Merge tag 's390-5.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Heiko Carstens:

 - fix stack unwinder: the stack unwinder rework has on off-by-one bug
   which prevents following stack backchains over more than one context
   (e.g. irq -> process).

 - fix address space detection in exception handler: if user space
   switches to access register mode, which is not supported anymore, the
   exception handler may resolve to the wrong address space.

* tag 's390-5.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/unwind: correct stack switching during unwind
  s390/mm: fix address space detection in exception handling

2 files changed, 5 insertions, 2 deletions

diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index 49634bfbecdd..0ae4bbf7779c 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -30,7 +30,7 @@ static inline bool on_stack(struct stack_info *info,
 		return false;
 	if (addr + len < addr)
 		return false;
-	return addr >= info->begin && addr + len < info->end;
+	return addr >= info->begin && addr + len <= info->end;
 }
 
 static inline unsigned long get_stack_pointer(struct task_struct *task,
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 91ce03fd0c84..df75d574246d 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -83,7 +83,6 @@ static inline int notify_page_fault(struct pt_regs *regs)
 
 /*
  * Find out which address space caused the exception.
- * Access register mode is impossible, ignore space == 3.
  */
 static enum fault_type get_fault_type(struct pt_regs *regs)
 {
@@ -108,6 +107,10 @@ static enum fault_type get_fault_type(struct pt_regs *regs)
 		}
 		return VDSO_FAULT;
 	}
+	if (trans_exc_code == 1) {
+		/* access register mode, not used in the kernel */
+		return USER_FAULT;
+	}
 	/* home space exception -> access via kernel ASCE */
 	return KERNEL_FAULT;
 }