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Date: Thu, 6 Apr 2023 22:37:38 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org,
	Lai Jiangshan <jiangshan.ljs@antgroup.com>,
	"H. Peter Anvin" <hpa@linux.intel.com>,
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	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
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	"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [RFC PATCH 1/7] x86/entry: Move PUSH_AND_CLEAR_REGS out of
 paranoid_entry
Message-ID: <20230406203738.GE405948@hirez.programming.kicks-ass.net>
References: <20230403140605.540512-1-jiangshanlai@gmail.com>
 <20230403140605.540512-2-jiangshanlai@gmail.com>
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In-Reply-To: <20230403140605.540512-2-jiangshanlai@gmail.com>

On Mon, Apr 03, 2023 at 10:05:59PM +0800, Lai Jiangshan wrote:
> @@ -915,11 +922,8 @@ SYM_CODE_END(xen_failsafe_callback)
>   * R14 - old CR3
>   * R15 - old SPEC_CTRL
>   */
> -SYM_CODE_START(paranoid_entry)
> +SYM_FUNC_START(paranoid_entry)
>  	ANNOTATE_NOENDBR
> -	UNWIND_HINT_FUNC

That isn't quite equivalent. SYM_FUNC_START() gets you ENDBR, while the
SYM_CODE_START(); ANNOTATE_NOENDBR; UNWIND_HINT_FUNC is
explicitly no ENDBR.


> -	PUSH_AND_CLEAR_REGS save_ret=1
> -	ENCODE_FRAME_POINTER 8
>  
>  	/*
>  	 * Always stash CR3 in %r14.  This value will be restored,