Messages in this thread | | | Date | Tue, 27 Jun 2023 06:25:38 +0200 | From | Borislav Petkov <> | Subject | Re: [Bug report] __arch_hweight32/64 x86 |
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On Mon, Jun 26, 2023 at 03:41:27PM -0700, Dave Hansen wrote: > I'm not even sure that UML needs GENERIC_HWEIGHT. From a quick glance, > it looks like x86 used to use GENERIC_HWEIGHT, but got arch-specific > versions later. UML just never moved over to the arch-specific versions.
Thanks - that could very well be the explanation.
That bug report made me blink a couple of times since I did take extra precaution to not clobber regs in arch/x86/lib/hweight.S as this was part of the whole pain back then with calling a function from asm where gcc doesn't even know we're calling a function, see:
f5967101e9de ("x86/hweight: Get rid of the special calling convention")
> I _think_ the attached patch might just fix the problems with the C > version and bring the x86/UML implementation back in line with the rest > of x86. > > Thoughts?
> diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig > index 186f13268401..76d507860be4 100644 > --- a/arch/x86/um/Kconfig > +++ b/arch/x86/um/Kconfig > @@ -44,6 +44,3 @@ config ARCH_HAS_SC_SIGNALS > > config ARCH_REUSE_HOST_VSYSCALL_AREA > def_bool !64BIT > - > -config GENERIC_HWEIGHT > - def_bool y
Yeah, we should do it. UML should not do anything different wrt calling conventions so it should be able to handle the arch/x86/lib/hweight.S versions just fine.
Richi?
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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