experimental x86 support for compcov in QEMU

2025-06-13 02:28:09 +00:00 · 2019-07-19 00:55:41 +02:00
parent 5b2cb426be
commit 81dd1aea82
6 changed files with 320 additions and 10 deletions
--- a/qemu_mode/patches/afl-qemu-cpu-translate-inl.h
+++ b/qemu_mode/patches/afl-qemu-cpu-translate-inl.h
@ -0,0 +1,125 @@
+/*
+   american fuzzy lop - high-performance binary-only instrumentation
+   -----------------------------------------------------------------
+
+   Written by Andrew Griffiths <agriffiths@google.com> and
+              Michal Zalewski <lcamtuf@google.com>
+
+   Idea & design very much by Andrew Griffiths.
+
+   TCG instrumentation and block chaining support by Andrea Biondo
+                                      <andrea.biondo965@gmail.com>
+   
+   QEMU 3.1.0 port, TCG thread-safety and CompareCoverage by Andrea Fioraldi
+                                      <andreafioraldi@gmail.com>
+
+   Copyright 2015, 2016, 2017 Google Inc. All rights reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at:
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+   This code is a shim patched into the separately-distributed source
+   code of QEMU 3.1.0. It leverages the built-in QEMU tracing functionality
+   to implement AFL-style instrumentation and to take care of the remaining
+   parts of the AFL fork server logic.
+
+   The resulting QEMU binary is essentially a standalone instrumentation
+   tool; for an example of how to leverage it for other purposes, you can
+   have a look at afl-showmap.c.
+
+ */
+
+#include "../../config.h"
+#include "tcg.h"
+#include "tcg-op.h"
+
+/* Declared in afl-qemu-cpu-inl.h */
+extern unsigned char *afl_area_ptr;
+extern unsigned int afl_inst_rms;
+extern abi_ulong afl_start_code, afl_end_code;
+extern u8 afl_enable_compcov;
+
+void tcg_gen_afl_compcov_log_call(void *func, target_ulong cur_loc,
+                                  TCGv_i64 arg1, TCGv_i64 arg2);
+
+static void afl_compcov_log_16(target_ulong cur_loc, target_ulong arg1,
+                               target_ulong arg2) {
+
+  if ((arg1 & 0xff) == (arg2 & 0xff)) {
+    afl_area_ptr[cur_loc]++;
+  }
+}
+
+static void afl_compcov_log_32(target_ulong cur_loc, target_ulong arg1,
+                               target_ulong arg2) {
+
+  if ((arg1 & 0xff) == (arg2 & 0xff)) {
+    afl_area_ptr[cur_loc]++;
+    if ((arg1 & 0xffff) == (arg2 & 0xffff)) {
+      afl_area_ptr[cur_loc +1]++;
+      if ((arg1 & 0xffffff) == (arg2 & 0xffffff)) {
+        afl_area_ptr[cur_loc +2]++;
+      }
+    }
+  }
+}
+
+static void afl_compcov_log_64(target_ulong cur_loc, target_ulong arg1,
+                               target_ulong arg2) {
+
+  if ((arg1 & 0xff) == (arg2 & 0xff)) {
+    afl_area_ptr[cur_loc]++;
+    if ((arg1 & 0xffff) == (arg2 & 0xffff)) {
+      afl_area_ptr[cur_loc +1]++;
+      if ((arg1 & 0xffffff) == (arg2 & 0xffffff)) {
+        afl_area_ptr[cur_loc +2]++;
+        if ((arg1 & 0xffffffff) == (arg2 & 0xffffffff)) {
+          afl_area_ptr[cur_loc +3]++;
+          if ((arg1 & 0xffffffff) == (arg2 & 0xffffffffff)) {
+            afl_area_ptr[cur_loc +4]++;
+            if ((arg1 & 0xffffffff) == (arg2 & 0xffffffffffff)) {
+              afl_area_ptr[cur_loc +5]++;
+              if ((arg1 & 0xffffffff) == (arg2 & 0xffffffffffffff)) {
+                afl_area_ptr[cur_loc +6]++;
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
+
+
+static void afl_gen_compcov(target_ulong cur_loc, TCGv_i64 arg1, TCGv_i64 arg2,
+                            TCGMemOp ot) {
+
+  void *func;
+  
+  if (!afl_enable_compcov || cur_loc > afl_end_code || cur_loc < afl_start_code)
+    return;
+
+  switch (ot) {
+    case MO_64:
+      func = &afl_compcov_log_64;
+      break;
+    case MO_32: 
+      func = &afl_compcov_log_32;
+      break;
+    case MO_16:
+      func = &afl_compcov_log_16;
+      break;
+    default:
+      return;
+  }
+  
+  cur_loc  = (cur_loc >> 4) ^ (cur_loc << 8);
+  cur_loc &= MAP_SIZE - 1;
+  
+  if (cur_loc >= afl_inst_rms) return;
+  
+  tcg_gen_afl_compcov_log_call(func, cur_loc, arg1, arg2);
+}