linux-kernel - Re: [PATCH V5 14/50] x86/entry: Expose the address of .Lgs

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Message-ID: <20211118201338.GN174703@worktop.programming.kicks-ass.net>
Date:   Thu, 18 Nov 2021 21:13:38 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Lai Jiangshan <jiangshanlai@...il.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.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>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH V5 14/50] x86/entry: Expose the address of .Lgs_change to
 entry64.c

On Wed, Nov 10, 2021 at 07:57:00PM +0800, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@...ux.alibaba.com>
> 
> The address of .Lgs_change will be used in traps.c in later patch when
> some entry code is implemented in entry64.c.  So the address of .Lgs_change
> is exposed to traps.c for preparation.
> 
> The label .Lgs_change is still needed in ASM code for extable due to it
> can not use asm_load_gs_index_gs_change.  Otherwise:
> 
> 	warning: objtool: __ex_table+0x0: don't know how to handle
> 	non-section reloc symbol asm_load_gs_index_gs_change
> 

I'm thinking commits:

  24ff65257375 ("objtool: Teach get_alt_entry() about more relocation types")
  4d8b35968bbf ("objtool: Remove reloc symbol type checks in get_alt_entry()")

Might have cured that.