user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/sysdeps/linux/aarch64/cp_syscall.S

@@ -0,0 +1,31 @@
+.section .text
+.global __mlibc_do_asm_cp_syscall
+.global __mlibc_syscall_begin
+.global __mlibc_syscall_end
+.type __mlibc_do_asm_cp_syscall, "function"
+__mlibc_do_asm_cp_syscall:
+	mov x8, x0
+	mov x0, x1
+	mov x1, x2
+	mov x2, x3
+	mov x3, x4
+	mov x4, x5
+	mov x5, x6
+
+	mrs x7, tpidr_el0
+	ldr w7, [x7, #-80] // Tcb::cancelBits. See asserts in tcb.hpp.
+__mlibc_syscall_begin:
+	// tcbCancelEnableBit && tcbCancelTriggerBit
+	mov x9, #((1 << 0) | (1 << 2))
+	and x7, x7, x9
+	cmp x7, x9
+	b.eq cancel
+	svc 0
+__mlibc_syscall_end:
+	ret
+
+cancel:
+	bl __mlibc_do_cancel
+	brk #0
+.section .note.GNU-stack,"",%progbits
+