Add custom getcontext() implementation for Android.

This adds a minimalistic implementation of getcontext()
for Android/ARM and Android/x86. The provided code is
in assembly and only implements the bare minimum required
by Breakpad to get the current processor state.

Note that:

- The FPU state is not saved to the ucontext_t on ARM.
  (that's actually the main difference with a normal
   getcontext() implementation).

  This is normal. On Linux/ARM, such state must be
  obtained with PTRACE_GETVFPREGS instead. This will
  be implemented in a future patch.

- On x86, only the 'regular' FPU state is saved, to
  mimic the GLibc/i386 implementation. The state of
  SSE/SSE2/etc registers is not part of the upstream
  getcontext() implementation.
Review URL: https://breakpad.appspot.com/444002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1024 4c0a9323-5329-0410-9bdc-e9ce6186880e

2 files changed, 33 insertions, 6 deletions

diff --git a/src/common/android/include/sys/ucontext.h b/src/common/android/include/sys/ucontext.h
index 7f0eb5a3..4a4e77c1 100644
--- a/src/common/android/include/sys/ucontext.h
+++ b/src/common/android/include/sys/ucontext.h
@@ -50,11 +50,15 @@ extern "C" {
 #include <asm/sigcontext.h>
 typedef struct sigcontext mcontext_t;
 
+// The ARM kernel uses a 64-bit signal mask.
+typedef uint32_t  kernel_sigmask_t[2];
+
 typedef struct ucontext {
   uint32_t uc_flags;
   struct ucontext* uc_link;
   stack_t uc_stack;
   mcontext_t uc_mcontext;
+  kernel_sigmask_t uc_sigmask;
   // Other fields are not used by Google Breakpad. Don't define them.
 } ucontext_t;
 
@@ -110,12 +114,16 @@ enum {
   REG_SS,
 };
 
+// The i386 kernel uses a 64-bit signal mask.
+typedef uint32_t kernel_sigmask_t[2];
+
 typedef struct ucontext {
   uint32_t uc_flags;
   struct ucontext* uc_link;
   stack_t uc_stack;
   mcontext_t uc_mcontext;
-  // Other fields are not used by Google Breakpad. Don't define them.
+  kernel_sigmask_t uc_sigmask;
+  struct _libc_fpstate __fpregs_mem;
 } ucontext_t;
 
 #elif defined(__mips__)
@@ -142,11 +150,15 @@ typedef struct {
   uint32_t lo3;
 } mcontext_t;
 
+// The MIPS kernel uses a 128-bit signal mask.
+typedef uint32_t kernel_sigmask_t[4];
+
 typedef struct ucontext {
   uint32_t uc_flags;
   struct ucontext* uc_link;
   stack_t uc_stack;
   mcontext_t uc_mcontext;
+  kernel_sigmask_t uc_sigmask;
   // Other fields are not used by Google Breakpad. Don't define them.
 } ucontext_t;
 
diff --git a/src/common/android/include/ucontext.h b/src/common/android/include/ucontext.h
index 6608e063..29db8ade 100644
--- a/src/common/android/include/ucontext.h
+++ b/src/common/android/include/ucontext.h
@@ -30,12 +30,27 @@
 #ifndef GOOGLE_BREAKPAD_COMMON_ANDROID_INCLUDE_UCONTEXT_H
 #define GOOGLE_BREAKPAD_COMMON_ANDROID_INCLUDE_UCONTEXT_H
 
+#include <sys/cdefs.h>
+
+#ifdef __BIONIC_UCONTEXT_H
+#include <ucontext.h>
+#else
+
 #include <sys/ucontext.h>
 
-// TODO: Provide a portable implementation of getcontext() then
-//        update ExceptionHandler::WriteMinidump() in
-//        src/client/linux/handler/exception_handler.cc to use it.
-//
-// extern int getcontext(ucontext_t* ucp);
+#ifdef __cplusplus
+extern "C" {
+#endif  // __cplusplus
+
+// Provided by src/android/common/breakpad_getcontext.S
+int breakpad_getcontext(ucontext_t* ucp);
+
+#define getcontext(x)   breakpad_getcontext(x)
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif  // __cplusplus
+
+#endif  // __BIONIC_UCONTEXT_H
 
 #endif  // GOOGLE_BREAKPAD_COMMON_ANDROID_INCLUDE_UCONTEXT_H