From: Ian Campbell <ian.campbell@citrix.com>
To: linux-kernel@vger.kernel.org
Cc: Pekka Enberg <penberg@kernel.org>,
Cyrill Gorcunov <gorcunov@gmail.com>,
"H. Peter Anvin" <hpa@zytor.com>, Andi Kleen <ak@linux.intel.com>,
Ian Campbell <ian.campbell@citrix.com>,
x86@kernel.org
Subject: [PATCH 2/3] x86: make 64 bit ret_from_fork a little more similar to 32 bit
Date: Mon, 25 Jul 2011 11:03:06 +0100 [thread overview]
Message-ID: <1311588187-20079-2-git-send-email-ian.campbell@citrix.com> (raw)
In-Reply-To: <1311587883.27940.20.camel@cthulhu.hellion.org.uk>
The 64 bit version resets EFLAGS before calling schedule_tail() and
therefore leaves EFLAGS.IF clear. 32 bit resets EFLAGS after calling
schedule_tail() and therefore leaves EFLAGS.IF set. I don't think
there is any practical difference between the two approaches since
interrupts are actually reenabled within schedule_tail
(schedule_tail->finish_task_switch->finish_lock_switch->raw_spin_unlock_irq->...->local_irq_enable)
so arbitrarily pick the 32 bit version and make 64 bit look like that.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: x86@kernel.org
---
arch/x86/kernel/entry_64.S | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index b50d142..9c28bd5 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -394,13 +394,14 @@ END(save_paranoid)
ENTRY(ret_from_fork)
DEFAULT_FRAME
- LOCK ; btr $TIF_FORK,TI_flags(%r8)
- pushq_cfi $0x0002
- popfq_cfi # reset kernel eflags
+ LOCK ; btr $TIF_FORK,TI_flags(%r8)
call schedule_tail # rdi: 'prev' task parameter
+ pushq_cfi $0x0202
+ popfq_cfi # reset kernel eflags
+
GET_THREAD_INFO(%rcx)
RESTORE_REST
--
1.7.2.5
next prev parent reply other threads:[~2011-07-25 10:03 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-25 9:58 [PATCH 0/3] minor cleanups to EFLAGS initialisation in ret_from_fork Ian Campbell
2011-07-25 10:03 ` [PATCH 1/3] x86: drop unnecessary kernel_eflags variable from 64 bit Ian Campbell
2011-07-25 10:03 ` Ian Campbell [this message]
2011-07-25 10:03 ` [PATCH 3/3] x86: ret_from_fork: use symbolic contants for bits in EFLAGS Ian Campbell
2011-07-25 10:19 ` [PATCH 0/3] minor cleanups to EFLAGS initialisation in ret_from_fork Cyrill Gorcunov
2011-07-25 18:20 ` Cyrill Gorcunov
2011-07-25 21:10 ` H. Peter Anvin
2011-07-25 21:47 ` Cyrill Gorcunov
2011-07-26 14:46 ` Peter Zijlstra
2011-07-26 15:51 ` Ian Campbell
2011-08-10 15:27 ` Ian Campbell
2011-08-10 15:35 ` Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2011-07-05 11:15 [Q x86-64] on kernel_eflags Cyrill Gorcunov
2011-07-05 13:00 ` [PATCH 2/3] x86: make 64 bit ret_from_fork a little more similar to 32 bit Ian Campbell
2011-07-06 9:41 ` Pekka Enberg
2010-02-09 15:56 [PATCH 0/3] x86: slightly unify ret_from_fork Ian Campbell
2010-02-09 15:56 ` [PATCH 2/3] x86: make 64 bit ret_from_fork a little more similar to 32 bit Ian Campbell
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