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);
  26 unsigned int getTrapType(unsigned int, unsigned int);
  27 unsigned int mallocObject(int);
  28
  29 #ifdef DBG_TRAP
  30 #define dprintf(args...) do { printf (args); } while (0);
  31 #else
  32 #define dprintf(args...)
  33 #endif
  34
  35 void *mate_ctx = NULL;
  36
  37 void *get_mate_context()
  38 {
  39         return mate_ctx;
  40 }
  41
  42 void *set_mate_context(void *ctx)
  43 {
  44         mate_ctx = ctx;
  45 }
  46
  47 void mainresult(unsigned int a)
  48 {
  49         dprintf("mainresult: 0x%08x\n", a);
  50 }
  51
  52 void staticcalltrap(int nSignal, siginfo_t *info, void *ctx)
  53 {
  54         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  55         unsigned int from = (unsigned int) mctx->gregs[REG_EIP] - 2;
  56         unsigned int *to_patch = (unsigned int *) (from + 1);
  57         dprintf("callertrap(mctx)  by 0x%08x\n", from);
  58         if (*to_patch != 0x90ffff90) {
  59                 dprintf("callertrap: something is wrong here. abort\n");
  60                 exit(0);
  61         }
  62         unsigned int patchme = getMethodEntry(from, 0);
  63
  64         unsigned char *insn = (unsigned char *) from;
  65         *insn = 0xe8; // call opcode
  66         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
  67         dprintf("*to_patch: 0x%08x\n", *to_patch);
  68         *to_patch = patchme - (from + 5);
  69         dprintf("*to_patch: 0x%08x\n", *to_patch);
  70         mctx->gregs[REG_EIP] = (unsigned long) insn;
  71 }
  72
  73 void sigsegvtrap(int nSignal, siginfo_t *info, void *ctx)
  74 {
  75         mcontext_t *mctx = &((ucontext_t *) ctx)->uc_mcontext;
  76         unsigned int from = (unsigned int) mctx->gregs[REG_EIP];
  77         unsigned int *esp = (unsigned int *) mctx->gregs[REG_ESP];
  78
  79         /* if from is not *the* eip: get actual eip from stack storage */
  80         unsigned int from_stack = (*esp) - 3;
  81         switch(getTrapType(from, from_stack)) {
  82                 default: case 0: {
  83                         dprintf("something is wrong here: abort\n");
  84                         exit(1);
  85                 } break;
  86                 case 1: { // invokevirtual
  87                         if (from > 0) {
  88                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
  89                         }
  90                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
  91                         unsigned char offset = *((unsigned char *) (*esp) - 1);
  92                         /* method entry to patch */
  93                         unsigned int *to_patch = (unsigned int*) (method_table_ptr + offset);
  94                         dprintf("invokevirtual by 0x%08x with offset 0x%08x\n", from_stack, offset);
  95                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
  96                         dprintf("*to_patch: 0x%08x\n", *to_patch);
  97                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
  98                         mctx->gregs[REG_EIP] = *to_patch;
  99                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 100                 } break;
 101                 case 4: { // invokeinterface
 102                         if (from > 0) {
 103                                 dprintf("from: 0x%08x but should be 0 :-(\n", from);
 104                         }
 105                         unsigned int method_table_ptr = (unsigned int) mctx->gregs[REG_EAX];
 106                         unsigned int interface_table_ptr = (unsigned int) mctx->gregs[REG_EBX];
 107                         unsigned char offset = *((unsigned char *) (*esp) - 1);
 108                         /* interface entry to patch */
 109                         unsigned int *to_patch = (unsigned int*) (interface_table_ptr + offset);
 110                         dprintf("invokeinterface by 0x%08x with offset 0x%08x\n", from_stack, offset);
 111                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 112                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 113                         *to_patch = getMethodEntry(from_stack, method_table_ptr);
 114                         mctx->gregs[REG_EIP] = *to_patch;
 115                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 116                 } break;
 117                 case 2: { // static field patch
 118                         unsigned int *to_patch = (unsigned int *) (from + 2);
 119                         dprintf("staticfieldtrap by 0x%08x\n", from);
 120                         if (*to_patch != 0x00000000) {
 121                                 dprintf("staticfieldtrap: something is wrong here. abort\n");
 122                                 exit(0);
 123                         }
 124                         unsigned int patchme = getStaticFieldAddr(from);
 125
 126                         dprintf(" to_patch: 0x%08x\n", (unsigned int) to_patch);
 127                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 128                         *to_patch = patchme;
 129                         dprintf("*to_patch: 0x%08x\n", *to_patch);
 130                 } break;
 131         }
 132 }
 133
 134 void register_signal(void)
 135 {
 136         struct sigaction illaction;
 137         illaction.sa_sigaction = staticcalltrap;
 138         sigemptyset(&illaction.sa_mask);
 139         illaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 140         sigaction(SIGILL, &illaction, NULL);
 141
 142         struct sigaction segvaction;
 143         segvaction.sa_sigaction = sigsegvtrap;
 144         sigemptyset(&segvaction.sa_mask);
 145         segvaction.sa_flags = SA_SIGINFO | SA_RESTART | SA_NODEFER;
 146         sigaction(SIGSEGV, &segvaction, NULL);
 147 }
 148
 149 unsigned int getaddr(void)
 150 {
 151         return (unsigned int) mainresult;
 152 }
 153
 154 unsigned int getMallocObjectAddr(void)
 155 {
 156         return (unsigned int) mallocObject;
 157 }