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authorMasami Hiramatsu <mhiramat@redhat.com>2010-02-25 08:34:15 -0500
committerIngo Molnar <mingo@elte.hu>2010-02-25 17:49:25 +0100
commitb2be84df99ebc93599c69e931a3c4a5105abfabc (patch)
tree35f720b12bed1cc98c7d261dc3a6af96916faa44 /kernel/kprobes.c
parentafd66255b9a48f5851326ddae50e2203fbf71dc9 (diff)
downloadlinux-2.6.34-ux500-b2be84df99ebc93599c69e931a3c4a5105abfabc.tar.gz
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/kprobes.c')
-rw-r--r--kernel/kprobes.c88
1 files changed, 85 insertions, 3 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 612af2d6161..fa034d29cf7 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -42,6 +42,7 @@
#include <linux/freezer.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
+#include <linux/sysctl.h>
#include <linux/kdebug.h>
#include <linux/memory.h>
#include <linux/ftrace.h>
@@ -360,6 +361,9 @@ static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
}
#ifdef CONFIG_OPTPROBES
+/* NOTE: change this value only with kprobe_mutex held */
+static bool kprobes_allow_optimization;
+
/*
* Call all pre_handler on the list, but ignores its return value.
* This must be called from arch-dep optimized caller.
@@ -428,7 +432,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
/* Lock modules while optimizing kprobes */
mutex_lock(&module_mutex);
mutex_lock(&kprobe_mutex);
- if (kprobes_all_disarmed)
+ if (kprobes_all_disarmed || !kprobes_allow_optimization)
goto end;
/*
@@ -471,7 +475,7 @@ static __kprobes void optimize_kprobe(struct kprobe *p)
struct optimized_kprobe *op;
/* Check if the kprobe is disabled or not ready for optimization. */
- if (!kprobe_optready(p) ||
+ if (!kprobe_optready(p) || !kprobes_allow_optimization ||
(kprobe_disabled(p) || kprobes_all_disarmed))
return;
@@ -588,6 +592,80 @@ static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
optimize_kprobe(ap);
}
+#ifdef CONFIG_SYSCTL
+static void __kprobes optimize_all_kprobes(void)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct kprobe *p;
+ unsigned int i;
+
+ /* If optimization is already allowed, just return */
+ if (kprobes_allow_optimization)
+ return;
+
+ kprobes_allow_optimization = true;
+ mutex_lock(&text_mutex);
+ for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+ head = &kprobe_table[i];
+ hlist_for_each_entry_rcu(p, node, head, hlist)
+ if (!kprobe_disabled(p))
+ optimize_kprobe(p);
+ }
+ mutex_unlock(&text_mutex);
+ printk(KERN_INFO "Kprobes globally optimized\n");
+}
+
+static void __kprobes unoptimize_all_kprobes(void)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct kprobe *p;
+ unsigned int i;
+
+ /* If optimization is already prohibited, just return */
+ if (!kprobes_allow_optimization)
+ return;
+
+ kprobes_allow_optimization = false;
+ printk(KERN_INFO "Kprobes globally unoptimized\n");
+ get_online_cpus(); /* For avoiding text_mutex deadlock */
+ mutex_lock(&text_mutex);
+ for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+ head = &kprobe_table[i];
+ hlist_for_each_entry_rcu(p, node, head, hlist) {
+ if (!kprobe_disabled(p))
+ unoptimize_kprobe(p);
+ }
+ }
+
+ mutex_unlock(&text_mutex);
+ put_online_cpus();
+ /* Allow all currently running kprobes to complete */
+ synchronize_sched();
+}
+
+int sysctl_kprobes_optimization;
+int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length,
+ loff_t *ppos)
+{
+ int ret;
+
+ mutex_lock(&kprobe_mutex);
+ sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
+ ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+
+ if (sysctl_kprobes_optimization)
+ optimize_all_kprobes();
+ else
+ unoptimize_all_kprobes();
+ mutex_unlock(&kprobe_mutex);
+
+ return ret;
+}
+#endif /* CONFIG_SYSCTL */
+
static void __kprobes __arm_kprobe(struct kprobe *p)
{
struct kprobe *old_p;
@@ -1610,10 +1688,14 @@ static int __init init_kprobes(void)
}
}
-#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
+#if defined(CONFIG_OPTPROBES)
+#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
/* Init kprobe_optinsn_slots */
kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
#endif
+ /* By default, kprobes can be optimized */
+ kprobes_allow_optimization = true;
+#endif
/* By default, kprobes are armed */
kprobes_all_disarmed = false;