switches.c

   1 /**
   2  * Author: Humberto Naves (hsnaves@gmail.com)
   3  */
   4
   5 #include "code.h"
   6 #include "utils.h"
   7
   8 static
   9 int check_switch (struct code *c, struct codeswitch *cs)
  10 {
  11   struct location *loc = cs->location;
  12   element el;
  13   uint32 def, used;
  14
  15   if (!loc->insn) return 0;
  16
  17   if (loc->insn->insn == I_LW) {
  18     def = location_gpr_defined (loc);
  19     while (1) {
  20       if (loc++ == c->end) return 0;
  21       if (!loc->insn) return 0;
  22       used = location_gpr_used (loc);
  23       if (used & def) {
  24         if (loc->insn->insn != I_JR)
  25           return 0;
  26         break;
  27       }
  28       if (loc->insn->flags & (INSN_JUMP | INSN_BRANCH)) return 0;
  29     }
  30   } else if (loc->insn->insn == I_ADDIU) {
  31     int count = 0;
  32     def = location_gpr_defined (loc);
  33     while (1) {
  34       if (loc++ == c->end) return 0;
  35       if (!loc->insn) return 0;
  36       used = location_gpr_used (loc);
  37       if (used & def) {
  38         if (count == 0) {
  39           if (loc->insn->insn != I_ADDU) return 0;
  40         } else if (count == 1) {
  41           if (loc->insn->insn != I_LW) return 0;
  42         } else {
  43           if (loc->insn->insn != I_JR)
  44             return 0;
  45           break;
  46         }
  47         count++;
  48         def = location_gpr_defined (loc);
  49       }
  50       if (loc->insn->flags & (INSN_JUMP | INSN_BRANCH)) return 0;
  51     }
  52   } else return 0;
  53
  54   cs->jumplocation = loc;
  55   cs->jumplocation->cswitch = cs;
  56
  57   el = list_head (cs->references);
  58   while (el) {
  59     struct location *target = element_getvalue (el);
  60     target->cswitch = cs;
  61     el = element_next (el);
  62   }
  63
  64   return 1;
  65 }
  66
  67 void extract_switches (struct code *c)
  68 {
  69   struct prx_reloc *aux;
  70   uint32 base, end, count = 0;
  71   uint32 i, j, tgt;
  72
  73   for (i = 0; i < c->file->relocnum; i++) {
  74     struct prx_reloc *rel = &c->file->relocsbyaddr[i];
  75     count = 0;
  76     do {
  77       if (rel->type != R_MIPS_32) break;
  78       tgt = (rel[count].target - c->baddr) >> 2;
  79       if (tgt >= c->numopc) break;
  80       if (rel[count].target & 0x03) break;
  81
  82       count++;
  83     } while ((i + count) < c->file->relocnum);
  84
  85     if (count == 0) continue;
  86
  87     base = end = prx_findreloc (c->file, rel->vaddr);
  88     if (base >= c->file->relocnum) continue;
  89     if (c->file->relocs[base].target != rel->vaddr) continue;
  90
  91     for (; end < c->file->relocnum; end++) {
  92       aux = &c->file->relocs[end];
  93       if (aux->target != rel->vaddr) {
  94         if (aux->target & 0x03) {
  95           error (__FILE__ ": relocation target not word aligned 0x%08X", aux->target);
  96           count = 0;
  97         } else if (count > ((aux->target - rel->vaddr) >> 2))
  98           count = (aux->target - rel->vaddr) >> 2;
  99         break;
 100       }
 101     }
 102
 103     if (count <= 1) continue;
 104
 105     for (;base < end; base++) {
 106       aux = &c->file->relocs[base];
 107       tgt = (aux->vaddr - c->baddr) >> 2;
 108       if (tgt >= c->numopc) continue;
 109       if (aux->vaddr & 0x03) {
 110         error (__FILE__ ": relocation vaddr not word aligned 0x%08X", aux->vaddr);
 111         continue;
 112       }
 113
 114       if (aux->type == R_MIPS_LO16) {
 115         struct codeswitch *cs;
 116
 117         cs = fixedpool_alloc (c->switchpool);
 118
 119         cs->jumpreloc = aux;
 120         cs->switchreloc = rel;
 121         cs->location = &c->base[tgt];
 122         cs->count = count;
 123         cs->references = list_alloc (c->lstpool);
 124         for (j = 0; j < count; j++) {
 125           tgt = (rel[j].target - c->baddr) >> 2;
 126           list_inserttail (cs->references, &c->base[tgt]);
 127         }
 128
 129         if (!check_switch (c, cs)) {
 130           fixedpool_free (c->switchpool, cs);
 131         }
 132       }
 133     }
 134   }
 135 }
 136
 137