From 6f333cfc914e7cfacc4d3ef3e034e4483f0ba8b2 Mon Sep 17 00:00:00 2001
From: Callum Farmer <gmbr3@opensuse.org>
Date: Wed, 21 Jun 2023 20:27:43 +0100
Subject: [PATCH] Tail calls break ctors/dtors

Add macro EFI_NO_TAIL_CALL which disables tail call
optimization on a per-function basis

Signed-off-by: Callum Farmer <gmbr3@opensuse.org>
---
 apps/ctors_dtors_priority_test.c |  8 ++++----
 apps/ctors_fns.c                 |  4 ++--
 inc/eficompiler.h                | 10 ++++++++++
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/apps/ctors_dtors_priority_test.c b/apps/ctors_dtors_priority_test.c
index 0458c08..e8a3990 100644
--- a/apps/ctors_dtors_priority_test.c
+++ b/apps/ctors_dtors_priority_test.c
@@ -2,22 +2,22 @@
 #include <efilib.h>
 
 // 101 in init_array, 65434 in ctors
-static void __attribute__((constructor(101))) ctors101() {
+static void __attribute__((constructor(101))) EFI_NO_TAIL_CALL ctors101() {
     Print(L"1) ctor with lower numbered priority \r\n");
 }
 
 // 65434 in init_array, 101 in ctors
-static void __attribute__((constructor(65434))) ctors65434() {
+static void __attribute__((constructor(65434))) EFI_NO_TAIL_CALL ctors65434() {
     Print(L"2) ctor with higher numbered priority \r\n");
 }
 
 // 101 in fini_array, 65434 in dtors
-static void __attribute__((destructor(101))) dtors101() {
+static void __attribute__((destructor(101))) EFI_NO_TAIL_CALL dtors101() {
     Print(L"4) dtor with lower numbered priority \r\n");
 }
 
 // 65434 in fini_array, 101 in dtors
-static void __attribute__((destructor(65434))) dtors65434() {
+static void __attribute__((destructor(65434))) EFI_NO_TAIL_CALL dtors65434() {
     Print(L"3) dtor with higher numbered priority \r\n");
 }
 
diff --git a/apps/ctors_fns.c b/apps/ctors_fns.c
index 6241904..7027447 100644
--- a/apps/ctors_fns.c
+++ b/apps/ctors_fns.c
@@ -9,14 +9,14 @@
 
 int constructed_value = 0;
 
-static void __attribute__((__constructor__)) ctor(void)
+static void __attribute__((__constructor__)) EFI_NO_TAIL_CALL ctor(void)
 {
 	Print(L"%a:%d:%a() constructed_value:%d\n", __FILE__, __LINE__, __func__, constructed_value);
 	constructed_value = 1;
 	Print(L"%a:%d:%a() constructed_value:%d\n", __FILE__, __LINE__, __func__, constructed_value);
 }
 
-static void __attribute__((__destructor__)) dtor(void)
+static void __attribute__((__destructor__)) EFI_NO_TAIL_CALL dtor(void)
 {
 	Print(L"%a:%d:%a() constructed_value:%d\n", __FILE__, __LINE__, __func__, constructed_value);
 	constructed_value = 0;
diff --git a/inc/eficompiler.h b/inc/eficompiler.h
index 26636c7..3b66eb6 100644
--- a/inc/eficompiler.h
+++ b/inc/eficompiler.h
@@ -18,6 +18,16 @@ Abstract:
 #define EFI_UNUSED __attribute__((__unused__))
 #endif
 
+#ifdef _MSC_EXTENSIONS
+#define EFI_NO_TAIL_CALL
+#else
+#ifdef __clang__
+#define EFI_NO_TAIL_CALL __attribute__((disable_tail_calls))
+#else
+#define EFI_NO_TAIL_CALL __attribute__((optimize("no-optimize-sibling-calls")))
+#endif
+#endif
+
 #ifdef _MSC_EXTENSIONS
 #define ALIGN(x) __declspec(align(x))
 #else