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

Browse source 
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
This commit is contained in:
Linus Torvalds 2014-08-24 16:16:55 -07:00
commit 44744bb344
2 changed files with 34 additions and 2 deletions
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23
kernel/events/core.c
View file

@ -41,6 +41,7 @@
#include <linux/cgroup.h> #include <linux/cgroup.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/mman.h> #include <linux/mman.h>
#include <linux/compat.h>
#include "internal.h" #include "internal.h"
@ -3717,6 +3718,26 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
return 0; 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) int perf_event_task_enable(void)
{ {
struct perf_event *event; struct perf_event *event;
@ -4222,7 +4243,7 @@ static const struct file_operations perf_fops = {
.read = perf_read, .read = perf_read,
.poll = perf_poll, .poll = perf_poll,
.unlocked_ioctl = perf_ioctl, .unlocked_ioctl = perf_ioctl,
.compat_ioctl = perf_ioctl, .compat_ioctl = perf_compat_ioctl,
.mmap = perf_mmap, .mmap = perf_mmap,
.fasync = perf_fasync, .fasync = perf_fasync,
}; };

11
kernel/kprobes.c
View file

@ -1778,6 +1778,17 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
unsigned long hash, flags = 0; unsigned long hash, flags = 0;
struct kretprobe_instance *ri; struct kretprobe_instance *ri;
/*
* 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 */ /* TODO: consider to only swap the RA after the last pre_handler fired */
hash = hash_ptr(current, KPROBE_HASH_BITS); hash = hash_ptr(current, KPROBE_HASH_BITS);
raw_spin_lock_irqsave(&rp->lock, flags); raw_spin_lock_irqsave(&rp->lock, flags);