xtensa: check TLB sanity on return to userspace

- check that user TLB mappings correspond to the current page table;
- check that TLB mapping VPN is in the kernel/user address range
  in accordance with its ASID.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

1 files changed, 8 insertions, 1 deletions

diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index fa94512ff84d..9298742f0fd0 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -458,7 +458,7 @@ common_exception_return:
 
         _bbsi.l a4, TIF_NEED_RESCHED, 3f
         _bbsi.l a4, TIF_NOTIFY_RESUME, 2f
-        _bbci.l a4, TIF_SIGPENDING, 4f
+        _bbci.l a4, TIF_SIGPENDING, 5f
 
 2:      l32i    a4, a1, PT_DEPC
         bgeui   a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
@@ -476,6 +476,13 @@ common_exception_return:
         callx4  a4
         j       1b
 
+5:
+#ifdef CONFIG_DEBUG_TLB_SANITY
+        l32i    a4, a1, PT_DEPC
+        bgeui   a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
+        movi    a4, check_tlb_sanity
+        callx4  a4
+#endif
 4:      /* Restore optional registers. */
 
         load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT