From: Wei Liu <wei.liu2@citrix.com>
To: Roger Pau Monne <roger.pau@citrix.com>
Cc: Sergey Dyasli <sergey.dyasli@citrix.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
Julien Grall <julien.grall@arm.com>,
Jan Beulich <jbeulich@suse.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH] mm: make opt_bootscrub non-init
Date: Sat, 24 Nov 2018 11:46:05 +0000 [thread overview]
Message-ID: <20181124114605.edwwe253rptmuamb@zion.uk.xensource.com> (raw)
In-Reply-To: <20181123143002.79743-1-roger.pau@citrix.com>
On Fri, Nov 23, 2018 at 03:30:02PM +0100, Roger Pau Monne wrote:
> LLVM code generation can attempt to load from a variable in the next
> condition of an expression under certain circumstances, thus turning
> the following condition:
>
> if ( system_state < SYS_STATE_active && opt_bootscrub == BOOTSCRUB_IDLE )
>
> Into:
>
> 0xffff82d080223967 <+103>: cmpl $0x3,0x37b032(%rip) # 0xffff82d08059e9a0 <system_state>
> 0xffff82d08022396e <+110>: setb -0x29(%rbp)
> 0xffff82d080223972 <+114>: cmpl $0x2,0x228a8b(%rip) # 0xffff82d08044c404 <opt_bootscrub>
>
> Such code will trigger a page fault if system_state >=
> SYS_STATE_active because opt_bootscrub will be unmapped.
>
> Fix this by making opt_bootscrub non-init, thus preventing the page
> fault. The LLVM bug with the discussion about this issue can be found
> at:
>
> https://bugs.llvm.org/show_bug.cgi?id=39707
>
> I haven't been able to find any other instances of such conditional
> expression that uses system_state together with an init variable or
> function.
>
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2018-11-24 11:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-23 14:30 [PATCH] mm: make opt_bootscrub non-init Roger Pau Monne
2018-11-23 14:50 ` Andrew Cooper
2018-11-23 14:51 ` Julien Grall
2018-11-23 15:41 ` Sergey Dyasli
2018-11-24 11:46 ` Wei Liu [this message]
2018-11-26 10:06 ` Jan Beulich
2018-11-26 12:04 ` Roger Pau Monné
2018-11-26 12:18 ` Jan Beulich
2018-11-26 12:25 ` Julien Grall
2018-11-26 12:36 ` Jan Beulich
2018-11-26 12:49 ` Roger Pau Monné
2018-11-26 13:01 ` Jan Beulich
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=20181124114605.edwwe253rptmuamb@zion.uk.xensource.com \
--to=wei.liu2@citrix.com \
--cc=George.Dunlap@eu.citrix.com \
--cc=andrew.cooper3@citrix.com \
--cc=ian.jackson@eu.citrix.com \
--cc=jbeulich@suse.com \
--cc=julien.grall@arm.com \
--cc=konrad.wilk@oracle.com \
--cc=roger.pau@citrix.com \
--cc=sergey.dyasli@citrix.com \
--cc=sstabellini@kernel.org \
--cc=tim@xen.org \
--cc=xen-devel@lists.xenproject.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.