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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1265730969-30145-3-git-send-email-ian.campbell@citrix.com>
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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/