From fe2716df216ec4a31818f6f1c0a47d64454a23f0 Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gbeutner@serenityos.org>
Date: Tue, 29 Jun 2021 17:56:04 +0200
Subject: [PATCH] Kernel: Disable __thread and TLS on x86_64 for now

They're not yet properly supported.
---
 CMakeLists.txt                            |  5 +++++
 Kernel/Syscalls/mmap.cpp                  |  2 +-
 Userland/Libraries/LibC/pthread_tls.cpp   |  5 ++++-
 Userland/Libraries/LibDl/dlfcn.cpp        | 12 ++++++++++--
 Userland/Libraries/LibPthread/pthread.cpp | 10 ++++++++--
 5 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 992292e470c..62fd60c7534 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -93,6 +93,11 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+if("${SERENITY_ARCH}" STREQUAL "x86_64")
+    # FIXME: Implement TLS support and get rid of this
+    add_compile_definitions(NO_TLS X86_64_NO_TLS)
+endif()
+
 add_compile_options(-Wno-literal-suffix)
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
     add_compile_options(-fconcepts)
diff --git a/Kernel/Syscalls/mmap.cpp b/Kernel/Syscalls/mmap.cpp
index f88bc4d51e8..dd0cc612044 100644
--- a/Kernel/Syscalls/mmap.cpp
+++ b/Kernel/Syscalls/mmap.cpp
@@ -612,7 +612,7 @@ KResultOr<FlatPtr> Process::sys$allocate_tls(Userspace<const char*> initial_data
     tls_descriptor.set_base(main_thread->thread_specific_data());
     tls_descriptor.set_limit(main_thread->thread_specific_region_size());
 #else
-    TODO();
+    dbgln("FIXME: Not setting FS_BASE for process.");
 #endif
 
     return m_master_tls_region.unsafe_ptr()->vaddr().get();
diff --git a/Userland/Libraries/LibC/pthread_tls.cpp b/Userland/Libraries/LibC/pthread_tls.cpp
index 6c32260dcd4..393964a7ed1 100644
--- a/Userland/Libraries/LibC/pthread_tls.cpp
+++ b/Userland/Libraries/LibC/pthread_tls.cpp
@@ -26,7 +26,10 @@ struct SpecificTable {
 
 static KeyTable s_keys;
 
-__thread SpecificTable t_specifics;
+#    ifndef X86_64_NO_TLS
+__thread
+#    endif
+    SpecificTable t_specifics;
 
 int __pthread_key_create(pthread_key_t* key, KeyDestructor destructor)
 {
diff --git a/Userland/Libraries/LibDl/dlfcn.cpp b/Userland/Libraries/LibDl/dlfcn.cpp
index 077f62a101e..861df60476d 100644
--- a/Userland/Libraries/LibDl/dlfcn.cpp
+++ b/Userland/Libraries/LibDl/dlfcn.cpp
@@ -11,8 +11,16 @@
 #include <string.h>
 
 // FIXME: use thread_local and a String once TLS works
-__thread char* s_dlerror_text = NULL;
-__thread bool s_dlerror_retrieved = false;
+#ifndef X86_64_NO_TLS
+__thread
+#endif
+    char* s_dlerror_text
+    = NULL;
+#ifndef X86_64_NO_TLS
+__thread
+#endif
+    bool s_dlerror_retrieved
+    = false;
 
 static void store_error(const String& error)
 {
diff --git a/Userland/Libraries/LibPthread/pthread.cpp b/Userland/Libraries/LibPthread/pthread.cpp
index 763de5b74da..831145d106b 100644
--- a/Userland/Libraries/LibPthread/pthread.cpp
+++ b/Userland/Libraries/LibPthread/pthread.cpp
@@ -33,8 +33,14 @@ static constexpr size_t required_stack_alignment = 4 * MiB;
 static constexpr size_t highest_reasonable_guard_size = 32 * PAGE_SIZE;
 static constexpr size_t highest_reasonable_stack_size = 8 * MiB; // That's the default in Ubuntu?
 
-__thread void* s_stack_location;
-__thread size_t s_stack_size;
+#ifndef X86_64_NO_TLS
+__thread
+#endif
+    void* s_stack_location;
+#ifndef X86_64_NO_TLS
+__thread
+#endif
+    size_t s_stack_size;
 
 #define __RETURN_PTHREAD_ERROR(rc) \
     return ((rc) < 0 ? -(rc) : 0)