Add API to skip dump if crashing thread doesn't reference a given module

This CL makes it possible to skip a dump if the crashing thread doesn't
have any pointers to a given module. The concrete use case is WebView
where we would like to skip generating microdump output when webview
is unreferenced by the stack and thus cannot be responsible for the
crash in a way that would be debuggable.

The range of interesting addresses is chosen by examining the process
mappings to find the one that contains a pointer that is known to be in
the right shared object (i.e. an appropriately chosen function pointer)
passed from the client.

If the extracted stack does not contain a pointer in this range, then we
do not generate a microdump. If the stack extraction fails, we still
generate a microdump (without a stack).

BUG=664460

Change-Id: If19406a13168264f7751245fc39591bd6cdbf5df
Reviewed-on: https://chromium-review.googlesource.com/419476
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Primiano Tucci <primiano@chromium.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/client/linux/dump_writer_common/mapping_info.h b/src/client/linux/dump_writer_common/mapping_info.h
index 5f247cfd..c09e48ab 100644
--- a/src/client/linux/dump_writer_common/mapping_info.h
+++ b/src/client/linux/dump_writer_common/mapping_info.h
@@ -41,8 +41,21 @@ namespace google_breakpad {
 // One of these is produced for each mapping in the process (i.e. line in
 // /proc/$x/maps).
 struct MappingInfo {
+  // On Android, relocation packing can mean that the reported start
+  // address of the mapping must be adjusted by a bias in order to
+  // compensate for the compression of the relocation section. The
+  // following two members hold (after LateInit) the adjusted mapping
+  // range. See crbug.com/606972 for more information.
   uintptr_t start_addr;
   size_t size;
+  // When Android relocation packing causes |start_addr| and |size| to
+  // be modified with a load bias, we need to remember the unbiased
+  // address range. The following structure holds the original mapping
+  // address range as reported by the operating system.
+  struct {
+    uintptr_t start_addr;
+    uintptr_t end_addr;
+  } system_mapping_info;
   size_t offset;  // offset into the backed file.
   bool exec;  // true if the mapping has the execute bit set.
   char name[NAME_MAX];