x86, vm86: fix VM86 syscalls: use asmlinkage calling convention

Commit Message

Alexander Van Heukelum March 27, 2013, 7:31 p.m. UTC

Hi Al,

Hans de Bruin found a regression due to one of your changes. I asked him to test a fix and he reported back that it worked. (Thanks!) Can you see if you agree with the fix? Patch is attached due to webmail...

Greetings,
    Alexander

Comments

Al Viro March 27, 2013, 7:46 p.m. UTC | #1

On Wed, Mar 27, 2013 at 08:31:02PM +0100, Alexander van Heukelum wrote:
> Hi Al,
> 
> Hans de Bruin found a regression due to one of your changes. I asked him to test a fix and he reported back that it worked. (Thanks!) Can you see if you agree with the fix? Patch is attached due to webmail...

Use SYSCALL_DEFINE{1,2} for vm86_old and vm86, please.

Patch

From 961a1b130aa79acb54f556a0accfcc643d1d3ed1 Mon Sep 17 00:00:00 2001
From: Alexander van Heukelum <[e-mail]>
Date: Tue, 26 Mar 2013 21:57:43 +0100
Subject: [PATCH] x86, vm86: fix VM86 syscalls: use asmlinkage calling convention

Commit 49cb25e9290 x86: 'get rid of pt_regs argument in vm86/vm86old'
got rid of the pt_regs stub for sys_vm86old and sys_vm86. The functions
were, however, not changed to use the asmlinkage calling convention.

The regression was reported and pinpointed by Hans de Bruin:
> commit 49cb25e9290 x86: 'get rid of pt_regs argument in vm86/vm86old'
> somehow breaks the colors when I play 'civilization I' under xdosemu.
> During the intro of the game something the colors get messed up. When
> the game begins the grass of the earth is red. Reverting the commit
> fixes the problem.

And he tested the patch too:
> Yep, the grass is green again.

Reported-and-tested-by: Hans de Bruin <[e-mail]>
Signed-off-by: Alexander van Heukelum <[e-mail]>
---
 arch/x86/include/asm/syscalls.h | 4 ++--
 arch/x86/kernel/vm86_32.c       | 6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index 6cf0a9c..a245b88 100644
--- a/arch/x86/include/asm/syscalls.h
+++ b/arch/x86/include/asm/syscalls.h
@@ -37,8 +37,8 @@  asmlinkage int sys_get_thread_area(struct user_desc __user *);
 unsigned long sys_sigreturn(void);
 
 /* kernel/vm86_32.c */
-int sys_vm86old(struct vm86_struct __user *);
-int sys_vm86(unsigned long, unsigned long);
+asmlinkage int sys_vm86old(struct vm86_struct __user *);
+asmlinkage int sys_vm86(unsigned long, unsigned long);
 
 #else /* CONFIG_X86_32 */
 
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 1cf5766..7f72807 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -202,7 +202,7 @@  out:
 static int do_vm86_irq_handling(int subfunction, int irqnumber);
 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
 
-int sys_vm86old(struct vm86_struct __user *v86)
+asmlinkage int sys_vm86old(struct vm86_struct __user *v86)
 {
 	struct kernel_vm86_struct info; /* declare this _on top_,
 					 * this avoids wasting of stack space.
@@ -227,11 +227,12 @@  int sys_vm86old(struct vm86_struct __user *v86)
 	do_sys_vm86(&info, tsk);
 	ret = 0;	/* we never return here */
 out:
+	asmlinkage_protect(1, ret, v86);
 	return ret;
 }
 
 
-int sys_vm86(unsigned long cmd, unsigned long arg)
+asmlinkage int sys_vm86(unsigned long cmd, unsigned long arg)
 {
 	struct kernel_vm86_struct info; /* declare this _on top_,
 					 * this avoids wasting of stack space.
@@ -278,6 +279,7 @@  int sys_vm86(unsigned long cmd, unsigned long arg)
 	do_sys_vm86(&info, tsk);
 	ret = 0;	/* we never return here */
 out:
+	asmlinkage_protect(2, ret, cmd, arg);
 	return ret;
 }
 
-- 
1.8.1.2