From: Gerald Schaefer gerald.schaefer@de.ibm.com
commit 962f0af83c239c0aef05639631e871c874b00f99 upstream.
Commit 0aaba41b58bc ("s390: remove all code using the access register mode") removed access register mode from the kernel, and also from the address space detection logic. However, user space could still switch to access register mode (trans_exc_code == 1), and exceptions in that mode would not be correctly assigned.
Fix this by adding a check for trans_exc_code == 1 to get_fault_type(), and remove the wrong comment line before that function.
Fixes: 0aaba41b58bc ("s390: remove all code using the access register mode") Reviewed-by: Janosch Frank frankja@linux.ibm.com Reviewed-by: Heiko Carstens heiko.carstens@de.ibm.com Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Gerald Schaefer gerald.schaefer@de.ibm.com Signed-off-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -83,7 +83,6 @@ static inline int notify_page_fault(stru
/* * Find out which address space caused the exception. - * Access register mode is impossible, ignore space == 3. */ static inline enum fault_type get_fault_type(struct pt_regs *regs) { @@ -108,6 +107,10 @@ static inline enum fault_type get_fault_ } 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; }