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Date:   Mon, 21 Mar 2022 14:04:05 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Stephen Rothwell <sfr@canb.auug.org.au>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        mhiramat@kernel.org, rostedt@goodmis.org, ast@kernel.org,
        hjl.tools@gmail.com, rick.p.edgecombe@intel.com, rppt@kernel.org,
        linux-toolchains@vger.kernel.org, Andrew.Cooper3@citrix.com,
        ndesaulniers@google.com
Subject: Re: linux-next: build warnings after merge of the tip tree
Message-ID: <Yjh3xZuuY3QcZ1Bn@hirez.programming.kicks-ass.net>
References: <20220321140327.777f9554@canb.auug.org.au>
 <Yjh11UjDZogc3foM@hirez.programming.kicks-ass.net>
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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, folks, I'm thinking we should start to move to __fexit__, if CET
SHSTK ever wants to come to kernel land return trampolines will
insta-stop working.

Hjl, do you think we could get -mfexit to go along with -mfentry ?