working sleep syscall

yes it turns out it was 100% completely broken before

src/arch/x86/kmain.cpp

@@ -193,7 +193,9 @@ void stress_tester() {
 void user_task() {
     while (true) {
         putchar('h');
-        __builtin_ia32_pause();
+        putchar('i');
+        putchar('\n');
+        sleep(100000);
     }
 }
 

src/arch/x86/syscalls.asm

@@ -15,7 +15,7 @@ _syscall_entrypoint:
     ; Do very complicated stuff here
     call syscall_impl
 
-    mov r11, 0x10016 ; TASK_POINTER->entry_ksp_val
+    mov r11, 0x10016 ; TASK_POINTER->ret_sp_val
     mov rsp, [r11]
     mov rcx, r15
     o64 sysret

src/arch/x86/syscalls.cpp

@@ -12,10 +12,14 @@
 #include "misc.hpp"
 #include "tty.hpp"
 
+// Don't forget the correct order
+// Shockingly, it doesn't immediately break and even something simple as putchar works
+// even with completely broken 16-bit segments somehow
+// But what happens with something more complex is completely bonkers
 struct STAR {
-    unsigned ret_cs_ss : 16;
-    unsigned call_cs_ss : 16;
     unsigned unused : 32;
+    unsigned call_cs_ss : 16;
+    unsigned ret_cs_ss : 16;
 } __attribute__((packed));
 
 static_assert(sizeof(STAR) == 8);
@@ -46,10 +50,17 @@ uint64_t syscall_putchar(char c) {
     return 0;
 }
 
+uint64_t syscall_sleep(uint64_t micros) {
+    sleep_self(micros);
+    return 0;
+}
+
 extern "C" uint64_t syscall_impl(uint64_t id_rdi, uint64_t a1_rsi, uint64_t a2_rdx, uint64_t a3_rcx) {
     switch (id_rdi) {
         case SYSCALL_PUTCHAR_ID:
             return syscall_putchar(a1_rsi);
+        case SYSCALL_SLEEP_ID:
+            return syscall_sleep(a1_rsi);
         default:
             return -1;
     }

src/arch/x86/task.cpp

@@ -26,7 +26,11 @@ void sanity_check_frame(struct task_frame *cur_frame) {
     assert2((void *) cur_frame->ip != NULL, "Sanity check");
     assert2((void *) cur_frame->sp != NULL, "Sanity check");
     assert2(cur_frame->guard == IDT_GUARD, "IDT Guard wrong!");
-    assert2((cur_frame->ss == GDTSEL(gdt_data) || cur_frame->ss == GDTSEL(gdt_data_user)) | 0x3, "SS wrong!");
+    assert(cur_frame->ss != 0);
+    assert(cur_frame->cs != 0);
+    assert(cur_frame->sp != 0);
+    assert2((cur_frame->ss == GDTSEL(gdt_data) || (cur_frame->ss == GDTSEL(gdt_data_user)) | 0x3), "SS wrong!");
+    assert2((cur_frame->cs == GDTSEL(gdt_code) || (cur_frame->ss == GDTSEL(gdt_code_user)) | 0x3), "CS wrong!");
 }
 
 std::atomic<uint64_t> max_pid = 0;
@@ -158,8 +162,8 @@ struct Task *new_utask(void (*fn)(), const char *name) {
     assert((newt->entry_ksp_val & 0xFULL) == 0);
 
     taskptr_real->taskptr = newt;
-    taskptr_real->entry_ksp_val = &newt->entry_ksp_val;
-    taskptr_real->ret_sp = 0xFEFE;
+    taskptr_real->entry_ksp_val = newt->entry_ksp_val;
+    taskptr_real->ret_sp = 0x0;
 
     void *ustack = newt->vma->mmap_mem(NULL, TASK_SS, 0, PAGE_RW | PAGE_USER);
 

src/arch/x86/task.hpp

@@ -44,7 +44,7 @@ struct Task {
 
 struct task_pointer {
     Task *taskptr;
-    uint64_t *entry_ksp_val;
+    uint64_t entry_ksp_val;
     uint64_t ret_sp;
 } __attribute__((packed));
 

src/kernel/VMA.cpp

@@ -22,8 +22,7 @@ void VMA::mark_taken(void *addr, size_t length) {
 
 void VMA::map_kern() {
     LockGuard l(space_lock);
-    for (uintptr_t i = (uint64_t) (0xFFFF800000000000ULL >> 39) & 0x01FF; i < 512; i++) {
-        assert(i >= 256);
+    for (uintptr_t i = 256; i < 512; i++) {
         space->get_cr3()[i] = KERN_AddressSpace->get_cr3()[i];
     }
 }

src/kernel/syscalls_defs.h

@@ -13,6 +13,7 @@ extern "C" {
 #endif
 
 #define SYSCALL_PUTCHAR_ID 1
+#define SYSCALL_SLEEP_ID 2
 
 #ifdef __cplusplus
 }

src/kernel/syscalls_interface.c

@@ -13,4 +13,14 @@ uint64_t putchar(char c) {
         : "Di"(id), "Si"(c)
         : "memory");
     return res;
+}
+
+uint64_t sleep(uint64_t micros) {
+    uint64_t res;
+    uint64_t id = SYSCALL_SLEEP_ID;
+    asm("syscall"
+        : "=r"(res)
+        : "Di"(id), "Si"(micros)
+        : "memory");
+    return res;
 }

src/kernel/syscalls_interface.h

@@ -13,6 +13,7 @@ extern "C" {
 #endif
 
 uint64_t putchar(char c);
+uint64_t sleep(uint64_t micros);
 
 #ifdef __cplusplus
 }