From 305b1523250faf9675919def94906775992ce52d Mon Sep 17 00:00:00 2001 From: Jan Glauber Date: Tue, 15 Mar 2011 17:08:22 +0100 Subject: [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: Jan Glauber Signed-off-by: Martin Schwidefsky --- arch/s390/mm/pageattr.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 arch/s390/mm/pageattr.c (limited to 'arch/s390/mm/pageattr.c') diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c new file mode 100644 index 000000000000..122ffbd08ce0 --- /dev/null +++ b/arch/s390/mm/pageattr.c @@ -0,0 +1,55 @@ +/* + * Copyright IBM Corp. 2011 + * Author(s): Jan Glauber + */ +#include +#include +#include +#include + +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); -- cgit v1.2.3