[S390] fix kprobes single stepping

Fix kprobes after git commit 1e54622e0403891b10f2105663e0f9dd595a1f17
broke it. The kprobe_handler is now called with interrupts in the state
at the time of the breakpoint. The single step of the replaced instruction
is done with interrupts off which makes it necessary to enable and disable
the interupts in the kprobes code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 10 insertions, 1 deletions

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 5efce7202984..1ecc337fb679 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -557,6 +557,7 @@ pgm_svcper:
 # per was called from kernel, must be kprobes
 #
 kernel_per:
+        REENABLE_IRQS
         mvi     SP_SVCNR(%r15),0xff     # set trap indication to pgm check
         mvi     SP_SVCNR+1(%r15),0xff
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index a2be23922f43..8f3e802174db 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -568,6 +568,7 @@ pgm_svcper:
 # per was called from kernel, must be kprobes
 #
 kernel_per:
+        REENABLE_IRQS
         xc      SP_SVCNR(2,%r15),SP_SVCNR(%r15) # clear svc number
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         brasl   %r14,do_single_step
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 2a3d2bf6f083..d60fc4398516 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -316,6 +316,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
                 return 1;
 
 ss_probe:
+        if (regs->psw.mask & (PSW_MASK_PER | PSW_MASK_IO))
+                local_irq_disable();
         prepare_singlestep(p, regs);
         kcb->kprobe_status = KPROBE_HIT_SS;
         return 1;
@@ -463,6 +465,8 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
                 goto out;
         }
         reset_current_kprobe();
+        if (regs->psw.mask & (PSW_MASK_PER | PSW_MASK_IO))
+                local_irq_enable();
 out:
         preempt_enable_no_resched();
 
@@ -502,8 +506,11 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
                 regs->psw.mask |= kcb->kprobe_saved_imask;
                 if (kcb->kprobe_status == KPROBE_REENTER)
                         restore_previous_kprobe(kcb);
-                else
+                else {
                         reset_current_kprobe();
+                        if (regs->psw.mask & (PSW_MASK_PER | PSW_MASK_IO))
+                                local_irq_enable();
+                }
                 preempt_enable_no_resched();
                 break;
         case KPROBE_HIT_ACTIVE: