linux-kernel - Re: [ 21/21] x86, vm86: fix VM86 syscalls: use SYSCALL

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Message-ID: <87li743a28.wl%satoru.takeuchi@gmail.com>
Date:	Fri, 24 May 2013 20:13:19 +0900
From:	Satoru Takeuchi <satoru.takeuchi@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Alexander van Heukelum <heukelum@...tmail.fm>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [ 21/21] x86, vm86: fix VM86 syscalls: use SYSCALL_DEFINEx(...)

At Wed, 22 May 2013 15:10:39 -0700,
Greg Kroah-Hartman wrote:
> 
> 3.9-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Alexander van Heukelum <heukelum@...tmail.fm>
> 
> commit 5522ddb3fc0dfd4a503c8278eafd88c9f2d3fada upstream.
> 
> 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 calling convention for syscalls.

> 
> [AV: killed asmlinkage_protect() - it's done automatically now]

The Patch itself is OK. But the above one line is not correct and should
be removed. This backport patch calls asmlinkage_protect() since 3.9
doesn't automatically call it. It's why the original upstream patch is
dropped from 3.9.3.

Thanks,
Satoru

> 
> Backported-by: Satoru Takeuchi <satoru.takeuchi@...il.com>
> Reported-and-tested-by: Hans de Bruin <jmdebruin@...net.nl>
> Signed-off-by: Alexander van Heukelum <heukelum@...tmail.fm>
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> 
> ---
>  arch/x86/include/asm/syscalls.h |    4 ++--
>  arch/x86/kernel/vm86_32.c       |   11 ++++++-----
>  2 files changed, 8 insertions(+), 7 deletions(-)
> 
> --- a/arch/x86/include/asm/syscalls.h
> +++ b/arch/x86/include/asm/syscalls.h
> @@ -37,8 +37,8 @@ asmlinkage int sys_get_thread_area(struc
>  unsigned long sys_sigreturn(void);
>  
>  /* kernel/vm86_32.c */
> -int sys_vm86old(struct vm86_struct __user *);
> -int sys_vm86(unsigned long, unsigned long);
> +asmlinkage long sys_vm86old(struct vm86_struct __user *);
> +asmlinkage long sys_vm86(unsigned long, unsigned long);
>  
>  #else /* CONFIG_X86_32 */
>  
> --- a/arch/x86/kernel/vm86_32.c
> +++ b/arch/x86/kernel/vm86_32.c
> @@ -33,6 +33,7 @@
>  #include <linux/capability.h>
>  #include <linux/errno.h>
>  #include <linux/interrupt.h>
> +#include <linux/syscalls.h>
>  #include <linux/sched.h>
>  #include <linux/kernel.h>
>  #include <linux/signal.h>
> @@ -48,7 +49,6 @@
>  #include <asm/io.h>
>  #include <asm/tlbflush.h>
>  #include <asm/irq.h>
> -#include <asm/syscalls.h>
>  
>  /*
>   * Known problems:
> @@ -202,17 +202,16 @@ 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)
> +SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86)
>  {
>  	struct kernel_vm86_struct info; /* declare this _on top_,
>  					 * this avoids wasting of stack space.
>  					 * This remains on the stack until we
>  					 * return to 32 bit user space.
>  					 */
> -	struct task_struct *tsk;
> +	struct task_struct *tsk = current;
>  	int tmp, ret = -EPERM;
>  
> -	tsk = current;
>  	if (tsk->thread.saved_sp0)
>  		goto out;
>  	tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
> @@ -227,11 +226,12 @@ int sys_vm86old(struct vm86_struct __use
>  	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)
> +SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
>  {
>  	struct kernel_vm86_struct info; /* declare this _on top_,
>  					 * this avoids wasting of stack space.
> @@ -278,6 +278,7 @@ int sys_vm86(unsigned long cmd, unsigned
>  	do_sys_vm86(&info, tsk);
>  	ret = 0;	/* we never return here */
>  out:
> +	asmlinkage_protect(2, ret, cmd, arg);
>  	return ret;
>  }
>  
> 
> 
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