X-Git-Url: http://git.joshuawise.com/netwatch.git/blobdiff_plain/2cd64cbf2e235c588ffee9f3de974903d5e7087e..9e2a82e4e9495f33b8e6423c335a9a157f056254:/aseg-paging/pagetable.c?ds=inline

diff --git a/aseg-paging/pagetable.c b/aseg-paging/pagetable.c
new file mode 100644
index 0000000..83a1e54
--- /dev/null
+++ b/aseg-paging/pagetable.c
@@ -0,0 +1,59 @@
+#include "vm_flags.h"
+#include <io.h>
+
+#define MAP_FLAGS	(PTE_PRESENT | PTE_READ_WRITE)
+
+void * pt_setup(int smbase) {
+	int i;
+	outb(0x80, 0x51);
+
+	/* The page directory and page table live at SMBASE and SMBASE + 0x1000,
+	 * respectively; clear them. */
+	int * pagedirectory = (int *) smbase;
+	int * pagetable = (int *) (smbase + 0x1000);
+
+	/* Clear out the page directory except for one entry pointing to the
+	 * page table, and clear the page table entirely. */
+	outb(0x80, 0x52);
+	pagedirectory[0] = (smbase + 0x1000) | PTE_PRESENT | PTE_READ_WRITE;
+	outb(0x80, 0x53);
+	for (i = 1; i < 1024; i++)
+	{
+		pagedirectory[i] = 0;
+	}
+
+	outb(0x80, 0x54);
+	for (i = 0; i < 1024; i++)
+	{
+		pagetable[i] = 0;
+	}
+	outb(0x80, 0x55);
+
+	/* The page at 0x10000 - 0x10FFF points to the SMI entry point,
+	 * SMBASE + 0x8000. */
+	pagetable[16] = (0x8000 + smbase) | MAP_FLAGS;
+
+	/* 0x11000 to 0x1EFFF map to the rest of ASEG up to SMBASE + 0xF000;
+	 * the page containing the saved state is not mappped to our code
+	 * region.  */
+
+	for (i = 0; i < 8; i++)
+	{
+		pagetable[17 + i] = (i * 0x1000 + smbase) | MAP_FLAGS;
+	}
+
+	for (i = 0; i < 6; i++)
+	{
+		pagetable[25 + i] = (smbase + 0x9000 + i * 0x1000) | MAP_FLAGS;
+	}
+
+	outb(0x80, 0x56);
+	/* Map 0xA8000 to itself. */
+	pagetable[0xA8] = 0xA8000 | MAP_FLAGS;
+	pagetable[0xA9] = 0xA9000 | MAP_FLAGS;
+
+	/* No TSEG yet. */
+
+	outb(0x80, 0x57);
+	return pagedirectory;
+}