Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Ingo Molnar:
 "A kprobes and a perf compat ioctl fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Handle compat ioctl
  kprobes: Skip kretprobe hit in NMI context to avoid deadlock

2 files changed, 34 insertions, 2 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1cf24b3e42ec..f9c1ed002dbc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -41,6 +41,7 @@
 #include <linux/cgroup.h>
 #include <linux/module.h>
 #include <linux/mman.h>
+#include <linux/compat.h>
 
 #include "internal.h"
 
@@ -3717,6 +3718,26 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         return 0;
 }
 
+#ifdef CONFIG_COMPAT
+static long perf_compat_ioctl(struct file *file, unsigned int cmd,
+                                unsigned long arg)
+{
+        switch (_IOC_NR(cmd)) {
+        case _IOC_NR(PERF_EVENT_IOC_SET_FILTER):
+        case _IOC_NR(PERF_EVENT_IOC_ID):
+                /* Fix up pointer size (usually 4 -> 8 in 32-on-64-bit case */
+                if (_IOC_SIZE(cmd) == sizeof(compat_uptr_t)) {
+                        cmd &= ~IOCSIZE_MASK;
+                        cmd |= sizeof(void *) << IOCSIZE_SHIFT;
+                }
+                break;
+        }
+        return perf_ioctl(file, cmd, arg);
+}
+#else
+# define perf_compat_ioctl NULL
+#endif
+
 int perf_event_task_enable(void)
 {
         struct perf_event *event;
@@ -4222,7 +4243,7 @@ static const struct file_operations perf_fops = {
         .read                   = perf_read,
         .poll                   = perf_poll,
         .unlocked_ioctl         = perf_ioctl,
-        .compat_ioctl           = perf_ioctl,
+        .compat_ioctl           = perf_compat_ioctl,
         .mmap                   = perf_mmap,
         .fasync                 = perf_fasync,
 };
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 734e9a7d280b..3995f546d0f3 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1778,7 +1778,18 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
         unsigned long hash, flags = 0;
         struct kretprobe_instance *ri;
 
-        /*TODO: consider to only swap the RA after the last pre_handler fired */
+        /*
+         * To avoid deadlocks, prohibit return probing in NMI contexts,
+         * just skip the probe and increase the (inexact) 'nmissed'
+         * statistical counter, so that the user is informed that
+         * something happened:
+         */
+        if (unlikely(in_nmi())) {
+                rp->nmissed++;
+                return 0;
+        }
+
+        /* TODO: consider to only swap the RA after the last pre_handler fired */
         hash = hash_ptr(current, KPROBE_HASH_BITS);
         raw_spin_lock_irqsave(&rp->lock, flags);
         if (!hlist_empty(&rp->free_instances)) {