From: Ian Campbell <ian.campbell@citrix.com>
To: linux-kernel@vger.kernel.org
Cc: 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: Tue, 9 Feb 2010 15:56:08 +0000 [thread overview]
Message-ID: <1265730969-30145-3-git-send-email-ian.campbell@citrix.com> (raw)
In-Reply-To: <1265730969-30145-1-git-send-email-ian.campbell@citrix.com>
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>
Cc: x86@kernel.org
---
arch/x86/kernel/entry_64.S | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 18e4c59..b771c2f 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -398,13 +398,13 @@ ENTRY(ret_from_fork)
LOCK ; btr $TIF_FORK,TI_flags(%r8)
- push $0x0002
+ call schedule_tail # rdi: 'prev' task parameter
+
+ push $0x0202
CFI_ADJUST_CFA_OFFSET 8
popf # reset kernel eflags
CFI_ADJUST_CFA_OFFSET -8
- call schedule_tail # rdi: 'prev' task parameter
-
GET_THREAD_INFO(%rcx)
RESTORE_REST
--
1.5.6.5
next prev parent reply other threads:[~2010-02-09 15:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-09 15:56 [PATCH 0/3] x86: slightly unify ret_from_fork Ian Campbell
2010-02-09 15:56 ` [PATCH 1/3] x86: drop unnecessary kernel_eflags variable from 64 bit Ian Campbell
2010-02-09 15:56 ` Ian Campbell [this message]
2010-02-09 15:56 ` [PATCH 3/3] x86: ret_from_fork: use symbolic contants for bits in EFLAGS Ian Campbell
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
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 2/3] x86: make 64 bit ret_from_fork a little more similar to 32 bit Ian Campbell
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