[PATCH] D27996: [XRay][AArch64] An attempt to fix test patching-unpatching.cc by flushing the instruction cache after code modification

[Serge Rogatch via Phabricator via llvm-commits]

rSerge updated this revision to Diff 82928.
rSerge added a comment.

At a minimum, during x86_64-Linux to AArch64-Linux cross-compilation it didn't compile because of `extern "C"` missing. And the compiled program runs well on QEmu-AArch64-Linux .
@rengolin , why do you mean by "testing native" ? If that's compiling LLVM on AArch64 machine (i.e. without cross-compilation), then it would be challenging for me to do because on QEmu a LLVM build takes about a week, and the OS in the Arm32/AArch64 machines our team has is not exactly Linux.


https://reviews.llvm.org/D27996

Files:
  lib/xray/xray_AArch64.cc
  test/xray/TestCases/Linux/patching-unpatching.cc


Index: test/xray/TestCases/Linux/patching-unpatching.cc
===================================================================
--- test/xray/TestCases/Linux/patching-unpatching.cc
+++ test/xray/TestCases/Linux/patching-unpatching.cc
@@ -3,7 +3,6 @@
 //
 // RUN: %clangxx_xray -fxray-instrument -std=c++11 %s -o %t
 // RUN: XRAY_OPTIONS="patch_premain=false" %run %t 2>&1 | FileCheck %s
-// REQUIRES: stable-runtime
 
 #include "xray/xray_interface.h"
 
Index: lib/xray/xray_AArch64.cc
===================================================================
--- lib/xray/xray_AArch64.cc
+++ lib/xray/xray_AArch64.cc
@@ -19,6 +19,8 @@
 #include <atomic>
 #include <cassert>
 
+extern "C" void __clear_cache(void* start, void* end);
+
 namespace __xray {
 
 uint64_t cycleFrequency() XRAY_NEVER_INSTRUMENT {
@@ -75,8 +77,8 @@
   //   B #32
 
   uint32_t *FirstAddress = reinterpret_cast<uint32_t *>(Sled.Address);
+  uint32_t *CurAddress = FirstAddress + 1;
   if (Enable) {
-    uint32_t *CurAddress = FirstAddress + 1;
     *CurAddress = uint32_t(PatchOpcodes::PO_LdrW0_12);
     CurAddress++;
     *CurAddress = uint32_t(PatchOpcodes::PO_LdrX16_12);
@@ -88,14 +90,17 @@
     *reinterpret_cast<void (**)()>(CurAddress) = TracingHook;
     CurAddress += 2;
     *CurAddress = uint32_t(PatchOpcodes::PO_LdpX0X30SP_16);
+    CurAddress++;
     std::atomic_store_explicit(
         reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
         uint32_t(PatchOpcodes::PO_StpX0X30SP_m16e), std::memory_order_release);
   } else {
     std::atomic_store_explicit(
         reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
         uint32_t(PatchOpcodes::PO_B32), std::memory_order_release);
   }
+  __clear_cache(reinterpret_cast<char*>(FirstAddress),
+      reinterpret_cast<char*>(CurAddress));
   return true;
 }
 


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