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 <asm/dbi_kprobes.h>
  29 #include <swap_uprobes.h>
  30 #include <asm/swap_uprobes.h>
  31 #include <dbi_insn_slots.h>
  32
  33 struct uprobe_ctlblk {
  34         unsigned long flags;
  35         struct kprobe *p;
  36 };
  37
  38 static DEFINE_PER_CPU(struct uprobe_ctlblk, ucb) = { 0, NULL };
  39
  40 int arch_prepare_uprobe(struct uprobe *up, struct hlist_head *page_list)
  41 {
  42         int ret = 0;
  43         struct kprobe *p = &up->kp;
  44         struct task_struct *task = up->task;
  45         kprobe_opcode_t insns[UPROBES_TRAMP_LEN];
  46
  47         if (!ret) {
  48                 kprobe_opcode_t insn[MAX_INSN_SIZE];
  49                 struct arch_specific_insn ainsn;
  50
  51                 if (!read_proc_vm_atomic(task, (unsigned long)p->addr, &insn, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
  52                         panic("failed to read memory %p!\n", p->addr);
  53
  54                 ainsn.insn = insn;
  55                 ret = arch_check_insn(&ainsn);
  56                 if (!ret) {
  57                         p->opcode = insn[0];
  58                         p->ainsn.insn = alloc_insn_slot(up->sm);
  59                         if (!p->ainsn.insn)
  60                                 return -ENOMEM;
  61
  62                         if (can_boost(insn))
  63                                 p->ainsn.boostable = 0;
  64                         else
  65                                 p->ainsn.boostable = -1;
  66
  67                         memcpy(&insns[UPROBES_TRAMP_INSN_IDX], insn, MAX_INSN_SIZE*sizeof(kprobe_opcode_t));
  68                         insns[UPROBES_TRAMP_RET_BREAK_IDX] = BREAKPOINT_INSTRUCTION;
  69
  70                         if (!write_proc_vm_atomic(task, (unsigned long)p->ainsn.insn, insns, sizeof(insns))) {
  71                                 free_insn_slot(up->sm, p->ainsn.insn);
  72                                 panic("failed to write memory %p!\n", p->ainsn.insn);
  73                                 return -EINVAL;
  74                         }
  75                 }
  76         }
  77
  78         return ret;
  79 }
  80
  81 int setjmp_upre_handler(struct kprobe *p, struct pt_regs *regs)
  82 {
  83         struct uprobe *up = container_of(p, struct uprobe, kp);
  84         struct ujprobe *jp = container_of(up, struct ujprobe, up);
  85         kprobe_pre_entry_handler_t pre_entry = (kprobe_pre_entry_handler_t)jp->pre_entry;
  86         entry_point_t entry = (entry_point_t)jp->entry;
  87         unsigned long addr, args[6];
  88
  89         /* FIXME some user space apps crash if we clean interrupt bit */
  90         //regs->EREG(flags) &= ~IF_MASK;
  91 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 18)
  92         trace_hardirqs_off();
  93 #endif
  94
  95         /* read first 6 args from stack */
  96         if (!read_proc_vm_atomic(current, regs->EREG(sp) + 4, args, sizeof(args)))
  97                 panic("failed to read user space func arguments %lx!\n", regs->EREG(sp) + 4);
  98
  99         if (pre_entry)
 100                 p->ss_addr = pre_entry(jp->priv_arg, regs);
 101
 102         if (entry)
 103                 entry(args[0], args[1], args[2], args[3], args[4], args[5]);
 104         else
 105                 arch_ujprobe_return();
 106
 107         return 0;
 108 }
 109
 110 void arch_prepare_uretprobe(struct uretprobe_instance *ri, struct pt_regs *regs)
 111 {
 112         /* Replace the return addr with trampoline addr */
 113         unsigned long ra = (unsigned long)(ri->rp->up.kp.ainsn.insn + UPROBES_TRAMP_RET_BREAK_IDX);
 114
 115         if (!read_proc_vm_atomic(current, regs->EREG(sp), &(ri->ret_addr), sizeof(ri->ret_addr)))
 116                 panic("failed to read user space func ra %lx!\n", regs->EREG(sp));
 117
 118         if (!write_proc_vm_atomic(current, regs->EREG(sp), &ra, sizeof(ra)))
 119                 panic("failed to write user space func ra %lx!\n", regs->EREG(sp));
 120 }
 121
 122 unsigned long arch_get_trampoline_addr(struct kprobe *p, struct pt_regs *regs)
 123 {
 124         return (unsigned long)(p->ainsn.insn + UPROBES_TRAMP_RET_BREAK_IDX);
 125 }
 126
 127 void arch_set_orig_ret_addr(unsigned long orig_ret_addr, struct pt_regs *regs)
 128 {
 129         regs->EREG(ip) = orig_ret_addr;
 130 }
 131
 132 static void set_user_jmp_op(void *from, void *to)
 133 {
 134         struct __arch_jmp_op
 135         {
 136                 char op;
 137                 long raddr;
 138         } __attribute__ ((packed)) jop;
 139
 140         jop.raddr = (long)(to) - ((long)(from) + 5);
 141         jop.op = RELATIVEJUMP_INSTRUCTION;
 142
 143         if (!write_proc_vm_atomic(current, (unsigned long)from, &jop, sizeof(jop)))
 144                 panic("failed to write jump opcode to user space %p!\n", from);
 145 }
 146
 147 static void resume_execution(struct kprobe *p, struct pt_regs *regs, unsigned long flags)
 148 {
 149         unsigned long *tos, tos_dword = 0;
 150         unsigned long copy_eip = (unsigned long)p->ainsn.insn;
 151         unsigned long orig_eip = (unsigned long)p->addr;
 152         kprobe_opcode_t insns[2];
 153
 154         regs->EREG(flags) &= ~TF_MASK;
 155
 156         tos = (unsigned long *)&tos_dword;
 157         if (!read_proc_vm_atomic(current, regs->EREG(sp), &tos_dword, sizeof(tos_dword)))
 158                 panic("failed to read dword from top of the user space stack %lx!\n", regs->EREG(sp));
 159
 160         if (!read_proc_vm_atomic(current, (unsigned long)p->ainsn.insn, insns, 2 * sizeof(kprobe_opcode_t)))
 161                 panic("failed to read first 2 opcodes of instruction copy from user space %p!\n", p->ainsn.insn);
 162
 163         switch (insns[0]) {
 164                 case 0x9c:              /* pushfl */
 165                         *tos &= ~(TF_MASK | IF_MASK);
 166                         *tos |= flags;
 167                         break;
 168                 case 0xc2:              /* iret/ret/lret */
 169                 case 0xc3:
 170                 case 0xca:
 171                 case 0xcb:
 172                 case 0xcf:
 173                 case 0xea:              /* jmp absolute -- eip is correct */
 174                         /* eip is already adjusted, no more changes required */
 175                         p->ainsn.boostable = 1;
 176                         goto no_change;
 177                 case 0xe8:              /* call relative - Fix return addr */
 178                         *tos = orig_eip + (*tos - copy_eip);
 179                         break;
 180                 case 0x9a:              /* call absolute -- same as call absolute, indirect */
 181                         *tos = orig_eip + (*tos - copy_eip);
 182
 183                         if (!write_proc_vm_atomic(current, regs->EREG (sp), &tos_dword, sizeof(tos_dword)))
 184                                 panic("failed to write dword to top of the user space stack %lx!\n", regs->EREG (sp));
 185
 186                         goto no_change;
 187                 case 0xff:
 188                         if ((insns[1] & 0x30) == 0x10) {
 189                                 /*
 190                                  * call absolute, indirect
 191                                  * Fix return addr; eip is correct.
 192                                  * But this is not boostable
 193                                  */
 194                                 *tos = orig_eip + (*tos - copy_eip);
 195
 196                                 if (!write_proc_vm_atomic(current, regs->EREG(sp), &tos_dword, sizeof(tos_dword)))
 197                                         panic("failed to write dword to top of the user space stack %lx!\n", regs->EREG(sp));
 198
 199                                 goto no_change;
 200                         } else if (((insns[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
 201                                    ((insns[1] & 0x31) == 0x21)) {
 202                                 /* jmp far, absolute indirect */
 203                                 /* eip is correct. And this is boostable */
 204                                 p->ainsn.boostable = 1;
 205                                 goto no_change;
 206                         }
 207                 default:
 208                         break;
 209         }
 210
 211         if (!write_proc_vm_atomic(current, regs->EREG(sp), &tos_dword, sizeof(tos_dword)))
 212                 panic("failed to write dword to top of the user space stack %lx!\n", regs->EREG(sp));
 213
 214         if (p->ainsn.boostable == 0) {
 215                 if ((regs->EREG(ip) > copy_eip) && (regs->EREG(ip) - copy_eip) + 5 < MAX_INSN_SIZE) {
 216                         /*
 217                          * These instructions can be executed directly if it
 218                          * jumps back to correct address.
 219                          */
 220                         set_user_jmp_op((void *) regs->EREG(ip), (void *)orig_eip + (regs->EREG(ip) - copy_eip));
 221                         p->ainsn.boostable = 1;
 222                 } else {
 223                         p->ainsn.boostable = -1;
 224                 }
 225         }
 226
 227         regs->EREG(ip) = orig_eip + (regs->EREG(ip) - copy_eip);
 228
 229 no_change:
 230         return;
 231 }
 232
 233 static int uprobe_handler(struct pt_regs *regs)
 234 {
 235         struct kprobe *p;
 236         kprobe_opcode_t *addr;
 237         struct task_struct *task = current;
 238         pid_t tgid = task->tgid;
 239
 240         addr = (kprobe_opcode_t *)(regs->EREG(ip) - sizeof(kprobe_opcode_t));
 241         p = get_ukprobe(addr, tgid);
 242
 243         if (p == NULL) {
 244                 p = get_ukprobe_by_insn_slot(addr, tgid, regs);
 245
 246                 if (p == NULL) {
 247                         printk("no_uprobe\n");
 248                         return 0;
 249                 }
 250
 251                 trampoline_uprobe_handler(p, regs);
 252         } else {
 253                 if (!p->pre_handler || !p->pre_handler(p, regs))
 254                         prepare_singlestep(p, regs);
 255         }
 256
 257         __get_cpu_var(ucb).p = p;
 258         __get_cpu_var(ucb).flags = (regs->EREG(flags) & (TF_MASK | IF_MASK));
 259
 260         return 1;
 261 }
 262
 263 static int post_uprobe_handler(struct pt_regs *regs)
 264 {
 265         struct kprobe *p = __get_cpu_var(ucb).p;
 266         unsigned long flags = __get_cpu_var(ucb).flags;
 267
 268         resume_execution(p, regs, flags);
 269
 270         return 1;
 271 }
 272
 273 static int uprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data)
 274 {
 275         struct die_args *args = (struct die_args *)data;
 276         int ret = NOTIFY_DONE;
 277
 278         if (args->regs && !user_mode_vm(args->regs))
 279                 return ret;
 280
 281         switch (val) {
 282 #ifdef CONFIG_KPROBES
 283                 case DIE_INT3:
 284 #else
 285                 case DIE_TRAP:
 286 #endif
 287                         if (uprobe_handler(args->regs))
 288                                 ret = NOTIFY_STOP;
 289                         break;
 290                 case DIE_DEBUG:
 291                         if (post_uprobe_handler(args->regs))
 292                                 ret = NOTIFY_STOP;
 293                         break;
 294                 default:
 295                         break;
 296         }
 297
 298         return ret;
 299 }
 300
 301 static struct notifier_block uprobe_exceptions_nb = {
 302         .notifier_call = uprobe_exceptions_notify,
 303         .priority = INT_MAX
 304 };
 305
 306 int swap_arch_init_uprobes(void)
 307 {
 308         return register_die_notifier(&uprobe_exceptions_nb);
 309 }
 310
 311 void swap_arch_exit_uprobes(void)
 312 {
 313         unregister_die_notifier(&uprobe_exceptions_nb);
 314 }
 315