Add functions to keep track of VA ranges mapped in a decorated page-table. This will be used when unmapping to ensure the same range is unmapped, at the same page-table level. This will also be used to handle mapping and unmapping of overlapping VA ranges.
Signed-off-by: Alexandre Chartre <[email protected]> --- arch/x86/include/asm/dpt.h | 12 ++++++++ arch/x86/mm/dpt.c | 60 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 72 insertions(+) diff --git a/arch/x86/include/asm/dpt.h b/arch/x86/include/asm/dpt.h index 5a38d97a70a8..0d74afb10141 100644 --- a/arch/x86/include/asm/dpt.h +++ b/arch/x86/include/asm/dpt.h @@ -16,6 +16,17 @@ enum page_table_level { PGT_LEVEL_PGD }; +/* + * Structure to keep track of address ranges mapped into a decorated + * page-table. + */ +struct dpt_range_mapping { + struct list_head list; + void *ptr; /* range start address */ + size_t size; /* range size */ + enum page_table_level level; /* mapping level */ +}; + /* * A decorated page-table (dpt) encapsulates a native page-table (e.g. * a PGD) and maintain additional attributes related to this page-table. @@ -24,6 +35,7 @@ struct dpt { spinlock_t lock; /* protect all attributes */ pgd_t *pagetable; /* the actual page-table */ unsigned int alignment; /* page-table alignment */ + struct list_head mapping_list; /* list of VA range mapping */ /* * A page-table can have direct references to another page-table, diff --git a/arch/x86/mm/dpt.c b/arch/x86/mm/dpt.c index 0e725344b921..12eb0d794d84 100644 --- a/arch/x86/mm/dpt.c +++ b/arch/x86/mm/dpt.c @@ -59,6 +59,24 @@ static int dpt_add_backend_page(struct dpt *dpt, void *addr, return 0; } +/* + * Return the range mapping starting at the specified address, or NULL if + * no such range is found. + */ +static struct dpt_range_mapping *dpt_get_range_mapping(struct dpt *dpt, + void *ptr) +{ + struct dpt_range_mapping *range; + + lockdep_assert_held(&dpt->lock); + list_for_each_entry(range, &dpt->mapping_list, list) { + if (range->ptr == ptr) + return range; + } + + return NULL; +} + /* * Check if an offset in the page-table is valid, i.e. check that the * offset is on a page effectively belonging to the page-table. @@ -563,6 +581,7 @@ static int dpt_copy_pgd_range(struct dpt *dpt, int dpt_map_range(struct dpt *dpt, void *ptr, size_t size, enum page_table_level level) { + struct dpt_range_mapping *range_mapping; unsigned long addr = (unsigned long)ptr; unsigned long end = addr + ((unsigned long)size); unsigned long flags; @@ -571,8 +590,36 @@ int dpt_map_range(struct dpt *dpt, void *ptr, size_t size, pr_debug("DPT %p: MAP %px/%lx/%d\n", dpt, ptr, size, level); spin_lock_irqsave(&dpt->lock, flags); + + /* check if the range is already mapped */ + range_mapping = dpt_get_range_mapping(dpt, ptr); + if (range_mapping) { + pr_debug("DPT %p: MAP %px/%lx/%d already mapped\n", + dpt, ptr, size, level); + err = -EBUSY; + goto done; + } + + /* map new range */ + range_mapping = kmalloc(sizeof(*range_mapping), GFP_KERNEL); + if (!range_mapping) { + err = -ENOMEM; + goto done; + } + err = dpt_copy_pgd_range(dpt, dpt->pagetable, current->mm->pgd, addr, end, level); + if (err) { + kfree(range_mapping); + goto done; + } + + INIT_LIST_HEAD(&range_mapping->list); + range_mapping->ptr = ptr; + range_mapping->size = size; + range_mapping->level = level; + list_add(&range_mapping->list, &dpt->mapping_list); +done: spin_unlock_irqrestore(&dpt->lock, flags); return err; @@ -611,6 +658,8 @@ struct dpt *dpt_create(unsigned int pgt_alignment) if (!dpt) return NULL; + INIT_LIST_HEAD(&dpt->mapping_list); + pagetable = (unsigned long)__get_free_pages(GFP_KERNEL_ACCOUNT | __GFP_ZERO, alloc_order); @@ -632,6 +681,7 @@ void dpt_destroy(struct dpt *dpt) { unsigned int pgt_alignment; unsigned int alloc_order; + struct dpt_range_mapping *range, *range_next; unsigned long index; void *entry; @@ -643,6 +693,16 @@ void dpt_destroy(struct dpt *dpt) free_page((unsigned long)DPT_BACKEND_PAGE_ADDR(entry)); } + list_for_each_entry_safe(range, range_next, &dpt->mapping_list, list) { + list_del(&range->list); + kfree(range); + } + + if (dpt->backend_pages_count) { + xa_for_each(&dpt->backend_pages, index, entry) + free_page((unsigned long)DPT_BACKEND_PAGE_ADDR(entry)); + } + if (dpt->pagetable) { pgt_alignment = dpt->alignment; alloc_order = round_up(PAGE_SIZE + pgt_alignment, -- 2.18.2
