1 files changed, 111 insertions, 0 deletions
diff --git a/arch/riscv/init/init.c b/arch/riscv/init/init.c
new file mode 100644
index 0000000..cdcfbb7
--- /dev/null
+++ b/arch/riscv/init/init.c
@@ -0,0 +1,111 @@
+#include <stddef.h>
+#include <apos/init.h>
+#include <apos/sizes.h>
+#include <pages.h>
+#include <vmap.h>
+
+struct page_ret {
+	size_t left;
+	size_t num;
+	void *top;
+};
+
+extern void main(struct mm_pagearr_info *pageinfo);
+
+void __init init_zero(void *ptr, size_t bytes)
+{
+	char *byte_ptr = ptr;
+
+	/* Not entirely sure if it would be faster to use a larget type than
+	 * char, Linux seems to have memset16/32/64 but I guess I should check
+	 * the generated assembly.
+	 */
+	while(bytes--)
+		*byte_ptr++ = 0;
+}
+
+struct page_ret __init init_pages(size_t ram_size, void *ram_top,
+		size_t page_size, size_t struct_size)
+{
+	size_t num_pages = ram_size / page_size;
+	size_t size_pages = num_pages * struct_size;
+
+	struct page_ret pageret;
+	pageret.top = ram_top - size_pages;
+	pageret.num = num_pages;
+	pageret.left = ram_size - (size_pages * page_size);
+
+	init_zero(pageret.top, size_pages);
+
+	return pageret;
+};
+
+size_t __init init_align_down(size_t num, size_t a)
+{
+	size_t rem = num % a;
+	return num - rem;
+}
+
+size_t __init init_align_up(size_t num, size_t a)
+{
+	return init_align_down(num, a) + a;
+}
+
+void __init init_enter_vm(unsigned long *root_page)
+{
+	asm volatile ("csrw 0x180, %0\n" "sfence.vma\n"
+			:
+			: "rK" (root_page)
+			: "memory");
+}
+
+void call_main()
+{
+}
+
+void __init init(void *ram_base, void *ram_top, void *initrd, void *fdt, void *boot)
+{
+	size_t ram_size = ram_top - ram_base;
+
+	struct mm_pagearr_info pagearr;
+	struct page_ret pageret;
+
+	/* create crude page status map at the top of physical RAM */
+	pageret = init_pages(ram_size, ram_top,
+			SZ_512G, sizeof(struct terapages));
+	pagearr.tera_num = pageret.num;
+	pagearr.tera_top = pageret.top;
+	
+	pageret = init_pages(pageret.left, pageret.top,
+			SZ_1G, sizeof(struct gigapages));
+	pagearr.giga_num = pageret.num;
+	pagearr.giga_top = pageret.top;
+
+	pageret = init_pages(pageret.left, pageret.top,
+			SZ_2M, sizeof(struct megapages));
+	pagearr.mega_num = pageret.num;
+	pagearr.mega_top = pageret.top;
+
+	pageret = init_pages(pageret.left, pageret.top,
+			SZ_4K, sizeof(struct kilopages));
+	pagearr.kilo_num = pageret.num;
+	pagearr.kilo_top = pageret.top;
+
+	unsigned long *root_page = (unsigned long *)
+		(init_align_down((size_t)pagearr.kilo_top, SZ_4K) - SZ_4K);
+
+	/* TODO: should init insert page data into the created arrays? */
+
+	/* map .text.* into top part of RAM */
+	root_page[511] = ((unsigned long)&main & VM_AL) | VM_V | VM_R | VM_W | VM_X;
+
+	/* temporarily map .init.* so that our current physical address matches
+	 * the virtual address */
+	root_page[0] = 0 | VM_V | VM_R | VM_W | VM_X;
+
+	/* enter virtual memory */
+	init_enter_vm(root_page);
+
+	/* enter main */
+	call_main();
+}