x86: Add support for starting 64-bit kernel
Add code to jump to a 64-bit Linux kernel. We need to set up a flat page
table structure, a new GDT and then go through a few hoops in the right
order.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
index 8c1eacc..2e25253 100644
--- a/arch/x86/cpu/cpu.c
+++ b/arch/x86/cpu/cpu.c
@@ -18,7 +18,10 @@
#include <common.h>
#include <command.h>
+#include <errno.h>
+#include <malloc.h>
#include <asm/control_regs.h>
+#include <asm/cpu.h>
#include <asm/processor.h>
#include <asm/processor-flags.h>
#include <asm/interrupt.h>
@@ -339,3 +342,45 @@
return 0;
}
+
+#define PAGETABLE_SIZE (6 * 4096)
+
+/**
+ * build_pagetable() - build a flat 4GiB page table structure for 64-bti mode
+ *
+ * @pgtable: Pointer to a 24iKB block of memory
+ */
+static void build_pagetable(uint32_t *pgtable)
+{
+ uint i;
+
+ memset(pgtable, '\0', PAGETABLE_SIZE);
+
+ /* Level 4 needs a single entry */
+ pgtable[0] = (uint32_t)&pgtable[1024] + 7;
+
+ /* Level 3 has one 64-bit entry for each GiB of memory */
+ for (i = 0; i < 4; i++) {
+ pgtable[1024 + i * 2] = (uint32_t)&pgtable[2048] +
+ 0x1000 * i + 7;
+ }
+
+ /* Level 2 has 2048 64-bit entries, each repesenting 2MiB */
+ for (i = 0; i < 2048; i++)
+ pgtable[2048 + i * 2] = 0x183 + (i << 21UL);
+}
+
+int cpu_jump_to_64bit(ulong setup_base, ulong target)
+{
+ uint32_t *pgtable;
+
+ pgtable = memalign(4096, PAGETABLE_SIZE);
+ if (!pgtable)
+ return -ENOMEM;
+
+ build_pagetable(pgtable);
+ cpu_call64((ulong)pgtable, setup_base, target);
+ free(pgtable);
+
+ return -EFAULT;
+}