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Commit e5253896 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt
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kprobes/x86: ftrace based optimization for x86 

Add function tracer based kprobe optimization support
handlers on x86. This allows kprobes to use function
tracer for probing on mcount call.

Link: http://lkml.kernel.org/r/20120605102838.27845.26317.stgit@localhost.localdomain



Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

[ Updated to new port of ftrace save regs functions ]

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent ae6aa16f

arch/x86/include/asm/kprobes.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <asm/insn.h>



#define  __ARCH_WANT_KPROBES_INSN_SLOT

#define  ARCH_SUPPORTS_KPROBES_ON_FTRACE



struct pt_regs;

struct kprobe;

arch/x86/kernel/kprobes.c

+48 −0
Original line number Diff line number Diff line
@@ -1052,6 +1052,54 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) 
	return 0;

}



#ifdef KPROBES_CAN_USE_FTRACE

/* Ftrace callback handler for kprobes */

void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,

				     struct ftrace_ops *ops, struct pt_regs *regs)

{

	struct kprobe *p;

	struct kprobe_ctlblk *kcb;

	unsigned long flags;



	/* Disable irq for emulating a breakpoint and avoiding preempt */

	local_irq_save(flags);



	p = get_kprobe((kprobe_opcode_t *)ip);

	if (unlikely(!p) || kprobe_disabled(p))

		goto end;



	kcb = get_kprobe_ctlblk();

	if (kprobe_running()) {

		kprobes_inc_nmissed_count(p);

	} else {

		regs->ip += sizeof(kprobe_opcode_t);



		__this_cpu_write(current_kprobe, p);

		kcb->kprobe_status = KPROBE_HIT_ACTIVE;

		if (p->pre_handler)

			p->pre_handler(p, regs);



		if (unlikely(p->post_handler)) {

			/* Emulate singlestep as if there is a 5byte nop */

			regs->ip = ip + MCOUNT_INSN_SIZE;

			kcb->kprobe_status = KPROBE_HIT_SSDONE;

			p->post_handler(p, regs, 0);

		}

		__this_cpu_write(current_kprobe, NULL);

		regs->ip = ip;	/* Recover for next callback */

	}

end:

	local_irq_restore(flags);

}



int __kprobes arch_prepare_kprobe_ftrace(struct kprobe *p)

{

	p->ainsn.insn = NULL;

	p->ainsn.boostable = -1;

	return 0;

}

#endif



int __init arch_init_kprobes(void)

{

	return arch_init_optprobes();

include/linux/kprobes.h

+1 −1
Original line number Diff line number Diff line
@@ -318,7 +318,7 @@ extern int proc_kprobes_optimization_handler(struct ctl_table *table, 
#endif /* CONFIG_OPTPROBES */

#ifdef KPROBES_CAN_USE_FTRACE

extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,

				  struct pt_regs *regs);

				  struct ftrace_ops *ops, struct pt_regs *regs);

extern int arch_prepare_kprobe_ftrace(struct kprobe *p);

#endif

kernel/kprobes.c

+1 −1
Original line number Diff line number Diff line
@@ -921,7 +921,7 @@ static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p) 


#ifdef KPROBES_CAN_USE_FTRACE

static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {

	.regs_func = kprobe_ftrace_handler,

	.func = kprobe_ftrace_handler,

	.flags = FTRACE_OPS_FL_SAVE_REGS,

};

static int kprobe_ftrace_enabled;