allow booting with Qemu's -kernel flag directly

+ Took some fairly significant changes, for one the kernel is no longer
  relocated at the start of a boot, instead it sits wherever the user
  decides the kernel should sit. Similarly, the initial kernel stack and
  page table are stored within the binary, slightly bloating the size
  but making it much safer to boot since there's really no chance of us
  overwriting the fdt or initrd in memory.

1 files changed, 16 insertions, 4 deletions

diff --git a/arch/riscv64/kernel/vmem.c b/arch/riscv64/kernel/vmem.c
index cc6f3ac..835f53d 100644
--- a/arch/riscv64/kernel/vmem.c
+++ b/arch/riscv64/kernel/vmem.c
@@ -399,13 +399,26 @@ static void __populate_dmap(struct vmem *branch)
 /** How many base pages we use for the rpc stack. Used fairly often so calculate
  * it at the start and then reference it. */
 static size_t rpc_pages;
+long riscv_init_stack[4096 / sizeof(long)];
+__attribute__((aligned(4096))) struct vmem bootvmem;
+
+struct vmem *direct_mapping()
+{
+	rpc_pages = order_size(MM_O1) / BASE_PAGE_SIZE;
+
+	__populate_dmap(&bootvmem);
+	populate_kvmem(&bootvmem);
+	__use_vmem(&bootvmem, DEFAULT_Sv_MODE);
+
+	return &bootvmem;
+}
+
 
 struct vmem *init_vmem(void *fdt)
 {
 	UNUSED(fdt);
 	struct vmem *b = create_vmem();
 	__populate_dmap(b);
-	rpc_pages = order_size(MM_O1) / BASE_PAGE_SIZE;
 	/* update which memory branch to use */
 	use_vmem(b);
 	return b;
@@ -415,14 +428,13 @@ struct vmem *create_vmem()
 {
 	struct vmem *b = (struct vmem *)alloc_page(MM_KPAGE);
 	memset(b, 0, MM_KPAGE_SIZE);
-
 	populate_kvmem(b);
 	return b;
 }
 
 stat_t use_vmem(struct vmem *b)
 {
-	__use_vmem(b, DEFAULT_Sv_MODE);
+	__use_vmem(__pa(b), DEFAULT_Sv_MODE);
 	return OK;
 }
 
@@ -457,7 +469,7 @@ vm_t setup_kernel_io(struct vmem *b, vm_t paddr)
 	 * modifying, or during the startup stage where we don't have a tcb yet.
 	 * I don't think checking the rpc context is necessary? */
 	if (!cur_tcb() || cur_tcb()->proc.vmem == b)
-		flush_tlb((uintptr_t)pte_addr(b->leaf[IO_PAGE]));
+		flush_tlb_full();
 
 	return -TOP_PAGE_SIZE + paddr - addr;
 }