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SubjectRe: [PATCH v7u1 04/31] x86, 64bit, mm: add generic kernel/ident mapping helper
On Fri, Jan 04, 2013 at 02:19:17PM -0800, Yinghai Lu wrote:
> On Fri, Jan 4, 2013 at 1:19 PM, Borislav Petkov <bp@alien8.de> wrote:
> > On Thu, Jan 03, 2013 at 04:48:24PM -0800, Yinghai Lu wrote:
> >> +int kernel_mapping_init(pgd_t *pgd_page, unsigned long addr, unsigned long end)
> >> +{
> >> + struct x86_mapping_info info = {
> >> + .alloc_pgt_page = alloc_pgt_page,
> >> + .pmd_flag = __PAGE_KERNEL_LARGE,
> >> + .kernel_mapping = true,
> >> + };
> >> +
> >> + return kernel_ident_mapping_init(&info, pgd_page, addr, end);
> >
> > This patch looks good so far except this:
> > kernel_ident_mapping_init says it initializes ident mapping but
> > this is wrong and the type of mapping is actually controlled by
> > info.kernel_mapping.
>
> it is not wrong, and it could do two things.
> kernel_mapping
> ident_mapping

I know that. But it has kernel_ident_mapping in the name although it can
do both. IMO, it should be like this:


int kernel_mapping_init_range(pgd_t *pgd_page, unsigned long addr, unsigned long end)

...
return kernel_mapping_init(&info, pgd_page, addr, end);

so that your workhorse is kernel_mapping_init and it can do both kernel
and ident mapping and the wrapper is kernel_mapping_init_range() which
gets a range of (addr, end), preps the &info descriptor and calls the
workhorse.

See what I mean?

> > So this function which gets &info, etc should be called
> > kernel_mapping_init, AFAICT. And wrt the one wrapping
> > kernel_ident_mapping_init, I can't seem to find where it is called.
> > What's up?
>
> this kernel_mapping_init is for -v8 ..., should be dropped if -v7 is
> used at last.

Well, this *DEFINITELY* should be in the commit message so that
reviewers don't go crazy looking for functions used in other branches.
Maan, this was absolutely insane.

--
Regards/Gruss,
Boris.


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