This was an oversight specific to these archs; others have always aligned the new stack pointer correctly.
@@ -6,6 +6,8 @@
.hidden __clone
.type __clone,@function
__clone:
+ l.xori r11, r0, -4
+ l.and r4, r4, r11
l.addi r4, r4, -8
l.sw 0(r4), r3
l.sw 4(r4), r6
@@ -8,6 +8,7 @@
.type __clone, %function
# Save func and arg to stack
+ andi a1, a1, -16
addi a1, a1, -16
sw a0, 0(a1)
sw a3, 4(a1)
sd a0, 0(a1)
sd a3, 8(a1)