externals: Update zydis to 4.0.0

Merge commit '6fa8d51479'

externals/zydis/examples/EncodeFromScratch.c

@@ -0,0 +1,132 @@
+/***************************************************************************************************
+
+  Zyan Disassembler Library (Zydis)
+
+  Original Author : Joel Hoener
+
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+
+***************************************************************************************************/
+
+/**
+ * @file
+ *
+ * Example on assembling a basic function returning `0x1337` in `rax`.
+ */
+
+#include <Zydis/Zydis.h>
+#include <Zycore/LibC.h>
+#include <Zycore/API/Memory.h>
+
+#include <inttypes.h>
+
+/* ============================================================================================== */
+/* Entry point                                                                                    */
+/* ============================================================================================== */
+
+static void ExpectSuccess(ZyanStatus status)
+{
+    if (ZYAN_FAILED(status))
+    {
+        fprintf(stderr, "Something failed: 0x%08X\n", status);
+        exit(EXIT_FAILURE);
+    }
+}
+
+static void AppendInstruction(const ZydisEncoderRequest* req, ZyanU8** buffer, 
+    ZyanUSize* buffer_length)
+{
+    assert(req);
+    assert(buffer);
+    assert(buffer_length);
+
+    ZyanUSize instr_length = *buffer_length;
+    ExpectSuccess(ZydisEncoderEncodeInstruction(req, *buffer, &instr_length));
+    *buffer += instr_length;
+    *buffer_length -= instr_length;
+}
+
+static ZyanUSize AssembleCode(ZyanU8* buffer, ZyanUSize buffer_length)
+{
+    assert(buffer);
+    assert(buffer_length);
+
+    ZyanU8* write_ptr = buffer;
+    ZyanUSize remaining_length = buffer_length;
+
+    // Assemble `mov rax, 0x1337`.
+    ZydisEncoderRequest req;
+    memset(&req, 0, sizeof(req));
+    req.mnemonic = ZYDIS_MNEMONIC_MOV;
+    req.machine_mode = ZYDIS_MACHINE_MODE_LONG_64;
+    req.operand_count = 2;
+    req.operands[0].type = ZYDIS_OPERAND_TYPE_REGISTER;
+    req.operands[0].reg.value = ZYDIS_REGISTER_RAX;
+    req.operands[1].type = ZYDIS_OPERAND_TYPE_IMMEDIATE;
+    req.operands[1].imm.u = 0x1337;
+    AppendInstruction(&req, &write_ptr, &remaining_length);
+
+    // Assemble `ret`.
+    memset(&req, 0, sizeof(req));
+    req.mnemonic = ZYDIS_MNEMONIC_RET;
+    req.machine_mode = ZYDIS_MACHINE_MODE_LONG_64;
+    AppendInstruction(&req, &write_ptr, &remaining_length);
+
+    return buffer_length - remaining_length;
+}
+
+int main(void)
+{
+    // Allocate 2 pages of memory. We won't need nearly as much, but it simplifies
+    // re-protecting the memory to RWX later.
+    const ZyanUSize page_size = 0x1000;
+    const ZyanUSize alloc_size = page_size * 2;
+    ZyanU8* buffer = malloc(alloc_size);
+
+    // Assemble our function.
+    const ZyanUSize length = AssembleCode(buffer, alloc_size);
+
+    // Print a hex-dump of the assembled code.
+    puts("Created byte-code:");
+    for (ZyanUSize i = 0; i < length; ++i)
+    {
+        printf("%02X ", buffer[i]);
+    }
+    puts("");
+
+#ifdef ZYAN_X64
+
+    // Align pointer to typical page size.
+    void* aligned = (void*)((ZyanUPointer)buffer & ~(page_size-1));
+
+    // Re-protect the heap region as RWX. Don't do this at home, kids!
+    ExpectSuccess(ZyanMemoryVirtualProtect(aligned, alloc_size, ZYAN_PAGE_EXECUTE_READWRITE));
+
+    // Create a function pointer for our buffer.
+    typedef ZyanU64(*FnPtr)();
+    const FnPtr func_ptr = (FnPtr)(uintptr_t)buffer;
+
+    // Call the function!
+    const ZyanU64 result = func_ptr();
+    printf("Return value of JITed code: 0x%016" PRIx64 "\n", result);
+
+#endif
+}
+
+/* ============================================================================================== */