Re: linux-5.10.11 build failure

[Josh Poimboeuf]

On Thu, Jan 28, 2021 at 11:24:47AM +0000, Thomas Backlund wrote:
> Den 28.1.2021 kl. 12:05, skrev Chris Clayton:
> > 
> > On 28/01/2021 09:34, Greg Kroah-Hartman wrote:
> >> On Thu, Jan 28, 2021 at 09:17:10AM +0000, Chris Clayton wrote:
> >>> Hi,
> >>>
> >>> Building 5.10.11 fails on my (x86-64) laptop thusly:
> >>>
> >>> ..
> >>>
> >>>   AS      arch/x86/entry/thunk_64.o
> >>>    CC      arch/x86/entry/vsyscall/vsyscall_64.o
> >>>    AS      arch/x86/realmode/rm/header.o
> >>>    CC      arch/x86/mm/pat/set_memory.o
> >>>    CC      arch/x86/events/amd/core.o
> >>>    CC      arch/x86/kernel/fpu/init.o
> >>>    CC      arch/x86/entry/vdso/vma.o
> >>>    CC      kernel/sched/core.o
> >>> arch/x86/entry/thunk_64.o: warning: objtool: missing symbol for insn at offset 0x3e
> >>>
> >>>    AS      arch/x86/realmode/rm/trampoline_64.o
> >>> make[2]: *** [scripts/Makefile.build:360: arch/x86/entry/thunk_64.o] Error 255
> >>> make[2]: *** Deleting file 'arch/x86/entry/thunk_64.o'
> >>> make[2]: *** Waiting for unfinished jobs....
> >>>
> >>> ..
> >>>
> >>> Compiler is latest snapshot of gcc-10.
> >>>
> >>> Happy to test the fix but please cc me as I'm not subscribed
> >>
> >> Can you do 'git bisect' to track down the offending commit?
> >>
> > 
> > Sure, but I'll hold that request for a while. I updated to binutils-2.36 on Monday and I'm pretty sure that is a feature
> > of this build fail. I've reverted binutils to 2.35.1, and the build succeeds. Updated to 2.36 again and, surprise,
> > surprise, the kernel build fails again.
> > 
> > I've had a glance at the binutils ML and there are all sorts of issues being reported, but it's beyond my knowledge to
> > assess if this build error is related to any of them.
> > 
> > I'll stick with binutils-2.35.1 for the time being.
> > 
> >> And what exact gcc version are you using?
> >>
> > 
> >   It's built from the 10-20210123 snapshot tarball.
> > 
> > I can report this to the binutils folks, but might it be better if the objtool maintainer looks at it first? The
> > binutils change might just have opened the gate to a bug in objtool.
> > 
> >> thanks,
> >>
> >> greg k-h
> >>
> > 
> 
> 
> AFAIK you need this in stable trees:
> 
>  From 1d489151e9f9d1647110277ff77282fe4d96d09b Mon Sep 17 00:00:00 2001
> From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Date: Thu, 14 Jan 2021 16:14:01 -0600
> Subject: [PATCH] objtool: Don't fail on missing symbol table

Actually I think you need:

  5e6dca82bcaa ("x86/entry: Emit a symbol for register restoring thunk")

I submitted a patch to stable list a few days ago.

(Though it's possible you need both commits, I'm not sure if binutils
 2.36 has the symbol stripping stuff)

-- 
Josh