Commit f984ba4e authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

kprobes: Use text_poke_smp_batch for unoptimizing 



Use text_poke_smp_batch() on unoptimization path for reducing
the number of stop_machine() issues. If the number of
unoptimizing probes is more than MAX_OPTIMIZE_PROBES(=256),
kprobes unoptimizes first MAX_OPTIMIZE_PROBES probes and kicks
optimizer for remaining probes.

Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20101203095434.2961.22657.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent cd7ebe22

arch/x86/kernel/kprobes.c

+40 −0
Original line number Diff line number Diff line
@@ -1457,6 +1457,46 @@ void __kprobes arch_optimize_kprobes(struct list_head *oplist) 
	text_poke_smp_batch(jump_poke_params, c);

}



static void __kprobes setup_unoptimize_kprobe(struct text_poke_param *tprm,

					      u8 *insn_buf,

					      struct optimized_kprobe *op)

{

	/* Set int3 to first byte for kprobes */

	insn_buf[0] = BREAKPOINT_INSTRUCTION;

	memcpy(insn_buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);



	tprm->addr = op->kp.addr;

	tprm->opcode = insn_buf;

	tprm->len = RELATIVEJUMP_SIZE;

}



/*

 * Recover original instructions and breakpoints from relative jumps.

 * Caller must call with locking kprobe_mutex.

 */

extern void arch_unoptimize_kprobes(struct list_head *oplist,

				    struct list_head *done_list)

{

	struct optimized_kprobe *op, *tmp;

	int c = 0;



	list_for_each_entry_safe(op, tmp, oplist, list) {

		/* Setup param */

		setup_unoptimize_kprobe(&jump_poke_params[c],

					jump_poke_bufs[c].buf, op);

		list_move(&op->list, done_list);

		if (++c >= MAX_OPTIMIZE_PROBES)

			break;

	}



	/*

	 * text_poke_smp doesn't support NMI/MCE code modifying.

	 * However, since kprobes itself also doesn't support NMI/MCE

	 * code probing, it's not a problem.

	 */

	text_poke_smp_batch(jump_poke_params, c);

}



/* Replace a relative jump with a breakpoint (int3).  */

void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op)

{

include/linux/kprobes.h

+2 −0
Original line number Diff line number Diff line
@@ -276,6 +276,8 @@ 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 void arch_optimize_kprobes(struct list_head *oplist);

extern void arch_unoptimize_kprobes(struct list_head *oplist,

				    struct list_head *done_list);

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);

kernel/kprobes.c

+4 −6
Original line number Diff line number Diff line
@@ -517,9 +517,9 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list) 
	/* Ditto to do_optimize_kprobes */

	get_online_cpus();

	mutex_lock(&text_mutex);

	list_for_each_entry_safe(op, tmp, &unoptimizing_list, list) {

		/* Unoptimize kprobes */

		arch_unoptimize_kprobe(op);

	arch_unoptimize_kprobes(&unoptimizing_list, free_list);

	/* Loop free_list for disarming */

	list_for_each_entry_safe(op, tmp, free_list, list) {

		/* Disarm probes if marked disabled */

		if (kprobe_disabled(&op->kp))

			arch_disarm_kprobe(&op->kp);
@@ -530,8 +530,6 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list) 
			 * (reclaiming is done by do_free_cleaned_kprobes.)

			 */

			hlist_del_rcu(&op->kp.hlist);

			/* Move only unused probes on free_list */

			list_move(&op->list, free_list);

		} else

			list_del_init(&op->list);

	}
@@ -592,7 +590,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) 
	mutex_unlock(&module_mutex);



	/* Step 5: Kick optimizer again if needed */

	if (!list_empty(&optimizing_list))

	if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))

		kick_kprobe_optimizer();

	else

		/* Wake up all waiters */

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