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Commit 305b1523 authored by Jan Glauber's avatar Jan Glauber Committed by Martin Schwidefsky
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[S390] Write protect module text and RO data 



Implement write protection for kernel modules text and read-only
data sections by implementing set_memory_[ro|rw] on s390.
Since s390 has no execute bit in the pte's NX is not supported.

set_memory_[ro|rw] will only work on normal pages and not on
large pages, so in case a large page should be modified bail
out with a warning.

Signed-off-by: default avatarJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent d54cddb6

arch/s390/Kconfig.debug

+3 −0
Original line number Diff line number Diff line
@@ -31,4 +31,7 @@ config DEBUG_STRICT_USER_COPY_CHECKS 


	  If unsure, or if you run an older (pre 4.4) gcc, say N.



config DEBUG_SET_MODULE_RONX

	def_bool y

	depends on MODULES

endmenu

arch/s390/include/asm/cacheflush.h

+4 −0
Original line number Diff line number Diff line
@@ -8,4 +8,8 @@ 
void kernel_map_pages(struct page *page, int numpages, int enable);

#endif



int set_memory_ro(unsigned long addr, int numpages);

int set_memory_rw(unsigned long addr, int numpages);

int set_memory_nx(unsigned long addr, int numpages);



#endif /* _S390_CACHEFLUSH_H */

arch/s390/mm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -6,3 +6,4 @@ obj-y := init.o fault.o extmem.o mmap.o vmem.o pgtable.o maccess.o \ 
	    page-states.o gup.o

obj-$(CONFIG_CMM) += cmm.o

obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o

obj-$(CONFIG_DEBUG_SET_MODULE_RONX) += pageattr.o

arch/s390/mm/pageattr.c

0 → 100644
+55 −0
Original line number Diff line number Diff line 
/*

 * Copyright IBM Corp. 2011

 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>

 */

#include <linux/module.h>

#include <linux/mm.h>

#include <linux/hugetlb.h>

#include <asm/pgtable.h>



static void change_page_attr(unsigned long addr, int numpages,

			     pte_t (*set) (pte_t))

{

	pte_t *ptep, pte;

	pmd_t *pmdp;

	pud_t *pudp;

	pgd_t *pgdp;

	int i;



	for (i = 0; i < numpages; i++) {

		pgdp = pgd_offset(&init_mm, addr);

		pudp = pud_offset(pgdp, addr);

		pmdp = pmd_offset(pudp, addr);

		if (pmd_huge(*pmdp)) {

			WARN_ON_ONCE(1);

			continue;

		}

		ptep = pte_offset_kernel(pmdp, addr + i * PAGE_SIZE);



		pte = *ptep;

		pte = set(pte);

		ptep_invalidate(&init_mm, addr + i * PAGE_SIZE, ptep);

		*ptep = pte;

	}

}



int set_memory_ro(unsigned long addr, int numpages)

{

	change_page_attr(addr, numpages, pte_wrprotect);

	return 0;

}

EXPORT_SYMBOL_GPL(set_memory_ro);



int set_memory_rw(unsigned long addr, int numpages)

{

	change_page_attr(addr, numpages, pte_mkwrite);

	return 0;

}

EXPORT_SYMBOL_GPL(set_memory_rw);



/* not possible */

int set_memory_nx(unsigned long addr, int numpages)

{

	return 0;

}

EXPORT_SYMBOL_GPL(set_memory_nx);