From b28c44de8c3131b45588f61569b1711c987ba1c3 Mon Sep 17 00:00:00 2001
From: Stefan O'Rear <sorear@fastmail.com>
Date: Thu, 3 Sep 2020 05:56:46 -0400
Subject: riscv32: add thread support

Identical to riscv64 except for stack offsets in clone.
---
 src/thread/riscv32/clone.s | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 src/thread/riscv32/clone.s

(limited to 'src/thread/riscv32/clone.s')

diff --git a/src/thread/riscv32/clone.s b/src/thread/riscv32/clone.s
new file mode 100644
index 00000000..3102239d
--- /dev/null
+++ b/src/thread/riscv32/clone.s
@@ -0,0 +1,34 @@
+# __clone(func, stack, flags, arg, ptid, tls, ctid)
+#           a0,    a1,    a2,  a3,   a4,  a5,   a6
+
+# syscall(SYS_clone, flags, stack, ptid, tls, ctid)
+#                a7     a0,    a1,   a2,  a3,   a4
+
+.global __clone
+.type  __clone, %function
+__clone:
+	# Save func and arg to stack
+	addi a1, a1, -16
+	sw a0, 0(a1)
+	sw a3, 4(a1)
+
+	# Call SYS_clone
+	mv a0, a2
+	mv a2, a4
+	mv a3, a5
+	mv a4, a6
+	li a7, 220 # SYS_clone
+	ecall
+
+	beqz a0, 1f
+	# Parent
+	ret
+
+	# Child
+1:      lw a1, 0(sp)
+	lw a0, 4(sp)
+	jalr a1
+
+	# Exit
+	li a7, 93 # SYS_exit
+	ecall
-- 
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