linux-kernel - Re: [PATCH] x86: pass in pt_regs pointer for syscalls that need it (take 2)

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Date:	Wed, 11 Feb 2009 13:50:55 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Brian Gerst <brgerst@...il.com>
CC:	Tejun Heo <tj@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: pass in pt_regs pointer for syscalls that need it
 (take 2)

Looks much better!

Brian Gerst wrote:
>  
>  #ifdef CONFIG_X86_32
> -/*
> - * Note: do not pass in pt_regs directly as with tail-call optimization
> - * GCC will incorrectly stomp on the caller's frame and corrupt user-space
> - * register state:
> - */
> -asmlinkage int sys_rt_sigreturn(unsigned long __unused)
> +int sys_rt_sigreturn(struct pt_regs *regs)
>  {
> -	struct pt_regs *regs = (struct pt_regs *)&__unused;
> -
>  	return do_rt_sigreturn(regs);
>  }
>  #else /* !CONFIG_X86_32 */

I observe with this sys_rt_sigreturn() is identical for both 32 and 64 
bits (since int == long for 32 bits.)  Furthermore, *both* are now no-op 
stubs around do_rt_sigreturn, so we can simply remove both stubs and 
change do_rt_sigreturn into sys_rt_sigreturn.

	-hpa
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