On Wed, Aug 2, 2017 at 8:09 PM, Aneesh Kumar K.V
<aneesh.ku...@linux.vnet.ibm.com> wrote:
> Balbir Singh <bsinghar...@gmail.com> writes:
>
>> Add support for set_memory_xx routines. With the STRICT_KERNEL_RWX
>> feature support we got support for changing the page permissions
>> for pte ranges. This patch adds support for both radix and hash
>> so that we can change their permissions via set/clear masks.
>>
>> A new helper is required for hash (hash__change_memory_range()
>> is changed to hash__change_boot_memory_range() as it deals with
>> bolted PTE's).
>>
>> hash__change_memory_range() works with vmalloc'ed PAGE_SIZE requests
>> for permission changes. hash__change_memory_range() does not invoke
>> updatepp, instead it changes the software PTE and invalidates the PTE.
>>
>> For radix, radix__change_memory_range() is setup to do the right
>> thing for vmalloc'd addresses. It takes a new parameter to decide
>> what attributes to set.
>>
> ....
>
>> +int hash__change_memory_range(unsigned long start, unsigned long end,
>> + unsigned long set, unsigned long clear)
>> +{
>> + unsigned long idx;
>> + pgd_t *pgdp;
>> + pud_t *pudp;
>> + pmd_t *pmdp;
>> + pte_t *ptep;
>> +
>> + start = ALIGN_DOWN(start, PAGE_SIZE);
>> + end = PAGE_ALIGN(end); // aligns up
>> +
>> + /*
>> + * Update the software PTE and flush the entry.
>> + * This should cause a new fault with the right
>> + * things setup in the hash page table
>> + */
>> + pr_debug("Changing flags on range %lx-%lx setting 0x%lx removing
>> 0x%lx\n",
>> + start, end, set, clear);
>> +
>> + for (idx = start; idx < end; idx += PAGE_SIZE) {
>
>
>> + pgdp = pgd_offset_k(idx);
>> + pudp = pud_alloc(&init_mm, pgdp, idx);
>> + if (!pudp)
>> + return -1;
>> + pmdp = pmd_alloc(&init_mm, pudp, idx);
>> + if (!pmdp)
>> + return -1;
>> + ptep = pte_alloc_kernel(pmdp, idx);
>> + if (!ptep)
>> + return -1;
>> + hash__pte_update(&init_mm, idx, ptep, clear, set, 0);
I think this does the needful, if H_PAGE_HASHPTE is set, the flush
will happen
>> + hash__flush_tlb_kernel_range(idx, idx + PAGE_SIZE);
>> + }
>
> You can use find_linux_pte_or_hugepte. with my recent patch series
> find_init_mm_pte() ?
>
for pte_mkwrite and pte_wrprotect?
Balbir Singh.
