Messages in this thread | | | Date | Wed, 01 Oct 2014 10:50:35 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 1/2] x86_64,entry: Filter RFLAGS.NT on entry from userspace |
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On 09/30/2014 04:21 PM, Thomas Gleixner wrote: >> >> If we ever want those cycles back, I bet that the compat sysenter path >> could be trimmed down a lot. For example, I think that all of the >> zero-extension stuff is unnecessary now that we have the magic syscall >> wrappers for all (?) syscalls. > > Emphasis on "(?)". So yes, once we verified that .... >
I don't think that's true. Many system calls use exactly the same entry point for compat and noncompat calls. I don't see any value in replicating that code in every system call.
The only time we need to do anything horribly special is when we have an argument which is a signed long, which fortunately is not at all common.
-hpa
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