From afd66255b9a48f5851326ddae50e2203fbf71dc9 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 25 Feb 2010 08:34:07 -0500 Subject: kprobes: Introduce kprobes jump optimization Introduce kprobes jump optimization arch-independent parts. Kprobes uses breakpoint instruction for interrupting execution flow, on some architectures, it can be replaced by a jump instruction and interruption emulation code. This gains kprobs' performance drastically. To enable this feature, set CONFIG_OPTPROBES=y (default y if the arch supports OPTPROBE). Changes in v9: - Fix a bug to optimize probe when enabling. - Check nearby probes can be optimize/unoptimize when disarming/arming kprobes, instead of registering/unregistering. This will help kprobe-tracer because most of probes on it are usually disabled. Changes in v6: - Cleanup coding style for readability. - Add comments around get/put_online_cpus(). Changes in v5: - Use get_online_cpus()/put_online_cpus() for avoiding text_mutex deadlock. Signed-off-by: Masami Hiramatsu Cc: systemtap Cc: DLE Cc: Ananth N Mavinakayanahalli Cc: Jim Keniston Cc: Srikar Dronamraju Cc: Christoph Hellwig Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Anders Kaseorg Cc: Tim Abbott Cc: Andi Kleen Cc: Jason Baron Cc: Mathieu Desnoyers Cc: Frederic Weisbecker Cc: Ananth N Mavinakayanahalli LKML-Reference: <20100225133407.6725.81992.stgit@localhost6.localdomain6> Signed-off-by: Ingo Molnar --- include/linux/kprobes.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'include/linux/kprobes.h') diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 1b672f74a32f..aed1f95c582f 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -122,6 +122,11 @@ struct kprobe { /* Kprobe status flags */ #define KPROBE_FLAG_GONE 1 /* breakpoint has already gone */ #define KPROBE_FLAG_DISABLED 2 /* probe is temporarily disabled */ +#define KPROBE_FLAG_OPTIMIZED 4 /* + * probe is really optimized. + * NOTE: + * this flag is only for optimized_kprobe. + */ /* Has this kprobe gone ? */ static inline int kprobe_gone(struct kprobe *p) @@ -134,6 +139,12 @@ static inline int kprobe_disabled(struct kprobe *p) { return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE); } + +/* Is this kprobe really running optimized path ? */ +static inline int kprobe_optimized(struct kprobe *p) +{ + return p->flags & KPROBE_FLAG_OPTIMIZED; +} /* * Special probe type that uses setjmp-longjmp type tricks to resume * execution at a specified entry with a matching prototype corresponding @@ -249,6 +260,31 @@ extern kprobe_opcode_t *get_insn_slot(void); extern void free_insn_slot(kprobe_opcode_t *slot, int dirty); extern void kprobes_inc_nmissed_count(struct kprobe *p); +#ifdef CONFIG_OPTPROBES +/* + * Internal structure for direct jump optimized probe + */ +struct optimized_kprobe { + struct kprobe kp; + struct list_head list; /* list for optimizing queue */ + struct arch_optimized_insn optinsn; +}; + +/* Architecture dependent functions for direct jump optimization */ +extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn); +extern int arch_check_optimized_kprobe(struct optimized_kprobe *op); +extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op); +extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); +extern int arch_optimize_kprobe(struct optimized_kprobe *op); +extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); +extern kprobe_opcode_t *get_optinsn_slot(void); +extern void free_optinsn_slot(kprobe_opcode_t *slot, int dirty); +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); +#endif /* CONFIG_OPTPROBES */ + /* Get the kprobe at this addr (if any) - called with preemption disabled */ struct kprobe *get_kprobe(void *addr); void kretprobe_hash_lock(struct task_struct *tsk, -- cgit v1.2.3