[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>

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index d60fc43..70cf73b 100644 (file)
--- 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];