1 files changed, 10 insertions, 4 deletions

diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index c19755815e53..05a85bc14c98 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -117,8 +117,8 @@ static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 
         /* Copy a 'clean' PSW mask to the user to avoid leaking
            information about whether PER is currently on.  */
-        user_sregs.regs.psw.mask = psw_user_bits | PSW_MASK_EA | PSW_MASK_BA |
-                                   (regs->psw.mask & PSW_MASK_USER);
+        user_sregs.regs.psw.mask = psw_user_bits |
+                (regs->psw.mask & PSW_MASK_USER);
         user_sregs.regs.psw.addr = regs->psw.addr;
         memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
@@ -145,9 +145,13 @@ static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
         if (err)
                 return err;
+        /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */
         regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
-                         (user_sregs.regs.psw.mask & PSW_MASK_USER);
-        regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
+                (user_sregs.regs.psw.mask & PSW_MASK_USER);
+        /* Check for invalid amode */
+        if (regs->psw.mask & PSW_MASK_EA)
+                regs->psw.mask |= PSW_MASK_BA;
+        regs->psw.addr = user_sregs.regs.psw.addr;
         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
                sizeof(sregs->regs.acrs));
@@ -290,6 +294,7 @@ static int setup_frame(int sig, struct k_sigaction *ka,
 
         /* Set up registers for signal handler */
         regs->gprs[15] = (unsigned long) frame;
+        regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 
         regs->gprs[2] = map_signal(sig);
@@ -358,6 +363,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 
         /* Set up registers for signal handler */
         regs->gprs[15] = (unsigned long) frame;
+        regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 
         regs->gprs[2] = map_signal(sig);