ELF executables and libraries may be loaded into memory in several
mappings, possibly with holes containing anonymous mappings
or mappings of other files. This method takes an input mapping and
attempts to find the mapping for file offset 0 of the same file.
Bug: crashpad:30
Change-Id: I79abf060b015d58ef0eba54a399a74315d7d2d77
Reviewed-on: https://chromium-review.googlesource.com/565223
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
The lots-of-regions tests in the MemoryMap test case were very
time-consuming, particularly in debug mode. MemoryMap.MapRunningChild
took as long as 15 seconds on-device (Nexus 5X), and the best result was
in the neighborhood of 7 seconds.
The bulk of the time spent in these tests was in ExpectMappings(), which
calls MemoryMap::FindMapping() in a loop to verify each region. Each
call to FindMapping() traverses the MemoryMap (internally, currently
just a std::vector<>) from the beginning. With the need to verify 4,096
regions, a single call to ExpectMappings() had to perform over 8,000,000
checks to find the regions it needed. In turn, ExpectMappings() is
called once by the SelfLargeMapFile test, and eight times by
MapRunningChild. By reducing the number of regions to 1,024, each call
to ExpectMappings() needs to perform “only” fewer than 600,000 checks.
After this change, MemoryMap.MapRunningChild completes in about a half a
second on-device.
https://crashpad.chromium.org/bug/181 is concerned with implementing a
RangeMap to serve MemoryMap and other similar code. After that’s done,
it, it should be feasible to raise the number of regions used for these
tests again.
Bug: crashpad:30, crashpad:181
Test: crashpad_util_test MemoryMap.SelfLargeMapFile:MemoryMap.MapRunningChild
Change-Id: I8ff88dac72a63c97ac937304b578fbe3b4ebf316
Reviewed-on: https://chromium-review.googlesource.com/494128
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
When the /proc/pid/maps file is not read atomically and the target
process is actively mapping memory, entries can be read multiple times
or missed entirely. This change makes MemoryMap read the whole contents
of the maps file before attempting to parse it as well as check for
duplication/overlap errors, retrying on failure. This change also adds
ptrace attachements to unit tests to reflect actual intended usage.
Bug: crashpad:30
Change-Id: Ie8549548e25c47baa418ee7439d82743f84ff41e
Reviewed-on: https://chromium-review.googlesource.com/491950
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Some of the new Linux/Android tests were failing in 32-bit code where
pointers were being casted via reinterpret_cast<>() to LinuxVMAddress,
an unsigned 64-bit type. The behavior of such casts is
implementation-defined, and in this case, sign-extension was being used
to convert the 32-bit pointers to 64 bits, resulting in very large
(unsigned) LinuxVMAddress values that could not possibly refer to proper
addresses in a 32-bit process’ address space.
The offending reinterpret_cast<>() conversions have been replaced with
the new FromPointerCast<>(), which is careful to do sign-extension when
converting to a signed type, and zero-extension when converting to an
unsigned type like LinuxVMAddress.
Bug: crashpad:30
Test: crashpad_util_test FromPointerCast*:MemoryMap.*:ProcessMemory.*
Change-Id: I6f1408dc63369a8740ecd6015d657e4407a7c271
Reviewed-on: https://chromium-review.googlesource.com/488264
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
