From 0f30d227497418c6d3bef7d52244407e30454504 Mon Sep 17 00:00:00 2001
From: Kacper <kacper@mail.openlinux.dev>
Date: Mon, 22 Dec 2025 23:27:56 +0100
Subject: Added c11 threads, fixed some locks and add *_unlocked functions

---
 lib/libc/thread/thrd_create.c | 113 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 lib/libc/thread/thrd_create.c

(limited to 'lib/libc/thread/thrd_create.c')

diff --git a/lib/libc/thread/thrd_create.c b/lib/libc/thread/thrd_create.c
new file mode 100644
index 00000000..e5b7405c
--- /dev/null
+++ b/lib/libc/thread/thrd_create.c
@@ -0,0 +1,113 @@
+#include <__thread.h>
+#include <asm/prctl.h>
+#include <errno.h>
+#include <libc.h>
+#include <linux/sched.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <syscall.h>
+#include <threads.h>
+#include <unistd.h>
+
+struct thread_start {
+	struct __thread_self *self;
+	thrd_start_t func;
+	void *arg;
+};
+
+static long __thread_start(void *arg)
+{
+	struct thread_start *ts = (struct thread_start *)arg;
+	syscall(set_tid_address, &ts->self->tid);
+	int r = ts->func(ts->arg);
+	thrd_exit(r);
+	__builtin_unreachable();
+}
+
+int thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
+{
+	struct thread_start *ts;
+
+	if ((void *)thr == NULL || func == NULL)
+		return thrd_error;
+
+	/* Ensure callers never observe an uninitialized thread handle on failure. */
+	*thr = NULL;
+
+	void *map;
+	size_t size = THREAD_GUARD_SIZE + THREAD_STACK_SIZE + __libc.tls.size + sizeof(struct __thread_self);
+	map = mmap(NULL, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (__predict_false(map == MAP_FAILED))
+		return thrd_nomem;
+
+	if (__predict_false(mprotect((unsigned char *)map + THREAD_GUARD_SIZE, size - THREAD_GUARD_SIZE,
+				     PROT_READ | PROT_WRITE) < 0)) {
+		munmap(map, size);
+		return thrd_error;
+	}
+
+	unsigned char *base = (unsigned char *)map;
+
+	/* Place TCB at the very end of the mapping. */
+	struct __thread_self *tcb = (struct __thread_self *)(base + size - sizeof(struct __thread_self));
+
+	/* Place TLS immediately below the TCB, aligned down. */
+	unsigned char *tls_end = (unsigned char *)tcb;
+
+	size_t tls_align = __libc.tls.align;
+	if (tls_align == 0 || (tls_align & (tls_align - 1)) != 0)
+		tls_align = sizeof(void *);
+	if (tls_align < sizeof(void *))
+		tls_align = sizeof(void *);
+
+	unsigned char *tls_start =
+		(unsigned char *)(((uintptr_t)(tls_end - __libc.tls.size)) & ~((uintptr_t)tls_align - 1));
+
+	__libc_tls_copy(tls_start);
+
+	/* Build initial stack just below TLS. */
+	unsigned char *stack_top = tls_start;
+	ts = (struct thread_start *)(stack_top - sizeof(struct thread_start));
+	stack_top -= sizeof(struct thread_start);
+
+	ts->self = tcb;
+	ts->func = func;
+	ts->arg = arg;
+
+	stack_top = (unsigned char *)((uintptr_t)stack_top & ~15UL);
+
+	tcb->self = tcb;
+	tcb->map_base = map;
+	tcb->map_size = size;
+	tcb->errno_v = 0;
+	tcb->dtv = 0;
+	tcb->state = THREAD_STATE_JOINABLE;
+
+	unsigned long flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
+			      CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID;
+
+#if defined(__x86_64__)
+	long tid = __clone(__thread_start, ts, flags, stack_top, &tcb->tid, tcb, &tcb->tid);
+#endif
+
+	if (__predict_false(tid < 0)) {
+		munmap(map, size);
+		return thrd_error;
+	}
+
+#if !defined(__x86_64__)
+	if (tid == 0) {
+		__thread_start(ts);
+		__builtin_unreachable();
+	}
+#endif
+
+	tcb->tid = tid;
+
+	*thr = tcb;
+
+	return thrd_success;
+}
-- 
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