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305b152325
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 <jang@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
/*
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* Copyright IBM Corp. 2011
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* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <asm/pgtable.h>
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static void change_page_attr(unsigned long addr, int numpages,
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pte_t (*set) (pte_t))
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{
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pte_t *ptep, pte;
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pmd_t *pmdp;
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pud_t *pudp;
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pgd_t *pgdp;
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int i;
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for (i = 0; i < numpages; i++) {
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pgdp = pgd_offset(&init_mm, addr);
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pudp = pud_offset(pgdp, addr);
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pmdp = pmd_offset(pudp, addr);
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if (pmd_huge(*pmdp)) {
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WARN_ON_ONCE(1);
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continue;
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}
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ptep = pte_offset_kernel(pmdp, addr + i * PAGE_SIZE);
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pte = *ptep;
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pte = set(pte);
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ptep_invalidate(&init_mm, addr + i * PAGE_SIZE, ptep);
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*ptep = pte;
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}
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}
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int set_memory_ro(unsigned long addr, int numpages)
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{
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change_page_attr(addr, numpages, pte_wrprotect);
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return 0;
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}
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EXPORT_SYMBOL_GPL(set_memory_ro);
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int set_memory_rw(unsigned long addr, int numpages)
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{
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change_page_attr(addr, numpages, pte_mkwrite);
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return 0;
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}
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EXPORT_SYMBOL_GPL(set_memory_rw);
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/* not possible */
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int set_memory_nx(unsigned long addr, int numpages)
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{
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return 0;
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}
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EXPORT_SYMBOL_GPL(set_memory_nx);
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