Add wrappers around the p4d/pud/pmd/pte offset kernel functions which ensure that page-table pointers are in the specified decorated page-table.
Signed-off-by: Alexandre Chartre <[email protected]> --- arch/x86/mm/dpt.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) diff --git a/arch/x86/mm/dpt.c b/arch/x86/mm/dpt.c index 6df2d4fde8ec..44aad99bc3dc 100644 --- a/arch/x86/mm/dpt.c +++ b/arch/x86/mm/dpt.c @@ -82,6 +82,72 @@ static bool dpt_valid_offset(struct dpt *dpt, void *offset) return valid; } +/* + * dpt_pXX_offset() functions are equivalent to kernel pXX_offset() + * functions but, in addition, they ensure that page table pointers + * are in the specified decorated page table. Otherwise an error is + * returned. + */ + +static pte_t *dpt_pte_offset(struct dpt *dpt, + pmd_t *pmd, unsigned long addr) +{ + pte_t *pte; + + pte = pte_offset_map(pmd, addr); + if (!dpt_valid_offset(dpt, pte)) { + pr_err("DPT %p: PTE %px not found\n", dpt, pte); + return ERR_PTR(-EINVAL); + } + + return pte; +} + +static pmd_t *dpt_pmd_offset(struct dpt *dpt, + pud_t *pud, unsigned long addr) +{ + pmd_t *pmd; + + pmd = pmd_offset(pud, addr); + if (!dpt_valid_offset(dpt, pmd)) { + pr_err("DPT %p: PMD %px not found\n", dpt, pmd); + return ERR_PTR(-EINVAL); + } + + return pmd; +} + +static pud_t *dpt_pud_offset(struct dpt *dpt, + p4d_t *p4d, unsigned long addr) +{ + pud_t *pud; + + pud = pud_offset(p4d, addr); + if (!dpt_valid_offset(dpt, pud)) { + pr_err("DPT %p: PUD %px not found\n", dpt, pud); + return ERR_PTR(-EINVAL); + } + + return pud; +} + +static p4d_t *dpt_p4d_offset(struct dpt *dpt, + pgd_t *pgd, unsigned long addr) +{ + p4d_t *p4d; + + p4d = p4d_offset(pgd, addr); + /* + * p4d is the same has pgd if we don't have a 5-level page table. + */ + if ((p4d != (p4d_t *)pgd) && !dpt_valid_offset(dpt, p4d)) { + pr_err("DPT %p: P4D %px not found\n", dpt, p4d); + return ERR_PTR(-EINVAL); + } + + return p4d; +} + /* * dpt_create - allocate a page-table and create a corresponding * decorated page-table. The page-table is allocated and aligned -- 2.18.2
