From: David Laight <David.Laight@ACULAB.COM>
To: 'Peter Zijlstra' <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>,
"Namhyung Kim" <namhyung@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: RE: "struct perf_sample_data" alignment
Date: Mon, 8 Mar 2021 10:01:20 +0000 [thread overview]
Message-ID: <f768c4e8085b45889971d623aeded560@AcuMS.aculab.com> (raw)
In-Reply-To: <YEHtjioucovbxbRt@hirez.programming.kicks-ass.net>
...
> What I remember is that since perf_sample_data is fairly large,
> unconditionally initializing the whole thing is *slow* (and
> -fauto-var-init=zero will hurt here).
That will hurt everywhere.
I can also imagine it hiding bugs and making people
shrink on-stack arrays to the point where they either overrun
or cause an unexpected error or string truncation.
Initialising to zero is a bad choice if the aim is to
avoid leaking stack.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
prev parent reply other threads:[~2021-03-08 10:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-05 3:45 "struct perf_sample_data" alignment Linus Torvalds
2021-03-05 8:36 ` Peter Zijlstra
2021-03-05 14:57 ` Peter Zijlstra
2021-03-05 15:57 ` Alexei Starovoitov
2021-03-06 13:14 ` Ingo Molnar
2021-03-08 10:01 ` David Laight [this message]
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