Commit 90ec5e89 authored Feb 22, 2017 by Naveen N. Rao Committed by Arnaldo Carvalho de Melo Mar 03, 2017

kretprobes: Ensure probe location is at function entry



kretprobes can be registered by specifying an absolute address or by
specifying offset to a symbol. However, we need to ensure this falls at
function entry so as to be able to determine the return address.

Validate the same during kretprobe registration. By default, there
should not be any offset from a function entry, as determined through a
kallsyms_lookup(). Introduce arch_function_offset_within_entry() as a
way for architectures to override this.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/f1583bc4839a3862cfc2acefcc56f9c8837fa2ba.1487770934.git.naveen.n.rao@linux.vnet.ibm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 58335964

include/linux/kprobes.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -267,6 +267,7 @@ extern int arch_init_kprobes(void);
		extern void show_registers(struct pt_regs *regs);
		extern void kprobes_inc_nmissed_count(struct kprobe *p);
		extern bool arch_within_kprobe_blacklist(unsigned long addr);
		extern bool arch_function_offset_within_entry(unsigned long offset);

		extern bool within_kprobe_blacklist(unsigned long addr);

kernel/kprobes.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -1875,12 +1875,25 @@ static int pre_handler_kretprobe(struct kprobe p, struct pt_regs regs)
		}
		NOKPROBE_SYMBOL(pre_handler_kretprobe);

		bool __weak arch_function_offset_within_entry(unsigned long offset)
		{
		return !offset;
		}

		int register_kretprobe(struct kretprobe *rp)
		{
		int ret = 0;
		struct kretprobe_instance *inst;
		int i;
		void *addr;
		unsigned long offset;

		addr = kprobe_addr(&rp->kp);
		if (!kallsyms_lookup_size_offset((unsigned long)addr, NULL, &offset))
		return -EINVAL;

		if (!arch_function_offset_within_entry(offset))
		return -EINVAL;

		if (kretprobe_blacklist_size) {
		addr = kprobe_addr(&rp->kp);