1 files changed, 36 insertions, 0 deletions
diff --git a/arch/riscv/lib/lshrdi3.S b/arch/riscv/lib/lshrdi3.S
new file mode 100644
index 000000000000..1af03985ccb7
--- /dev/null
+++ b/arch/riscv/lib/lshrdi3.S
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/**
+ * Adopted for the Linux kernel from IPXE project, see
+ * https://github.com/ipxe/ipxe/blob/master/src/arch/riscv32/libgcc/llshift.S
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+
+/**
+ * Logical shift right
+ *
+ * @v a1:a0             Value to shift
+ * @v a2                Shift amount
+ * @ret a1:a0           Shifted value
+ */
+
+SYM_FUNC_START(__lshrdi3)
+
+        /* Perform shift by 32 bits, if applicable */
+        li      t0, 32
+        sub     t1, t0, a2
+        bgtz    t1, 1f
+        mv      a0, a1
+        mv      a1, zero
+1:      /* Perform shift by modulo-32 bits, if applicable */
+        andi    a2, a2, 0x1f
+        beqz    a2, 2f
+        sll     t2, a1, t1
+        srl     a1, a1, a2
+        srl     a0, a0, a2
+        or      a0, a0, t2
+2:      ret
+
+SYM_FUNC_END(__lshrdi3)
+EXPORT_SYMBOL(__lshrdi3)