Provide functions to copy page-table entries from the kernel page-table to a decorated page-table for a specified VA range. These functions are based on the copy_pxx_range() functions defined in mm/memory.c. A first difference is that a level parameter can be specified to indicate the page-table level (PGD, P4D, PUD PMD, PTE) at which the copy should be done. Also functions don't rely on mm or vma, and they don't alter the source page-table even if an entry is bad. Finally, the VA range start and size don't need to be page-aligned.
Signed-off-by: Alexandre Chartre <[email protected]> --- arch/x86/include/asm/dpt.h | 3 + arch/x86/mm/dpt.c | 205 +++++++++++++++++++++++++++++++++++++ 2 files changed, 208 insertions(+) diff --git a/arch/x86/include/asm/dpt.h b/arch/x86/include/asm/dpt.h index b9cba051ebf2..85d2c5051acb 100644 --- a/arch/x86/include/asm/dpt.h +++ b/arch/x86/include/asm/dpt.h @@ -40,5 +40,8 @@ struct dpt { extern struct dpt *dpt_create(unsigned int pgt_alignment); extern void dpt_destroy(struct dpt *dpt); +extern int dpt_map_range(struct dpt *dpt, void *ptr, size_t size, + enum page_table_level level); +extern int dpt_map(struct dpt *dpt, void *ptr, unsigned long size); #endif diff --git a/arch/x86/mm/dpt.c b/arch/x86/mm/dpt.c index 7a1b4cd53b03..0e725344b921 100644 --- a/arch/x86/mm/dpt.c +++ b/arch/x86/mm/dpt.c @@ -384,6 +384,211 @@ static int dpt_set_pgd(struct dpt *dpt, pgd_t *pgd, pgd_t pgd_value) return 0; } +static int dpt_copy_pte_range(struct dpt *dpt, pmd_t *dst_pmd, pmd_t *src_pmd, + unsigned long addr, unsigned long end) +{ + pte_t *src_pte, *dst_pte; + + dst_pte = dpt_pte_alloc(dpt, dst_pmd, addr); + if (IS_ERR(dst_pte)) + return PTR_ERR(dst_pte); + + addr &= PAGE_MASK; + src_pte = pte_offset_map(src_pmd, addr); + + do { + dpt_set_pte(dpt, dst_pte, *src_pte); + + } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr < end); + + return 0; +} + +static int dpt_copy_pmd_range(struct dpt *dpt, pud_t *dst_pud, pud_t *src_pud, + unsigned long addr, unsigned long end, + enum page_table_level level) +{ + pmd_t *src_pmd, *dst_pmd; + unsigned long next; + int err; + + dst_pmd = dpt_pmd_alloc(dpt, dst_pud, addr); + if (IS_ERR(dst_pmd)) + return PTR_ERR(dst_pmd); + + src_pmd = pmd_offset(src_pud, addr); + + do { + next = pmd_addr_end(addr, end); + if (level == PGT_LEVEL_PMD || pmd_none(*src_pmd) || + pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) { + err = dpt_set_pmd(dpt, dst_pmd, *src_pmd); + if (err) + return err; + continue; + } + + if (!pmd_present(*src_pmd)) { + pr_warn("DPT %p: PMD not present for [%lx,%lx]\n", + dpt, addr, next - 1); + pmd_clear(dst_pmd); + continue; + } + + err = dpt_copy_pte_range(dpt, dst_pmd, src_pmd, addr, next); + if (err) { + pr_err("DPT %p: PMD error copying PTE addr=%lx next=%lx\n", + dpt, addr, next); + return err; + } + + } while (dst_pmd++, src_pmd++, addr = next, addr < end); + + return 0; +} + +static int dpt_copy_pud_range(struct dpt *dpt, p4d_t *dst_p4d, p4d_t *src_p4d, + unsigned long addr, unsigned long end, + enum page_table_level level) +{ + pud_t *src_pud, *dst_pud; + unsigned long next; + int err; + + dst_pud = dpt_pud_alloc(dpt, dst_p4d, addr); + if (IS_ERR(dst_pud)) + return PTR_ERR(dst_pud); + + src_pud = pud_offset(src_p4d, addr); + + do { + next = pud_addr_end(addr, end); + if (level == PGT_LEVEL_PUD || pud_none(*src_pud) || + pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) { + err = dpt_set_pud(dpt, dst_pud, *src_pud); + if (err) + return err; + continue; + } + + err = dpt_copy_pmd_range(dpt, dst_pud, src_pud, addr, next, + level); + if (err) { + pr_err("DPT %p: PUD error copying PMD addr=%lx next=%lx\n", + dpt, addr, next); + return err; + } + + } while (dst_pud++, src_pud++, addr = next, addr < end); + + return 0; +} + +static int dpt_copy_p4d_range(struct dpt *dpt, pgd_t *dst_pgd, pgd_t *src_pgd, + unsigned long addr, unsigned long end, + enum page_table_level level) +{ + p4d_t *src_p4d, *dst_p4d; + unsigned long next; + int err; + + dst_p4d = dpt_p4d_alloc(dpt, dst_pgd, addr); + if (IS_ERR(dst_p4d)) + return PTR_ERR(dst_p4d); + + src_p4d = p4d_offset(src_pgd, addr); + + do { + next = p4d_addr_end(addr, end); + if (level == PGT_LEVEL_P4D || p4d_none(*src_p4d)) { + err = dpt_set_p4d(dpt, dst_p4d, *src_p4d); + if (err) + return err; + continue; + } + + err = dpt_copy_pud_range(dpt, dst_p4d, src_p4d, addr, next, + level); + if (err) { + pr_err("DPT %p: P4D error copying PUD addr=%lx next=%lx\n", + dpt, addr, next); + return err; + } + + } while (dst_p4d++, src_p4d++, addr = next, addr < end); + + return 0; +} + +static int dpt_copy_pgd_range(struct dpt *dpt, + pgd_t *dst_pagetable, pgd_t *src_pagetable, + unsigned long addr, unsigned long end, + enum page_table_level level) +{ + pgd_t *src_pgd, *dst_pgd; + unsigned long next; + int err; + + dst_pgd = pgd_offset_pgd(dst_pagetable, addr); + src_pgd = pgd_offset_pgd(src_pagetable, addr); + + do { + next = pgd_addr_end(addr, end); + if (level == PGT_LEVEL_PGD || pgd_none(*src_pgd)) { + err = dpt_set_pgd(dpt, dst_pgd, *src_pgd); + if (err) + return err; + continue; + } + + err = dpt_copy_p4d_range(dpt, dst_pgd, src_pgd, addr, next, + level); + if (err) { + pr_err("DPT %p: PGD error copying P4D addr=%lx next=%lx\n", + dpt, addr, next); + return err; + } + + } while (dst_pgd++, src_pgd++, addr = next, addr < end); + + return 0; +} + +/* + * Copy page table entries from the current page table (i.e. from the + * kernel page table) to the specified decorated page-table. The level + * parameter specifies the page-table level (PGD, P4D, PUD PMD, PTE) + * at which the copy should be done. + */ +int dpt_map_range(struct dpt *dpt, void *ptr, size_t size, + enum page_table_level level) +{ + unsigned long addr = (unsigned long)ptr; + unsigned long end = addr + ((unsigned long)size); + unsigned long flags; + int err; + + pr_debug("DPT %p: MAP %px/%lx/%d\n", dpt, ptr, size, level); + + spin_lock_irqsave(&dpt->lock, flags); + err = dpt_copy_pgd_range(dpt, dpt->pagetable, current->mm->pgd, + addr, end, level); + spin_unlock_irqrestore(&dpt->lock, flags); + + return err; +} +EXPORT_SYMBOL(dpt_map_range); + +/* + * Copy page-table PTE entries from the current page-table to the + * specified decorated page-table. + */ +int dpt_map(struct dpt *dpt, void *ptr, unsigned long size) +{ + return dpt_map_range(dpt, ptr, size, PGT_LEVEL_PTE); +} +EXPORT_SYMBOL(dpt_map); + /* * dpt_create - allocate a page-table and create a corresponding * decorated page-table. The page-table is allocated and aligned -- 2.18.2
