Re: [PATCH v2 2/5] arm64, mm: Move generic mmap layout functions to mm

[Alexandre Ghiti]

On 04/10/2019 08:59 AM, Christoph Hellwig wrote:
> On Thu, Apr 04, 2019 at 01:51:25AM -0400, Alexandre Ghiti wrote:
> > - fix the case where stack randomization should not be taken into
> >    account.
> Hmm.  This sounds a bit vague.  It might be better if something
> considered a fix is split out to a separate patch with a good
> description.

Ok, I will move this fix in another patch.

> > +config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> > +	bool
> > +	help
> > +	  This allows to use a set of generic functions to determine mmap base
> > +	  address by giving priority to top-down scheme only if the process
> > +	  is not in legacy mode (compat task, unlimited stack size or
> > +	  sysctl_legacy_va_layout).
> Given that this is an option that is just selected by other Kconfig
> options the help text won't ever be shown.  I'd just move it into a
> comment bove the definition.

Oh yes, it does not appear, thanks, I'll move it above the definition.

> > +#ifdef CONFIG_MMU
> > +#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> I don't think we need the #ifdef CONFIG_MMU here,
> CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT should only be selected
> if the MMU is enabled to start with.

Ok, thanks.

> > +#ifdef CONFIG_ARCH_HAS_ELF_RANDOMIZE
> > +unsigned long arch_mmap_rnd(void)
> Now that a bunch of architectures use a version in common code
> the arch_ prefix is a bit mislead.  Probably not worth changing
> here, but some time in the future it could use a new name.

Ok I'll keep it in mind for later,

Thanks for your time,

Alex