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Message-ID: <tip-b2be84df99ebc93599c69e931a3c4a5105abfabc@git.kernel.org>
Date: Thu, 25 Feb 2010 19:28:46 GMT
From: tip-bot for Masami Hiramatsu <mhiramat@...hat.com>
To: linux-tip-commits@...r.kernel.org
Cc: mingo@...hat.com, andersk@...lice.com, fweisbec@...il.com,
dle-develop@...ts.sourceforge.net, rostedt@...dmis.org,
compudj@...stal.dyndns.org, jbaron@...hat.com, tglx@...utronix.de,
mhiramat@...hat.com, systemtap@...rces.redhat.com,
linux-kernel@...r.kernel.org, hpa@...or.com, jkenisto@...ibm.com,
andi@...stfloor.org, tabbott@...lice.com, hch@...radead.org,
ananth@...ibm.com, srikar@...ux.vnet.ibm.com, mingo@...e.hu
Subject: [tip:perf/probes] kprobes: Jump optimization sysctl interface
Commit-ID: b2be84df99ebc93599c69e931a3c4a5105abfabc
Gitweb: http://git.kernel.org/tip/b2be84df99ebc93599c69e931a3c4a5105abfabc
Author: Masami Hiramatsu <mhiramat@...hat.com>
AuthorDate: Thu, 25 Feb 2010 08:34:15 -0500
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 25 Feb 2010 17:49:25 +0100
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@...hat.com>
Cc: systemtap <systemtap@...rces.redhat.com>
Cc: DLE <dle-develop@...ts.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Jim Keniston <jkenisto@...ibm.com>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Anders Kaseorg <andersk@...lice.com>
Cc: Tim Abbott <tabbott@...lice.com>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: Jason Baron <jbaron@...hat.com>
Cc: Mathieu Desnoyers <compudj@...stal.dyndns.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
LKML-Reference: <20100225133415.6725.8274.stgit@...alhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
include/linux/kprobes.h | 8 ++++
kernel/kprobes.c | 88 +++++++++++++++++++++++++++++++++++++++++++++--
kernel/sysctl.c | 12 ++++++
3 files changed, 105 insertions(+), 3 deletions(-)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index aed1f95..e7d1b2e 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -283,6 +283,14 @@ extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
unsigned long addr);
extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
+
+#ifdef CONFIG_SYSCTL
+extern int sysctl_kprobes_optimization;
+extern int proc_kprobes_optimization_handler(struct ctl_table *table,
+ int write, void __user *buffer,
+ size_t *length, loff_t *ppos);
+#endif
+
#endif /* CONFIG_OPTPROBES */
/* Get the kprobe at this addr (if any) - called with preemption disabled */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 612af2d..fa034d2 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;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8a68b24..40d791d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -50,6 +50,7 @@
#include <linux/ftrace.h>
#include <linux/slow-work.h>
#include <linux/perf_event.h>
+#include <linux/kprobes.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@@ -1450,6 +1451,17 @@ static struct ctl_table debug_table[] = {
.proc_handler = proc_dointvec
},
#endif
+#if defined(CONFIG_OPTPROBES)
+ {
+ .procname = "kprobes-optimization",
+ .data = &sysctl_kprobes_optimization,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_kprobes_optimization_handler,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+#endif
{ }
};
--
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