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flat assembler > Heap > IntelCPU security bug for decades (fix degrades performance)

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Furs



Joined: 04 Mar 2016
Posts: 946

IntelCPU security bug for decades (fix degrades performance)

Very old bug discovered, affects all Intel CPUs for at least a decade (incorrect behavior due to optimizations -- privilege checks not early enough when doing speculative execution). Seemingly, doesn't affect AMD CPUs, maybe it's the reason Intel CPUs were faster at single-core performance than AMD, who knows?

https://hothardware.com/news/intel-cpu-bug-kernel-memory-isolation-linux-windows-macos
https://www.reddit.com/r/sysadmin/comments/7nl8r0/intel_bug_incoming/

Patch incurs massive performance penalty on task switches or exceptions. Sad

This bug also seems to be for ARM64, guess they went the same route as Intel for optimizations. Confused

Time to get AMD? Ryzen looks good, plus it has fast loop instruction!! So it must be good especially for asm programmers Wink
Post 03 Jan 2018, 18:09
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 6714
Location: Kraków, Poland

Re: IntelCPU security bug for decades (fix degrades performance)


Furs wrote:
Time to get AMD? Ryzen looks good, plus it has fast loop instruction!! So it must be good especially for asm programmers Wink

Oh yeah, I've been planning to buy a Ryzen anyway.
Post 03 Jan 2018, 19:03
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 15368
Location: 77256 23rd Street

AMD is slower though. I think that even with the new kernel changes the Intel chips will till be "faster". Laughing

Naturally it depends upon what one is doing as to whether or not it makes any difference.
Post 03 Jan 2018, 22:38
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neville



Joined: 13 Jul 2008
Posts: 507
Location: New Zealand


revolution wrote:
AMD is slower though.

A very un-revolution-like generaliistion Wink Based on... ?

revolution wrote:
I think that even with the new kernel changes the Intel chips will till be "faster". Laughing

Thank you for this reassurance. I feel better now Razz

revolution wrote:
Naturally it depends upon what one is doing as to whether or not it makes any difference.

Ah yes, that covers it: very profound!

We should also speculate that the release of this information came from AMD sources. The timing is afterall somewhat co-incidental. Shocked

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Post 05 Jan 2018, 07:28
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 15368
Location: 77256 23rd Street


neville wrote:

revolution wrote:
AMD is slower though.

A very un-revolution-like generaliistion Wink Based on... ?

IME Laughing
Post 05 Jan 2018, 13:15
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Furs



Joined: 04 Mar 2016
Posts: 946

Are AMD really slower on same price range? I don't think that's true anymore. (Let's exclude Bulldozer please, wish it never existed)

Obviously if you compare with higher end Intel CPU it's slower, but then you don't even get what you pay for (typically you get far less extra performance than the price multiple you pay for it).
Post 05 Jan 2018, 13:35
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neville



Joined: 13 Jul 2008
Posts: 507
Location: New Zealand


revolution wrote:
IME Laughing

Well I'm glad you didn't just make it up on a whim, but a revolution-like response would be:
"slower that what? under what conditions? how measured?,,,,," Laughing

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Post 05 Jan 2018, 19:40
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sleepsleep



Joined: 05 Oct 2006
Posts: 6992
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any suggestion as to what os to use, what processors and etc, to have safe computing environment?
Post 05 Jan 2018, 21:03
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Tomasz Grysztar
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Joined: 16 Jun 2003
Posts: 6714
Location: Kraków, Poland


sleepsleep wrote:
any suggestion as to what os to use, what processors and etc, to have safe computing environment?

I still sometimes use my old Pentium (P5 generation) machine with MS-DOS. Actually, this processor could be safe from the speculative execution tricks, because it had no out-of-order execution (this was introduced by Pentium Pro, P6 generation). Back in the 90s I used to run some Linux on that machine, too (I believe it was some early version of S.u.S.E, I had it on CD attached to the book about Linux I bought back then to learn about that OS) and it was running quite well, so this could be an option for a safe environment. Anyway, even in MS-DOS (which is inherently unsafe environment, since all programs basically have access to all the hardware) I do not feel at risk, but that is simply because that computer has no network card at all. Wink
Post 05 Jan 2018, 22:46
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 15368
Location: 77256 23rd Street


Furs wrote:
Are AMD really slower on same price range?

For me, yes. For anything non-trivial they always finish behind the Intel based machines. But then my tasks use the FPU/SSE/AVX units which is where AMD has reduced resources and shares one unit between two cores.
Post 05 Jan 2018, 23:04
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yeohhs



Joined: 19 Jan 2004
Posts: 88
Location: N 5.43564° E 100.3091°

Some people use Tails. By the way, Tails 3.3 released since November 14, 2017. Very Happy

https://tails.boum.org/news/version_3.3/index.en.html
Post 05 Jan 2018, 23:06
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sleepsleep



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i think i got some ancient pc with swollen capacitors inside my room, maybe meltdown could really motivates me to have them repaired, Smile

saw this in hackers news,
https://www.raspberrypi.org/blog/why-raspberry-pi-isnt-vulnerable-to-spectre-or-meltdown/

connected devices always possessed higher risks, like all our mobile phones, Laughing

the stock Android should come with processes and network monitors, instead of just one icon indicates only having transmission or no,

i couldn't understand why they don't want to include such essential and very important features into stock Android?
Post 06 Jan 2018, 08:16
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 6714
Location: Kraków, Poland

The MS-DOS was the only system where I really felt I knew what the computer was doing at any given moment. A perfect demonstration of that was when once in 90s I discovered that one of the programs I freshly copied from a friend had a virus. When I was changing a directory in DOS Navigator, it was taking a little bit longer than usual and the "click" of the hard drive sounded a bit different. I immediately knew that system is doing something more than usual. Turned out it was a virus that installed as a TSR a hooked interrupt 21h to look for new files to infect. Every times I was changing directory it was looking through the executable files there and I could immediately tell that something is wrong. I then assembled some tiny example programs to let it infect them, booted clean from the floppy, analyzed the files, found a way to cure the infection and wrote a simple single-target AV to check the entire drive.

In any modern system, with their disk buffering, multitasking and random slowdowns caused by who-knows-what-background-processes-built-into-OS I could never really tell if a computer was doing something suspicious anymore.
Post 06 Jan 2018, 10:13
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neville



Joined: 13 Jul 2008
Posts: 507
Location: New Zealand


Tomasz Grysztar wrote:
The MS-DOS was the only system where I really felt I knew what the computer was doing at any given moment....In any modern system, with their disk buffering, multitasking and random slowdowns caused by who-knows-what-background-processes-built-into-OS I could never really tell if a computer was doing something suspicious anymore.

Exactly right, but MS-DOS was so clumsy to access 32-bit memory, that's one of the main reasons I wrote FAMOS. No "expanded" or "extended" memory or cumbersome DPMI, just pure flat 32-bit memory and I always know what the processor is doing!

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Post 07 Jan 2018, 10:58
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