Date: Fri, 12 Jun 2020 20:38:35 +0200 From: Adam Zabrocki <pi3@....com.pl> To: lkrg-users@...ts.openwall.com Subject: Re: RE: ISRA optimized functions On Fri, Jun 12, 2020 at 07:03:06PM +0200, Mikhail Morfikov wrote: > On 12/06/2020 16:07, Adam Zabrocki wrote: > > As you can see, even CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE is configured, so this > > is "lowlatency" kernel, and CONSTPROP optimization is enforced in various > > places (590 funtions was optimized using this method), function "lookup_fast" > > is not touched. This is Ubuntu 20.xx kernel package. > > The main reason why you have that problem is unusual and specific kernel > > configuration which allows for such optimization. > > But the kernel config I have is the same I had with gcc9 -- nothing has changed > here, and in the case of gcc9 I also have lookup_fast without the constprop, > which I already mentioned. So something has changed in gcc10 itself, and I don't > know what that would be. Maybe you could try building a kernel with gcc10 and > check whether you also have this issue? In this way we could confirm that > there's a problem with gcc10. > Using GCC version 10.0.1, exactly: gcc version 10.0.1 20200411 (experimental) [master revision bb87d5cc77d:75961caccb7:f883c46b4877f637e0fa5025b4d6b5c9040ec566] (Ubuntu 10-20200411-0ubuntu1) Kernel: $ cat /proc/version Linux version 5.7.0-g4 (root@oi3) (gcc version 10.0.1 20200411 (experimental) [master revision bb87d5cc77d:75961caccb7:f883c46b4877f637e0fa5025b4d6b5c9040ec566] (Ubuntu 10-20200411-0ubuntu1), GNU ld (GNU Binutils for Ubuntu) 2.34) #28 SMP PREEMPT Fri Jun 12 18:09:14 UTC 2020 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ $ cat /proc/kallsyms |grep lookup_fast|head -1 0000000000000000 t lookup_fast $ However, as I mentioned in my previous emails, I need to discuss and research more in details if adding such non-standard kernel configuration / compilation support makes sense from LKRG perspective. Maybe it does, maybe not. Thanks, Adam -- pi3 (pi3ki31ny) - pi3 (at) itsec pl http://pi3.com.pl
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