From: "H.J. Lu" <hjl.tools@gmail.com>
To: GNU C Library <libc-alpha@sourceware.org>,
GCC Development <gcc@gcc.gnu.org>,
"Carlos O'Donell" <carlos@redhat.com>
Subject: RFA: Need to extend x86 psABI to support thread cancellation and alternate signal stack
Date: Mon, 26 Mar 2018 22:43:00 -0000 [thread overview]
Message-ID: <CAMe9rOp_ODUck1Oa6cRPKVRkedQ=sq8RrNwPtBQ5RSvyEun-iw@mail.gmail.com> (raw)
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.
One possibility is
1. Add _URC_NO_REASON_CANCEL.
2. unwind_stop in libpthread returns _URC_NO_REASON_CANCEL.
3. _Unwind_ForcedUnwind_Phase2 sets frames to 1 for
_URC_NO_REASON_CANCEL
BTW, I opened:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85086
--
H.J.
next reply other threads:[~2018-03-26 22:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-26 22:43 H.J. Lu [this message]
2018-03-27 6:31 ` Florian Weimer
2018-03-27 11:26 ` H.J. Lu
2018-03-27 15:43 ` Florian Weimer
2018-03-27 15:55 ` H.J. Lu
2018-03-28 13:04 ` H.J. Lu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMe9rOp_ODUck1Oa6cRPKVRkedQ=sq8RrNwPtBQ5RSvyEun-iw@mail.gmail.com' \
--to=hjl.tools@gmail.com \
--cc=carlos@redhat.com \
--cc=gcc@gcc.gnu.org \
--cc=libc-alpha@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).