ffi/trap.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3
   4 #include "../debug.h"
   5
   6 /* TODO(bernhard): use {u,}int* types */
   7
   8 #define __USE_GNU
   9 // Note by hs: my signal.h includes sys/uconctext which conflicts with
  10 // asm/ucontext - this hack kinda solves the problem for me ;-)
  11 // so feel free to blame me for that s**t
  12 #if defined __USE_XOPEN2K8
  13 #undef __USE_XOPEN2K8
  14 #define RESTORE
  15 #warning hs-hack: undefining __USE_XOPEN2K8 for signal.h
  16 #endif
  17 #include <signal.h>
  18 #ifdef RESTORE
  19 #define __USE_XOPEN2K8
  20 #endif
  21
  22 #include <sys/ucontext.h>
  23
  24 unsigned int getMethodEntry(unsigned int, unsigned int);
  25 unsigned int getStaticFieldAddr(unsigned int, void*);
  26 unsigned int getTrapType(unsigned int, unsigned int);
  27
  28 #ifdef DBG_TRAP
  29 #define dprintf(args...) do { printf (args); } while (0);
  30 #else
  31 #define dprintf(args...)
  32 #endif
  33
  34 #define NEW_MAP(prefix) \
  35         void* prefix ## _map = NULL; \
  36         void set_ ## prefix ## map(void *map) \
  37         { \
  38                 dprintf("set_%s: 0x%08x\n", #prefix , (unsigned int) map); \
  39                 prefix ## _map = map; \
  40         } \
  41         void *get_ ## prefix ## map() \
  42         { \
  43                 dprintf("get_%s: 0x%08x\n", #prefix , (unsigned int) prefix ## _map); \
  44                 return prefix ## _map; \
  45         }
  46
  47 NEW_MAP(method)
  48 NEW_MAP(trap)
  49 NEW_MAP(class)
  50 NEW_MAP(virtual)
  51 NEW_MAP(strings)
  52 NEW_MAP(interfaces)
  53 NEW_MAP(interfacemethod)
  54
  55
  56 void mainresult(unsigned int a)
  57 {
  58         dprintf("mainresult: 0x%08x\n", a);
  59 }
  60
  61 void staticcalltrap(int nSignal, siginfo_t *info, void *ctx)
  62 {
  63         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  64         unsigned int from = (unsigned int) mctx->gregs[REG_EIP] - 2;
  65         unsigned int *to_patch = (unsigned int *) (from + 1);
  66         dprintf("callertrap(mctx)  by 0x%08x\n", from);
  67         if (*to_patch != 0x90ffff90) {
  68                 dprintf("callertrap: something is wrong here. abort\n");
  69                 exit(0);
  70         }
  71         unsigned int patchme = getMethodEntry(from, 0);
  72
  73         unsigned char *insn = (unsigned char *) from;
  74         *insn = 0xe8; // call opcode
  75         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
  76         dprintf("*to_patch: 0x%08x\n", *to_patch);
  77         *to_patch = patchme - (from + 5);
  78         dprintf("*to_patch: 0x%08x\n", *to_patch);
  79         mctx->gregs[REG_EIP] = (unsigned long) insn;
  80 }
  81
  82 void sigsegvtrap(int nSignal, siginfo_t *info, void *ctx)
  83 {
  84         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  85         unsigned int from = (unsigned int) mctx->gregs[REG_EIP];
  86         unsigned int *esp = (unsigned int *) mctx->gregs[REG_ESP];
  87
  88         /* if from is not *the* eip: get actual eip from stack storage */
  89         unsigned int from_stack = (*esp) - 3;
  90         switch(getTrapType(from, from_stack)) {
  91                 default: case 0: {
  92                         dprintf("something is wrong here: abort\n");
  93                         exit(1);
  94                 } break;
  95                 case 1: { // invokevirtual
  96                         if (from > 0) {
  97                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
  98                         }
  99                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
 100                         unsigned char offset = *((unsigned char *) (*esp) - 1);
 101                         /* method entry to patch */
 102                         unsigned int *to_patch = (unsigned int*) (method_table_ptr + offset);
 103                         dprintf("invokevirtual by 0x%08x with offset 0x%08x\n", from_stack, offset);
 104                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 105                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 106                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
 107                         mctx->gregs[REG_EIP] = *to_patch;
 108                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 109                 } break;
 110                 case 4: { // invokeinterface
 111                         if (from > 0) {
 112                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
 113                         }
 114                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
 115                         unsigned int interface_table_ptr = (unsigned int) mctx->gregs[REG_EBX];
 116                         unsigned char offset = *((unsigned char *) (*esp) - 1);
 117                         /* interface entry to patch */
 118                         unsigned int *to_patch = (unsigned int*) (interface_table_ptr + offset);
 119                         dprintf("invokeinterface by 0x%08x with offset 0x%08x\n", from_stack, offset);
 120                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 121                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 122                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
 123                         mctx->gregs[REG_EIP] = *to_patch;
 124                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 125                 } break;
 126                 case 2: { // static field patch
 127                         unsigned int *to_patch = (unsigned int *) (from + 2);
 128                         dprintf("staticfieldtrap by 0x%08x\n", from);
 129                         if (*to_patch != 0x00000000) {
 130                                 dprintf("staticfieldtrap: something is wrong here. abort\n");
 131                                 exit(0);
 132                         }
 133                         unsigned int patchme = getStaticFieldAddr(from, trap_map);
 134
 135                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 136                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 137                         *to_patch = patchme;
 138                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 139                 } break;
 140         }
 141 }
 142
 143 void register_signal(void)
 144 {
 145         struct sigaction illaction;
 146         illaction.sa_sigaction = staticcalltrap;
 147         sigemptyset(&illaction.sa_mask);
 148         illaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 149         sigaction(SIGILL, &illaction, NULL);
 150
 151         struct sigaction segvaction;
 152         segvaction.sa_sigaction = sigsegvtrap;
 153         sigemptyset(&segvaction.sa_mask);
 154         segvaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 155         sigaction(SIGSEGV, &segvaction, NULL);
 156 }
 157
 158 unsigned int getaddr(void)
 159 {
 160         return (unsigned int) mainresult;
 161 }
 162
 163 unsigned int getMallocAddr(void)
 164 {
 165         return (unsigned int) malloc;
 166 }