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authorMasami Hiramatsu <mhiramat@redhat.com>2010-02-25 08:34:15 -0500
committerIngo Molnar <mingo@elte.hu>2010-02-25 11:49:25 -0500
commitb2be84df99ebc93599c69e931a3c4a5105abfabc (patch)
tree35f720b12bed1cc98c7d261dc3a6af96916faa44 /kernel
parentafd66255b9a48f5851326ddae50e2203fbf71dc9 (diff)
kprobes: Jump optimization sysctl interface
Add /proc/sys/debug/kprobes-optimization sysctl which enables and disables kprobes jump optimization on the fly for debugging. Changes in v7: - Remove ctl_name = CTL_UNNUMBERED for upstream compatibility. Changes in v6: - Update comments and coding style. Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Cc: systemtap <systemtap@sources.redhat.com> Cc: DLE <dle-develop@lists.sourceforge.net> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Anders Kaseorg <andersk@ksplice.com> Cc: Tim Abbott <tabbott@ksplice.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> LKML-Reference: <20100225133415.6725.8274.stgit@localhost6.localdomain6> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kprobes.c88
-rw-r--r--kernel/sysctl.c12
2 files changed, 97 insertions, 3 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 612af2d61614..fa034d29cf73 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -42,6 +42,7 @@
42#include <linux/freezer.h> 42#include <linux/freezer.h>
43#include <linux/seq_file.h> 43#include <linux/seq_file.h>
44#include <linux/debugfs.h> 44#include <linux/debugfs.h>
45#include <linux/sysctl.h>
45#include <linux/kdebug.h> 46#include <linux/kdebug.h>
46#include <linux/memory.h> 47#include <linux/memory.h>
47#include <linux/ftrace.h> 48#include <linux/ftrace.h>
@@ -360,6 +361,9 @@ static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
360} 361}
361 362
362#ifdef CONFIG_OPTPROBES 363#ifdef CONFIG_OPTPROBES
364/* NOTE: change this value only with kprobe_mutex held */
365static bool kprobes_allow_optimization;
366
363/* 367/*
364 * Call all pre_handler on the list, but ignores its return value. 368 * Call all pre_handler on the list, but ignores its return value.
365 * This must be called from arch-dep optimized caller. 369 * This must be called from arch-dep optimized caller.
@@ -428,7 +432,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
428 /* Lock modules while optimizing kprobes */ 432 /* Lock modules while optimizing kprobes */
429 mutex_lock(&module_mutex); 433 mutex_lock(&module_mutex);
430 mutex_lock(&kprobe_mutex); 434 mutex_lock(&kprobe_mutex);
431 if (kprobes_all_disarmed) 435 if (kprobes_all_disarmed || !kprobes_allow_optimization)
432 goto end; 436 goto end;
433 437
434 /* 438 /*
@@ -471,7 +475,7 @@ static __kprobes void optimize_kprobe(struct kprobe *p)
471 struct optimized_kprobe *op; 475 struct optimized_kprobe *op;
472 476
473 /* Check if the kprobe is disabled or not ready for optimization. */ 477 /* Check if the kprobe is disabled or not ready for optimization. */
474 if (!kprobe_optready(p) || 478 if (!kprobe_optready(p) || !kprobes_allow_optimization ||
475 (kprobe_disabled(p) || kprobes_all_disarmed)) 479 (kprobe_disabled(p) || kprobes_all_disarmed))
476 return; 480 return;
477 481
@@ -588,6 +592,80 @@ static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
588 optimize_kprobe(ap); 592 optimize_kprobe(ap);
589} 593}
590 594
595#ifdef CONFIG_SYSCTL
596static void __kprobes optimize_all_kprobes(void)
597{
598 struct hlist_head *head;
599 struct hlist_node *node;
600 struct kprobe *p;
601 unsigned int i;
602
603 /* If optimization is already allowed, just return */
604 if (kprobes_allow_optimization)
605 return;
606
607 kprobes_allow_optimization = true;
608 mutex_lock(&text_mutex);
609 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
610 head = &kprobe_table[i];
611 hlist_for_each_entry_rcu(p, node, head, hlist)
612 if (!kprobe_disabled(p))
613 optimize_kprobe(p);
614 }
615 mutex_unlock(&text_mutex);
616 printk(KERN_INFO "Kprobes globally optimized\n");
617}
618
619static void __kprobes unoptimize_all_kprobes(void)
620{
621 struct hlist_head *head;
622 struct hlist_node *node;
623 struct kprobe *p;
624 unsigned int i;
625
626 /* If optimization is already prohibited, just return */
627 if (!kprobes_allow_optimization)
628 return;
629
630 kprobes_allow_optimization = false;
631 printk(KERN_INFO "Kprobes globally unoptimized\n");
632 get_online_cpus(); /* For avoiding text_mutex deadlock */
633 mutex_lock(&text_mutex);
634 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
635 head = &kprobe_table[i];
636 hlist_for_each_entry_rcu(p, node, head, hlist) {
637 if (!kprobe_disabled(p))
638 unoptimize_kprobe(p);
639 }
640 }
641
642 mutex_unlock(&text_mutex);
643 put_online_cpus();
644 /* Allow all currently running kprobes to complete */
645 synchronize_sched();
646}
647
648int sysctl_kprobes_optimization;
649int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
650 void __user *buffer, size_t *length,
651 loff_t *ppos)
652{
653 int ret;
654
655 mutex_lock(&kprobe_mutex);
656 sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
657 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
658
659 if (sysctl_kprobes_optimization)
660 optimize_all_kprobes();
661 else
662 unoptimize_all_kprobes();
663 mutex_unlock(&kprobe_mutex);
664
665 return ret;
666}
667#endif /* CONFIG_SYSCTL */
668
591static void __kprobes __arm_kprobe(struct kprobe *p) 669static void __kprobes __arm_kprobe(struct kprobe *p)
592{ 670{
593 struct kprobe *old_p; 671 struct kprobe *old_p;
@@ -1610,10 +1688,14 @@ static int __init init_kprobes(void)
1610 } 1688 }
1611 } 1689 }
1612 1690
1613#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT) 1691#if defined(CONFIG_OPTPROBES)
1692#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
1614 /* Init kprobe_optinsn_slots */ 1693 /* Init kprobe_optinsn_slots */
1615 kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; 1694 kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
1616#endif 1695#endif
1696 /* By default, kprobes can be optimized */
1697 kprobes_allow_optimization = true;
1698#endif
1617 1699
1618 /* By default, kprobes are armed */ 1700 /* By default, kprobes are armed */
1619 kprobes_all_disarmed = false; 1701 kprobes_all_disarmed = false;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8a68b2448468..40d791d616b5 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -50,6 +50,7 @@
50#include <linux/ftrace.h> 50#include <linux/ftrace.h>
51#include <linux/slow-work.h> 51#include <linux/slow-work.h>
52#include <linux/perf_event.h> 52#include <linux/perf_event.h>
53#include <linux/kprobes.h>
53 54
54#include <asm/uaccess.h> 55#include <asm/uaccess.h>
55#include <asm/processor.h> 56#include <asm/processor.h>
@@ -1450,6 +1451,17 @@ static struct ctl_table debug_table[] = {
1450 .proc_handler = proc_dointvec 1451 .proc_handler = proc_dointvec
1451 }, 1452 },
1452#endif 1453#endif
1454#if defined(CONFIG_OPTPROBES)
1455 {
1456 .procname = "kprobes-optimization",
1457 .data = &sysctl_kprobes_optimization,
1458 .maxlen = sizeof(int),
1459 .mode = 0644,
1460 .proc_handler = proc_kprobes_optimization_handler,
1461 .extra1 = &zero,
1462 .extra2 = &one,
1463 },
1464#endif
1453 { } 1465 { }
1454}; 1466};
1455 1467