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>
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@ -283,6 +283,14 @@ extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
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unsigned long addr);
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extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
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#ifdef CONFIG_SYSCTL
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extern int sysctl_kprobes_optimization;
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extern int proc_kprobes_optimization_handler(struct ctl_table *table,
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int write, void __user *buffer,
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size_t *length, loff_t *ppos);
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#endif
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#endif /* CONFIG_OPTPROBES */
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/* Get the kprobe at this addr (if any) - called with preemption disabled */
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@ -42,6 +42,7 @@
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#include <linux/freezer.h>
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#include <linux/seq_file.h>
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#include <linux/debugfs.h>
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#include <linux/sysctl.h>
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#include <linux/kdebug.h>
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#include <linux/memory.h>
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#include <linux/ftrace.h>
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@ -360,6 +361,9 @@ static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
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}
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#ifdef CONFIG_OPTPROBES
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/* NOTE: change this value only with kprobe_mutex held */
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static bool kprobes_allow_optimization;
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/*
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* Call all pre_handler on the list, but ignores its return value.
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* This must be called from arch-dep optimized caller.
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@ -428,7 +432,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
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/* Lock modules while optimizing kprobes */
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mutex_lock(&module_mutex);
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mutex_lock(&kprobe_mutex);
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if (kprobes_all_disarmed)
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if (kprobes_all_disarmed || !kprobes_allow_optimization)
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goto end;
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/*
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@ -471,7 +475,7 @@ static __kprobes void optimize_kprobe(struct kprobe *p)
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struct optimized_kprobe *op;
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/* Check if the kprobe is disabled or not ready for optimization. */
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if (!kprobe_optready(p) ||
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if (!kprobe_optready(p) || !kprobes_allow_optimization ||
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(kprobe_disabled(p) || kprobes_all_disarmed))
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return;
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@ -588,6 +592,80 @@ static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
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optimize_kprobe(ap);
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}
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#ifdef CONFIG_SYSCTL
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static void __kprobes optimize_all_kprobes(void)
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{
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struct hlist_head *head;
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struct hlist_node *node;
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struct kprobe *p;
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unsigned int i;
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/* If optimization is already allowed, just return */
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if (kprobes_allow_optimization)
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return;
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kprobes_allow_optimization = true;
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mutex_lock(&text_mutex);
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for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
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head = &kprobe_table[i];
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hlist_for_each_entry_rcu(p, node, head, hlist)
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if (!kprobe_disabled(p))
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optimize_kprobe(p);
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}
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mutex_unlock(&text_mutex);
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printk(KERN_INFO "Kprobes globally optimized\n");
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}
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static void __kprobes unoptimize_all_kprobes(void)
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{
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struct hlist_head *head;
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struct hlist_node *node;
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struct kprobe *p;
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unsigned int i;
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/* If optimization is already prohibited, just return */
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if (!kprobes_allow_optimization)
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return;
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kprobes_allow_optimization = false;
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printk(KERN_INFO "Kprobes globally unoptimized\n");
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get_online_cpus(); /* For avoiding text_mutex deadlock */
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mutex_lock(&text_mutex);
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for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
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head = &kprobe_table[i];
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hlist_for_each_entry_rcu(p, node, head, hlist) {
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if (!kprobe_disabled(p))
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unoptimize_kprobe(p);
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}
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}
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mutex_unlock(&text_mutex);
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put_online_cpus();
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/* Allow all currently running kprobes to complete */
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synchronize_sched();
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}
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int sysctl_kprobes_optimization;
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int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *length,
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loff_t *ppos)
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{
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int ret;
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mutex_lock(&kprobe_mutex);
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sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
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ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
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if (sysctl_kprobes_optimization)
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optimize_all_kprobes();
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else
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unoptimize_all_kprobes();
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mutex_unlock(&kprobe_mutex);
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return ret;
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}
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#endif /* CONFIG_SYSCTL */
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static void __kprobes __arm_kprobe(struct kprobe *p)
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{
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struct kprobe *old_p;
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@ -1610,10 +1688,14 @@ static int __init init_kprobes(void)
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}
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}
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#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
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#if defined(CONFIG_OPTPROBES)
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#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
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/* Init kprobe_optinsn_slots */
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kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
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#endif
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/* By default, kprobes can be optimized */
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kprobes_allow_optimization = true;
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#endif
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/* By default, kprobes are armed */
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kprobes_all_disarmed = false;
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@ -50,6 +50,7 @@
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#include <linux/ftrace.h>
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#include <linux/slow-work.h>
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#include <linux/perf_event.h>
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#include <linux/kprobes.h>
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#include <asm/uaccess.h>
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#include <asm/processor.h>
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@ -1449,6 +1450,17 @@ static struct ctl_table debug_table[] = {
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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#endif
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#if defined(CONFIG_OPTPROBES)
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{
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.procname = "kprobes-optimization",
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.data = &sysctl_kprobes_optimization,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_kprobes_optimization_handler,
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.extra1 = &zero,
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.extra2 = &one,
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},
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#endif
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{ }
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};
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