lib: Add mlibc

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/mlibc/sysdeps/linux/riscv64/thread_entry.S b/lib/mlibc/sysdeps/linux/riscv64/thread_entry.S
new file mode 100644
index 0000000..fe170fa
--- /dev/null
+++ b/lib/mlibc/sysdeps/linux/riscv64/thread_entry.S
@@ -0,0 +1,29 @@
+.section .text
+.global __mlibc_spawn_thread
+.type __mlibc_spawn_thread, "function"
+__mlibc_spawn_thread:
+	// __mlibc_spawn_thread(flags, stack, pid_out, child_tid, tls)
+	//                         a0,     a1,     a2,        a3,  a4
+	//           syscall(NR_clone, flags, stack, ptid, tls, ctid)
+	//                         a7,    a0,    a1,   a2,  a3,   a4
+
+	// Swap a3 <-> a4
+	mv a5, a4
+	mv a4, a3
+	mv a3, a5
+
+	li a7, 220 // NR_clone
+	ecall
+	bnez a0, .parent
+
+	ld a0, 0(sp)
+	ld a1, 8(sp)
+	addi sp, sp, 8
+	andi sp, sp, -16
+	call __mlibc_enter_thread
+	unimp
+
+.parent:
+	ret
+.section .note.GNU-stack,"",%progbits
+