parisc: Implement kretprobes (e0b59b7b) · Commits · e / devices / android_kernel_fairphone_FP5

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);
		}