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 <alexandre.chartre@xxxxxxxxxx>
---
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
