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[Dle-develop] [RFC PATCH -tip v3 3/7] kprobes: Jump optimization sysctl interface
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From: Masami H. <mhi...@re...> - 2009-07-07 00:58:05
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Add /proc/sys/debug/kprobes-optimization sysctl which enables and disables
kprobes jump optimization on the fly for debugging.
Signed-off-by: Masami Hiramatsu <mhi...@re...>
Cc: Ananth N Mavinakayanahalli <an...@in...>
Cc: Ingo Molnar <mi...@el...>
Cc: Jim Keniston <jke...@us...>
Cc: Srikar Dronamraju <sr...@li...>
Cc: Christoph Hellwig <hc...@in...>
Cc: Steven Rostedt <ro...@go...>
Cc: Frederic Weisbecker <fwe...@gm...>
Cc: H. Peter Anvin <hp...@zy...>
Cc: Anders Kaseorg <an...@ks...>
Cc: Tim Abbott <ta...@ks...>
Cc: Andi Kleen <an...@fi...>
---
include/linux/kprobes.h | 9 +++++
kernel/kprobes.c | 85 +++++++++++++++++++++++++++++++++++++++++++++--
kernel/sysctl.c | 13 +++++++
3 files changed, 104 insertions(+), 3 deletions(-)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 6f75014..de592ea 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -283,6 +283,15 @@ 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, struct file *file,
+ 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 0cbb607..1350e3d 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -44,6 +44,7 @@
#include <linux/debugfs.h>
#include <linux/kdebug.h>
#include <linux/memory.h>
+#include <linux/sysctl.h>
#include <asm-generic/sections.h>
#include <asm/cacheflush.h>
@@ -374,6 +375,9 @@ 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.
@@ -434,7 +438,7 @@ 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;
/* Wait quiesence period for ensuring all interrupts are done */
@@ -458,7 +462,7 @@ 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;
@@ -570,6 +574,77 @@ static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
optimize_kprobe(ap);
return;
}
+
+#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");
+ 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);
+ /* Allow all currently running kprobes to complete */
+ synchronize_sched();
+}
+
+int sysctl_kprobes_optimization;
+int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
+ struct file *file, 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, file, buffer, length, ppos);
+
+ if (sysctl_kprobes_optimization)
+ optimize_all_kprobes();
+ else
+ unoptimize_all_kprobes();
+ mutex_unlock(&kprobe_mutex);
+ return ret;
+}
+#endif /* CONFIG_SYSCTL */
+
#else /* !CONFIG_OPTPROBES */
#define get_optimized_kprobe(addr) (NULL)
#define optimize_kprobe(p) do {} while (0)
@@ -1550,10 +1625,14 @@ 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 32460ea..4359d61 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -51,6 +51,7 @@
#include <linux/ftrace.h>
#include <linux/slow-work.h>
#include <linux/perf_counter.h>
+#include <linux/kprobes.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@@ -1551,6 +1552,18 @@ static struct ctl_table debug_table[] = {
.proc_handler = proc_dointvec
},
#endif
+#if defined(CONFIG_OPTPROBES)
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "kprobes-optimization",
+ .data = &sysctl_kprobes_optimization,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_kprobes_optimization_handler,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+#endif
{ .ctl_name = 0 }
};
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhi...@re...
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