lkml.org 
[lkml]   [2017]   [Nov]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 01/18] x86/entry/64: Fix entry_SYSCALL_64_after_hwframe IRQ tracing

* Andy Lutomirski <luto@kernel.org> wrote:

> When I added entry_SYSCALL_64_after_hwframe, I left TRACE_IRQS_OFF
> before it. This means that users of entry_SYSCALL_64_after_hwframe
> were responsible for invoking TRACE_IRQS_OFF, and the one and only
> user (added in the same commit) got it wrong.
>
> I think this would manifest as a warning if a Xen PV guest with
> CONFIG_DEBUG_LOCKDEP=y were used with context tracking. (The
> context tracking bit is to cause lockdep to get invoked before we
> turn IRQs back on.) I haven't tested that for real yet because I
> can't get a kernel configured like that to boot at all on Xen PV.
> I've reported it upstream. The problem seems to be that Xen PV is
> missing early #UD handling, is hitting some WARN, and we rely on

JFYI, seems the changelog got truncated at this point - I simply removed that
partial sentence as I suppose those details will be explained in the Xen fix
anyway.

> Move TRACE_IRQS_OFF below the label.

Thanks,

Ingo

\
 
 \ /
  Last update: 2017-11-22 06:36    [W:0.210 / U:0.832 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site