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Message-ID: <73ab8319a67a2d894564019c6bb0a806455987c6.camel@infradead.org>
Subject: Re: [PATCH] x86, retpolines: entirely disable switch jump tables
 when retpolines are enabled
From:   David Woodhouse <dwmw2@infradead.org>
To:     Daniel Borkmann <daniel@iogearbox.net>, tglx@linutronix.de
Cc:     linux-kernel@vger.kernel.org, mliska@suse.cz,
        "H . J . Lu" <hjl.tools@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        =?ISO-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn.topel@intel.com>,
        Magnus Karlsson <magnus.karlsson@intel.com>,
        Alexei Starovoitov <ast@kernel.org>,
        "David S . Miller" <davem@davemloft.net>
Date:   Mon, 25 Mar 2019 14:28:51 +0000
In-Reply-To: <20190325135620.14882-1-daniel@iogearbox.net>
References: <20190325135620.14882-1-daniel@iogearbox.net>
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On Mon, 2019-03-25 at 14:56 +0100, Daniel Borkmann wrote:
> More than 20 switch cases are not expected to be fast-path critical, but
> it would still be good to align with gcc behavior for versions < 8.4.0 in
> order to have consistency across supported gcc versions. vmlinux size is
> slightly growing by 0.27% for older gcc. This flag is only set to work
> around affected gcc, no change for clang.

I note your final sentence doesn't actually say that clang doesn't have
this problem, and doesn't *need* this (or an equivalent) change.

It should say that (if it's true). And if it isn't true, then other
remedial action would be in order.


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