From: "Andy Lutomirski" <luto@kernel.org>
To: "Ali Raza" <aliraza@bu.edu>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Cc: "Jonathan Corbet" <corbet@lwn.net>,
masahiroy@kernel.org, michal.lkml@markovi.net,
"Nick Desaulniers" <ndesaulniers@google.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Kees Cook" <keescook@chromium.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Arnd Bergmann" <arnd@arndb.de>,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, "Steven Rostedt" <rostedt@goodmis.org>,
"Ben Segall" <bsegall@google.com>,
mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com,
"Paolo Bonzini" <pbonzini@redhat.com>,
jpoimboe@kernel.org, linux-doc@vger.kernel.org,
linux-kbuild@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org,
"the arch/x86 maintainers" <x86@kernel.org>,
rjones@redhat.com, munsoner@bu.edu, tommyu@bu.edu,
drepper@redhat.com, lwoodman@redhat.com, mboydmcse@gmail.com,
okrieg@bu.edu, rmancuso@bu.edu
Subject: Re: [RFC UKL 07/10] x86/signal: Adjust signal handler register values and return frame
Date: Tue, 04 Oct 2022 10:34:12 -0700 [thread overview]
Message-ID: <40484dc2-8da3-486d-9c53-02ae23a50fbb@app.fastmail.com> (raw)
In-Reply-To: <20221003222133.20948-8-aliraza@bu.edu>
On Mon, Oct 3, 2022, at 3:21 PM, Ali Raza wrote:
> For a UKL thread, returning to a signal handler is not done with iret or
> sysret. This means we need to adjust the way the return stack frame is
> handled for these threads. When constructing the signal frame, we leave
> the previous frame in place because we will return to it from the signal
> handler. We also leave space for pushing eflags and the return address.
> UKL threads will only use the __KERNEL_DS value in the ss register and 0xC3
> in the cs register.
This is unclear. Are you taking about returning from the kernel fault code *to* the signal handler or are you talking about returning *from* the user signal hander to the user code that was running when the signal happened?
In any case, I don't see what this has to do with iret or sysret. Surely UKL can use a sigreturn() just like regular Linux.
The part where a UKL thread has permission to return to a CPL0 context should be a separate patch.
--Andy
next prev parent reply other threads:[~2022-10-04 17:34 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-03 22:21 [RFC UKL 00/10] Unikernel Linux (UKL) Ali Raza
2022-10-03 22:21 ` [RFC UKL 01/10] kbuild: Add sections and symbols to linker script for UKL support Ali Raza
2022-10-03 22:21 ` [RFC UKL 02/10] x86/boot: Load the PT_TLS segment for Unikernel configs Ali Raza
2022-10-04 17:30 ` Andy Lutomirski
2022-10-06 21:00 ` Ali Raza
2022-10-03 22:21 ` [RFC UKL 03/10] sched: Add task_struct tracking of kernel or application execution Ali Raza
2022-10-03 22:21 ` [RFC UKL 04/10] x86/entry: Create alternate entry path for system calls Ali Raza
2022-10-04 17:43 ` Andy Lutomirski
2022-10-06 21:12 ` Ali Raza
2022-10-03 22:21 ` [RFC UKL 05/10] x86/uaccess: Make access_ok UKL aware Ali Raza
2022-10-04 17:36 ` Andy Lutomirski
2022-10-06 21:16 ` Ali Raza
2022-10-03 22:21 ` [RFC UKL 06/10] x86/fault: Skip checking kernel mode access to user address space for UKL Ali Raza
2022-10-03 22:21 ` [RFC UKL 07/10] x86/signal: Adjust signal handler register values and return frame Ali Raza
2022-10-04 17:34 ` Andy Lutomirski [this message]
2022-10-06 21:20 ` Ali Raza
2022-10-03 22:21 ` [RFC UKL 08/10] exec: Make exec path for starting UKL application Ali Raza
2022-10-03 22:21 ` [RFC UKL 09/10] exec: Give userspace a method for starting UKL process Ali Raza
2022-10-04 17:35 ` Andy Lutomirski
2022-10-06 21:25 ` Ali Raza
2022-10-03 22:21 ` [RFC UKL 10/10] Kconfig: Add config option for enabling and sample for testing UKL Ali Raza
2022-10-04 2:11 ` Bagas Sanjaya
2022-10-06 21:28 ` Ali Raza
2022-10-07 10:21 ` Masahiro Yamada
2022-10-13 17:08 ` Ali Raza
2022-10-06 21:27 ` [RFC UKL 00/10] Unikernel Linux (UKL) H. Peter Anvin
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=40484dc2-8da3-486d-9c53-02ae23a50fbb@app.fastmail.com \
--to=luto@kernel.org \
--cc=aliraza@bu.edu \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=bristot@redhat.com \
--cc=bsegall@google.com \
--cc=corbet@lwn.net \
--cc=dave.hansen@linux.intel.com \
--cc=dietmar.eggemann@arm.com \
--cc=drepper@redhat.com \
--cc=ebiederm@xmission.com \
--cc=hpa@zytor.com \
--cc=jpoimboe@kernel.org \
--cc=juri.lelli@redhat.com \
--cc=keescook@chromium.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lwoodman@redhat.com \
--cc=masahiroy@kernel.org \
--cc=mboydmcse@gmail.com \
--cc=mgorman@suse.de \
--cc=michal.lkml@markovi.net \
--cc=mingo@redhat.com \
--cc=munsoner@bu.edu \
--cc=ndesaulniers@google.com \
--cc=okrieg@bu.edu \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rjones@redhat.com \
--cc=rmancuso@bu.edu \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=tommyu@bu.edu \
--cc=vincent.guittot@linaro.org \
--cc=viro@zeniv.linux.org.uk \
--cc=vschneid@redhat.com \
--cc=x86@kernel.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 NNTP newsgroup(s).