syscall/fork: FORK_SHAREMEM for primitive "threads"

3 files changed, 23 insertions, 0 deletions

diff --git a/src/user/lib/thread.S b/src/user/lib/thread.S
new file mode 100644
index 0000000..3cd3500
--- /dev/null
+++ b/src/user/lib/thread.S
@@ -0,0 +1,8 @@
+.section .text
+.global chstack
+.type chstack, @function
+// _Noreturn void chstack(void *arg, void (*fn)(void*), void *esp);
+chstack:
+	mov %rdx, %rsp
+	call *%rsi
+	jmp 0 // "exit"
diff --git a/src/user/lib/thread.c b/src/user/lib/thread.c
new file mode 100644
index 0000000..25d98a9
--- /dev/null
+++ b/src/user/lib/thread.c
@@ -0,0 +1,11 @@
+#include <camellia/flags.h>
+#include <camellia/syscalls.h>
+#include <stdlib.h>
+#include <user/lib/thread.h>
+
+void thread_create(int flags, void (*fn)(void*), void *arg) {
+	if (!_syscall_fork(flags | FORK_SHAREMEM, NULL)) {
+		void *stack = malloc(4096);
+		chstack(arg, fn, stack + 4096);
+	}
+}
diff --git a/src/user/lib/thread.h b/src/user/lib/thread.h
new file mode 100644
index 0000000..0d7376a
--- /dev/null
+++ b/src/user/lib/thread.h
@@ -0,0 +1,4 @@
+#pragma once
+
+void thread_create(int flags, void (*fn)(void*), void *arg);
+_Noreturn void chstack(void *arg, void (*fn)(void*), void *esp);