Subject: Re: linux-next: build warnings after merge of the tip tree

From: Peter Zijlstra <[email-masked]>
Date: Mon, 21 Mar 2022 16:45:40 +0100

On Mon, Mar 21, 2022 at 04:28:06PM +0100, Peter Zijlstra wrote:
> On Mon, Mar 21, 2022 at 02:45:16PM +0100, Peter Zijlstra wrote:
> > On Mon, Mar 21, 2022 at 02:08:23PM +0100, Peter Zijlstra wrote:
> > > On Mon, Mar 21, 2022 at 02:04:05PM +0100, Peter Zijlstra wrote:
> > > > On Mon, Mar 21, 2022 at 01:55:49PM +0100, Peter Zijlstra wrote:
> > > > > On Mon, Mar 21, 2022 at 02:03:27PM +1100, Stephen Rothwell wrote:
> > > > > > Hi all,
> > > > > > 
> > > > > > After merging the tip tree, today's linux-next build (x864 allmodconfig)
> > > > > > produced these new warnings:
> > > > > > 
> > > > > > vmlinux.o: warning: objtool: arch_rethook_prepare()+0x55: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: arch_rethook_trampoline_callback()+0x3e: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x93e: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x5f2: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: unwind_next_frame()+0x4a7: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: __rethook_find_ret_addr()+0x81: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: __rethook_find_ret_addr()+0x90: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: rethook_trampoline_handler()+0x8c: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > > vmlinux.o: warning: objtool: rethook_trampoline_handler()+0x9b: relocation to !ENDBR: arch_rethook_trampoline+0x0
> > > > > 
> > > > > Hurmph, lemme go figure out where that code comes from, I've not seen
> > > > > those.
> > > > 
> > > > Ahh, something tracing. I'll go do some patches on top of it.
> > > 
> > > Also, that x86 patch has never his [email-masked] and doesn't have an
> > > ACK from any x86 person :-(((
> > 
> > Worse, it adds a 3rd return trampoline without replacing any of the
> > existing two :-(
> > 
> > Why was this merged?
> 
> It additionally gets ret wrong:
> 
>   vmlinux.o: warning: objtool: arch_rethook_trampoline()+0x4a: missing int3 after ret
> 
> and afaict regs->ss is garbage (much like kretprobes it appears).
> 
> Can we please unmerge this stuff and try again later?

This landing in -next only today (after having been committed last
friday night) is another clue it should probably go next round.