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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        Brian Gerst <brgerst@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Will Deacon <will@kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Wei Liu <wei.liu@kernel.org>,
        Michael Kelley <mikelley@microsoft.com>,
        Jason Chen CJ <jason.cj.chen@intel.com>,
        Zhao Yakui <yakui.zhao@intel.com>
Subject: Re: [patch V6 00/37] x86/entry: Rework leftovers and merge plan
In-Reply-To: <20200519083826.GC279861@hirez.programming.kicks-ass.net>
References: <20200518160750.GA279861@hirez.programming.kicks-ass.net> <87367xvvmy.fsf@nanos.tec.linutronix.de> <20200519083826.GC279861@hirez.programming.kicks-ass.net>
Date:   Tue, 19 May 2020 11:06:26 +0200
Message-ID: <87ftbwuwdp.fsf@nanos.tec.linutronix.de>
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Peter Zijlstra <peterz@infradead.org> writes:
> On Mon, May 18, 2020 at 10:24:53PM +0200, Thomas Gleixner wrote:
> So tglx/entry-v8-full + below patch:
>
> $ make O=defconfig-build clean
> ...
> $ make CC=gcc-9 O=defconfig-build/ vmlinux -j40 -s
> vmlinux.o: warning: objtool: exc_debug()+0x158: call to trace_hwlat_timestamp() leaves .noinstr.text section
> vmlinux.o: warning: objtool: exc_nmi()+0x190: call to trace_hwlat_timestamp() leaves .noinstr.text section
> vmlinux.o: warning: objtool: do_machine_check()+0x46: call to mce_rdmsrl() leaves .noinstr.text section
> $
>
> (it really isn't defconfig, but your config-fail + DEBUG_ENTRY)
>  
> +#ifdef CONFIG_DEBUG_ENTRY
>  /* Begin/end of an instrumentation safe region */
> -#define instrumentation_begin() ({						\
> +#define instrumentation_begin() ({					\
>  	asm volatile("%c0:\n\t"						\
>  		     ".pushsection .discard.instr_begin\n\t"		\
>  		     ".long %c0b - .\n\t"				\
>  		     ".popsection\n\t" : : "i" (__COUNTER__));		\
>  })
>  
> -#define instrumentation_end() ({							\
> -	asm volatile("%c0:\n\t"						\
> +#define instrumentation_end() ({					\
> +	asm volatile("%c0: nop\n\t"					\

Bah. I fatfingered that nop out when I fixed up that noinstr wreckage.
With that added back it does was it claims to do.