linux-kernel - Re: [PATCH V4 1/7] x86/traps: Move pt_regs only in fixup_bad

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Date:   Mon, 11 Apr 2022 11:36:51 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Lai Jiangshan <jiangshanlai@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        Lai Jiangshan <jiangshan.ljs@...group.com>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Tai <thomas.tai@...cle.com>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH V4 1/7] x86/traps: Move pt_regs only in fixup_bad_iret()

On Fri, Mar 18, 2022 at 10:30:10PM +0800, Lai Jiangshan wrote:
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 1563fb995005..9fe9cd9d3eeb 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -892,13 +892,8 @@ asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *r
>  }
>  #endif
>  
> -struct bad_iret_stack {
> -	void *error_entry_ret;
> -	struct pt_regs regs;
> -};
> -
>  asmlinkage __visible noinstr
> -struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
> +struct pt_regs *fixup_bad_iret(struct pt_regs *bad_regs)
>  {
>  	/*
>  	 * This is called from entry_64.S early in handling a fault

While at it, unbreak that line:

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 9fe9cd9d3eeb..28591132e885 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -892,8 +892,7 @@ asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *r
 }
 #endif
 
-asmlinkage __visible noinstr
-struct pt_regs *fixup_bad_iret(struct pt_regs *bad_regs)
+asmlinkage __visible noinstr struct pt_regs *fixup_bad_iret(struct pt_regs *bad_regs)
 {
 	/*
 	 * This is called from entry_64.S early in handling a fault

-- 
Regards/Gruss,
    Boris.

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