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Commit d01ad8dd authored by Jan Beulich's avatar Jan Beulich Committed by Andi Kleen
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[PATCH] x86: Improve handling of kernel mappings in change_page_attr 



Fix various broken corner cases in i386 and x86-64 change_page_attr.

AK: split off from tighten kernel image access rights

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 90a0a06a

arch/i386/mm/pageattr.c

+2 −2
Original line number Diff line number Diff line
@@ -142,7 +142,7 @@ __change_page_attr(struct page *page, pgprot_t prot) 
		return -EINVAL;

	kpte_page = virt_to_page(kpte);

	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) { 

		if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 

		if (!pte_huge(*kpte)) {

			set_pte_atomic(kpte, mk_pte(page, prot)); 

		} else {

			pgprot_t ref_prot;
@@ -158,7 +158,7 @@ __change_page_attr(struct page *page, pgprot_t prot) 
			kpte_page = split;

		}

		page_private(kpte_page)++;

	} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 

	} else if (!pte_huge(*kpte)) {

		set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));

		BUG_ON(page_private(kpte_page) == 0);

		page_private(kpte_page)--;

arch/x86_64/mm/pageattr.c

+12 −4
Original line number Diff line number Diff line
@@ -179,16 +179,24 @@ __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot, 
int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)

{

	unsigned long phys_base_pfn = __pa_symbol(__START_KERNEL_map) >> PAGE_SHIFT;

	int err = 0; 

	int err = 0, kernel_map = 0;

	int i; 



	if (address >= __START_KERNEL_map

	    && address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {

		address = (unsigned long)__va(__pa(address));

		kernel_map = 1;

	}



	down_write(&init_mm.mmap_sem);

	for (i = 0; i < numpages; i++, address += PAGE_SIZE) {

		unsigned long pfn = __pa(address) >> PAGE_SHIFT;



		if (!kernel_map || pte_present(pfn_pte(0, prot))) {

			err = __change_page_attr(address, pfn, prot, PAGE_KERNEL);

			if (err)

				break;

		}

		/* Handle kernel mapping too which aliases part of the

		 * lowmem */

		if ((pfn >= phys_base_pfn) &&

include/asm-i386/pgtable.h

+2 −0
Original line number Diff line number Diff line
@@ -159,6 +159,7 @@ void paging_init(void); 


extern unsigned long long __PAGE_KERNEL, __PAGE_KERNEL_EXEC;

#define __PAGE_KERNEL_RO		(__PAGE_KERNEL & ~_PAGE_RW)

#define __PAGE_KERNEL_RX		(__PAGE_KERNEL_EXEC & ~_PAGE_RW)

#define __PAGE_KERNEL_NOCACHE		(__PAGE_KERNEL | _PAGE_PCD)

#define __PAGE_KERNEL_LARGE		(__PAGE_KERNEL | _PAGE_PSE)

#define __PAGE_KERNEL_LARGE_EXEC	(__PAGE_KERNEL_EXEC | _PAGE_PSE)
@@ -166,6 +167,7 @@ extern unsigned long long __PAGE_KERNEL, __PAGE_KERNEL_EXEC; 
#define PAGE_KERNEL		__pgprot(__PAGE_KERNEL)

#define PAGE_KERNEL_RO		__pgprot(__PAGE_KERNEL_RO)

#define PAGE_KERNEL_EXEC	__pgprot(__PAGE_KERNEL_EXEC)

#define PAGE_KERNEL_RX		__pgprot(__PAGE_KERNEL_RX)

#define PAGE_KERNEL_NOCACHE	__pgprot(__PAGE_KERNEL_NOCACHE)

#define PAGE_KERNEL_LARGE	__pgprot(__PAGE_KERNEL_LARGE)

#define PAGE_KERNEL_LARGE_EXEC	__pgprot(__PAGE_KERNEL_LARGE_EXEC)