From: David Laight <David.Laight@ACULAB.COM>
To: "'hpa@zytor.com'" <hpa@zytor.com>,
Ian Rogers <irogers@google.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>,
"x86@kernel.org" <x86@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
"Josh Poimboeuf" <jpoimboe@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Numfor Mbiziwo-Tiapo <nums@google.com>
Subject: RE: [PATCH v2] x86/insn, tools/x86: Fix some potential undefined behavior.
Date: Fri, 16 Oct 2020 08:47:33 +0000 [thread overview]
Message-ID: <ba2fdf7e25f3476ca4a48b48065614f0@AcuMS.aculab.com> (raw)
In-Reply-To: <5E711F64-A9BF-48EC-83A3-3C644D80F848@zytor.com>
From: hpa@zytor.com
> Sent: 15 October 2020 22:35
> >Don't perform unaligned loads in __get_next and __peek_nbyte_next as
> >these are forms of undefined behavior.
...
> > #define __get_next(t, insn) \
> >- ({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
> >+ ({ t r; memcpy(&r, insn->next_byte, sizeof(t)); insn->next_byte += sizeof(t); r; })
Interesting other idea.
Can you add an 'aligned(1)' into the '*(t *)' cast?
I think '*(t aligned(1) *)' is the right cast.
(gcc seems to accept it either size of the type.)
David
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next prev parent reply other threads:[~2020-10-16 8:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 16:12 Ian Rogers
2020-10-15 21:34 ` hpa
2020-10-15 21:47 ` Ian Rogers
2020-10-16 8:24 ` David Laight
2020-10-16 8:47 ` David Laight [this message]
2020-10-16 9:37 ` Peter Zijlstra
2020-10-16 1:33 ` Masami Hiramatsu
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