Slashdot Mirror
'Kernel Memory Leaking' Intel Processor Design Flaw Forces Linux, Windows Redesign (theregister.co.uk)
According to The Register, "A fundamental design flaw in Intel's processor chips has forced a significant redesign of the Linux and Windows kernels to defang the chip-level security bug." From the report: Programmers are scrambling to overhaul the open-source Linux kernel's virtual memory system. Meanwhile, Microsoft is expected to publicly introduce the necessary changes to its Windows operating system in this month's Patch Tuesday: these changes were seeded to beta testers running fast-ring Windows Insider builds in November and December. Crucially, these updates to both Linux and Windows will incur a performance hit on Intel products. The effects are still being benchmarked, however we're looking at a ballpark figure of five to 30 per cent slow down, depending on the task and the processor model. More recent Intel chips have features -- specifically, PCID -- to reduce the performance hit. Similar operating systems, such as Apple's 64-bit macOS, will also need to be updated -- the flaw is in the Intel x86 hardware, and it appears a microcode update can't address it. It has to be fixed in software at the OS level, or buy a new processor without the design blunder. Details of the vulnerability within Intel's silicon are under wraps: an embargo on the specifics is due to lift early this month, perhaps in time for Microsoft's Patch Tuesday next week. Indeed, patches for the Linux kernel are available for all to see but comments in the source code have been redacted to obfuscate the issue. The report goes on to share some details of the flaw that have surfaced. "It is understood the bug is present in modern Intel processors produced in the past decade," reports The Register. "It allows normal user programs -- from database applications to JavaScript in web browsers -- to discern to some extent the contents of protected kernel memory. The fix is to separate the kernel's memory completely from user processes using what's called Kernel Page Table Isolation, or KPTI."
Linux Weekly News has been covering this for quite a while.
5% slowdown on average, with up to 30% for some particularly bad network operations.
ARM64 is also affected, so it's not just intel
-- Sometimes you have to turn the lights off in order to see.
Some PostgreSQL results have just been released: up to 23% performance loss. This is indeed huge.
Looks like you missed this commit from Tom Lendacky at AMD.
Doesn't look like it's everybody. https://lkml.org/lkml/2017/12/...
And what is interesting, AMD is immune to that, proof: https://lkml.org/lkml/2017/12/...
The summary is not fully explicit: this is not a flaw in Intel x86 ISA, but specific to CPUs made by Intel. AMD processors don't have the problem, so they should not need the patch.
https://lkml.org/lkml/2017/12/...
This could be a huge win for AMD, because the patch incurs a measurable slowdown. At the moment, though, the Linux fix doesn't seem to distinguish between manufacturers. I expect the distinction will appear later -- better safe than sorry.
Escher was the first MC and Giger invented the HR department.
F00F
This bug has been known and reported about since early November; the original paper was presented in July of 2017, and code has been in Github since Feburary.
Motley Fool is just noting that the Intel CEO isn't holding any more stock than he needs to.
And there are good reasons:
* AMD is back from the dead.
* Intel's GPU hasn't been that successful -- they've even teamed up with AMD to put Radeon GPU's in the same die as an Intel CPU.
* PC sales are declining as consumers shift from Intel PC's to using ARM-powered tablets & phones instead.
* ARM is making inroads into the "desktop and laptop computer" marketplace.
* ARM is powering most consumer electronics as well (TV's, Blu-ray players, Smart Speakers, etc)
* Intel is absolutely nowhere in the mobile world. Mobile has one ARM to rule them all.
* Intel missed the boat for the current generation of XBOX and PlayStation consoles.
Intel is looking more and more like a one trick pony, and its competitors are beginning to do that one trick better too.
-- Sometimes you have to turn the lights off in order to see.
I don't think you understand how drastic this fix is. Every time a user mode to kernel mode transition happens and every time a hardware interrupt happens, the entire page table directory layout has to be switched. This means all the TLB caches are flushed as well and that's where the main performance hit comes from.
So if you're doing something like crypto currency mining you're not going to see much of a hit. But if you're doing a lot of I/O (file servers, database servers, web servers, etc.) you're going to see that 25-35% performance hit.
And that's why hardware bugs are so serious. Sometimes you get lucky and it's a microcode update with no penalty. Sometimes it's a simple fix with barely any performance penalty. But sometimes you get unlucky and the fix hurts a lot and the only way to get the performance back is to swap out the hardware.
really sorry to bust your ARM bubble. https://lwn.net/Articles/74039...
I'm saying that Intel tried to cripple all processors but the dude from AMD told him their products weren't vulnerable and didn't need to be slowed down.