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Commit da07ab03 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

x86: return probe-booster for x86-64 



This patch adds kretprobe-booster to kprobes_64.c.

- Changes are based on x86-32.
- Rewrite register saving/restoring code

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent aa470140

arch/x86/kernel/kprobes_64.c

+65 −27
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ 
 *		Fixed to handle %rip-relative addressing mode correctly.

 * 2005-May     Rusty Lynch <rusty.lynch@intel.com>

 *              Added function return probes functionality

 * 2007-Dec	Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster

 * 		and kretprobe-booster for x86-64

 */



#include <linux/kprobes.h>
@@ -507,21 +509,65 @@ no_kprobe: 
}



/*

 * For function-return probes, init_kprobes() establishes a probepoint

 * here. When a retprobed function returns, this probe is hit and

 * trampoline_probe_handler() runs, calling the kretprobe's handler.

 * When a retprobed function returns, this code saves registers and

 * calls trampoline_handler() runs, which calls the kretprobe's handler.

 */

 void kretprobe_trampoline_holder(void)

 void __kprobes kretprobe_trampoline_holder(void)

 {

 	asm volatile (  ".global kretprobe_trampoline\n"

			"kretprobe_trampoline: \n"

 			"nop\n");

			/* We don't bother saving the ss register */

			"	pushq %rsp\n"

			"	pushfq\n"

			/*

			 * Skip cs, ip, orig_ax.

			 * trampoline_handler() will plug in these values

			 */

			"	subq $24, %rsp\n"

			"	pushq %rdi\n"

			"	pushq %rsi\n"

			"	pushq %rdx\n"

			"	pushq %rcx\n"

			"	pushq %rax\n"

			"	pushq %r8\n"

			"	pushq %r9\n"

			"	pushq %r10\n"

			"	pushq %r11\n"

			"	pushq %rbx\n"

			"	pushq %rbp\n"

			"	pushq %r12\n"

			"	pushq %r13\n"

			"	pushq %r14\n"

			"	pushq %r15\n"

			"	movq %rsp, %rdi\n"

			"	call trampoline_handler\n"

			/* Replace saved sp with true return address. */

			"	movq %rax, 152(%rsp)\n"

			"	popq %r15\n"

			"	popq %r14\n"

			"	popq %r13\n"

			"	popq %r12\n"

			"	popq %rbp\n"

			"	popq %rbx\n"

			"	popq %r11\n"

			"	popq %r10\n"

			"	popq %r9\n"

			"	popq %r8\n"

			"	popq %rax\n"

			"	popq %rcx\n"

			"	popq %rdx\n"

			"	popq %rsi\n"

			"	popq %rdi\n"

			/* Skip orig_ax, ip, cs */

			"	addq $24, %rsp\n"

			"	popfq\n"

			"	ret\n");

 }



/*

 * Called when we hit the probe point at kretprobe_trampoline

 * Called from kretprobe_trampoline

 */

int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)

fastcall void * __kprobes trampoline_handler(struct pt_regs *regs)

{

	struct kretprobe_instance *ri = NULL;

	struct hlist_head *head, empty_rp;
@@ -532,6 +578,10 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) 
	INIT_HLIST_HEAD(&empty_rp);

	spin_lock_irqsave(&kretprobe_lock, flags);

	head = kretprobe_inst_table_head(current);

	/* fixup rt_regs */

	regs->cs = __KERNEL_CS;

	regs->ip = trampoline_address;

	regs->orig_ax = 0xffffffffffffffff;



	/*

	 * It is possible to have multiple instances associated with a given
@@ -551,8 +601,12 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) 
			/* another task is sharing our hash bucket */

			continue;



		if (ri->rp && ri->rp->handler)

		if (ri->rp && ri->rp->handler) {

			__get_cpu_var(current_kprobe) = &ri->rp->kp;

			get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;

			ri->rp->handler(ri, regs);

			__get_cpu_var(current_kprobe) = NULL;

		}



		orig_ret_address = (unsigned long)ri->ret_addr;

		recycle_rp_inst(ri, &empty_rp);
@@ -567,22 +621,14 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) 
	}



	kretprobe_assert(ri, orig_ret_address, trampoline_address);

	regs->ip = orig_ret_address;



	reset_current_kprobe();

	spin_unlock_irqrestore(&kretprobe_lock, flags);

	preempt_enable_no_resched();



	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {

		hlist_del(&ri->hlist);

		kfree(ri);

	}

	/*

	 * By returning a non-zero value, we are telling

	 * kprobe_handler() that we don't want the post_handler

	 * to run (and have re-enabled preemption)

	 */

	return 1;

	return (void *)orig_ret_address;

}



/*
@@ -881,20 +927,12 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) 
	return 0;

}



static struct kprobe trampoline_p = {

	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,

	.pre_handler = trampoline_probe_handler

};



int __init arch_init_kprobes(void)

{

	return register_kprobe(&trampoline_p);

	return 0;

}



int __kprobes arch_trampoline_kprobe(struct kprobe *p)

{

	if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)

		return 1;



	return 0;

}