linux-kernel - [PATCH 2/3] x86: make 64 bit ret_from_fork a little more similar to 32 bit

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Date:	Tue,  9 Feb 2010 15:56:08 +0000
From:	Ian Campbell <ian.campbell@...rix.com>
To:	linux-kernel@...r.kernel.org
Cc:	Ian Campbell <ian.campbell@...rix.com>, x86@...nel.org
Subject: [PATCH 2/3] x86: make 64 bit ret_from_fork a little more similar to 32 bit

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@...rix.com>
Cc: x86@...nel.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

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