exit syscall

src/arch/x86/boot.cpp

@@ -35,7 +35,7 @@ real_start() {
 
 // Set up the address space for the kernel and prepare other structures to work without the bootloader,
 // then call real_start with this address space and the new stack.
-extern "C" void _start(void) {
+extern "C" __attribute__((unused)) void _start(void) {
     _sse_setup();
     barrier();
     Arch::GDT::gdt_setup();

src/arch/x86/syscalls.cpp

@@ -16,6 +16,7 @@
 #include "FDT.hpp"
 #include "File.hpp"
 #include "memman.hpp"
+#include "task.hpp"
 #include "timer.hpp"
 
 // Don't forget the correct order
@@ -51,6 +52,10 @@ void setup_syscalls() {
     wrmsr(0xC0000080, rdmsr(0xC0000080) | 0b1);
 }
 
+void syscall_exit() {
+    Scheduler::remove_self();
+}
+
 uint64_t syscall_putchar(char c) {
     GlobalTtyManager.all_tty_putchar(c);
     return 0;
@@ -132,6 +137,7 @@ uint64_t syscall_print_tasks() {
 
     return 0;
 }
+
 uint64_t syscall_print_mem() {
     String buf;
     buf += "=====\n";
@@ -159,6 +165,9 @@ uint64_t syscall_print_mem() {
 extern "C" uint64_t syscall_impl(uint64_t id_rdi, uint64_t a1_rsi, uint64_t a2_rdx, uint64_t a3_rcx) {
     assert2(are_interrupts_enabled(), "why wouldn't they be?");
     switch (id_rdi) {
+        case SYSCALL_EXIT_ID:
+            syscall_exit();
+            return 0;
         case SYSCALL_PUTCHAR_ID:
             return syscall_putchar(a1_rsi);
         case SYSCALL_SLEEP_ID:

src/arch/x86/task.cpp

@@ -67,7 +67,7 @@ cgistd::priority_queue<List<Task *>::Node *, cgistd::vector<List<Task *>::Node *
 static std::atomic<bool> initialized = false;
 
 //
-static void remove_self() {
+void Scheduler::remove_self() {
     assert(RunningTask != nullptr);
     {
         LockGuard l(TasksToFree_lock);
@@ -86,7 +86,7 @@ static void remove_self() {
 
 static void trampoline(void *rdi, void (*rsi_entrypoint)()) {
     rsi_entrypoint();
-    remove_self();
+    Scheduler::remove_self();
 }
 
 Task::Task(Task::TaskMode mode, void (*entrypoint)(), const char *name) {

src/arch/x86/task.hpp

@@ -89,6 +89,8 @@ namespace Scheduler {
 
     void                sleep_self(uint64_t diff);
 
+    void                remove_self();
+
     void                self_block();
     void                self_block(Spinlock &to_unlock);
     void                self_block(Mutex &to_unlock);

src/iso/CMakeLists.txt

@@ -5,11 +5,13 @@ add_custom_target(iso
         COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CMAKE_CURRENT_SOURCE_DIR}/limine.cfg ${CMAKE_CURRENT_BINARY_DIR}/isodir/
         COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:kernel.elf> ${CMAKE_CURRENT_BINARY_DIR}/isodir/os2.elf
         COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:hello> ${CMAKE_CURRENT_BINARY_DIR}/isodir/hello
+        COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:hello2> ${CMAKE_CURRENT_BINARY_DIR}/isodir/hello2
         COMMAND xorriso -as mkisofs -b limine-bios-cd.bin -no-emul-boot -boot-load-size 4 -boot-info-table --efi-boot limine-uefi-cd.bin -efi-boot-part --efi-boot-image --protective-msdos-label ${CMAKE_CURRENT_BINARY_DIR}/isodir -o ${CMAKE_CURRENT_BINARY_DIR}/os2.iso
         COMMAND ${tools}/limine/prefix/bin/limine bios-install ${CMAKE_CURRENT_BINARY_DIR}/os2.iso
         VERBATIM
         DEPENDS kernel.elf
         DEPENDS hello
+        DEPENDS hello2
         DEPENDS iso_limine
 )
 

src/iso/limine.cfg

@@ -10,7 +10,8 @@ TIMEOUT=1
     KERNEL_PATH=boot:///os2.elf
 
     MODULE_PATH=boot:///hello
- 
+    MODULE_PATH=boot:///hello2
+
 # Same thing, but without KASLR.
 :os2 (KASLR off)
     PROTOCOL=limine
@@ -20,3 +21,4 @@ TIMEOUT=1
  
     KERNEL_PATH=boot:///os2.elf
     MODULE_PATH=boot:///hello
+    MODULE_PATH=boot:///hello2

src/test/CMakeLists.txt

@@ -7,3 +7,12 @@ target_include_directories(hello PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
 target_link_options(hello PRIVATE "SHELL:-T${CMAKE_CURRENT_SOURCE_DIR}/linker.ld")
 set_target_properties(hello PROPERTIES LINK_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/linker.ld")
 
+add_executable(hello2 hello2.c)
+
+target_link_libraries(hello2 syscalls_interface)
+
+target_include_directories(hello2 PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+
+target_link_options(hello2 PRIVATE "SHELL:-T${CMAKE_CURRENT_SOURCE_DIR}/linker.ld")
+set_target_properties(hello2 PROPERTIES LINK_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/linker.ld")
+

src/test/hello.c

@@ -1,7 +1,7 @@
 #include "syscalls_interface.h"
 
 
-void _start() {
+__attribute__((unused)) void _start() {
     //    putchar('h');
     //    putchar('i');
     //    putchar('\n');

src/test/hello2.c

@@ -0,0 +1,9 @@
+#include "syscalls_interface.h"
+
+
+__attribute__((unused)) void _start() {
+    putchar('h');
+    putchar('i');
+    putchar('\n');
+    exit();
+}

src/uapi/syscalls_defs.h

@@ -14,6 +14,8 @@ extern "C" {
 
 #include "FileOpts.h"
 
+#define SYSCALL_EXIT_ID     0
+
 #define SYSCALL_PUTCHAR_ID  1
 #define SYSCALL_SLEEP_ID    2
 #define SYSCALL_READCHAR_ID 3

src/uapi/syscalls_interface.c

@@ -16,6 +16,10 @@ uint64_t do_syscall(uint64_t id_rdi, uint64_t a1_rsi, uint64_t a2_rdx, uint64_t
     return res;
 }
 
+void exit() {
+    do_syscall(SYSCALL_EXIT_ID, 0, 0, 0);
+}
+
 uint64_t readchar() {
     return do_syscall(SYSCALL_READCHAR_ID, 0, 0, 0);
 }

src/uapi/syscalls_interface.h

@@ -16,6 +16,8 @@ extern "C" {
 
 #include "FileOpts.h"
 
+void     exit();
+
 uint64_t putchar(char c);
 uint64_t readchar();
 uint64_t sleep(uint64_t micros);