Palacios Public Git Repository

To checkout Palacios execute

  git clone http://v3vee.org/palacios/palacios.web/palacios.git
This will give you the master branch. You probably want the devel branch or one of the release branches. To switch to the devel branch, simply execute
  cd palacios
  git checkout --track -b devel origin/devel
The other branches are similar.


Split telemetry into global and per-core to avoid race printing core telemetry
[palacios.git] / palacios / src / palacios / vmm_emulator.c
index 3294aa0..20c6ecb 100644 (file)
@@ -11,7 +11,8 @@
  * Copyright (c) 2008, The V3VEE Project <http://www.v3vee.org> 
  * All rights reserved.
  *
- * Author: Jack Lange <jarusl@cs.northwestern.edu>
+ * Authors: Jack Lange <jarusl@cs.northwestern.edu>
+ *          Peter Dinda <pdinda@northwestern.edu> (full hook/string ops)
  *
  * This is free software.  You are permitted to use,
  * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
 
 #include <palacios/vmm.h>
 #include <palacios/vmm_emulator.h>
-#include <palacios/vm_guest_mem.h>
 #include <palacios/vmm_decoder.h>
-#include <palacios/vmm_debug.h>
-#include <palacios/vmcb.h>
+#include <palacios/vmm_instr_emulator.h>
 #include <palacios/vmm_ctrl_regs.h>
 
-static const char VMMCALL[3] = {0x0f, 0x01, 0xd9};
-
-#ifndef DEBUG_EMULATOR
+#ifndef V3_CONFIG_DEBUG_EMULATOR
 #undef PrintDebug
 #define PrintDebug(fmt, args...)
 #endif
 
 
-int init_emulator(struct guest_info * info) {
-  struct emulation_state * emulator = &(info->emulator);
-
-  emulator->num_emulated_pages = 0;
-  INIT_LIST_HEAD(&(emulator->emulated_pages));
-
-
-  emulator->num_saved_pages = 0;
-  INIT_LIST_HEAD(&(emulator->saved_pages));
-  
-  emulator->num_write_regions = 0;
-  INIT_LIST_HEAD(&(emulator->write_regions));
-
-  emulator->running = 0;
-  emulator->instr_length = 0;
-
-  emulator->tf_enabled = 0;
-
-  return 0;
-}
-
-static addr_t get_new_page() {
-  void * page = V3_AllocPages(1);
-  memset(page, 0, PAGE_SIZE);
-
-  return (addr_t)page;
-}
-
-/*
-static int setup_code_page(struct guest_info * info, char * instr, struct basic_instr_info * instr_info ) {
-  addr_t code_page_offset = PT32_PAGE_OFFSET(info->rip);
-  addr_t code_page = get_new_page();
-  struct emulated_page * new_code_page = V3_Malloc(sizeof(struct emulated_page));
-  struct saved_page * saved_code_page = V3_Malloc(sizeof(struct saved_page));
-
-
-  saved_code_page->va = PT32_PAGE_ADDR(info->rip);
-
-  new_code_page->page_addr = code_page; 
-  new_code_page->va = PT32_PAGE_ADDR(info->rip);
-
-  new_code_page->pte.present = 1;
-  new_code_page->pte.writable = 0;
-  new_code_page->pte.user_page = 1;
-  new_code_page->pte.page_base_addr = PT32_BASE_ADDR(code_page);
-
-  memcpy((void *)(code_page + code_page_offset), instr, instr_info->instr_length);
-  memcpy((void *)(code_page + code_page_offset + instr_info->instr_length), VMMCALL, 3);
-
-#ifdef DEBUG_EMULATOR
-  PrintDebug("New Instr Stream:\n");
-  PrintTraceMemDump((void *)(code_page + code_page_offset), 32);
-  PrintDebug("rip =%x\n", info->rip);
+static int run_op(struct guest_info * info, v3_op_type_t op_type, 
+                 addr_t src_addr, addr_t dst_addr, 
+                 int src_op_size, int dst_op_size) {
+
+    if (src_op_size == 1) {
+       PrintDebug("Executing 8 bit instruction\n");
+
+       switch (op_type) {
+           case V3_OP_ADC:
+               adc8((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_ADD:
+               add8((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_AND:
+               and8((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_OR:
+               or8((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_XOR:
+               xor8((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SUB:
+               sub8((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+           case V3_OP_MOV:
+               mov8((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+
+           case V3_OP_MOVZX:
+               movzx8((addr_t *)dst_addr, (addr_t *)src_addr, dst_op_size);
+               break;
+           case V3_OP_MOVSX:
+               movsx8((addr_t *)dst_addr, (addr_t *)src_addr, dst_op_size);
+               break;
+
+           case V3_OP_NOT:
+               not8((addr_t *)dst_addr);
+               break;
+           case V3_OP_XCHG:
+               xchg8((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+      
+
+           case V3_OP_INC:
+               inc8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_DEC:
+               dec8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_NEG:
+               neg8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETB:
+               setb8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETBE:
+               setbe8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETL:
+               setl8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETLE:
+               setle8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNB:
+               setnb8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNBE:
+               setnbe8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNL:
+               setnl8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNLE:
+               setnle8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNO:
+               setno8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNP:
+               setnp8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNS:
+               setns8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETNZ:
+               setnz8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETO:
+               seto8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETP:
+               setp8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETS:
+               sets8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SETZ:
+               setz8((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+           default:
+               PrintError("Unknown 8 bit instruction\n");
+               return -1;
+       }
+
+    } else if (src_op_size == 2) {
+       PrintDebug("Executing 16 bit instruction\n");
+
+       switch (op_type) {
+           case V3_OP_ADC:
+               adc16((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_ADD:
+               add16((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_AND:
+               and16((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_OR:
+               or16((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_XOR:
+               xor16((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SUB:
+               sub16((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+
+           case V3_OP_INC:
+               inc16((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_DEC:
+               dec16((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_NEG:
+               neg16((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+           case V3_OP_MOV:
+               mov16((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+           case V3_OP_MOVZX:
+               movzx16((addr_t *)dst_addr, (addr_t *)src_addr, dst_op_size);
+               break;
+           case V3_OP_MOVSX:
+               movsx16((addr_t *)dst_addr, (addr_t *)src_addr, dst_op_size);
+               break;
+           case V3_OP_NOT:
+               not16((addr_t *)dst_addr);
+               break;
+           case V3_OP_XCHG:
+               xchg16((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+      
+           default:
+               PrintError("Unknown 16 bit instruction\n");
+               return -1;
+       }
+
+    } else if (src_op_size == 4) {
+       PrintDebug("Executing 32 bit instruction\n");
+
+       switch (op_type) {
+           case V3_OP_ADC:
+               adc32((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_ADD:
+               add32((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_AND:
+               and32((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_OR:
+               or32((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_XOR:
+               xor32((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SUB:
+               sub32((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+           case V3_OP_INC:
+               inc32((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_DEC:
+               dec32((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_NEG:
+               neg32((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+           case V3_OP_MOV:
+               mov32((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+
+           case V3_OP_NOT:
+               not32((addr_t *)dst_addr);
+               break;
+           case V3_OP_XCHG:
+               xchg32((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+      
+           default:
+               PrintError("Unknown 32 bit instruction\n");
+               return -1;
+       }
+
+#ifdef __V3_64BIT__
+    } else if (src_op_size == 8) {
+       PrintDebug("Executing 64 bit instruction\n");
+
+       switch (op_type) {
+           case V3_OP_ADC:
+               adc64((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_ADD:
+               add64((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_AND:
+               and64((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_OR:
+               or64((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_XOR:
+               xor64((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_SUB:
+               sub64((addr_t *)dst_addr, (addr_t *)src_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+           case V3_OP_INC:
+               inc64((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_DEC:
+               dec64((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+           case V3_OP_NEG:
+               neg64((addr_t *)dst_addr, (addr_t *)&(info->ctrl_regs.rflags));
+               break;
+
+           case V3_OP_MOV:
+               mov64((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+
+           case V3_OP_NOT:
+               not64((addr_t *)dst_addr);
+               break;
+           case V3_OP_XCHG:
+               xchg64((addr_t *)dst_addr, (addr_t *)src_addr);
+               break;
+      
+           default:
+               PrintError("Unknown 64 bit instruction\n");
+               return -1;
+       }
 #endif
 
+    } else {
+       PrintError("Invalid Operation Size\n");
+       return -1;
+    }
 
-
-  v3_replace_shdw_page32(info, new_code_page->va, &(new_code_page->pte), &(saved_code_page->pte));
-
-
-  list_add(&(new_code_page->page_list), &(info->emulator.emulated_pages));
-  info->emulator.num_emulated_pages++;
-
-  list_add(&(saved_code_page->page_list), &(info->emulator.saved_pages));
-  info->emulator.num_saved_pages++;
-
-  return 0;
+    return 0;
 }
-*/
-
-
-static int set_stepping(struct guest_info * info) {
-  vmcb_ctrl_t * ctrl_area = GET_VMCB_CTRL_AREA((vmcb_t*)(info->vmm_data));
-  ctrl_area->exceptions.db = 1;
 
-  info->emulator.tf_enabled = ((struct rflags *)&(info->ctrl_regs.rflags))->tf;
 
-  ((struct rflags *)&(info->ctrl_regs.rflags))->tf = 1;
-
-  return 0;
-}
 
+/* Returns the number of bytes written, or -1 if there is an error */
+static int run_str_op(struct guest_info * core, struct x86_instr * instr, 
+                     addr_t src_addr, addr_t dst_addr, 
+                     int op_size, int rep_cnt) {
 
-static int unset_stepping(struct guest_info * info) {
-  vmcb_ctrl_t * ctrl_area = GET_VMCB_CTRL_AREA((vmcb_t*)(info->vmm_data));
-  ctrl_area->exceptions.db = 0;
+    addr_t tmp_rcx = rep_cnt;
+    int emulation_length = op_size * rep_cnt;
+    struct rflags * flags_reg = (struct rflags *)&(core->ctrl_regs.rflags);
 
-  ((struct rflags *)&(info->ctrl_regs.rflags))->tf = info->emulator.tf_enabled;
 
-  if (info->emulator.tf_enabled) {
-    // Inject breakpoint exception into guest
-  }
+    PrintDebug("Emulation_len=%d, tmp_rcx=%d\n", emulation_length, (uint_t)tmp_rcx);
 
-  return 0;
 
+    if (instr->op_type == V3_OP_MOVS) {
+       if (op_size== 1) {
+           movs8((addr_t *)&dst_addr, &src_addr, &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+       } else if (op_size == 2) {
+           movs16((addr_t *)&dst_addr, &src_addr, &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+       } else if (op_size == 4) {
+           movs32((addr_t *)&dst_addr, &src_addr, &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+#ifdef __V3_64BIT__
+       } else if (op_size == 8) {
+           movs64((addr_t *)&dst_addr, &src_addr, &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+#endif
+       } else {
+           PrintError("Invalid operand length\n");
+           return -1;
+       }
+
+       if (flags_reg->df == 0) {
+           core->vm_regs.rdi += emulation_length;
+           core->vm_regs.rsi += emulation_length;
+       } else {
+           core->vm_regs.rdi -= emulation_length;
+           core->vm_regs.rsi -= emulation_length;
+       }
+
+       // RCX is only modified if the rep prefix is present
+       if (instr->prefixes.rep == 1) {
+           core->vm_regs.rcx -= rep_cnt;
+       }
+
+     } else if (instr->op_type == V3_OP_STOS) {
+       if (op_size == 1) {
+           stos8((addr_t *)&dst_addr, (addr_t  *)&(core->vm_regs.rax), &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+       } else if (op_size == 2) {
+           stos16((addr_t *)&dst_addr, (addr_t  *)&(core->vm_regs.rax), &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+       } else if (op_size == 4) {
+           stos32((addr_t *)&dst_addr, (addr_t  *)&(core->vm_regs.rax), &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+#ifdef __V3_64BIT__
+       } else if (op_size == 8) {
+           stos64((addr_t *)&dst_addr, (addr_t  *)&(core->vm_regs.rax), &tmp_rcx, (addr_t *)&(core->ctrl_regs.rflags));
+#endif
+       } else {
+           PrintError("Invalid operand length\n");
+           return -1;
+       }
+
+
+
+       if (flags_reg->df == 0) {
+           core->vm_regs.rdi += emulation_length;
+       } else {
+           core->vm_regs.rdi -= emulation_length;
+       }
+
+       // RCX is only modified if the rep prefix is present
+       if (instr->prefixes.rep == 1) {
+           core->vm_regs.rcx -= rep_cnt;
+       }
+    } else {
+       PrintError("Unimplemented String operation\n");
+       return -1;
+    }
+    
+    return emulation_length;
 }
 
 
-// get the current instr
-// check if rep + remove
-// put into new page, vmexit after
-// replace new page with current eip page
-// 
-int v3_emulate_memory_read(struct guest_info * info, addr_t read_gva, 
-                          int (*read)(addr_t read_addr, void * dst, uint_t length, void * priv_data), 
-                          addr_t read_gpa, void * private_data) {
-  struct basic_instr_info instr_info;
-  uchar_t instr[15];
-  int ret;
-  struct emulated_page * data_page = V3_Malloc(sizeof(struct emulated_page));
-  addr_t data_addr_offset = PT32_PAGE_OFFSET(read_gva);
-  pte32_t saved_pte;
-
-  PrintDebug("Emulating Read\n");
-
-  if (info->mem_mode == PHYSICAL_MEM) { 
-    ret = read_guest_pa_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
-  } else { 
-    ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
-  }
-
-#ifdef DEBUG_EMULATOR
-  PrintDebug("Instr (15 bytes) at %x:\n", instr);
-  PrintTraceMemDump(instr, 15);
-#endif  
-
-
-  if (v3_basic_mem_decode(info, (addr_t)instr, &instr_info) == -1) {
-    PrintError("Could not do a basic memory instruction decode\n");
-    V3_Free(data_page);
-    return -1;
-  }
-
-  /*
-  if (instr_info.has_rep == 1) {
-    PrintError("We currently don't handle rep* instructions\n");
-    V3_Free(data_page);
-    return -1;
-  }
-  */
-
-  data_page->page_addr = get_new_page();
-  data_page->va = PT32_PAGE_ADDR(read_gva);
-  data_page->pte.present = 1;
-  data_page->pte.writable = 0;
-  data_page->pte.user_page = 1;
-  data_page->pte.page_base_addr = PT32_BASE_ADDR(data_page->page_addr);
-
-
-  // Read the data directly onto the emulated page
-  if (read(read_gpa, (void *)(data_page->page_addr + data_addr_offset), instr_info.op_size, private_data) != instr_info.op_size) {
-    PrintError("Read error in emulator\n");
-    V3_FreePage((void *)(data_page->page_addr));
-    V3_Free(data_page);
-    return -1;
-  }
-
-  v3_replace_shdw_page32(info, data_page->va, &(data_page->pte), &saved_pte);
-
-
-  list_add(&(data_page->page_list), &(info->emulator.emulated_pages));
-  info->emulator.num_emulated_pages++;
-
-  if (saved_pte.present == 1) {
-    struct saved_page * saved_data_page = V3_Malloc(sizeof(struct saved_page));
-    saved_data_page->pte = saved_pte;
-    saved_data_page->va = PT32_PAGE_ADDR(read_gva);
-
-    list_add(&(saved_data_page->page_list), &(info->emulator.saved_pages));
-    info->emulator.num_saved_pages++;
-  }
 
+int v3_emulate(struct guest_info * core, struct x86_instr * instr, 
+              int mem_op_size, addr_t mem_hva_src, addr_t mem_hva_dst) {
 
-  // setup_code_page(info, instr, &instr_info);
-  set_stepping(info);
-
-  info->emulator.running = 1;
-  info->run_state = VM_EMULATING;
-  info->emulator.instr_length = instr_info.instr_length;
-
-  return 0;
-}
+    addr_t src_hva = 0;
+    addr_t dst_hva = 0;
 
 
+    if (instr->src_operand.type == MEM_OPERAND) {
+       src_hva = mem_hva_src;
+    } else if (instr->src_operand.type == REG_OPERAND) {
+       src_hva = instr->src_operand.operand;
+    } else {
+       src_hva = (addr_t)&(instr->src_operand.operand);
+    }
 
-int v3_emulate_memory_write(struct guest_info * info, addr_t write_gva,
-                           int (*write)(addr_t write_addr, void * src, uint_t length, void * priv_data), 
-                           addr_t write_gpa, void * private_data) {
+    if (instr->dst_operand.type == MEM_OPERAND) {
+       dst_hva = mem_hva_dst;
+    } else if (instr->dst_operand.type == REG_OPERAND) {
+       dst_hva = instr->dst_operand.operand;
+    } else {
+       dst_hva = (addr_t)&(instr->dst_operand.operand);
+    }
 
-  struct basic_instr_info instr_info;
-  uchar_t instr[15];
-  int ret;
-  struct write_region * write_op = V3_Malloc(sizeof(struct write_region ));
-  struct emulated_page * data_page = V3_Malloc(sizeof(struct emulated_page));
-  addr_t data_addr_offset = PT32_PAGE_OFFSET(write_gva);
-  pte32_t saved_pte;
-  int i;
+    if (instr->is_str_op == 0) {
+       int src_op_len = instr->src_operand.size;
+       int dst_op_len = instr->dst_operand.size;
+       
+       run_op(core, instr->op_type, src_hva, dst_hva, src_op_len, dst_op_len);
 
-  PrintDebug("Emulating Write for instruction at 0x%x\n",info->rip);
+       return dst_op_len;
+    } else {
+       // String Operation
+       int rep_cnt = 0;
 
-  if (info->mem_mode == PHYSICAL_MEM) { 
-    ret = read_guest_pa_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
-  } else { 
-    ret = read_guest_va_memory(info, get_addr_linear(info, info->rip, &(info->segments.cs)), 15, instr);
-  }
+       /* Both src and dst operand sizes should be identical */
+       rep_cnt = mem_op_size / instr->src_operand.size;
 
+       return run_str_op(core, instr, src_hva, dst_hva, instr->src_operand.size, rep_cnt);
+    }
 
-  PrintDebug("Instruction is");
-  for (i=0;i<15;i++) { PrintDebug(" 0x%x",instr[i]); } 
-  PrintDebug("\n");
-  
-  if (v3_basic_mem_decode(info, (addr_t)instr, &instr_info) == -1) {
-    PrintError("Could not do a basic memory instruction decode\n");
-    V3_Free(write_op);
-    V3_Free(data_page);
-    return -1;
-  }
-
-  if (instr_info.has_rep==1) { 
-    PrintDebug("Emulated instruction has rep\n");
-  }
 
-  /*
-  if (instr_info.has_rep == 1) {
-    PrintError("We currently don't handle rep* instructions\n");
-    V3_Free(write_op);
-    V3_Free(data_page);
     return -1;
-  }
-  */
-
-  data_page->page_addr = get_new_page();
-  data_page->va = PT32_PAGE_ADDR(write_gva);
-  data_page->pte.present = 1;
-  data_page->pte.writable = 1;
-  data_page->pte.user_page = 1;
-  data_page->pte.page_base_addr = PT32_BASE_ADDR(data_page->page_addr);
-
-
-
-  write_op->write = write;
-  write_op->write_addr = write_gpa;
-  write_op->length = instr_info.op_size;
-  write_op->private_data = private_data;
-
-  write_op->write_data = (void *)(data_page->page_addr + data_addr_offset);
-
-  list_add(&(write_op->write_list), &(info->emulator.write_regions));
-  info->emulator.num_write_regions--;
-
-  v3_replace_shdw_page32(info, data_page->va, &(data_page->pte), &saved_pte);
-
-
-  list_add(&(data_page->page_list), &(info->emulator.emulated_pages));
-  info->emulator.num_emulated_pages++;
-
-  if (saved_pte.present == 1) {
-    struct saved_page * saved_data_page = V3_Malloc(sizeof(struct saved_page));
-    saved_data_page->pte = saved_pte;
-    saved_data_page->va = PT32_PAGE_ADDR(write_gva);
-
-    list_add(&(saved_data_page->page_list), &(info->emulator.saved_pages));
-    info->emulator.num_saved_pages++;
-  }
-
-
-  if (info->emulator.running == 0) {
-    //    setup_code_page(info, instr, &instr_info);
-    set_stepping(info);
-    info->emulator.running = 1;
-    info->run_state = VM_EMULATING;
-    info->emulator.instr_length = instr_info.instr_length;
-  }
-
-  return 0;
-}
-
-
-// end emulation
-int v3_emulation_exit_handler(struct guest_info * info) {
-  struct saved_page * svpg, * p_svpg;
-  struct emulated_page * empg, * p_empg;
-  struct write_region * wr_reg, * p_wr_reg;
-  pte32_t dummy_pte;
-
-  // Complete the writes
-  // delete writes
-  // swap out emulated pages with blank dummies
-  // swap in saved pages
-  // increment rip
-  
-  PrintDebug("V3 Emulation Exit Handler\n");
-
-  list_for_each_entry_safe(wr_reg, p_wr_reg, &(info->emulator.write_regions), write_list) {
-    wr_reg->write(wr_reg->write_addr, wr_reg->write_data, wr_reg->length, wr_reg->private_data);
-    PrintDebug("Writing \n");
-    
-    list_del(&(wr_reg->write_list));
-    V3_Free(wr_reg);
-
-  }
-  info->emulator.num_write_regions = 0;
-
-
-  *(uint_t *)&dummy_pte = 0;
-  
-  list_for_each_entry_safe(empg, p_empg, &(info->emulator.emulated_pages), page_list) {
-    pte32_t empte32_t;
-
-    PrintDebug("wiping page %x\n", empg->va); 
-
-    v3_replace_shdw_page32(info, empg->va, &dummy_pte, &empte32_t);
-    V3_FreePage((void *)(empg->page_addr));
-
-    list_del(&(empg->page_list));
-    V3_Free(empg);
-  }
-  info->emulator.num_emulated_pages = 0;
-
-  list_for_each_entry_safe(svpg, p_svpg, &(info->emulator.saved_pages), page_list) {
-
-    PrintDebug("Setting Saved page %x back\n", svpg->va); 
-    v3_replace_shdw_page32(info, empg->va, &(svpg->pte), &dummy_pte);
-    
-    list_del(&(svpg->page_list));
-    V3_Free(svpg);
-  }
-  info->emulator.num_saved_pages = 0;
-
-  info->run_state = VM_RUNNING;
-  info->emulator.running = 0;
-  //info->rip += info->emulator.instr_length;
-
-
-  PrintDebug("Returning to rip: 0x%x\n", info->rip);
-
-  info->emulator.instr_length = 0;
-  
-  
-  unset_stepping(info);
-
-
-  PrintDebug("returning from emulation\n");
-
-  return 0;
 }