#ifdef CONFIG_VMAP_STACK
handle_kernel_stack_overflow:
+ /*
+ * Takes the psuedo-spinlock for the shadow stack, in case multiple
+ * harts are concurrently overflowing their kernel stacks. We could
+ * store any value here, but since we're overflowing the kernel stack
+ * already we only have SP to use as a scratch register. So we just
+ * swap in the address of the spinlock, as that's definately non-zero.
+ *
+ * Pairs with a store_release in handle_bad_stack().
+ */
+1: la sp, spin_shadow_stack
+ REG_AMOSWAP_AQ sp, sp, (sp)
+ bnez sp, 1b
+
la sp, shadow_stack
addi sp, sp, SHADOW_OVERFLOW_STACK_SIZE