From ccb0fcb78c0d22ebaeb9aa37f1941b0d44c98038 Mon Sep 17 00:00:00 2001
From: Fabian Imhof <fabian.imhof@ost.ch>
Date: Sun, 4 May 2025 11:07:48 +0000
Subject: move user-mode code into own namespace and linker section

---
 arch/x86_64/src/context_switching/main.cpp | 27 ++--------------------
 arch/x86_64/src/user/main.cpp              | 36 ++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 25 deletions(-)
 create mode 100644 arch/x86_64/src/user/main.cpp

(limited to 'arch/x86_64/src')

diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index 6c6ec1a..a112924 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -8,6 +8,7 @@
 #include "arch/kernel/cpu/if.hpp"
 #include "arch/kernel/cpu/segment_register.hpp"
 #include "arch/kernel/cpu/tr.hpp"
+#include "arch/user/main.hpp"
 #include "arch/video/vga/text.hpp"
 
 namespace teachos::arch::context_switching
@@ -24,30 +25,6 @@ namespace teachos::arch::context_switching
         4U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER};
 
     auto reload_gdtr() -> void { kernel::cpu::call(KERNEL_CODE_POINTER); }
-
-    auto user_mode_main() -> void
-    {
-      // TODO: Remove or replace this wall of text
-      // RFLAGS is saved into R11, RIP of the next instruction into RCX
-      // Required for SYSRETURN to know where to return too.
-      // Additional state needs to be saved by calling convention:
-
-      // Syscall Number: RAX, Return Value: RAX (0 indicating no error, and -1 indicating an error, use as a boolean)
-      // Argument in this order (max 6. no argument on stack): RDI, RSI, RDX, R10, R8, R9
-      // Not used registers: RBX, RSP, R12, R13, R14
-
-      // Actual Source: https://man7.org/linux/man-pages/man2/syscall.2.html More cleare documentation:
-      // https://sys.readthedocs.io/en/latest/doc/05_calling_system_calls.html
-
-      const char syscall_message[68] = "Successfully entered user mode and wrote to VGA buffer via syscall!";
-      auto error = syscall::syscall(syscall::WRITE, {reinterpret_cast<uint64_t>(&syscall_message)});
-
-      if (!error)
-      {
-        video::vga::text::write("Successfully made a SYSCALL and returned with SYSRETQ!",
-                                video::vga::text::common_attributes::green_on_black);
-      }
-    }
   }  // namespace
 
   auto initialize_descriptor_tables() -> descriptor_tables
@@ -76,7 +53,7 @@ namespace teachos::arch::context_switching
   auto switch_to_user_mode() -> void
   {
     syscall::enable_syscall();
-    switch_context(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR, user_mode_main);
+    switch_context(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR, user::main);
   }
 
   auto switch_context(interrupt_descriptor_table::segment_selector data_segment,
diff --git a/arch/x86_64/src/user/main.cpp b/arch/x86_64/src/user/main.cpp
new file mode 100644
index 0000000..6d8eea7
--- /dev/null
+++ b/arch/x86_64/src/user/main.cpp
@@ -0,0 +1,36 @@
+#include "arch/user/main.hpp"
+
+#include "arch/context_switching/syscall/main.hpp"
+
+// TODO: Disallow this import
+#include "arch/video/vga/text.hpp"
+
+namespace teachos::arch::user
+{
+
+  [[gnu::section(".user_text")]]
+  auto main() -> void
+  {
+    // TODO: Remove or replace this wall of text
+    // RFLAGS is saved into R11, RIP of the next instruction into RCX
+    // Required for SYSRETURN to know where to return too.
+    // Additional state needs to be saved by calling convention:
+
+    // Syscall Number: RAX, Return Value: RAX (0 indicating no error, and -1 indicating an error, use as a boolean)
+    // Argument in this order (max 6. no argument on stack): RDI, RSI, RDX, R10, R8, R9
+    // Not used registers: RBX, RSP, R12, R13, R14
+
+    // Actual Source: https://man7.org/linux/man-pages/man2/syscall.2.html More cleare documentation:
+    // https://sys.readthedocs.io/en/latest/doc/05_calling_system_calls.html
+
+    const char syscall_message[68] = "Successfully entered user mode and wrote to VGA buffer via syscall!";
+    auto error = context_switching::syscall::syscall(context_switching::syscall::WRITE,
+                                                     {reinterpret_cast<uint64_t>(&syscall_message)});
+
+    if (!error)
+    {
+      video::vga::text::write("Successfully made a SYSCALL and returned with SYSRETQ!",
+                              video::vga::text::common_attributes::green_on_black);
+    }
+  }
+}  // namespace teachos::arch::user
\ No newline at end of file
-- 
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