x86: identity map guest address to host address. this fixes issue #300

qemu/softmmu_template.h

@@ -238,8 +238,7 @@ WORD_TYPE helper_le_ld_name(CPUArchState *env, target_ulong addr, int mmu_idx,
                                        uc, UC_MEM_READ_PROT, addr, DATA_SIZE, 0,
                                        uc->hook_callbacks[uc->hook_mem_read_prot_idx].user_data)) {
             env->invalid_error = UC_ERR_OK;
-        }
-        else {
+        } else {
             env->invalid_addr = addr;
             env->invalid_error = UC_ERR_READ_PROT;
             // printf("***** Invalid memory read (non-readable) at " TARGET_FMT_lx "\n", addr);

qemu/target-i386/helper.c

@@ -764,6 +764,8 @@ do_check_protect_pse36:
         }
     }
  do_mapping:
+
+#if 0
     pte = pte & env->a20_mask;
 
     /* align to page_size */
@@ -774,6 +776,12 @@ do_check_protect_pse36:
     vaddr = addr & TARGET_PAGE_MASK;
     page_offset = vaddr & (page_size - 1);
     paddr = pte + page_offset;
+#endif
+
+    // Unicorn: indentity map guest virtual address to host virtual address
+    vaddr = addr & TARGET_PAGE_MASK;
+    paddr = vaddr;
+    //printf(">>> map address %"PRIx64" to %"PRIx64"\n", vaddr, paddr);
 
     tlb_set_page(cs, vaddr, paddr, prot, mmu_idx, page_size);
     return 0;

tests/unit/Makefile

@@ -19,6 +19,8 @@ test: ${ALL_TESTS}
 	./test_sanity
 	./test_x86
 	./test_mem_map
+	./test_mem_map_ptr
+	./test_mem_high
 
 test_sanity: test_sanity.c
 test_x86: test_x86.c