The main motivation for this change is to handle very large stack
traces, normally the result of infinite recursion. This part is
actually fairly simple, relaxing a few self-imposed limits on how
many frames we can unwind and the max size for stack memory.
Relaxing these limits requires stricter and more consistent checks for
stack unwinding. There are a number of unwinding invariants that apply
to all the platforms:
1. stack pointer (and frame pointer) must be within the stack memory
(frame pointer, if preset, must point to the right frame too)
2. unwinding must monotonically increase SP
(except for the first frame unwind, this must be a strict increase)
3. Instruction pointer (return address) must point to a valid location
4. stack pointer (and frame pointer) must be appropriately aligned
This change is focused on 2), which is enough to guarantee that the
unwinding doesn't get stuck in an infinite loop.
1) is implicitly validated part of accessing the stack memory
(explicit checks might be nice though).
4) is ABI specific and while it may be valuable in catching suspicious
frames is not in the scope of this change.
3) is also an interesting check but thanks to just-in-time compilation
it's more complex than just calling
StackWalker::InstructionAddressSeemsValid()
and we don't want to drop parts of the callstack due to an overly
conservative check.
Bug: chromium:735989
Change-Id: I9aaba77c7fd028942d77c87d51b5e6f94e136ddd
Reviewed-on: https://chromium-review.googlesource.com/563771
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Ivan Penkov <ivanpe@chromium.org>
Currently on MIPS we accidentally terminate stackwalk if $sp value doesn't change between frames
which results in incomplete callchain terminated at the point of first tailcall encountered.
Change-Id: I8f1ed1df958d8f0a9eb11fd7800062184d8f1ee2
Reviewed-on: https://chromium-review.googlesource.com/449755
Reviewed-by: Mark Mentovai <mark@chromium.org>
These compile errors occur when building the check target with:
CXX=clang++-3.8
CXXFLAGS="-Werror -Wconstant-conversion -g -O2 -std=c++11"
src/processor/stackwalker_mips.cc:60:9: error: comparison of constant
18446744073709551615 with expression of type 'bool' is always false
[Werror,-Wtautological-constant-out-of-range-compare]
> 0xffffffffffffffff) {
^ ~~~~~~~~~~~~~~~~~~
src/processor/stackwalker_mips.cc:68:66: error: comparison of constant
4294967295 with expression of type 'bool' is always false
[-Werror,-Wtautological-constant-out-of-range-compare]
if ((memory_ && memory_->GetBase() + memory_->GetSize() - 1) > 0xffffffff) {
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~
Change-Id: I29eed8f4a67b9feeb274aa1fc6c79a019135e8d6
Reviewed-on: https://chromium-review.googlesource.com/438445
Reviewed-by: Mike Frysinger <vapier@chromium.org>
