linux-kernel - Re: [PATCH 22/24] x86/entry: Implement and use do_paranoid_entry() and paranoid

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Message-ID: <YTCoenvIaHjLQmAC@hirez.programming.kicks-ass.net>
Date:   Thu, 2 Sep 2021 12:33:30 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Lai Jiangshan <jiangshanlai@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Lai Jiangshan <laijs@...ux.alibaba.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Joerg Roedel <jroedel@...e.de>,
        Youquan Song <youquan.song@...el.com>,
        Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH 22/24] x86/entry: Implement and use do_paranoid_entry()
 and paranoid_exit()

On Wed, Sep 01, 2021 at 01:50:23AM +0800, Lai Jiangshan wrote:

> +	call	do_paranoid_entry
>  	ret

That's normally spelled like:

	jmp do_paranoid_entry

But the same comment as for error_entry but more; pretty much all that's
left in asm is things like:


	call paranoid_entry;

	# setup args
	call \cfunc

	call paranoid_exit

which seems like prime material to also pull into C to avoid the
back-and-forth thing. In fact, why can't you call paranoid_entry/exit
from \cfunc itself? The IDT macros should be able to help.