linux-kernel - Re: [PATCH V7 3/6] x86/entry: Move PUSH_AND_CLEAR_REGS out of error

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Date:   Tue, 3 May 2022 09:23:07 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Lai Jiangshan <jiangshanlai@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     Borislav Petkov <bp@...en8.de>,
        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>
Subject: Re: [PATCH V7 3/6] x86/entry: Move PUSH_AND_CLEAR_REGS out of
 error_entry()

On 03.05.22 05:21, Lai Jiangshan wrote:
> From: Lai Jiangshan <jiangshan.ljs@...group.com>
> 
> The macro idtentry calls error_entry() unconditionally even on XENPV.
> But the code XENPV needs in error_entry() is PUSH_AND_CLEAR_REGS only.
> 
> And PUSH_AND_CLEAR_REGS in error_entry() makes the stack not return to
> its original place when the function returns, which means it is not
> possible to convert it to a C function.
> 
> Move PUSH_AND_CLEAR_REGS out of error_entry(), add a function to wrap
> PUSH_AND_CLEAR_REGS and call it before error_entry().
> 
> It will allow for error_entry() to be not called on XENPV and for
> error_entry() to be converted to C code.
> 
> Cc: Juergen Gross <jgross@...e.com>
> Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>

Reviewed-by: Juergen Gross <jgross@...e.com>


Juergen

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