Re: 4.4-rc5: ugly warn on: 5 W+X pages found

From: Pavel Machek
Date: Tue Dec 15 2015 - 09:08:45 EST

On Tue 2015-12-15 05:26:00, Arjan van de Ven wrote:
> On 12/14/2015 11:56 PM, Pavel Machek wrote:
> >On Mon 2015-12-14 13:24:08, Arjan van de Ven wrote:
> >>
> >>>That's weird. The only API to do that seems to be manually setting
> >>>kmap_prot to _PAGE_KERNEL_EXEC, and nothing does that. (Why is
> >>>kmap_prot a variable on x86 at all? It has exactly one writer, and
> >>>that's the code that initializes it in the first place. Shouldn't we
> >>>#define kmap_prot _PAGE_KERNEL?
> >>
> >>iirc it changes based on runtime detection of NX capability
> >
> >Huh. Is it possible that core duo is so old that it has no NX?
> really stupid question I guess, but is PAE on ?
> (64 bit pagetables are required for NX)


pavel@duo:/data/l/linux$ cat /proc/cpuinfo | grep pae
flags : fpu vme de pse tsc msr pae mce cx8 apic
sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
nx constant_tsc arch_perfmon bts aperfmperf pni monitor vmx est tm2
xtpr pdcm dtherm

But it still says:

address sizes : 32 bits physical, 32 bits virtual

I thought pae would be 36bit virtual?

I'm attaching /proc/config.gz..

(cesky, pictures)

Attachment: config.gz
Description: application/gzip