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x86: a new API for drivers/etc to control cache and other page attributes
Right now, if drivers or other code want to change, say, a cache attribute of a page, the only API they have is change_page_attr(). c-p-a is a really bad API for this, because it forces the caller to know *ALL* the attributes he wants for the page, not just the 1 thing he wants to change. So code that wants to set a page uncachable, needs to be aware of the NX status as well etc etc etc. This patch introduces a set of new APIs for this, set_pages_<attr> and set_memory_<attr>, that offer a logical change to the user, and leave all attributes not implied by the requested logical change alone. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -211,6 +211,8 @@ repeat:
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* mem_map entry (pfn_valid() is false).
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*
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* See change_page_attr() documentation for more details.
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*
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* Modules and drivers should use the set_memory_* APIs instead.
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*/
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int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
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@ -273,6 +275,8 @@ int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
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* (e.g. in user space) * This function only deals with the kernel linear map.
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*
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* For MMIO areas without mem_map use change_page_attr_addr() instead.
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*
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* Modules and drivers should use the set_pages_* APIs instead.
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*/
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int change_page_attr(struct page *page, int numpages, pgprot_t prot)
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{
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@ -282,6 +286,199 @@ int change_page_attr(struct page *page, int numpages, pgprot_t prot)
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}
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EXPORT_SYMBOL(change_page_attr);
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/**
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* change_page_attr_set - Change page table attributes in the linear mapping.
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* @addr: Virtual address in linear mapping.
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* @numpages: Number of pages to change
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* @prot: Protection/caching type bits to set (PAGE_*)
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*
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* Returns 0 on success, otherwise a negated errno.
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*
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* This should be used when a page is mapped with a different caching policy
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* than write-back somewhere - some CPUs do not like it when mappings with
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* different caching policies exist. This changes the page attributes of the
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* in kernel linear mapping too.
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*
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* Caller must call global_flush_tlb() later to make the changes active.
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*
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* The caller needs to ensure that there are no conflicting mappings elsewhere
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* (e.g. in user space) * This function only deals with the kernel linear map.
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*
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* This function is different from change_page_attr() in that only selected bits
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* are impacted, all other bits remain as is.
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*/
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int change_page_attr_set(unsigned long addr, int numpages, pgprot_t prot)
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{
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pgprot_t current_prot;
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int level;
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pte_t *pte;
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pte = lookup_address(addr, &level);
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if (pte)
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current_prot = pte_pgprot(*pte);
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else
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pgprot_val(current_prot) = 0;
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pgprot_val(prot) = pgprot_val(current_prot) | pgprot_val(prot);
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return change_page_attr_addr(addr, numpages, prot);
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}
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/**
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* change_page_attr_clear - Change page table attributes in the linear mapping.
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* @addr: Virtual address in linear mapping.
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* @numpages: Number of pages to change
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* @prot: Protection/caching type bits to clear (PAGE_*)
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*
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* Returns 0 on success, otherwise a negated errno.
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*
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* This should be used when a page is mapped with a different caching policy
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* than write-back somewhere - some CPUs do not like it when mappings with
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* different caching policies exist. This changes the page attributes of the
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* in kernel linear mapping too.
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*
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* Caller must call global_flush_tlb() later to make the changes active.
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*
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* The caller needs to ensure that there are no conflicting mappings elsewhere
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* (e.g. in user space) * This function only deals with the kernel linear map.
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*
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* This function is different from change_page_attr() in that only selected bits
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* are impacted, all other bits remain as is.
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*/
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int change_page_attr_clear(unsigned long addr, int numpages, pgprot_t prot)
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{
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pgprot_t current_prot;
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int level;
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pte_t *pte;
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pte = lookup_address(addr, &level);
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if (pte)
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current_prot = pte_pgprot(*pte);
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else
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pgprot_val(current_prot) = 0;
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pgprot_val(prot) = pgprot_val(current_prot) & ~pgprot_val(prot);
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return change_page_attr_addr(addr, numpages, prot);
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}
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int set_memory_uc(unsigned long addr, int numpages)
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{
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pgprot_t uncached;
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pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
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return change_page_attr_set(addr, numpages, uncached);
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}
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EXPORT_SYMBOL(set_memory_uc);
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int set_memory_wb(unsigned long addr, int numpages)
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{
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pgprot_t uncached;
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pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
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return change_page_attr_clear(addr, numpages, uncached);
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}
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EXPORT_SYMBOL(set_memory_wb);
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int set_memory_x(unsigned long addr, int numpages)
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{
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pgprot_t nx;
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pgprot_val(nx) = _PAGE_NX;
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return change_page_attr_clear(addr, numpages, nx);
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}
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EXPORT_SYMBOL(set_memory_x);
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int set_memory_nx(unsigned long addr, int numpages)
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{
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pgprot_t nx;
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pgprot_val(nx) = _PAGE_NX;
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return change_page_attr_set(addr, numpages, nx);
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}
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EXPORT_SYMBOL(set_memory_nx);
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int set_memory_ro(unsigned long addr, int numpages)
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{
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pgprot_t rw;
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pgprot_val(rw) = _PAGE_RW;
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return change_page_attr_clear(addr, numpages, rw);
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}
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EXPORT_SYMBOL(set_memory_ro);
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int set_memory_rw(unsigned long addr, int numpages)
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{
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pgprot_t rw;
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pgprot_val(rw) = _PAGE_RW;
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return change_page_attr_set(addr, numpages, rw);
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}
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EXPORT_SYMBOL(set_memory_rw);
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int set_pages_uc(struct page *page, int numpages)
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{
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unsigned long addr = (unsigned long)page_address(page);
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pgprot_t uncached;
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pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
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return change_page_attr_set(addr, numpages, uncached);
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}
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EXPORT_SYMBOL(set_pages_uc);
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int set_pages_wb(struct page *page, int numpages)
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{
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unsigned long addr = (unsigned long)page_address(page);
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pgprot_t uncached;
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pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
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return change_page_attr_clear(addr, numpages, uncached);
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}
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EXPORT_SYMBOL(set_pages_wb);
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int set_pages_x(struct page *page, int numpages)
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{
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unsigned long addr = (unsigned long)page_address(page);
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pgprot_t nx;
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pgprot_val(nx) = _PAGE_NX;
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return change_page_attr_clear(addr, numpages, nx);
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}
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EXPORT_SYMBOL(set_pages_x);
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int set_pages_nx(struct page *page, int numpages)
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{
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unsigned long addr = (unsigned long)page_address(page);
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pgprot_t nx;
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pgprot_val(nx) = _PAGE_NX;
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return change_page_attr_set(addr, numpages, nx);
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}
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EXPORT_SYMBOL(set_pages_nx);
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int set_pages_ro(struct page *page, int numpages)
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{
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unsigned long addr = (unsigned long)page_address(page);
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pgprot_t rw;
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pgprot_val(rw) = _PAGE_RW;
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return change_page_attr_clear(addr, numpages, rw);
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}
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EXPORT_SYMBOL(set_pages_ro);
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int set_pages_rw(struct page *page, int numpages)
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{
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unsigned long addr = (unsigned long)page_address(page);
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pgprot_t rw;
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pgprot_val(rw) = _PAGE_RW;
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return change_page_attr_set(addr, numpages, rw);
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}
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EXPORT_SYMBOL(set_pages_rw);
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void clflush_cache_range(void *addr, int size)
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{
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int i;
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@ -27,6 +27,21 @@
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void global_flush_tlb(void);
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int change_page_attr(struct page *page, int numpages, pgprot_t prot);
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int change_page_attr_addr(unsigned long addr, int numpages, pgprot_t prot);
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int set_pages_uc(struct page *page, int numpages);
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int set_pages_wb(struct page *page, int numpages);
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int set_pages_x(struct page *page, int numpages);
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int set_pages_nx(struct page *page, int numpages);
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int set_pages_ro(struct page *page, int numpages);
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int set_pages_rw(struct page *page, int numpages);
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int set_memory_uc(unsigned long addr, int numpages);
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int set_memory_wb(unsigned long addr, int numpages);
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int set_memory_x(unsigned long addr, int numpages);
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int set_memory_nx(unsigned long addr, int numpages);
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int set_memory_ro(unsigned long addr, int numpages);
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int set_memory_rw(unsigned long addr, int numpages);
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void clflush_cache_range(void *addr, int size);
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#ifdef CONFIG_DEBUG_RODATA
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