[S390] kprobes: disable interrupts throughout

Execute the kprobe exception and fault handler with interrupts disabled.
To disable the interrupts only while a single step is in progress is not
good enough, a kprobe from interrupt context while another kprobe is
handled can confuse the internal house keeping.

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

1 files changed, 27 insertions, 14 deletions

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index d60fc4398516..70cf73bdba25 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -30,6 +30,7 @@
 #include <asm/sections.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/hardirq.h>
 
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
@@ -212,7 +213,7 @@ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
         /* Set the PER control regs, turns on single step for this address */
         __ctl_load(kprobe_per_regs, 9, 11);
         regs->psw.mask |= PSW_MASK_PER;
-        regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
+        regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
 }
 
 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
@@ -239,7 +240,7 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
         __get_cpu_var(current_kprobe) = p;
         /* Save the interrupt and per flags */
         kcb->kprobe_saved_imask = regs->psw.mask &
-            (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
+                (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
         /* Save the control regs that govern PER */
         __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
 }
@@ -316,8 +317,6 @@ 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;
@@ -465,8 +464,6 @@ 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();
 
@@ -482,7 +479,7 @@ out:
         return 1;
 }
 
-int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr)
 {
         struct kprobe *cur = kprobe_running();
         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -508,8 +505,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
                         restore_previous_kprobe(kcb);
                 else {
                         reset_current_kprobe();
-                        if (regs->psw.mask & (PSW_MASK_PER | PSW_MASK_IO))
-                                local_irq_enable();
                 }
                 preempt_enable_no_resched();
                 break;
@@ -553,6 +548,18 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
         return 0;
 }
 
+int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+        int ret;
+
+        if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
+                local_irq_disable();
+        ret = kprobe_trap_handler(regs, trapnr);
+        if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
+                local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
+        return ret;
+}
+
 /*
  * Wrapper routine to for handling exceptions.
  */
@@ -560,8 +567,12 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
                                        unsigned long val, void *data)
 {
         struct die_args *args = (struct die_args *)data;
+        struct pt_regs *regs = args->regs;
         int ret = NOTIFY_DONE;
 
+        if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
+                local_irq_disable();
+
         switch (val) {
         case DIE_BPT:
                 if (kprobe_handler(args->regs))
@@ -572,16 +583,17 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
                         ret = NOTIFY_STOP;
                 break;
         case DIE_TRAP:
-                /* kprobe_running() needs smp_processor_id() */
-                preempt_disable();
-                if (kprobe_running() &&
-                    kprobe_fault_handler(args->regs, args->trapnr))
+                if (!preemptible() && kprobe_running() &&
+                    kprobe_trap_handler(args->regs, args->trapnr))
                         ret = NOTIFY_STOP;
-                preempt_enable();
                 break;
         default:
                 break;
         }
+
+        if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
+                local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
+
         return ret;
 }
 
@@ -595,6 +607,7 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 
         /* setup return addr to the jprobe handler routine */
         regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
+        regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
 
         /* r14 is the function return address */
         kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];