write wrapper function for syscall

1 files changed, 8 insertions, 63 deletions

diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index 06c0810..7fe159e 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -1,11 +1,11 @@
 #include "arch/context_switching/main.hpp"
 
 #include "arch/boot/pointers.hpp"
+#include "arch/context_switching/syscall/main.hpp"
 #include "arch/exception_handling/assert.hpp"
 #include "arch/kernel/cpu/call.hpp"
 #include "arch/kernel/cpu/control_register.hpp"
 #include "arch/kernel/cpu/if.hpp"
-#include "arch/kernel/cpu/msr.hpp"
 #include "arch/kernel/cpu/segment_register.hpp"
 #include "arch/kernel/cpu/tr.hpp"
 #include "arch/video/vga/text.hpp"
@@ -14,10 +14,6 @@ namespace teachos::arch::context_switching
 {
   namespace
   {
-    auto constexpr IA32_STAR_ADDRESS = 0xC0000081;
-    auto constexpr IA32_LSTAR_ADDRESS = 0xC0000082;
-    auto constexpr IA32_FMASK_ADDRESS = 0xC0000084;
-
     constexpr interrupt_descriptor_table::segment_selector KERNEL_CODE_SEGMENT_SELECTOR{
         1U, interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_KERNEL};
     constexpr kernel::cpu::far_pointer KERNEL_CODE_POINTER{&kernel::cpu::reload_data_segment_registers,
@@ -31,8 +27,6 @@ namespace teachos::arch::context_switching
 
     auto user_mode_main() -> void
     {
-      video::vga::text::write("Successfully entered user mode!", video::vga::text::common_attributes::green_on_black);
-
       // 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:
@@ -43,65 +37,16 @@ namespace teachos::arch::context_switching
 
       // 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
-      uint64_t syscall_number = 60U;
-      asm volatile("mov %[input], %%rax"
-                   : /* no output from call */
-                   : [input] "r"(syscall_number)
-                   : "memory");
-      asm volatile("syscall");
-
-      // Reading RAX decrements value by one in 32-bit compatability mode it also crashes vga write, therfore use
-      // SYSRETQ instead of SYSRET so we do not return into 32-bit compatability mode.
-      asm volatile("mov %%rax, %[output]" : [output] "=r"(syscall_number));
-      video::vga::text::write("Successfully made a SYSCALL and returned with SYSRETQ!",
-                              video::vga::text::common_attributes::green_on_black);
-    }
 
-    auto syscall_handler() -> void
-    {
-      uint64_t syscall_number, arg_0, arg_1, arg_2, arg_3, arg_4, arg_5 = {};
-      asm volatile("mov %%rax, %[output]" : [output] "=r"(syscall_number));
-      asm volatile("mov %%rdi, %[output]" : [output] "=r"(arg_0));
-      asm volatile("mov %%rsi, %[output]" : [output] "=r"(arg_1));
-      asm volatile("mov %%rdx, %[output]" : [output] "=r"(arg_2));
-      asm volatile("mov %%r10, %[output]" : [output] "=r"(arg_3));
-      asm volatile("mov %%r8, %[output]" : [output] "=r"(arg_4));
-      asm volatile("mov %%r9, %[output]" : [output] "=r"(arg_5));
-
-      switch (syscall_number)
+      const char syscall_message[32] = "Successfully entered user mode!";
+      auto error = syscall::syscall(syscall::WRITE, {reinterpret_cast<uint64_t>(&syscall_message)});
+
+      if (!error)
       {
-        case 1:
-          // Write VGA
-          break;
-        case 60U:
-          // Exit
-          break;
-        default:
-          break;
+        video::vga::text::write("Successfully made a SYSCALL and returned with SYSRETQ!",
+                                video::vga::text::common_attributes::green_on_black);
       }
-
-      uint64_t result = 0U;
-      asm volatile("mov %[input], %%rax"
-                   : /* no output from call */
-                   : [input] "r"(result)
-                   : "memory");
-
-      asm volatile("sysretq");
     }
-
-    auto enable_systemcall() -> void
-    {
-      uint64_t const syscall_function = reinterpret_cast<uint64_t>(syscall_handler);
-      kernel::cpu::write_msr(IA32_LSTAR_ADDRESS, syscall_function);
-      kernel::cpu::write_msr(IA32_FMASK_ADDRESS, 0U);
-
-      uint64_t const kernel_cs = KERNEL_CODE_SEGMENT_SELECTOR;
-      uint64_t const star_value = (kernel_cs << 32) | (kernel_cs << 48);
-      kernel::cpu::write_msr(IA32_STAR_ADDRESS, star_value);
-
-      kernel::cpu::set_efer_bit(kernel::cpu::efer_flags::SCE);
-    }
-
   }  // namespace
 
   auto initialize_descriptor_tables() -> descriptor_tables
@@ -129,7 +74,7 @@ namespace teachos::arch::context_switching
 
   auto switch_to_user_mode() -> void
   {
-    enable_systemcall();
+    syscall::enable_syscall();
     switch_context(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR, user_mode_main);
   }