From edb6b509c249e58261968ce0624802aeea53171f Mon Sep 17 00:00:00 2001
From: Romain Malmain <romain.malmain@pm.me>
Date: Mon, 13 May 2024 11:58:19 +0200
Subject: [PATCH] Generate stub bindings less aggressively. (#2164)

Emit warning when using runtime files for an incompatible architecture.
---
 libafl_qemu/build_linux.rs                    | 10 +++---
 libafl_qemu/libafl_qemu_build/Cargo.toml      |  1 +
 libafl_qemu/libafl_qemu_build/src/lib.rs      | 26 +++++++++++++++
 libafl_qemu/libafl_qemu_sys/build_linux.rs    | 33 +------------------
 .../src/x86_64_stub_bindings.rs               |  1 -
 libafl_qemu/runtime/libafl_qemu.h             | 10 +++---
 6 files changed, 39 insertions(+), 42 deletions(-)

diff --git a/libafl_qemu/build_linux.rs b/libafl_qemu/build_linux.rs
index bca4fd97c0..4ec63e82e2 100644
--- a/libafl_qemu/build_linux.rs
+++ b/libafl_qemu/build_linux.rs
@@ -4,6 +4,8 @@ use std::{
     process::Command,
 };
 
+use libafl_qemu_build::maybe_generate_stub_bindings;
+
 #[allow(clippy::too_many_lines)]
 pub fn build() {
     // Note: Unique features are checked in libafl_qemu_sys
@@ -114,11 +116,11 @@ pub fn build() {
         .write_to_file(&runtime_bindings_file)
         .expect("Could not write bindings.");
 
-    libafl_qemu_build::store_generated_content_if_different(
+    maybe_generate_stub_bindings(
+        &cpu_target,
+        &emulation_mode,
         &stub_runtime_bindings_file,
-        fs::read(&runtime_bindings_file)
-            .expect("Could not read generated bindings file")
-            .as_slice(),
+        &runtime_bindings_file
     );
 
     if (emulation_mode == "usermode") && (qemu_asan || qemu_asan_guest) {
diff --git a/libafl_qemu/libafl_qemu_build/Cargo.toml b/libafl_qemu/libafl_qemu_build/Cargo.toml
index e864e4c0d3..9ce6e047ee 100644
--- a/libafl_qemu/libafl_qemu_build/Cargo.toml
+++ b/libafl_qemu/libafl_qemu_build/Cargo.toml
@@ -36,3 +36,4 @@ shell-words = "1.1"
 pkg-config = "0.3.26"
 cc = "1.0"
 regex = "1"
+rustversion = "1.0"
diff --git a/libafl_qemu/libafl_qemu_build/src/lib.rs b/libafl_qemu/libafl_qemu_build/src/lib.rs
index bb013f1d23..fcb7de8d32 100644
--- a/libafl_qemu/libafl_qemu_build/src/lib.rs
+++ b/libafl_qemu/libafl_qemu_build/src/lib.rs
@@ -292,3 +292,29 @@ pub fn store_generated_content_if_different(file_to_update: &PathBuf, fresh_cont
             .unwrap_or_else(|_| panic!("Unable to write in {}", file_to_update.display()));
     }
 }
+#[rustversion::nightly]
+pub fn maybe_generate_stub_bindings(
+    cpu_target: &str,
+    emulation_mode: &str,
+    stub_bindings_file: &PathBuf,
+    bindings_file: &PathBuf,
+) {
+    if cpu_target == "x86_64" && emulation_mode == "usermode" {
+        store_generated_content_if_different(
+            stub_bindings_file,
+            fs::read(bindings_file)
+                .expect("Could not read generated bindings file")
+                .as_slice(),
+        );
+    }
+}
+
+#[rustversion::not(nightly)]
+pub fn maybe_generate_stub_bindings(
+    _cpu_target: &str,
+    _emulation_mode: &str,
+    _stub_bindings_file: &PathBuf,
+    _bindings_file: &PathBuf,
+) {
+    // Do nothing
+}
diff --git a/libafl_qemu/libafl_qemu_sys/build_linux.rs b/libafl_qemu/libafl_qemu_sys/build_linux.rs
index 0a312462e9..7fc92c4fe7 100644
--- a/libafl_qemu/libafl_qemu_sys/build_linux.rs
+++ b/libafl_qemu/libafl_qemu_sys/build_linux.rs
@@ -1,10 +1,6 @@
-#[rustversion::nightly]
-use std::fs;
 use std::{env, fs::copy, path::PathBuf};
 
-use libafl_qemu_build::build_with_bindings;
-#[rustversion::nightly]
-use libafl_qemu_build::store_generated_content_if_different;
+use libafl_qemu_build::{build_with_bindings, maybe_generate_stub_bindings};
 
 #[macro_export]
 macro_rules! assert_unique_feature {
@@ -18,33 +14,6 @@ macro_rules! assert_unique_feature {
     }
 }
 
-#[rustversion::nightly]
-fn maybe_generate_stub_bindings(
-    cpu_target: &str,
-    emulation_mode: &str,
-    stub_bindings_file: &PathBuf,
-    bindings_file: &PathBuf,
-) {
-    if cpu_target == "x86_64" && emulation_mode == "usermode" {
-        store_generated_content_if_different(
-            stub_bindings_file,
-            fs::read(bindings_file)
-                .expect("Could not read generated bindings file")
-                .as_slice(),
-        );
-    }
-}
-
-#[rustversion::not(nightly)]
-fn maybe_generate_stub_bindings(
-    _cpu_target: &str,
-    _emulation_mode: &str,
-    _stub_bindings_file: &PathBuf,
-    _bindings_file: &PathBuf,
-) {
-    // Do nothing
-}
-
 pub fn build() {
     println!(r#"cargo::rustc-check-cfg=cfg(emulation_mode, values("usermode", "systemmode"))"#);
     println!(
diff --git a/libafl_qemu/libafl_qemu_sys/src/x86_64_stub_bindings.rs b/libafl_qemu/libafl_qemu_sys/src/x86_64_stub_bindings.rs
index 8e1cd142f4..22f43e20da 100644
--- a/libafl_qemu/libafl_qemu_sys/src/x86_64_stub_bindings.rs
+++ b/libafl_qemu/libafl_qemu_sys/src/x86_64_stub_bindings.rs
@@ -2340,7 +2340,6 @@ pub type DeviceReset = ::std::option::Option<unsafe extern "C" fn(dev: *mut Devi
 #[derive(Debug, Copy, Clone)]
 pub struct DeviceClass {
     pub parent_class: ObjectClass,
-    #[doc = " @categories: device categories device belongs to"]
     pub categories: [::std::os::raw::c_ulong; 1usize],
     #[doc = " @fw_name: name used to identify device to firmware interfaces"]
     pub fw_name: *const ::std::os::raw::c_char,
diff --git a/libafl_qemu/runtime/libafl_qemu.h b/libafl_qemu/runtime/libafl_qemu.h
index 3da0ccc903..3e10f1b7a7 100644
--- a/libafl_qemu/runtime/libafl_qemu.h
+++ b/libafl_qemu/runtime/libafl_qemu.h
@@ -80,7 +80,7 @@ typedef enum LibaflQemuEndStatus {
       #endif
 #else
 
-  #ifdef __x86_64__
+  #if defined(__x86_64__)
     #define LIBAFL_DEFINE_FUNCTIONS(name, opcode)                                                   \
       libafl_word LIBAFL_CALLING_CONVENTION _libafl_##name##_call0(                                 \
           libafl_word action) {                                                                     \
@@ -126,9 +126,8 @@ typedef enum LibaflQemuEndStatus {
         ); \
         return ret;                                                                                 \
       }
-  #endif
 
-  #ifdef __arm__
+  #elif defined(__arm__)
     #define LIBAFL_DEFINE_FUNCTIONS(name, opcode)                                                   \
       libafl_word LIBAFL_CALLING_CONVENTION _libafl_##name##_call0(                                 \
           libafl_word action) {                                                                     \
@@ -174,9 +173,8 @@ typedef enum LibaflQemuEndStatus {
     );   \
         return ret;                                                                                 \
       }
-  #endif
 
-  #ifdef __aarch64__
+  #elif defined(__aarch64__)
     #define LIBAFL_DEFINE_FUNCTIONS(name, opcode)                                                   \
       libafl_word LIBAFL_CALLING_CONVENTION _libafl_##name##_call0(                                 \
           libafl_word action) {                                                                     \
@@ -222,6 +220,8 @@ typedef enum LibaflQemuEndStatus {
     );   \
         return ret;                                                                                 \
       }
+  #else
+    #warning "LibAFL QEMU Runtime does not support your architecture yet, please leave an issue."
   #endif
 
 #endif