From d63a30728c7ed50f1deead0390908dbfa31c100d Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@justin.cm>
Date: Sat, 22 Aug 2020 16:34:58 -0700
Subject: [PATCH] [kernel] Add get_caller function

Added a function to get the callsite of the current function invocation.
---
 src/kernel/debug.h | 1 +
 src/kernel/debug.s | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/src/kernel/debug.h b/src/kernel/debug.h
index de08ffe..0f9c8b6 100644
--- a/src/kernel/debug.h
+++ b/src/kernel/debug.h
@@ -7,6 +7,7 @@
 extern "C" {
 	uintptr_t get_rsp();
 	uintptr_t get_rip();
+	uintptr_t get_caller();
 	uintptr_t get_frame(int frame);
 	uintptr_t get_gsbase();
 	void _halt();
diff --git a/src/kernel/debug.s b/src/kernel/debug.s
index 646dc0d..421695c 100644
--- a/src/kernel/debug.s
+++ b/src/kernel/debug.s
@@ -8,6 +8,12 @@ get_rip:
 	pop rax ; do the same thing as 'ret', except with 'jmp'
 	jmp rax ; with the return address still in rax
 
+global get_caller
+get_caller:
+	; No prelude - don't touch rsp or rbp
+	mov rax, [rbp+8]
+	ret
+
 global get_gsbase
 get_gsbase:
 	rdgsbase rax