 static void set_current_probe(struct kprobe *p)
66 __get_cpu_var(ucb).p = p;
69 static void reset_current_probe(void)
71 set_current_probe(NULL);
74 static void save_current_flags(struct pt_regs *regs)
76 __get_cpu_var(ucb).flags = regs->EREG(flags);
79 static void restore_current_flags(struct pt_regs *regs)
81 regs->EREG(flags) &= ~IF_MASK;
82 regs->EREG(flags) |= __get_cpu_var(ucb).flags & IF_MASK;
86 * @brief Prepares uprobe for x86.
88 * @param up Pointer to the uprobe.
89 * @return 0 on success,\n
92 int arch_prepare_uprobe(struct uprobe *up)
95 struct kprobe *p = up2kp(up);
96 struct task_struct *task = up->task;
97 u8 *tramp = up->atramp.tramp;
98 enum { call_relative_opcode = 0xe8 };
100 if (!read_proc_vm_atomic(task, (unsigned long)p->addr,
101 tramp, MAX_INSN_SIZE))
102 panic("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;
120 * @brief Jump pre-handler.
122 * @param p Pointer to the uprobe's kprobe.
123 * @param regs Pointer to CPU register data.
126 int setjmp_upre_handler(struct kprobe *p, struct pt_regs *regs)
128 struct uprobe *up = container_of(p, struct uprobe, kp);
129 struct ujprobe *jp = container_of(up, struct ujprobe, up);
130 kprobe_pre_entry_handler_t pre_entry =
131 (kprobe_pre_entry_handler_t)jp->pre_entry;
132 entry_point_t entry = (entry_point_t)jp->entry;
133 unsigned long args[6];
135 /* FIXME some user space apps crash if we clean interrupt bit */
136 /* regs->EREG(flags) &= ~IF_MASK; */
137 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 18)
138 trace_hardirqs_off();
141 /* read first 6 args from stack */
142 if (!read_proc_vm_atomic(current, regs->EREG(sp) + 4,
144 panic("failed to read user space func arguments %lx!\n",
148 p->ss_addr[smp_processor_id()] = (kprobe_opcode_t *)
149 pre_entry(jp->priv_arg, regs);
152 entry(args[0], args[1], args[2], args[3], args[4], args[5]);
154 arch_ujprobe_return();
160 * @brief Prepares uretprobe for x86.
162 * @param ri Pointer to the uretprobe instance.
163 * @param regs Pointer to CPU register data.
166 void arch_prepare_uretprobe(struct uretprobe_instance *ri, struct pt_regs *regs)
168 /* Replace the return addr with trampoline addr */
169 unsigned long ra = trampoline_addr(&ri->rp->up);
170 ri->sp = (kprobe_opcode_t *)regs->sp;
172 if (!read_proc_vm_atomic(current, regs->EREG(sp), &(ri->ret_addr),
173 sizeof(ri->ret_addr)))
174 panic("failed to read user space func ra %lx!\n",
177 if (!write_proc_vm_atomic(current, regs->EREG(sp), &ra, sizeof(ra)))
178 panic("failed to write user space func ra %lx!\n",
183 * @brief Disarms uretprobe on x86 arch.
185 * @param ri Pointer to the uretprobe instance.
186 * @param task Pointer to the task for which the probe.
187 * @return 0 on success,\n
188 * negative error code on error.
190 int arch_disarm_urp_inst(struct uretprobe_instance *ri,
191 struct task_struct *task)
194 unsigned long ret_addr;
195 unsigned long sp = (unsigned long)ri->sp;
196 unsigned long tramp_addr = trampoline_addr(&ri->rp->up);
197 len = read_proc_vm_atomic(task, sp, &ret_addr, sizeof(ret_addr));
198 if (len != sizeof(ret_addr)) {
199 printk(KERN_INFO "---> %s (%d/%d): failed to read stack from %08lx\n",
200 task->comm, task->tgid, task->pid, sp);
204 if (tramp_addr == ret_addr) {
205 len = write_proc_vm_atomic(task, sp, &ri->ret_addr,
206 sizeof(ri->ret_addr));
207 if (len != sizeof(ri->ret_addr)) {
208 printk(KERN_INFO "---> %s (%d/%d): failed to write "
209 "orig_ret_addr to %08lx",
210 task->comm, task->tgid, task->pid, sp);
214 printk(KERN_INFO "---> %s (%d/%d): trampoline NOT found at sp = %08lx\n",
215 task->comm, task->tgid, task->pid, sp);
223 * @brief Gets trampoline address.
225 * @param p Pointer to the uprobe's kprobe.
226 * @param regs Pointer to CPU register data.
227 * @return Trampoline address.
229 unsigned long arch_get_trampoline_addr(struct kprobe *p, struct pt_regs *regs)
231 return trampoline_addr(kp2up(p));
235 * @brief Restores return address.
237 * @param orig_ret_addr Original return address.
238 * @param regs Pointer to CPU register data.
241 void arch_set_orig_ret_addr(unsigned long orig_ret_addr, struct pt_regs *regs)
243 regs->EREG(ip) = orig_ret_addr;
247 * @brief Removes uprobe.
249 * @param up Pointer to the target uprobe.
252 void arch_remove_uprobe(struct uprobe *up)
254 struct kprobe *p = up2kp(up);
256 swap_slot_free(up->sm, p->ainsn.insn);
259 static void set_user_jmp_op(void *from, void *to)
261 struct __arch_jmp_op {
266 jop.raddr = (long)(to) - ((long)(from) + 5);
267 jop.op = RELATIVEJUMP_INSTRUCTION;
269 if (!write_proc_vm_atomic(current, (unsigned long)from, &jop,
271 panic("failed to write jump opcode to user space %p!\n", from);
274 static void resume_execution(struct kprobe *p,
275 struct pt_regs *regs,
278 unsigned long *tos, tos_dword = 0;
279 unsigned long copy_eip = (unsigned long)p->ainsn.insn;
280 unsigned long orig_eip = (unsigned long)p->addr;
281 kprobe_opcode_t insns[2];
283 regs->EREG(flags) &= ~TF_MASK;
285 tos = (unsigned long *)&tos_dword;
286 if (!read_proc_vm_atomic(current, regs->EREG(sp), &tos_dword,
288 panic("failed to read dword from top of the user space stack "
289 "%lx!\n", regs->EREG(sp));
291 if (!read_proc_vm_atomic(current, (unsigned long)p->ainsn.insn, insns,
292 2 * sizeof(kprobe_opcode_t)))
293 panic("failed to read first 2 opcodes of instruction copy "
294 "from user space %p!\n", p->ainsn.insn);
297 case 0x9c: /* pushfl */
298 *tos &= ~(TF_MASK | IF_MASK);
299 *tos |= flags & (TF_MASK | IF_MASK);
301 case 0xc2: /* iret/ret/lret */
306 case 0xea: /* jmp absolute -- eip is correct */
307 /* eip is already adjusted, no more changes required */
308 p->ainsn.boostable = 1;
310 case 0xe8: /* call relative - Fix return addr */
311 *tos = orig_eip + (*tos - copy_eip);
313 case 0x9a: /* call absolute -- same as call absolute, indirect */
314 *tos = orig_eip + (*tos - copy_eip);
316 if (!write_proc_vm_atomic(current,
320 panic("failed to write dword to top of the"
321 " user space stack %lx!\n",
326 if ((insns[1] & 0x30) == 0x10) {
328 * call absolute, indirect
329 * Fix return addr; eip is correct.
330 * But this is not boostable
332 *tos = orig_eip + (*tos - copy_eip);
334 if (!write_proc_vm_atomic(current, regs->EREG(sp),
337 panic("failed to write dword to top of the "
338 "user space stack %lx!\n",
342 } else if (((insns[1] & 0x31) == 0x20) || /* jmp near, absolute
344 ((insns[1] & 0x31) == 0x21)) {
345 /* jmp far, absolute indirect */
346 /* eip is correct. And this is boostable */
347 p->ainsn.boostable = 1;
351 if (insns[1] == 0xc3)
352 /* repz ret special handling: no more changes */
359 if (!write_proc_vm_atomic(current, regs->EREG(sp), &tos_dword,
361 panic("failed to write dword to top of the user space stack "
362 "%lx!\n", regs->EREG(sp));
364 if (p->ainsn.boostable == 0) {
365 if ((regs->EREG(ip) > copy_eip) && (regs->EREG(ip) - copy_eip) +
368 * These instructions can be executed directly if it
369 * jumps back to correct address.
371 set_user_jmp_op((void *) regs->EREG(ip),
373 (regs->EREG(ip) - copy_eip));
374 p->ainsn.boostable = 1;
376 p->ainsn.boostable = -1;
380 regs->EREG(ip) = orig_eip + (regs->EREG(ip) - copy_eip);
386 static int make_trampoline(struct uprobe *up)
388 struct kprobe *p = up2kp(up);
389 struct task_struct *task = up->task;
392 tramp = swap_slot_alloc(up->sm);
394 printk(KERN_INFO "trampoline out of memory\n");
398 if (!write_proc_vm_atomic(task, (unsigned long)tramp,
400 sizeof(up->atramp.tramp))) {
401 swap_slot_free(up->sm, tramp);
402 panic("failed to write memory %p!\n", tramp);
406 p->ainsn.insn = tramp;
411 static int uprobe_handler(struct pt_regs *regs)
414 kprobe_opcode_t *addr;
415 struct task_struct *task = current;
416 pid_t tgid = task->tgid;
418 save_current_flags(regs);
420 addr = (kprobe_opcode_t *)(regs->EREG(ip) - sizeof(kprobe_opcode_t));
421 p = get_ukprobe(addr, tgid);
424 void *tramp_addr = (void *)addr - UPROBES_TRAMP_RET_BREAK_IDX;
426 p = get_ukprobe_by_insn_slot(tramp_addr, tgid, regs);
428 printk(KERN_INFO "no_uprobe\n");
432 trampoline_uprobe_handler(p, regs);
435 if (p->ainsn.insn == NULL) {
436 struct uprobe *up = kp2up(p);
444 if (!p->pre_handler || !p->pre_handler(p, regs)) {
446 if (p->ainsn.boostable == 1 && !p->post_handler) {
447 if (p->ss_addr[smp_processor_id()]) {
448 regs->EREG(ip) = (unsigned long)p->ss_addr[smp_processor_id()];
449 p->ss_addr[smp_processor_id()] = NULL;
451 regs->EREG(ip) = (unsigned long)p->ainsn.insn;
456 prepare_singlestep(p, regs);
460 set_current_probe(p);
465 static int post_uprobe_handler(struct pt_regs *regs)
467 struct kprobe *p = get_current_probe();
468 unsigned long flags = __get_cpu_var(ucb).flags;
473 resume_execution(p, regs, flags);
474 restore_current_flags(regs);
476 reset_current_probe();
481 static int uprobe_exceptions_notify(struct notifier_block *self,
482 unsigned long val, void *data)
484 struct die_args *args = (struct die_args *)data;
485 int ret = NOTIFY_DONE;
487 if (args->regs == NULL || !user_mode_vm(args->regs))
491 #ifdef CONFIG_KPROBES
496 if (uprobe_handler(args->regs))
500 if (post_uprobe_handler(args->regs))
510 static struct notifier_block uprobe_exceptions_nb = {
511 .notifier_call = uprobe_exceptions_notify,
516 * @brief Registers notify.
518 * @return register_die_notifier result.
520 int swap_arch_init_uprobes(void)
522 return register_die_notifier(&uprobe_exceptions_nb);
526 * @brief Unregisters notify.
530 void swap_arch_exit_uprobes(void)
532 unregister_die_notifier(&uprobe_exceptions_nb);