Commit df91c5bc authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
Browse files

kprobes: Enable stacktrace from pt_regs in kretprobe handler 

Since the ORC unwinder from pt_regs requires setting up regs->ip
correctly, set the correct return address to the regs->ip before
calling user kretprobe handler.

This allows the kretrprobe handler to trace stack from the
kretprobe's pt_regs by stack_trace_save_regs() (eBPF will do
this), instead of stack tracing from the handler context by
stack_trace_save() (ftrace will do this).

Link: https://lkml.kernel.org/r/163163053237.489837.4272653874525136832.stgit@devnote2



Suggested-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Tested-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 7391dd19

kernel/kprobes.c

+7 −0
Original line number Diff line number Diff line
@@ -1937,6 +1937,13 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, 
		BUG_ON(1);

	}



	/*

	 * Set the return address as the instruction pointer, because if the

	 * user handler calls stack_trace_save_regs() with this 'regs',

	 * the stack trace will start from the instruction pointer.

	 */

	instruction_pointer_set(regs, (unsigned long)correct_ret_addr);



	/* Run the user handler of the nodes. */

	first = current->kretprobe_instances.first;

	while (first) {