One of the interesting things about this new feature is that user-mode PTEs are now marked as "global", preventing their flushing from TLB on process switch. Presumably because the OS can now do more targeted manual flushing as well as use PCID/PASID.
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Wasn't Kaiser shown to be ineffective and with a rather large cost to syscalls?
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Source? :-)
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Did not find the lwn article on Kaiser's inefficacy that I read, but I did find this: https://lwn.net/Articles/737940/ …
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Well, I’m sure the perf costs (especially on modern hardware with PASID/PCID) will be weighed against the security benefits, and people that care about loopback perf can turn it off in the registry. Remember this is WIP so it may never ship.
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Reasonable. Can't imagine Microsoft will ship it if the perf hit on syscalls is ~40%.
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I could easily measure it but MS gets mad if I ruin features ahead of time. I do quite like this one though and have nothing to bitch about :)
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Fonts are now userspace and appcontainerized. Shit is getting real/hard/real hard.
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cant wait to the OS be 50% slower!!
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I thought ASLR has virtually no impact on performance?
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We’re talking about dual page tables here :)
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Oh...yes. right. i missed that point. Last time i looked closely at a windows kernel it had no ASLR and it put everything in only two possible ringX. So having ASLR (in 2017) at all is an improvement already.
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KASLR was added in Vista and improved in Windows 10. Not sure what you mean about two possible RingX? There may be some vocabulary confusion here :)
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Linus has merged the concept into the mainlinehttps://lwn.net/Articles/742404/ …
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And it’s being backported to 4.14
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It'll be cherry picked into LTS kernels for major vendors, there's no way it remains 4.14+.
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Can you eventually publish blog about this? I don't understand on what this new feature are..
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I will probably _eventually_ publish a blog post... sometime after mid-January :)
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Ok thanks
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