Remapping ELF section headers to match loaded code

Remap ELF headers when rsloaderCreateExec is called so the object can be registered with GDB.

Change-Id: I89de5caaee8caad5136d817698cf9fc8a5bd545b

2 files changed, 27 insertions, 2 deletions

diff --git a/android/librsloader.cpp b/android/librsloader.cpp
index 4847fe2..53cb54d 100644
--- a/android/librsloader.cpp
+++ b/android/librsloader.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright 2011, The Android Open Source Project
+ * Copyright 2011-2012, The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,7 @@
 #include "cutils/log.h"
 
 #include <llvm/ADT/OwningPtr.h>
+#include <llvm/Support/ELF.h>
 
 static inline RSExecRef wrap(ELFObject<32> *object) {
   return reinterpret_cast<RSExecRef>(object);
@@ -55,6 +56,28 @@ rsloaderCreateExec(unsigned char const *buf,
   return wrap(object.take());
 }
 
+extern "C" void rsloaderUpdateSectionHeaders(RSExecRef object_,
+                                             unsigned char *buf) {
+  ELFObject<32> *object = unwrap(object_);
+
+  // Remap the section header addresses to match the loaded code
+  llvm::ELF::Elf32_Ehdr* header = reinterpret_cast<llvm::ELF::Elf32_Ehdr*>(buf);
+
+  llvm::ELF::Elf32_Shdr* shtab =
+      reinterpret_cast<llvm::ELF::Elf32_Shdr*>(buf + header->e_shoff);
+
+  for (int i = 0; i < header->e_shnum; i++) {
+    if (shtab[i].sh_flags & SHF_ALLOC) {
+      ELFSectionBits<32>* bits =
+          static_cast<ELFSectionBits<32>*>(object->getSectionByIndex(i));
+      if (bits) {
+        const unsigned char* addr = bits->getBuffer();
+        shtab[i].sh_addr = reinterpret_cast<llvm::ELF::Elf32_Addr>(addr);
+      }
+    }
+  }
+}
+
 extern "C" void rsloaderDisposeExec(RSExecRef object) {
   delete unwrap(object);
 }
diff --git a/android/librsloader.h b/android/librsloader.h
index 8f0429d..e12fe63 100644
--- a/android/librsloader.h
+++ b/android/librsloader.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2011, The Android Open Source Project
+ * Copyright 2011-2012, The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,6 +31,8 @@ RSExecRef rsloaderCreateExec(unsigned char const *buf,
                              void *(*find_symbol)(void *, char const *),
                              void *find_symbol_context);
 
+void rsloaderUpdateSectionHeaders(RSExecRef object, unsigned char *buf);
+
 void rsloaderDisposeExec(RSExecRef object);
 
 void *rsloaderGetSymbolAddress(RSExecRef object, char const *name);