pageattr.c

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/*
 * Copyright IBM Corp. 2011
 * Author(s): Jan Glauber <[email protected]>
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <asm/cacheflush.h>
#include <asm/pgtable.h>

static pte_t *walk_page_table(unsigned long addr)
{
    pgd_t *pgdp;
    pud_t *pudp;
    pmd_t *pmdp;
    pte_t *ptep;

    pgdp = pgd_offset_k(addr);
    if (pgd_none(*pgdp))
        return NULL;
    pudp = pud_offset(pgdp, addr);
    if (pud_none(*pudp))
        return NULL;
    pmdp = pmd_offset(pudp, addr);
    if (pmd_none(*pmdp) || pmd_large(*pmdp))
        return NULL;
    ptep = pte_offset_kernel(pmdp, addr);
    if (pte_none(*ptep))
        return NULL;
    return ptep;
}

static void change_page_attr(unsigned long addr, int numpages,
                 pte_t (*set) (pte_t))
{
    pte_t *ptep, pte;
    int i;

    for (i = 0; i < numpages; i++) {
        ptep = walk_page_table(addr);
        if (WARN_ON_ONCE(!ptep))
            break;
        pte = *ptep;
        pte = set(pte);
        __ptep_ipte(addr, ptep);
        *ptep = pte;
        addr += PAGE_SIZE;
    }
}

int set_memory_ro(unsigned long addr, int numpages)
{
    change_page_attr(addr, numpages, pte_wrprotect);
    return 0;
}

int set_memory_rw(unsigned long addr, int numpages)
{
    change_page_attr(addr, numpages, pte_mkwrite);
    return 0;
}

/* not possible */
int set_memory_nx(unsigned long addr, int numpages)
{
    return 0;
}

int set_memory_x(unsigned long addr, int numpages)
{
    return 0;
}