https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85086
Bug ID: 85086
Summary: _Unwind_Resume can't unwind shadow stack with thread
cancellation and alternate signal stack
Product: gcc
Version: 8.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libgcc
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
Target Milestone: ---
Target: x86
On Linux, when alternate signal stack is used with thread cancellation,
_Unwind_Resume fails when it tries to unwind shadow stack from signal
handler on alternate signal stack. The issue is that signal handler on
alternate signal stack uses a separate shadow stack and we must switch
to the original shadow stack to unwind it. But frame count will be wrong
in this case. For thread cancellation, there is no need to unwind shadow
stack since it will long jump back and exit.
