linux-kernel - Re: [PATCH] strange work_notifysig code since 2.6.16

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Date:	Wed, 25 Oct 2006 10:29:23 -0400
From:	Joe Korty <joe.korty@...r.com>
To:	Matt Mackall <mpm@...enic.com>
Cc:	akpm@...l.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] strange work_notifysig code since 2.6.16

> I suspect this won't link with CONFIG_VM86 disabled because save_v86_state
> goes away. I think we just need to move the #endif up a few lines.

Hi Matt,
Since that also makes the 'then' and 'else' branches identical, perhaps
this patch would be better .. it eliminates the VM86 test entirely when
CONFIG_VM86=n.

Boot tested with CONFIG_VM86=y.

Regards,
Joe

The entry.S code at work_notifysig is surely wrong.  It drops into unrelated
code if the branch to work_notifysig_v86 is taken, and CONFIG_VM86=n.

	[PATCH] Make vm86 support optional
	tree 9b5daef5280800a0006343a17f63072658d91a1d
	pushed to git Jan 8, 2006, and first appears in 2.6.16

The 'fix' here is to also compile out the vm86 test & branch when
CONFIG_VM86=n.

Signed-off-by: Joe Korty <joe.korty@...r.com>

Index: 2.6.18.1/arch/i386/kernel/entry.S
===================================================================
--- 2.6.18.1.orig/arch/i386/kernel/entry.S	2006-10-25 10:06:25.000000000 -0400
+++ 2.6.18.1/arch/i386/kernel/entry.S	2006-10-25 10:10:38.000000000 -0400
@@ -447,6 +447,7 @@
 
 work_notifysig:				# deal with pending signals and
 					# notify-resume requests
+#ifdef CONFIG_VM86
 	testl $VM_MASK, EFLAGS(%esp)
 	movl %esp, %eax
 	jne work_notifysig_v86		# returning to kernel-space or
@@ -457,17 +458,18 @@
 
 	ALIGN
 work_notifysig_v86:
-#ifdef CONFIG_VM86
 	pushl %ecx			# save ti_flags for do_notify_resume
 	CFI_ADJUST_CFA_OFFSET 4
 	call save_v86_state		# %eax contains pt_regs pointer
 	popl %ecx
 	CFI_ADJUST_CFA_OFFSET -4
 	movl %eax, %esp
+#else
+	movl %esp, %eax
+#endif
 	xorl %edx, %edx
 	call do_notify_resume
 	jmp resume_userspace_sig
-#endif
 
 	# perform syscall exit tracing
 	ALIGN
-
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