uprobe/arch/asm-x86/swap_uprobes.c

   1 /*
   2  *  Dynamic Binary Instrumentation Module based on KProbes
   3  *  modules/uprobe/arch/asm-x86/swap_uprobes.c
   4  *
   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.
   9  *
  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.
  14  *
  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.
  18  *
  19  * Copyright (C) Samsung Electronics, 2006-2010
  20  *
  21  * 2008-2009    Alexey Gerenkov <a.gerenkov@samsung.com> User-Space
  22  *              Probes initial implementation; Support x86/ARM/MIPS for both user and kernel spaces.
  23  * 2010         Ekaterina Gorelkina <e.gorelkina@samsung.com>: redesign module for separating core and arch parts
  24  *
  25  */
  26
  27 #include <linux/kdebug.h>
  28 #include <kprobe/arch/asm/dbi_kprobes.h>
  29 #include <uprobe/swap_uprobes.h>
  30 #include <uprobe/arch/asm/swap_uprobes.h>
  31 #include <kprobe/dbi_insn_slots.h>
  32
  33 struct uprobe_ctlblk {
  34         unsigned long flags;
  35         struct kprobe *p;
  36 };
  37
  38 static unsigned long trampoline_addr(struct uprobe *up)
  39 {
  40         return (unsigned long)(up->kp.ainsn.insn +
  41                                UPROBES_TRAMP_RET_BREAK_IDX);
  42 }
  43
  44 static DEFINE_PER_CPU(struct uprobe_ctlblk, ucb) = { 0, NULL };
  45
  46 static struct kprobe *get_current_probe(void)
  47 {
  48         return __get_cpu_var(ucb).p;
  49 }
  50
  51 static void set_current_probe(struct kprobe *p)
  52 {
  53         __get_cpu_var(ucb).p = p;
  54 }
  55
  56 static void reset_current_probe(void)
  57 {
  58         set_current_probe(NULL);
  59 }
  60
  61 static void save_current_flags(struct pt_regs *regs)
  62 {
  63         __get_cpu_var(ucb).flags = regs->EREG(flags);
  64 }
  65
  66 static void restore_current_flags(struct pt_regs *regs)
  67 {
  68         regs->EREG(flags) &= ~IF_MASK;
  69         regs->EREG(flags) |= __get_cpu_var(ucb).flags & IF_MASK;
  70 }
  71
  72 int arch_prepare_uprobe(struct uprobe *up)
  73 {
  74         int ret = 0;
  75         struct kprobe *p = up2kp(up);
  76         struct task_struct *task = up->task;
  77         u8 *tramp = up->atramp.tramp;
  78
  79         if (!read_proc_vm_atomic(task, (unsigned long)p->addr,
  80                                  tramp, MAX_INSN_SIZE))
  81                 panic("failed to read memory %p!\n", p->addr);
  82
  83         tramp[UPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
  84
  85         /* TODO: remove dual info */
  86         p->opcode = tramp[0];
  87
  88         p->ainsn.boostable = can_boost(tramp) ? 0 : -1;
  89
  90         return ret;
  91 }
  92
  93 int setjmp_upre_handler(struct kprobe *p, struct pt_regs *regs)
  94 {
  95         struct uprobe *up = container_of(p, struct uprobe, kp);
  96         struct ujprobe *jp = container_of(up, struct ujprobe, up);
  97         kprobe_pre_entry_handler_t pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
  98         entry_point_t entry = (entry_point_t)jp->entry;
  99         unsigned long args[6];
 100
 101         /* FIXME some user space apps crash if we clean interrupt bit */
 102         //regs->EREG(flags) &= ~IF_MASK;
 103 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 18)
 104         trace_hardirqs_off();
 105 #endif
 106
 107         /* read first 6 args from stack */
 108         if (!read_proc_vm_atomic(current, regs->EREG(sp) + 4, args, sizeof(args)))
 109                 panic("failed to read user space func arguments %lx!\n", regs->EREG(sp) + 4);
 110
 111         if (pre_entry)
 112                 p->ss_addr = (kprobe_opcode_t *)pre_entry(jp->priv_arg, regs);
 113
 114         if (entry)
 115                 entry(args[0], args[1], args[2], args[3], args[4], args[5]);
 116         else
 117                 arch_ujprobe_return();
 118
 119         return 0;
 120 }
 121
 122 void arch_prepare_uretprobe(struct uretprobe_instance *ri, struct pt_regs *regs)
 123 {
 124         /* Replace the return addr with trampoline addr */
 125         unsigned long ra = trampoline_addr(&ri->rp->up);
 126         ri->sp = (kprobe_opcode_t *)regs->sp;
 127
 128         if (!read_proc_vm_atomic(current, regs->EREG(sp), &(ri->ret_addr), sizeof(ri->ret_addr)))
 129                 panic("failed to read user space func ra %lx!\n", regs->EREG(sp));
 130
 131         if (!write_proc_vm_atomic(current, regs->EREG(sp), &ra, sizeof(ra)))
 132                 panic("failed to write user space func ra %lx!\n", regs->EREG(sp));
 133 }
 134
 135 int arch_disarm_urp_inst(struct uretprobe_instance *ri,
 136                          struct task_struct *task)
 137 {
 138         int len;
 139         unsigned long ret_addr;
 140         unsigned long sp = (unsigned long)ri->sp;
 141         unsigned long tramp_addr = trampoline_addr(&ri->rp->up);
 142         len = read_proc_vm_atomic(task, sp, &ret_addr, sizeof(ret_addr));
 143         if (len != sizeof(ret_addr)) {
 144                 printk("---> %s (%d/%d): failed to read stack from %08lx\n",
 145                        task->comm, task->tgid, task->pid, sp);
 146                 return -EFAULT;
 147         }
 148
 149         if (tramp_addr == ret_addr) {
 150                 len = write_proc_vm_atomic(task, sp, &ri->ret_addr,
 151                                            sizeof(ri->ret_addr));
 152                 if (len != sizeof(ri->ret_addr)) {
 153                         printk("---> %s (%d/%d): failed to write "
 154                                "orig_ret_addr to %08lx",
 155                                task->comm, task->tgid, task->pid, sp);
 156                         return -EFAULT;
 157                 }
 158         } else {
 159                 printk("---> %s (%d/%d): trampoline NOT found at sp = %08lx\n",
 160                        task->comm, task->tgid, task->pid, sp);
 161                 return -ENOENT;
 162         }
 163
 164         return 0;
 165 }
 166
 167 unsigned long arch_get_trampoline_addr(struct kprobe *p, struct pt_regs *regs)
 168 {
 169         return trampoline_addr(kp2up(p));
 170 }
 171
 172 void arch_set_orig_ret_addr(unsigned long orig_ret_addr, struct pt_regs *regs)
 173 {
 174         regs->EREG(ip) = orig_ret_addr;
 175 }
 176
 177 static void set_user_jmp_op(void *from, void *to)
 178 {
 179         struct __arch_jmp_op
 180         {
 181                 char op;
 182                 long raddr;
 183         } __attribute__ ((packed)) jop;
 184
 185         jop.raddr = (long)(to) - ((long)(from) + 5);
 186         jop.op = RELATIVEJUMP_INSTRUCTION;
 187
 188         if (!write_proc_vm_atomic(current, (unsigned long)from, &jop, sizeof(jop)))
 189                 panic("failed to write jump opcode to user space %p!\n", from);
 190 }
 191
 192 static void resume_execution(struct kprobe *p, struct pt_regs *regs, unsigned long flags)
 193 {
 194         unsigned long *tos, tos_dword = 0;
 195         unsigned long copy_eip = (unsigned long)p->ainsn.insn;
 196         unsigned long orig_eip = (unsigned long)p->addr;
 197         kprobe_opcode_t insns[2];
 198
 199         regs->EREG(flags) &= ~TF_MASK;
 200
 201         tos = (unsigned long *)&tos_dword;
 202         if (!read_proc_vm_atomic(current, regs->EREG(sp), &tos_dword, sizeof(tos_dword)))
 203                 panic("failed to read dword from top of the user space stack %lx!\n", regs->EREG(sp));
 204
 205         if (!read_proc_vm_atomic(current, (unsigned long)p->ainsn.insn, insns, 2 * sizeof(kprobe_opcode_t)))
 206                 panic("failed to read first 2 opcodes of instruction copy from user space %p!\n", p->ainsn.insn);
 207
 208         switch (insns[0]) {
 209                 case 0x9c:              /* pushfl */
 210                         *tos &= ~(TF_MASK | IF_MASK);
 211                         *tos |= flags & (TF_MASK | IF_MASK);
 212                         break;
 213                 case 0xc2:              /* iret/ret/lret */
 214                 case 0xc3:
 215                 case 0xca:
 216                 case 0xcb:
 217                 case 0xcf:
 218                 case 0xea:              /* jmp absolute -- eip is correct */
 219                         /* eip is already adjusted, no more changes required */
 220                         p->ainsn.boostable = 1;
 221                         goto no_change;
 222                 case 0xe8:              /* call relative - Fix return addr */
 223                         *tos = orig_eip + (*tos - copy_eip);
 224                         break;
 225                 case 0x9a:              /* call absolute -- same as call absolute, indirect */
 226                         *tos = orig_eip + (*tos - copy_eip);
 227
 228                         if (!write_proc_vm_atomic(current, regs->EREG (sp), &tos_dword, sizeof(tos_dword)))
 229                                 panic("failed to write dword to top of the user space stack %lx!\n", regs->EREG (sp));
 230
 231                         goto no_change;
 232                 case 0xff:
 233                         if ((insns[1] & 0x30) == 0x10) {
 234                                 /*
 235                                  * call absolute, indirect
 236                                  * Fix return addr; eip is correct.
 237                                  * But this is not boostable
 238                                  */
 239                                 *tos = orig_eip + (*tos - copy_eip);
 240
 241                                 if (!write_proc_vm_atomic(current, regs->EREG(sp), &tos_dword, sizeof(tos_dword)))
 242                                         panic("failed to write dword to top of the user space stack %lx!\n", regs->EREG(sp));
 243
 244                                 goto no_change;
 245                         } else if (((insns[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
 246                                    ((insns[1] & 0x31) == 0x21)) {
 247                                 /* jmp far, absolute indirect */
 248                                 /* eip is correct. And this is boostable */
 249                                 p->ainsn.boostable = 1;
 250                                 goto no_change;
 251                         }
 252                 default:
 253                         break;
 254         }
 255
 256         if (!write_proc_vm_atomic(current, regs->EREG(sp), &tos_dword, sizeof(tos_dword)))
 257                 panic("failed to write dword to top of the user space stack %lx!\n", regs->EREG(sp));
 258
 259         if (p->ainsn.boostable == 0) {
 260                 if ((regs->EREG(ip) > copy_eip) && (regs->EREG(ip) - copy_eip) + 5 < MAX_INSN_SIZE) {
 261                         /*
 262                          * These instructions can be executed directly if it
 263                          * jumps back to correct address.
 264                          */
 265                         set_user_jmp_op((void *) regs->EREG(ip), (void *)orig_eip + (regs->EREG(ip) - copy_eip));
 266                         p->ainsn.boostable = 1;
 267                 } else {
 268                         p->ainsn.boostable = -1;
 269                 }
 270         }
 271
 272         regs->EREG(ip) = orig_eip + (regs->EREG(ip) - copy_eip);
 273
 274 no_change:
 275         return;
 276 }
 277
 278 static int make_trampoline(struct uprobe *up)
 279 {
 280         struct kprobe *p = up2kp(up);
 281         struct task_struct *task = up->task;
 282         void *tramp;
 283
 284         tramp = alloc_insn_slot(up->sm);
 285         if (tramp == 0) {
 286                 printk("trampoline out of memory\n");
 287                 return -ENOMEM;
 288         }
 289
 290         if (!write_proc_vm_atomic(task, (unsigned long)tramp,
 291                                   up->atramp.tramp,
 292                                   sizeof(up->atramp.tramp))) {
 293                 free_insn_slot(up->sm, tramp);
 294                 panic("failed to write memory %p!\n", tramp);
 295                 return -EINVAL;
 296         }
 297
 298         p->ainsn.insn = tramp;
 299
 300         return 0;
 301 }
 302
 303 static int uprobe_handler(struct pt_regs *regs)
 304 {
 305         struct kprobe *p;
 306         kprobe_opcode_t *addr;
 307         struct task_struct *task = current;
 308         pid_t tgid = task->tgid;
 309
 310         save_current_flags(regs);
 311
 312         addr = (kprobe_opcode_t *)(regs->EREG(ip) - sizeof(kprobe_opcode_t));
 313         p = get_ukprobe(addr, tgid);
 314
 315         if (p == NULL) {
 316                 void *tramp_addr = (void *)addr - UPROBES_TRAMP_RET_BREAK_IDX;
 317
 318                 p = get_ukprobe_by_insn_slot(tramp_addr, tgid, regs);
 319                 if (p == NULL) {
 320                         printk("no_uprobe\n");
 321                         return 0;
 322                 }
 323
 324                 trampoline_uprobe_handler(p, regs);
 325                 return 1;
 326         } else {
 327                 if (p->ainsn.insn == NULL) {
 328                         struct uprobe *up = kp2up(p);
 329
 330                         make_trampoline(up);
 331
 332                         /* for uretprobe */
 333                         add_uprobe_table(p);
 334                 }
 335
 336                 if (!p->pre_handler || !p->pre_handler(p, regs)) {
 337                         if (p->ainsn.boostable == 1 && !p->post_handler) {
 338                                 regs->EREG(ip) = (unsigned long)p->ainsn.insn;
 339                                 return 1;
 340                         }
 341
 342                         prepare_singlestep(p, regs);
 343                 }
 344         }
 345
 346         set_current_probe(p);
 347
 348         return 1;
 349 }
 350
 351 static int post_uprobe_handler(struct pt_regs *regs)
 352 {
 353         struct kprobe *p = get_current_probe();
 354         unsigned long flags = __get_cpu_var(ucb).flags;
 355
 356         if (p == NULL)
 357                 return 0;
 358
 359         resume_execution(p, regs, flags);
 360         restore_current_flags(regs);
 361
 362         reset_current_probe();
 363
 364         return 1;
 365 }
 366
 367 static int uprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data)
 368 {
 369         struct die_args *args = (struct die_args *)data;
 370         int ret = NOTIFY_DONE;
 371
 372         if (args->regs && !user_mode_vm(args->regs))
 373                 return ret;
 374
 375         switch (val) {
 376 #ifdef CONFIG_KPROBES
 377                 case DIE_INT3:
 378 #else
 379                 case DIE_TRAP:
 380 #endif
 381                         if (uprobe_handler(args->regs))
 382                                 ret = NOTIFY_STOP;
 383                         break;
 384                 case DIE_DEBUG:
 385                         if (post_uprobe_handler(args->regs))
 386                                 ret = NOTIFY_STOP;
 387                         break;
 388                 default:
 389                         break;
 390         }
 391
 392         return ret;
 393 }
 394
 395 static struct notifier_block uprobe_exceptions_nb = {
 396         .notifier_call = uprobe_exceptions_notify,
 397         .priority = INT_MAX
 398 };
 399
 400 int swap_arch_init_uprobes(void)
 401 {
 402         return register_die_notifier(&uprobe_exceptions_nb);
 403 }
 404
 405 void swap_arch_exit_uprobes(void)
 406 {
 407         unregister_die_notifier(&uprobe_exceptions_nb);
 408 }
 409