Hi Thomas,
On Sun, Sep 16, 2018 at 04:43:55PM +0200, Thomas Gleixner wrote:
> On Sun, 16 Sep 2018, Feng Tang wrote:
> > diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> > index e848a4811785..a927f5f39bee 100644
> > --- a/arch/x86/mm/pgtable.c
> > +++ b/arch/x86/mm/pgtable.c
> > @@ -637,6 +637,16 @@ void __native_set_fixmap(enum fixed_addresses idx,
> > pte_t pte)
> > {
> > unsigned long address = __fix_to_virt(idx);
> >
> > +#ifdef CONFIG_X86_64
> > + /*
> > + * In arch/x86/kernel/head_64.S, the static page table has
> > + * been setup for fixmap. Add a sanity compiling check
> > + * whether fixmap space has exceeded the capacity.
> > + */
> > + BUILD_BUG_ON((__end_of_permanent_fixed_addresses + 511)/512
> > + > FIXMAP_PMD_NUM);
>
> There exist macros for rounding up and doing this in the header file is
> perfectly fine.
I'll find the sample for the round up.
And for the header file check, I initially put this check directly in
the fixmap.h like:
#if ((__end_of_permanent_fixed_addresses + 511)/512 > FIXMAP_PMD_NUM)
#erro "some warning...."
#endif
But failed to compile, I got the warning
warning: "__end_of_permanent_fixed_addresses" is not defined
I guess the header file preprocessing can't handle it.
>
> > +#endif
> > +
> > if (idx >= __end_of_fixed_addresses) {
> > BUG();
> > return;
> > diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
> > index 45b700ac5fe7..b0aa2364a3c6 100644
> > --- a/arch/x86/xen/mmu_pv.c
> > +++ b/arch/x86/xen/mmu_pv.c
> > @@ -1953,7 +1953,10 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd,
> > unsigned long max_pfn)
> > set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO);
> > set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
> > set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO);
> > - set_page_prot(level1_fixmap_pgt, PAGE_KERNEL_RO);
> > +
> > + for (i = 0; i < FIXMAP_PMD_NUM; i++)
> > + set_page_prot(level1_fixmap_pgt + i * 512,
> > + PAGE_KERNEL_RO);
>
> The line break is there because?
Will fix it. I used a MACRO before changing to 512 and forgot to remove
the line break :)
Thanks,
Feng
