add initial smp bringup

1 files changed, 23 insertions, 0 deletions

diff --git a/arch/riscv64/kernel/core_bringup.S b/arch/riscv64/kernel/core_bringup.S
new file mode 100644
index 0000000..aff9b0b
--- /dev/null
+++ b/arch/riscv64/kernel/core_bringup.S
@@ -0,0 +1,23 @@
+#include "asm.h"
+
+/* pic forces core_bringup to be placed in .got that we can access both from
+ * direct mapped and virtual memory. Which is kind of strange, as core_bringup()
+ * is fixed in place by the VM, so it could be possible to just load the address
+ * directly into a register, but apparently that's annoying to do */
+.option pic
+.global riscv_bringup
+riscv_bringup:
+	/* immediately switch to virtual memory through argument in a1 */
+	csrw satp, a1
+	sfence.vma
+
+	/* fetch the stack allocated to us at our hart index in smp_init_stacks */
+	la t0, smp_init_stacks
+	slli t1, a0, RW_SHIFT
+	add t0, t0, t1
+	lr sp, 0(t0)
+	mv tp, sp
+
+	/* jump to C to handle rest of bringup */
+	la t0, core_bringup
+	jr t0