[PATCHv7 10/14] x86/mm: Add sync_global_pgds() for configuration with 5-level paging

Kirill A. Shutemov
2017-06-06T11:32:24Z

This basically restores slightly modified version of original
sync_global_pgds() which we had before folded p4d was introduced.

The only modification is protection against 'addr' overflow.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/mm/init_64.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 95651dc58e09..7a9497ac468d 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -92,6 +92,44 @@ __setup("noexec32=", nonx32_setup);
* When memory was added make sure all the processes MM have
* suitable PGD entries in the local PGD level page.
*/
+#ifdef CONFIG_X86_5LEVEL
+void sync_global_pgds(unsigned long start, unsigned long end)
+{
+ unsigned long addr;
+
+ for (addr = start; addr <= end; addr = ALIGN(addr + 1, PGDIR_SIZE)) {
+ const pgd_t *pgd_ref = pgd_offset_k(addr);
+ struct page *page;
+
+ /* Check for overflow */
+ if (addr < start)
+ break;
+
+ if (pgd_none(*pgd_ref))
+ continue;
+
+ spin_lock(&pgd_lock);
+ list_for_each_entry(page, &pgd_list, lru) {
+ pgd_t *pgd;
+ spinlock_t *pgt_lock;
+
+ pgd = (pgd_t *)page_address(page) + pgd_index(addr);
+ /* the pgt_lock only for Xen */
+ pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
+ spin_lock(pgt_lock);
+
+ if (!pgd_none(*pgd_ref) && !pgd_none(*pgd))
+ BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
+
+ if (pgd_none(*pgd))
+ set_pgd(pgd, *pgd_ref);
+
+ spin_unlock(pgt_lock);
+ }
+ spin_unlock(&pgd_lock);
+ }
+}
+#else
void sync_global_pgds(unsigned long start, unsigned long end)
{
unsigned long addr;
@@ -135,6 +173,7 @@ void sync_global_pgds(unsigned long start, unsigned long end)
spin_unlock(&pgd_lock);
}
}
+#endif

/*
* NOTE: This function is marked __ref because it calls __init function
--
2.11.0