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x86: use the pfn from the page when change its attributes
When changing the attributes of a pte, we should use the PFN from the existing PTE rather than going through hoops calculating what we think it might have been; this is both fragile and totally unneeded. It also makes it more hairy to call any of these functions on non-direct maps for no good reason whatsover. With this change, __change_page_attr() no longer takes a pfn as argument, which simplifies all the callers. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@tglx.de>
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@ -277,17 +277,12 @@ out_unlock:
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}
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static int
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__change_page_attr(unsigned long address, unsigned long pfn,
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pgprot_t mask_set, pgprot_t mask_clr)
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__change_page_attr(unsigned long address, pgprot_t mask_set, pgprot_t mask_clr)
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{
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struct page *kpte_page;
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int level, err = 0;
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pte_t *kpte;
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#ifdef CONFIG_X86_32
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BUG_ON(pfn > max_low_pfn);
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#endif
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repeat:
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kpte = lookup_address(address, &level);
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if (!kpte)
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@ -298,17 +293,25 @@ repeat:
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BUG_ON(PageCompound(kpte_page));
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if (level == PG_LEVEL_4K) {
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pgprot_t new_prot = pte_pgprot(*kpte);
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pte_t new_pte, old_pte = *kpte;
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pgprot_t new_prot = pte_pgprot(old_pte);
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if(!pte_val(old_pte)) {
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WARN_ON_ONCE(1);
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return -EINVAL;
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}
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pgprot_val(new_prot) &= ~pgprot_val(mask_clr);
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pgprot_val(new_prot) |= pgprot_val(mask_set);
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new_prot = static_protections(new_prot, address);
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new_pte = pfn_pte(pfn, canon_pgprot(new_prot));
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BUG_ON(pte_pfn(new_pte) != pte_pfn(old_pte));
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/*
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* We need to keep the pfn from the existing PTE,
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* after all we're only going to change it's attributes
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* not the memory it points to
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*/
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new_pte = pfn_pte(pte_pfn(old_pte), canon_pgprot(new_prot));
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set_pte_atomic(kpte, new_pte);
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} else {
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err = split_large_page(kpte, address);
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@ -337,11 +340,11 @@ static int
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change_page_attr_addr(unsigned long address, pgprot_t mask_set,
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pgprot_t mask_clr)
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{
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unsigned long phys_addr = __pa(address);
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unsigned long pfn = phys_addr >> PAGE_SHIFT;
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int err;
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#ifdef CONFIG_X86_64
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unsigned long phys_addr = __pa(address);
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/*
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* If we are inside the high mapped kernel range, then we
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* fixup the low mapping first. __va() returns the virtual
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@ -351,7 +354,7 @@ change_page_attr_addr(unsigned long address, pgprot_t mask_set,
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address = (unsigned long) __va(phys_addr);
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#endif
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err = __change_page_attr(address, pfn, mask_set, mask_clr);
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err = __change_page_attr(address, mask_set, mask_clr);
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if (err)
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return err;
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@ -375,7 +378,7 @@ change_page_attr_addr(unsigned long address, pgprot_t mask_set,
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* everything between 0 and KERNEL_TEXT_SIZE, so do
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* not propagate lookup failures back to users:
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*/
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__change_page_attr(address, pfn, mask_set, mask_clr);
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__change_page_attr(address, mask_set, mask_clr);
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}
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#endif
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return err;
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