[Xen-devel] Re: [RFC PATCH 08/35] Add Xen-specific memory management definitions

["Martin J. Bligh" <mbligh@xxxxxxxxxx>]

> +#define virt_to_ptep(__va)                                             \
> +({                                                                     \
> +       pgd_t *__pgd = pgd_offset_k((unsigned long)(__va));             \
> +       pud_t *__pud = pud_offset(__pgd, (unsigned long)(__va));        \
> +       pmd_t *__pmd = pmd_offset(__pud, (unsigned long)(__va));        \
> +       pte_offset_kernel(__pmd, (unsigned long)(__va));                \
> +})
Do we really need yet another function to do this?
Especially one in a mult-line #define instead of a real function call,
and that doesn't seem to error check at each step?

> +
> +#define arbitrary_virt_to_machine(__va)                                        
> \
> +({                                                                     \
> +       maddr_t m = (maddr_t)pte_mfn(*virt_to_ptep(__va)) << PAGE_SHIFT;\
> +       m | ((unsigned long)(__va) & (PAGE_SIZE-1));                        \
> +})
> +
> +#define make_lowmem_page_readonly(va, feature) do {            \
> +       pte_t *pte;                                             \
> +       int rc;                                                 \
> +                                                               \
> +       if (xen_feature(feature))                               \
> +               return;                                         \
> +                                                               \
> +       pte = virt_to_ptep(va);                                 \
> +       rc = HYPERVISOR_update_va_mapping(                      \
> +               (unsigned long)va, pte_wrprotect(*pte), 0);     \
> +       BUG_ON(rc);                                             \
> +} while (0)
Things this long should definitely not be #defines.

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