From 196db62779287efb098943c2d4f2433e4b8ea592 Mon Sep 17 00:00:00 2001
From: "A. Wilcox" <AWilcox@Wilcox-Tech.com>
Date: Mon, 25 Apr 2022 23:34:32 -0500
Subject: [PATCH] Revert "x86: port to use common trampoline"

This reverts commit 388edbe12138e8300e230e2bc9c08a8f273e98d9.
---
 arch/x86/defs.h         |  3 ---
 arch/x86/startcontext.S | 41 +++++++++++++++++++++++++++++++++++++++++
 arch/x86/trampoline.c   |  3 ---
 3 files changed, 41 insertions(+), 6 deletions(-)
 create mode 100644 arch/x86/startcontext.S
 delete mode 100644 arch/x86/trampoline.c

diff --git a/arch/x86/defs.h b/arch/x86/defs.h
index 9370869..e0166e5 100644
--- a/arch/x86/defs.h
+++ b/arch/x86/defs.h
@@ -57,9 +57,6 @@
 
 #define MCONTEXT_GREGS	(20)
 
-#define FETCH_LINKPTR(dest) \
-	asm("movl (%%esp, %%ebx, 4), %0" : "=r" ((dest)));
-
 #include "common-defs.h"
 
 #endif
diff --git a/arch/x86/startcontext.S b/arch/x86/startcontext.S
new file mode 100644
index 0000000..1cbc68c
--- /dev/null
+++ b/arch/x86/startcontext.S
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2018, 2020 Ariadne Conill <ariadne@dereferenced.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#include "defs.h"
+
+FUNC(libucontext_trampoline)
+	/* get the proper context into position and test for NULL */
+	leal	(%esp,%ebx,4), %esp
+	cmpl	$0, (%esp)
+
+	/* restore global offset table, exit@plt and libucontext_setcontext@plt need this */
+	call	__i686.get_pc_thunk.bx
+	addl	$_GLOBAL_OFFSET_TABLE_, %ebx
+
+	/* if we have no linked context, lets get out of here */
+	je	no_linked_context
+
+	/* call setcontext to switch to the linked context */
+	call	libucontext_setcontext@plt
+	movl	%eax, (%esp)
+
+no_linked_context:
+	/* we are returning into a null context, it seems, so maybe we should exit */
+	call	exit@plt
+
+	/* something is really hosed, call hlt to force termination */
+	hlt
+
+__i686.get_pc_thunk.bx:
+	mov	(%esp), %ebx
+	ret
+END(libucontext_trampoline)
diff --git a/arch/x86/trampoline.c b/arch/x86/trampoline.c
deleted file mode 100644
index 699a050..0000000
--- a/arch/x86/trampoline.c
+++ /dev/null
@@ -1,3 +0,0 @@
-#include "defs.h"
-#include <libucontext/libucontext.h>
-#include "common-trampoline.c"
-- 
2.32.0 (Apple Git-132)