core: Add memory and scheduler related system calls

core/src/sys/mem.zig

@@ -0,0 +1,26 @@
+const interrupts = @import("../arch/interrupts.zig").arch;
+const sys = @import("syscall.zig");
+const pmm = @import("../pmm.zig");
+
+pub fn allocFrame(_: *interrupts.InterruptStackFrame, _: *sys.Arguments, retval: *isize) anyerror!void {
+    const allocator = pmm.lockGlobalAllocator();
+    defer pmm.unlockGlobalAllocator();
+
+    const frame = try pmm.allocFrame(allocator);
+
+    retval.* = @bitCast(frame.address);
+}
+
+pub fn freeFrame(_: *interrupts.InterruptStackFrame, args: *sys.Arguments, _: *isize) anyerror!void {
+    const allocator = pmm.lockGlobalAllocator();
+    defer pmm.unlockGlobalAllocator();
+
+    try pmm.freeFrame(allocator, args.arg0);
+}
+
+pub fn lockFrame(_: *interrupts.InterruptStackFrame, args: *sys.Arguments, _: *isize) anyerror!void {
+    const allocator = pmm.lockGlobalAllocator();
+    defer pmm.unlockGlobalAllocator();
+
+    try pmm.lockFrame(allocator, args.arg0);
+}

core/src/sys/sched.zig

@@ -0,0 +1,7 @@
+const interrupts = @import("../arch/interrupts.zig").arch;
+const sys = @import("syscall.zig");
+const thread = @import("../thread.zig");
+
+pub fn yield(regs: *interrupts.InterruptStackFrame, _: *sys.Arguments, _: *isize) anyerror!void {
+    thread.scheduleNewTask(regs);
+}

core/src/sys/syscall.zig

@@ -1,6 +1,8 @@
 const std = @import("std");
 const interrupts = @import("../arch/interrupts.zig").arch;
 const print = @import("print.zig").print;
+const mem = @import("mem.zig");
+const sched = @import("sched.zig");
 
 pub const Arguments = struct {
     arg0: usize,
@@ -13,7 +15,7 @@ pub const Arguments = struct {
 
 const SystemCall = *const fn (frame: *interrupts.InterruptStackFrame, args: *Arguments, retval: *isize) anyerror!void;
 
-const syscalls = [_]SystemCall{print};
+const syscalls = [_]SystemCall{ print, mem.allocFrame, mem.lockFrame, mem.freeFrame, sched.yield };
 
 pub fn invokeSyscall(number: usize, frame: *interrupts.InterruptStackFrame, args: *Arguments, retval: *isize) void {
     if (number >= syscalls.len) {