ffi/trap.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3
   4 /* TODO(bernhard): use {u,}int* types */
   5
   6 #define __USE_GNU
   7 // Note by hs: my signal.h includes sys/uconctext which conflicts with
   8 // asm/ucontext - this hack kinda solves the problem for me ;-)
   9 // so feel free to blame me for that s**t
  10 #if defined __USE_XOPEN2K8
  11 #undef __USE_XOPEN2K8
  12 #define RESTORE
  13 #warning hs-hack: undefining __USE_XOPEN2K8 for signal.h
  14 #endif
  15 #include <signal.h>
  16 #ifdef RESTORE
  17 #define __USE_XOPEN2K8
  18 #endif
  19
  20 #include <sys/ucontext.h>
  21
  22 unsigned int getMethodEntry(unsigned int, unsigned int);
  23 unsigned int getStaticFieldAddr(unsigned int, void*);
  24 unsigned int getTrapType(unsigned int, unsigned int);
  25
  26 #ifdef DEBUG
  27 #define dprintf(args...) do { printf (args); } while (0);
  28 #else
  29 #define dprintf(args...)
  30 #endif
  31
  32 #define NEW_MAP(prefix) \
  33         void* prefix ## _map = NULL; \
  34         void set_ ## prefix ## map(void *map) \
  35         { \
  36                 dprintf("set_%s: 0x%08x\n", #prefix , (unsigned int) map); \
  37                 prefix ## _map = map; \
  38         } \
  39         void *get_ ## prefix ## map() \
  40         { \
  41                 dprintf("get_%s: 0x%08x\n", #prefix , (unsigned int) prefix ## _map); \
  42                 return prefix ## _map; \
  43         }
  44
  45 NEW_MAP(method)
  46 NEW_MAP(trap)
  47 NEW_MAP(class)
  48 NEW_MAP(virtual)
  49 NEW_MAP(strings)
  50 NEW_MAP(interfaces)
  51 NEW_MAP(interfacemethod)
  52
  53
  54 void mainresult(unsigned int a)
  55 {
  56         dprintf("mainresult: 0x%08x\n", a);
  57 }
  58
  59 void staticcalltrap(int nSignal, siginfo_t *info, void *ctx)
  60 {
  61         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  62         unsigned int from = (unsigned int) mctx->gregs[REG_EIP] - 2;
  63         unsigned int *to_patch = (unsigned int *) (from + 1);
  64         dprintf("callertrap(mctx)  by 0x%08x\n", from);
  65         if (*to_patch != 0x90ffff90) {
  66                 dprintf("callertrap: something is wrong here. abort\n");
  67                 exit(0);
  68         }
  69         unsigned int patchme = getMethodEntry(from, 0);
  70
  71         unsigned char *insn = (unsigned char *) from;
  72         *insn = 0xe8; // call opcode
  73         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
  74         dprintf("*to_patch: 0x%08x\n", *to_patch);
  75         *to_patch = patchme - (from + 5);
  76         dprintf("*to_patch: 0x%08x\n", *to_patch);
  77         mctx->gregs[REG_EIP] = (unsigned long) insn;
  78 }
  79
  80 void sigsegvtrap(int nSignal, siginfo_t *info, void *ctx)
  81 {
  82         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  83         unsigned int from = (unsigned int) mctx->gregs[REG_EIP];
  84         unsigned int *esp = (unsigned int *) mctx->gregs[REG_ESP];
  85
  86         /* if from is not *the* eip: get actual eip from stack storage */
  87         unsigned int from_stack = (*esp) - 3;
  88         switch(getTrapType(from, from_stack)) {
  89                 default: case 0: {
  90                         dprintf("something is wrong here: abort\n");
  91                         exit(1);
  92                 } break;
  93                 case 1: { // invokevirtual
  94                         if (from > 0) {
  95                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
  96                         }
  97                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
  98                         unsigned char offset = *((unsigned char *) (*esp) - 1);
  99                         /* method entry to patch */
 100                         unsigned int *to_patch = (unsigned int*) (method_table_ptr + offset);
 101                         dprintf("invokevirtual by 0x%08x with offset 0x%08x\n", from_stack, offset);
 102                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 103                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 104                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
 105                         mctx->gregs[REG_EIP] = *to_patch;
 106                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 107                 } break;
 108                 case 4: { // invokeinterface
 109                         if (from > 0) {
 110                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
 111                         }
 112                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
 113                         unsigned int interface_table_ptr = (unsigned int) mctx->gregs[REG_EBX];
 114                         unsigned char offset = *((unsigned char *) (*esp) - 1);
 115                         /* interface entry to patch */
 116                         unsigned int *to_patch = (unsigned int*) (interface_table_ptr + offset);
 117                         dprintf("invokeinterface by 0x%08x with offset 0x%08x\n", from_stack, offset);
 118                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 119                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 120                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
 121                         mctx->gregs[REG_EIP] = *to_patch;
 122                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 123                 } break;
 124                 case 2: { // static field patch
 125                         unsigned int *to_patch = (unsigned int *) (from + 2);
 126                         dprintf("staticfieldtrap by 0x%08x\n", from);
 127                         if (*to_patch != 0x00000000) {
 128                                 dprintf("staticfieldtrap: something is wrong here. abort\n");
 129                                 exit(0);
 130                         }
 131                         unsigned int patchme = getStaticFieldAddr(from, trap_map);
 132
 133                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 134                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 135                         *to_patch = patchme;
 136                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 137                 } break;
 138         }
 139 }
 140
 141 void register_signal(void)
 142 {
 143         struct sigaction illaction;
 144         illaction.sa_sigaction = staticcalltrap;
 145         sigemptyset(&illaction.sa_mask);
 146         illaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 147         sigaction(SIGILL, &illaction, NULL);
 148
 149         struct sigaction segvaction;
 150         segvaction.sa_sigaction = sigsegvtrap;
 151         sigemptyset(&segvaction.sa_mask);
 152         segvaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 153         sigaction(SIGSEGV, &segvaction, NULL);
 154 }
 155
 156 unsigned int getaddr(void)
 157 {
 158         return (unsigned int) mainresult;
 159 }
 160
 161 unsigned int getMallocAddr(void)
 162 {
 163         return (unsigned int) malloc;
 164 }