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Commit 75cbade8 authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Ingo Molnar
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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: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e81d5dc4

arch/x86/mm/pageattr.c

+197 −0
Original line number Diff line number Diff line
@@ -211,6 +211,8 @@ repeat: 
 * mem_map entry (pfn_valid() is false).

 *

 * See change_page_attr() documentation for more details.

 *

 * Modules and drivers should use the set_memory_* APIs instead.

 */



int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
@@ -273,6 +275,8 @@ int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot) 
 * (e.g. in user space) * This function only deals with the kernel linear map.

 *

 * For MMIO areas without mem_map use change_page_attr_addr() instead.

 *

 * Modules and drivers should use the set_pages_* APIs instead.

 */

int change_page_attr(struct page *page, int numpages, pgprot_t prot)

{
@@ -282,6 +286,199 @@ int change_page_attr(struct page *page, int numpages, pgprot_t prot) 
}

EXPORT_SYMBOL(change_page_attr);



/**

 * change_page_attr_set - Change page table attributes in the linear mapping.

 * @addr: Virtual address in linear mapping.

 * @numpages: Number of pages to change

 * @prot: Protection/caching type bits to set (PAGE_*)

 *

 * Returns 0 on success, otherwise a negated errno.

 *

 * This should be used when a page is mapped with a different caching policy

 * than write-back somewhere - some CPUs do not like it when mappings with

 * different caching policies exist. This changes the page attributes of the

 * in kernel linear mapping too.

 *

 * Caller must call global_flush_tlb() later to make the changes active.

 *

 * The caller needs to ensure that there are no conflicting mappings elsewhere

 * (e.g. in user space) * This function only deals with the kernel linear map.

 *

 * This function is different from change_page_attr() in that only selected bits

 * are impacted, all other bits remain as is.

 */

int change_page_attr_set(unsigned long addr, int numpages, pgprot_t prot)

{

	pgprot_t current_prot;

	int level;

	pte_t *pte;



	pte = lookup_address(addr, &level);

	if (pte)

		current_prot = pte_pgprot(*pte);

	else

		pgprot_val(current_prot) = 0;



	pgprot_val(prot) = pgprot_val(current_prot) | pgprot_val(prot);



	return change_page_attr_addr(addr, numpages, prot);

}



/**

 * change_page_attr_clear - Change page table attributes in the linear mapping.

 * @addr: Virtual address in linear mapping.

 * @numpages: Number of pages to change

 * @prot: Protection/caching type bits to clear (PAGE_*)

 *

 * Returns 0 on success, otherwise a negated errno.

 *

 * This should be used when a page is mapped with a different caching policy

 * than write-back somewhere - some CPUs do not like it when mappings with

 * different caching policies exist. This changes the page attributes of the

 * in kernel linear mapping too.

 *

 * Caller must call global_flush_tlb() later to make the changes active.

 *

 * The caller needs to ensure that there are no conflicting mappings elsewhere

 * (e.g. in user space) * This function only deals with the kernel linear map.

 *

 * This function is different from change_page_attr() in that only selected bits

 * are impacted, all other bits remain as is.

 */

int change_page_attr_clear(unsigned long addr, int numpages, pgprot_t prot)

{

	pgprot_t current_prot;

	int level;

	pte_t *pte;



	pte = lookup_address(addr, &level);

	if (pte)

		current_prot = pte_pgprot(*pte);

	else

		pgprot_val(current_prot) = 0;



	pgprot_val(prot) = pgprot_val(current_prot) & ~pgprot_val(prot);



	return change_page_attr_addr(addr, numpages, prot);

}







int set_memory_uc(unsigned long addr, int numpages)

{

	pgprot_t uncached;



	pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;

	return change_page_attr_set(addr, numpages, uncached);

}

EXPORT_SYMBOL(set_memory_uc);



int set_memory_wb(unsigned long addr, int numpages)

{

	pgprot_t uncached;



	pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;

	return change_page_attr_clear(addr, numpages, uncached);

}

EXPORT_SYMBOL(set_memory_wb);



int set_memory_x(unsigned long addr, int numpages)

{

	pgprot_t nx;



	pgprot_val(nx) = _PAGE_NX;

	return change_page_attr_clear(addr, numpages, nx);

}

EXPORT_SYMBOL(set_memory_x);



int set_memory_nx(unsigned long addr, int numpages)

{

	pgprot_t nx;



	pgprot_val(nx) = _PAGE_NX;

	return change_page_attr_set(addr, numpages, nx);

}

EXPORT_SYMBOL(set_memory_nx);



int set_memory_ro(unsigned long addr, int numpages)

{

	pgprot_t rw;



	pgprot_val(rw) = _PAGE_RW;

	return change_page_attr_clear(addr, numpages, rw);

}

EXPORT_SYMBOL(set_memory_ro);



int set_memory_rw(unsigned long addr, int numpages)

{

	pgprot_t rw;



	pgprot_val(rw) = _PAGE_RW;

	return change_page_attr_set(addr, numpages, rw);

}

EXPORT_SYMBOL(set_memory_rw);



int set_pages_uc(struct page *page, int numpages)

{

	unsigned long addr = (unsigned long)page_address(page);

	pgprot_t uncached;



	pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;

	return change_page_attr_set(addr, numpages, uncached);

}

EXPORT_SYMBOL(set_pages_uc);



int set_pages_wb(struct page *page, int numpages)

{

	unsigned long addr = (unsigned long)page_address(page);

	pgprot_t uncached;



	pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;

	return change_page_attr_clear(addr, numpages, uncached);

}

EXPORT_SYMBOL(set_pages_wb);



int set_pages_x(struct page *page, int numpages)

{

	unsigned long addr = (unsigned long)page_address(page);

	pgprot_t nx;



	pgprot_val(nx) = _PAGE_NX;

	return change_page_attr_clear(addr, numpages, nx);

}

EXPORT_SYMBOL(set_pages_x);



int set_pages_nx(struct page *page, int numpages)

{

	unsigned long addr = (unsigned long)page_address(page);

	pgprot_t nx;



	pgprot_val(nx) = _PAGE_NX;

	return change_page_attr_set(addr, numpages, nx);

}

EXPORT_SYMBOL(set_pages_nx);



int set_pages_ro(struct page *page, int numpages)

{

	unsigned long addr = (unsigned long)page_address(page);

	pgprot_t rw;



	pgprot_val(rw) = _PAGE_RW;

	return change_page_attr_clear(addr, numpages, rw);

}

EXPORT_SYMBOL(set_pages_ro);



int set_pages_rw(struct page *page, int numpages)

{

	unsigned long addr = (unsigned long)page_address(page);

	pgprot_t rw;



	pgprot_val(rw) = _PAGE_RW;

	return change_page_attr_set(addr, numpages, rw);

}

EXPORT_SYMBOL(set_pages_rw);





void clflush_cache_range(void *addr, int size)

{

	int i;

include/asm-x86/cacheflush.h

+15 −0
Original line number Diff line number Diff line
@@ -27,6 +27,21 @@ 
void global_flush_tlb(void);

int change_page_attr(struct page *page, int numpages, pgprot_t prot);

int change_page_attr_addr(unsigned long addr, int numpages, pgprot_t prot);



int set_pages_uc(struct page *page, int numpages);

int set_pages_wb(struct page *page, int numpages);

int set_pages_x(struct page *page, int numpages);

int set_pages_nx(struct page *page, int numpages);

int set_pages_ro(struct page *page, int numpages);

int set_pages_rw(struct page *page, int numpages);



int set_memory_uc(unsigned long addr, int numpages);

int set_memory_wb(unsigned long addr, int numpages);

int set_memory_x(unsigned long addr, int numpages);

int set_memory_nx(unsigned long addr, int numpages);

int set_memory_ro(unsigned long addr, int numpages);

int set_memory_rw(unsigned long addr, int numpages);



void clflush_cache_range(void *addr, int size);



#ifdef CONFIG_DEBUG_RODATA