From: Dave Hansen <dave.hansen@linux.intel.com>
To: Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, LKML <linux-kernel@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC 1/2] x86/entry/64: Use the TSS sp2 slot for rsp_scratch
Date: Mon, 23 Jul 2018 05:38:27 -0700 [thread overview]
Message-ID: <854ac759-efec-3e35-59a9-8da35b2b5156@linux.intel.com> (raw)
In-Reply-To: <38b5a24f3c9f519dd7dc98171eb3a3c669fff48c.1532281180.git.luto@kernel.org>
On 07/22/2018 10:45 AM, Andy Lutomirski wrote:
> + /*
> + * sp2 is scratch space used by the SYSCALL64 handler. Linux does
> + * not use rung 2, so sp2 is not otherwise needed.
> + */
> u64 sp2;
Could we call out the actual thing that we use this slot for, and the
symbol name so folks can find the corresponding code that does this?
While I know the spot in entry_64 you're talking about, it might not be
patently obvious to everyone, and it's also a bit more challenging to
grep for than normal C code.
Maybe:
/*
* Since Linux does not use ring 2, the 'sp2' slot is unused.
* entry_SYSCALL_64 uses this as scratch space to stash the user
* %RSP value.
*/
next prev parent reply other threads:[~2018-07-23 12:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-22 17:45 [RFC 0/2] Get rid of the entry trampoline Andy Lutomirski
2018-07-22 17:45 ` [RFC 1/2] x86/entry/64: Use the TSS sp2 slot for rsp_scratch Andy Lutomirski
2018-07-22 20:12 ` Ingo Molnar
2018-07-23 12:38 ` Dave Hansen [this message]
2018-07-24 2:36 ` Andy Lutomirski
2018-07-22 17:45 ` [RFC 2/2] x86/pti/64: Remove the SYSCALL64 entry trampoline Andy Lutomirski
2018-07-22 18:27 ` Linus Torvalds
2018-07-22 20:59 ` Andy Lutomirski
2018-07-23 12:59 ` Dave Hansen
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=854ac759-efec-3e35-59a9-8da35b2b5156@linux.intel.com \
--to=dave.hansen@linux.intel.com \
--cc=bp@alien8.de \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=torvalds@linux-foundation.org \
--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).