On 11/20/2015 03:29 AM, Ian Lance Taylor wrote:
On Thu, Nov 19, 2015 at 2:24 AM, Avi Kivity <avi@xxxxxxxxxxxx> wrote:
I am using the swapcontext family to implement user-level threading.
Specifically, only getcontext(), setcontext(), and makecontext() are used,
during thread creation and teardown. Beyond the initial switch into a
thread, I use setjmp()/longjmp() as they are significantly faster.
This works well, except that in combination with Address Sanitizer I
stack-buffer-overflow errors accessing variables on a user-level-thread
stack, which, as far as I can tell, are false positives.
See for example https://github.com/scylladb/scylla/issues/533.
Is there any workaround for this? I am willing to write an alternate code
path for debugging. What would work here? sigaltstack()?
If you #include <asan_interface.h>, you can use macros like
ASAN_UNPOISON_MEMORY to tell asan that certain memory is OK to access.
I am not sure which memory I should unpoison. The user-level-thread
stack was allocated by the program, using malloc(), so it is visible to
asan.
