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

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

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1cf24b3e42ece4f2de8854bd882f127165866af6..f9c1ed002dbc81997e6e062f358c57b6e459ce84 100644 (file)
--- 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 734e9a7d280bd22a046566cc40b1edf159f250bf..3995f546d0f3f9c7bc845e7053f7a099088108a2 100644 (file)
--- 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)) {