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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: natechancellor@gmail.com, Andrew Lutomirski <luto@kernel.org>,
	nick.desaulniers@gmail.com,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/mm: annotate no_context with UNWIND_HINTS
Date: Mon, 15 Oct 2018 11:20:22 -0500	[thread overview]
Message-ID: <20181015162022.jia673dbkruo7k6f@treble> (raw)
In-Reply-To: <CALCETrWtgjxSZOg=hqGe3hDDvpuBDZtjptHFDAuHYOaxs1CO_w@mail.gmail.com>

On Mon, Oct 15, 2018 at 09:03:40AM -0700, Andy Lutomirski wrote:
> That being said, the generic macro is:
> 
> # define unreachable() do { annotate_reachable(); do { } while (1); } while (0)
> 
> I'm probably missing some subtlety here, but shouldn't that be
> annotate_*un*reachable()?

That code should have had a comment, but that subtlety was intentional.
As I mentioned earlier, that was a hack for old versions of GCC which
didn't have __builtin_unreachable().  In those cases, GCC doesn't treat
"ud2" as fatal, so this was a way of telling objtool that.  Luckily we
can get rid of this hack now that the minimum supported GCC version has
gone up to 4.6.

-- 
Josh

  parent reply	other threads:[~2018-10-15 16:20 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-15  0:37 [PATCH] x86/mm: annotate no_context with UNWIND_HINTS Nick Desaulniers
2018-10-15  3:43 ` Andy Lutomirski
2018-10-15  5:17   ` Nathan Chancellor
2018-10-15 14:22     ` Josh Poimboeuf
2018-10-15 14:34     ` Andy Lutomirski
2018-10-15 15:22       ` Nathan Chancellor
2018-10-15 15:31         ` Josh Poimboeuf
2018-10-15 16:03           ` Andy Lutomirski
2018-10-15 16:07             ` Nathan Chancellor
2018-10-15 16:20             ` Josh Poimboeuf [this message]
2018-10-15 16:57             ` Nick Desaulniers
2018-10-15 17:23               ` Nick Desaulniers

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