[NFC][compiler-rt][hwasan] Move allocation functions into their own file

[leonardchan]

Summary

This removes the __sanitizer_* allocation function definitions from hwasan_interceptors.cpp and moves them into their own file. This way implementations that do not use interceptors at all can just ignore (almost) everything in hwasan_interceptors.cpp.

Also remove some unused headers in hwasan_interceptors.cpp after the move.

[eugenis]

s/vfork/fork/ in the description

I'm afraid removing the fork interceptor will break Android. This is a pretty uncommon condition, but still. It is interesting to note that ASan does not have this fork protection, see https://github.com/google/sanitizers/issues/774 for some history.

I wonder if this could be replaced with pthread_atfork. The order of callback execution seems right, as long as hwasan is registered first. Or, if you want to make progress, add SANITIZER_ANDROID ifdef somewhere.

[mcgrathr]

I think probably the better refactoring here would be to split this file in two: one containing just the allocation functions; and a second with everything else.
On Fuchsia, we'll use the allocation functions but none of the rest of it. So the second whole file could just be under #if !SANITIZER_FUCHSIA.

[leonardchan]

In D103564#2795287, @mcgrathr wrote:

I think probably the better refactoring here would be to split this file in two: one containing just the allocation functions; and a second with everything else.
On Fuchsia, we'll use the allocation functions but none of the rest of it. So the second whole file could just be under #if !SANITIZER_FUCHSIA.

I don't think we can move the __sanitizer_* allocation functions since they're used for aliases for their libc equivalents which require definitions in the same TU:

/usr/local/google/home/leonardchan/llvm-monorepo/llvm-project-4/compiler-rt/lib/hwasan/hwasan_interceptors.cpp:59:1: error: alias must point to a defined variable or function
INTERCEPTOR_ALIAS(void *, aligned_alloc, SIZE_T alignment, SIZE_T size);
^
/usr/local/google/home/leonardchan/llvm-monorepo/llvm-project-4/compiler-rt/lib/hwasan/hwasan_interceptors.cpp:53:7: note: expanded from macro 'INTERCEPTOR_ALIAS'
      ALIAS("__sanitizer_" #FN);                                             \
      ^

Perhaps it might just be easier to just wrap the part of hwasan_interceptors.cpp that don't include the allocation functions with #if !SANITIZER_FUCHSIA, or as @eugenis suggested wrap the fork interceptor with #if SANITIZER_ANDROID.

[mcgrathr]

In D103564#2797657, @leonardchan wrote:

I don't think we can move the __sanitizer_* allocation functions since they're used for aliases for their libc equivalents which require definitions in the same TU:

What I suggested is moving *everything* related to the allocation functions into a separate file.

[leonardchan]

Followed up with Roland's suggestion and moved everything relating to the allocation functions.

[mcgrathr]

compiler-rt/lib/hwasan/hwasan_interceptors.cpp

351

blank lines around #else and #endif lines. But here I think you just omit this. We can define the empty function in a fuchsia-specific file.

[vitalybuka]

compiler-rt/lib/hwasan/hwasan_interceptors.cpp

351

+1 to "empty function in a fuchsia-specific file"

[leonardchan]

compiler-rt/lib/hwasan/hwasan_interceptors.cpp

351

Will add in an eventual hwasan_fuchsia.cpp.

[thakis]

this breaks tests: http://45.33.8.238/linux/48401/step_10.txt

// CHECK: #0 {{.*}} in {{.*}}free{{.*}} {{.*}}hwasan_interceptors.cpp

vs

13: #0 0x5647a467e9a0 in free ../../compiler-rt/lib/hwasan/hwasan_allocation_functions.cpp:75:3

need to update the path in that test

[leonardchan]

In D103564#2806292, @thakis wrote:

this breaks tests: http://45.33.8.238/linux/48401/step_10.txt

// CHECK: #0 {{.*}} in {{.*}}free{{.*}} {{.*}}hwasan_interceptors.cpp

vs

13: #0 0x5647a467e9a0 in free ../../compiler-rt/lib/hwasan/hwasan_allocation_functions.cpp:75:3

need to update the path in that test

Fixed in a9ea0a6a77b30305bfbe1b06c30bf6136f64c1ad.

compiler-rt/lib/hwasan/hwasan_interceptors.cpp

 INTERCEPTOR(void, longjmp, __hw_jmp_buf env, int val) {
   InternalLongjmp(env[0].__jmpbuf, val);
 }
 #undef SIG_BLOCK
 #undef SIG_SETMASK
 
 #endif // HWASAN_WITH_INTERCEPTORS && __aarch64__
 
+#if HWASAN_WITH_INTERCEPTORS
 static void BeforeFork() {
   StackDepotLockAll();
 }
 
 static void AfterFork() {
   StackDepotUnlockAll();
 }
 
 INTERCEPTOR(int, fork, void) {
   ENSURE_HWASAN_INITED();
   BeforeFork();
   int pid = REAL(fork)();
   AfterFork();
   return pid;
 }
+#endif  // HWASAN_WITH_INTERCEPTORS
 
 namespace __hwasan {
 
 int OnExit() {
   // FIXME: ask frontend whether we need to return failure.
   return 0;
 }
 
 } // namespace __hwasan
 
 namespace __hwasan {
 
 void InitializeInterceptors() {
   static int inited = 0;
   CHECK_EQ(inited, 0);
 
+#if HWASAN_WITH_INTERCEPTORS
   INTERCEPT_FUNCTION(fork);
 
-#if HWASAN_WITH_INTERCEPTORS
 #if defined(__linux__)
   INTERCEPT_FUNCTION(vfork);
 #endif  // __linux__
   INTERCEPT_FUNCTION(pthread_create);
 #endif
 
   inited = 1;
 }
 } // namespace __hwasan