Commit e0b59b7b authored by Sven Schnelle's avatar Sven Schnelle Committed by Helge Deller
Browse files

parisc: Implement kretprobes 



Implement kretprobes on parisc, parts stolen from powerpc.

Signed-off-by: default avatarSven Schnelle <svens@stackframe.org>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent 1253d18d

arch/parisc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ config PARISC 
	select NEED_SG_DMA_LENGTH

	select HAVE_ARCH_KGDB

	select HAVE_KPROBES

	select HAVE_KRETPROBES



	help

	  The PA-RISC microprocessor is designed by Hewlett-Packard and used

arch/parisc/kernel/kprobes.c

+109 −1
Original line number Diff line number Diff line
@@ -172,6 +172,112 @@ int __kprobes parisc_kprobe_ss_handler(struct pt_regs *regs) 
	return 1;

}



static inline void kretprobe_trampoline(void)

{

	asm volatile("nop");

	asm volatile("nop");

}



static int __kprobes trampoline_probe_handler(struct kprobe *p,

					      struct pt_regs *regs);



static struct kprobe trampoline_p = {

	.pre_handler = trampoline_probe_handler

};



static int __kprobes trampoline_probe_handler(struct kprobe *p,

					      struct pt_regs *regs)

{

	struct kretprobe_instance *ri = NULL;

	struct hlist_head *head, empty_rp;

	struct hlist_node *tmp;

	unsigned long flags, orig_ret_address = 0;

	unsigned long trampoline_address = (unsigned long)trampoline_p.addr;

	kprobe_opcode_t *correct_ret_addr = NULL;



	INIT_HLIST_HEAD(&empty_rp);

	kretprobe_hash_lock(current, &head, &flags);



	/*

	 * It is possible to have multiple instances associated with a given

	 * task either because multiple functions in the call path have

	 * a return probe installed on them, and/or more than one return

	 * probe was registered for a target function.

	 *

	 * We can handle this because:

	 *     - instances are always inserted at the head of the list

	 *     - when multiple return probes are registered for the same

	 *       function, the first instance's ret_addr will point to the

	 *       real return address, and all the rest will point to

	 *       kretprobe_trampoline

	 */

	hlist_for_each_entry_safe(ri, tmp, head, hlist) {

		if (ri->task != current)

			/* another task is sharing our hash bucket */

			continue;



		orig_ret_address = (unsigned long)ri->ret_addr;



		if (orig_ret_address != trampoline_address)

			/*

			 * This is the real return address. Any other

			 * instances associated with this task are for

			 * other calls deeper on the call stack

			 */

			break;

	}



	kretprobe_assert(ri, orig_ret_address, trampoline_address);



	correct_ret_addr = ri->ret_addr;

	hlist_for_each_entry_safe(ri, tmp, head, hlist) {

		if (ri->task != current)

			/* another task is sharing our hash bucket */

			continue;



		orig_ret_address = (unsigned long)ri->ret_addr;

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

			__this_cpu_write(current_kprobe, &ri->rp->kp);

			get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;

			ri->ret_addr = correct_ret_addr;

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

			__this_cpu_write(current_kprobe, NULL);

		}



		recycle_rp_inst(ri, &empty_rp);



		if (orig_ret_address != trampoline_address)

			/*

			 * This is the real return address. Any other

			 * instances associated with this task are for

			 * other calls deeper on the call stack

			 */

			break;

	}



	kretprobe_hash_unlock(current, &flags);



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

		hlist_del(&ri->hlist);

		kfree(ri);

	}

	instruction_pointer_set(regs, orig_ret_address);

	return 1;

}



void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,

				      struct pt_regs *regs)

{

	ri->ret_addr = (kprobe_opcode_t *)regs->gr[2];



	/* Replace the return addr with trampoline addr. */

	regs->gr[2] = (unsigned long)trampoline_p.addr;

}



int __kprobes arch_trampoline_kprobe(struct kprobe *p)

{

	return p->addr == trampoline_p.addr;

}

bool arch_kprobe_on_func_entry(unsigned long offset)

{

	return !offset;
@@ -179,5 +285,7 @@ bool arch_kprobe_on_func_entry(unsigned long offset) 


int __init arch_init_kprobes(void)

{

	return 0;

	trampoline_p.addr = (kprobe_opcode_t *)

		dereference_function_descriptor(kretprobe_trampoline);

	return register_kprobe(&trampoline_p);

}