/*
 * vlibc — x86_64 thread-pointer installer (todo 44).
 *
 * __set_thread_area(tp): install tp as the calling thread's FS base via
 * arch_prctl(ARCH_SET_FS). After this, %fs-relative TLS offsets resolve
 * against tp exactly as the linker baked them (see src/start/tcb.h for the
 * placement contract), and __builtin_thread_pointer() / %fs:0 returns tp.
 *
 * Must be executed IN the thread whose FS base is being set: arch_prctl
 * operates on the current task, so pthread_create (#45) calls this from the
 * new thread's entry point, never from the parent.
 *
 * Return convention: the raw syscall result is left in %eax — 0 on success,
 * a negative errno on failure. No errno write happens here; the caller maps
 * the result however its context needs (this mirrors musl's
 * src/thread/x86_64/__set_thread_area.s, which also returns raw).
 *
 * arch_prctl codes (kernel UAPI asm/prctl.h): ARCH_SET_FS 0x1002,
 * SYS_arch_prctl 158. Kept as literals because there is no internal header
 * for them yet; src/start/tls.c defines the same values locally.
 */

.text
.global __set_thread_area
.hidden __set_thread_area
.type __set_thread_area,@function
__set_thread_area:
	mov %rdi,%rsi
	movl $0x1002,%edi
	movl $158,%eax
	syscall
	ret
.size __set_thread_area,.-__set_thread_area
.section .note.GNU-stack,"",@progbits