Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 2 Jul 2018 16:22:12 -0700 | Subject | Re: [RFC PATCH for 4.18] rseq: use __u64 for rseq_cs fields, validate user inputs |
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On Mon, Jul 2, 2018 at 4:17 PM Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote: > > Are there any kind of guarantees that a __u64 update on a 32-bit architecture > won't be torn into something daft like byte-per-byte stores when performed > from C code ?
Guarantees? No. Not that there are any guarantees that the same won't happen for a plain 32-bit value either.
Will compilers generate that kind of code? I guess some crazy compiler could simply be really bad at handling 64-bit values, and just happen to handle 32-bit values better. So in that sense a 64-bit entity is certainly a bit riskier. But that would be a really bad compiler, I have to say.
Linus
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