refine syscalls

kernel/include/sys/Syscall.h

@@ -0,0 +1,18 @@
+#pragma once
+#include "interrupts/Context.h"
+#include <stddef.h>
+
+#define SYS_exit 0
+#define SYS_yield 1
+#define SYS_sleep 2
+#define SYS_write 3
+
+namespace Syscall
+{
+    void entry(Context* context);
+}
+
+void sys_exit(Context* context);
+void sys_yield(Context* context);
+void sys_sleep(Context* context, uint64_t ms);
+void sys_write(Context* context, const char* addr, size_t size);

kernel/include/thread/Scheduler.h

@@ -17,7 +17,6 @@ namespace Scheduler
 
     void task_yield(Context* context);
     void task_tick(Context* context);
-    void task_sleep(Context* context);
 
     void reap_task(Task* task);
     void reap_tasks();

kernel/src/interrupts/Entry.cpp

@@ -9,6 +9,7 @@
 #include "misc/hang.h"
 #include "panic/Panic.h"
 #include "std/stdio.h"
+#include "sys/Syscall.h"
 #include "thread/Scheduler.h"
 #include "trace/StackTracer.h"
 
@@ -54,10 +55,7 @@ extern "C" void common_handler(Context* context)
         }
     }
     if (context->number == 8) { int_panic(context, "Double fault, halting"); }
-    if (context->number == 48) { Scheduler::task_yield(context); }
-    if (context->number == 49) { Scheduler::task_exit(context); }
-    if (context->number == 50) { Serial::print((const char*)context->rdi); }
-    if (context->number == 51) { Scheduler::task_sleep(context); }
+    if (context->number == 66) { Syscall::entry(context); }
     if (context->number == 256) { kwarnln("Unused interrupt"); }
     return;
 }

kernel/src/interrupts/Install.cpp

@@ -45,10 +45,7 @@ extern "C"
     void isr45();
     void isr46();
     void isr47();
-    void isr48();
-    void isr49();
-    void isr50();
-    void isr51();
+    void isr66();
 }
 
 #define INSTALL_TRAP(x) IDT::add_handler(x, (void*)&isr##x, IDT_TA_TrapGate)
@@ -108,11 +105,8 @@ void Interrupts::install()
     INSTALL_ISR(45);
     INSTALL_ISR(46);
     INSTALL_ISR(47);
-    kdbgln("Installing handler stubs for user-accessible syscalls 48, 49, 50, 51 (30h, 31h, 32h, 33h)");
-    INSTALL_USER_ISR(48);
-    INSTALL_USER_ISR(49);
-    INSTALL_USER_ISR(50);
-    INSTALL_USER_ISR(51);
     kdbgln("Installing unused handler stubs for the rest of the IDT");
-    for (int i = 52; i < 256; i++) { INSTALL_UNUSED(i); }
+    for (int i = 48; i < 256; i++) { INSTALL_UNUSED(i); }
+    kdbgln("Installing syscall handler stub");
+    INSTALL_USER_ISR(66);
 }

kernel/src/interrupts/InterruptEntry.asm

@@ -133,7 +133,4 @@ IRQ 44, 12
 IRQ 45, 13
 IRQ 46, 14
 IRQ 47, 15
-SOFT 48
-SOFT 49
-SOFT 50
-SOFT 51
+SOFT 66

kernel/src/main.asm

@@ -8,17 +8,22 @@ _main:
 global _userspace
 _userspace:
     mov rdi, 4000 ; 4000 ms / 4 seconds
-    int 33h ; Sleep
+    mov rax, 2 ; sys_sleep
+    int 42h ; syscall
     mov rcx, 10
 .loop:
     dec rcx
     mov rdi, .message
-    int 32h ; Print string
+    mov rsi, 22
+    mov rax, 3 ; sys_write
+    int 42h ; syscall
     mov rdi, 200 ; 200 ms / 0.2 seconds
-    int 33h ; Sleep
+    mov rax, 2
+    int 42h ; syscall
     cmp rcx, 0
     jne .loop
     cli ; WE ARE IN RING 3!! So this should GPF and the kernel should exit us as "misbehaved"
-    int 31h ; Exit current task
+    mov rax, 0
+    int 42h ; Exit current task
 .message:
     db "hello from userspace!", 0xA, 0

kernel/src/sys/Syscall.cpp

@@ -0,0 +1,24 @@
+#include "sys/Syscall.h"
+#include "io/Serial.h"
+#include "thread/Scheduler.h"
+
+void Syscall::entry(Context* context)
+{
+    asm volatile("cli");
+    switch (context->rax)
+    {
+    case SYS_exit: // sys_exit
+        sys_exit(context);
+        break;
+    case SYS_yield: // sys_yield
+        sys_yield(context);
+        break;
+    case SYS_sleep: // sys_sleep
+        sys_sleep(context, context->rdi);
+        break;
+    case SYS_write: // sys_write
+        sys_write(context, (const char*)context->rdi, context->rsi);
+        break;
+    default: context->rax = -1; break;
+    }
+}

kernel/src/sys/sched.cpp

@@ -0,0 +1,21 @@
+#include "thread/Scheduler.h"
+
+void sys_exit(Context* context)
+{
+    Scheduler::task_exit(context);
+}
+
+void sys_yield(Context* context)
+{
+    context->rax = 0;
+    Scheduler::task_yield(context);
+}
+
+void sys_sleep(Context* context, uint64_t ms)
+{
+    context->rax = 0;
+    Task* task = Scheduler::current_task();
+    task->task_sleep = ms;
+    task->state = task->Sleeping;
+    Scheduler::task_yield(context);
+}

kernel/src/sys/stdio.cpp

@@ -0,0 +1,8 @@
+#include "interrupts/Context.h"
+#include "io/Serial.h"
+
+void sys_write(Context* context, const char* addr, size_t size)
+{
+    context->rax = size;
+    Serial::write(addr, size);
+}

kernel/src/thread/Scheduler.cpp

@@ -253,29 +253,19 @@ void Scheduler::task_yield(Context* context)
     return;
 }
 
-void Scheduler::task_sleep(Context* context)
-{
-    ASSERT(Interrupts::is_in_handler());
-    Interrupts::disable();
-    Task* task = current_task();
-    task->task_sleep = context->rdi;
-    task->state = task->Sleeping;
-    task_yield(context);
-}
-
 void Scheduler::yield()
 {
-    asm volatile("int $48");
+    asm volatile("int $0x42" : : "a"(1));
 }
 
 void Scheduler::exit()
 {
-    asm volatile("int $49");
+    asm volatile("int $0x42" : : "a"(0));
 }
 
 void Scheduler::sleep(unsigned long ms)
 {
-    asm volatile("int $51" : : "D"(ms));
+    asm volatile("int $0x42" : : "D"(ms), "a"(2));
 }
 
 Task* Scheduler::current_task()