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

1 files changed, 85 insertions, 0 deletions

diff --git a/src/common/android/ucontext_constants.h b/src/common/android/ucontext_constants.h
new file mode 100644
index 00000000..9c7a6971
--- /dev/null
+++ b/src/common/android/ucontext_constants.h
@@ -0,0 +1,85 @@
+// Copyright (c) 2012, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This header can be included either from a C, C++ or Assembly file.
+// Its purpose is to contain constants that must match the offsets of
+// various fields in ucontext_t.
+//
+// They should match the definitions from
+// src/common/android/include/sys/ucontext.h
+//
+// Used by src/common/android/breakpad_getcontext.S
+// Tested by src/common/android/testing/breakpad_getcontext_unittest.cc
+
+#ifndef GOOGLEBREAKPAD_COMMON_ANDROID_UCONTEXT_CONSTANTS_H
+#define GOOGLEBREAKPAD_COMMON_ANDROID_UCONTEXT_CONSTANTS_H
+
+#if defined(__arm__)
+
+#define  MCONTEXT_GREGS_OFFSET     32
+#define  UCONTEXT_SIGMASK_OFFSET   104
+
+#elif defined(__i386__)
+
+#define  MCONTEXT_GREGS_OFFSET     20
+#define  MCONTEXT_GS_OFFSET        (MCONTEXT_GREGS_OFFSET + 0*4)
+#define  MCONTEXT_FS_OFFSET        (MCONTEXT_GREGS_OFFSET + 1*4)
+#define  MCONTEXT_ES_OFFSET        (MCONTEXT_GREGS_OFFSET + 2*4)
+#define  MCONTEXT_DS_OFFSET        (MCONTEXT_GREGS_OFFSET + 3*4)
+#define  MCONTEXT_EDI_OFFSET       (MCONTEXT_GREGS_OFFSET + 4*4)
+#define  MCONTEXT_ESI_OFFSET       (MCONTEXT_GREGS_OFFSET + 5*4)
+#define  MCONTEXT_EBP_OFFSET       (MCONTEXT_GREGS_OFFSET + 6*4)
+#define  MCONTEXT_ESP_OFFSET       (MCONTEXT_GREGS_OFFSET + 7*4)
+#define  MCONTEXT_EBX_OFFSET       (MCONTEXT_GREGS_OFFSET + 8*4)
+#define  MCONTEXT_EDX_OFFSET       (MCONTEXT_GREGS_OFFSET + 9*4)
+#define  MCONTEXT_ECX_OFFSET       (MCONTEXT_GREGS_OFFSET + 10*4)
+#define  MCONTEXT_EAX_OFFSET       (MCONTEXT_GREGS_OFFSET + 11*4)
+#define  MCONTEXT_TRAPNO_OFFSET    (MCONTEXT_GREGS_OFFSET + 12*4)
+#define  MCONTEXT_ERR_OFFSET       (MCONTEXT_GREGS_OFFSET + 13*4)
+#define  MCONTEXT_EIP_OFFSET       (MCONTEXT_GREGS_OFFSET + 14*4)
+#define  MCONTEXT_CS_OFFSET        (MCONTEXT_GREGS_OFFSET + 15*4)
+#define  MCONTEXT_EFL_OFFSET       (MCONTEXT_GREGS_OFFSET + 16*4)
+#define  MCONTEXT_UESP_OFFSET      (MCONTEXT_GREGS_OFFSET + 17*4)
+#define  MCONTEXT_SS_OFFSET        (MCONTEXT_GREGS_OFFSET + 18*4)
+
+#define  UCONTEXT_SIGMASK_OFFSET   108
+
+#define  UCONTEXT_FPREGS_OFFSET       96
+#define  UCONTEXT_FPREGS_MEM_OFFSET   116
+
+#elif defined(__mips__)
+
+#define  MCONTEXT_GREGS_OFFSET     0
+#define  UCONTEXT_SIGMASK_OFFSET   0
+
+#else
+#error "This header has not been ported for your CPU"
+#endif
+
+#endif  // GOOGLEBREAKPAD_COMMON_ANDROID_UCONTEXT_CONSTANTS_H