1 files changed, 231 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/machine_kexec.c b/arch/x86_64/kernel/machine_kexec.c
new file mode 100644
index 00000000000..89fab51e20f
--- /dev/null
+++ b/arch/x86_64/kernel/machine_kexec.c
@@ -0,0 +1,231 @@
+/*
+ * machine_kexec.c - handle transition of Linux booting another kernel
+ * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2.  See the file COPYING for more details.
+ */
+
+#include <linux/mm.h>
+#include <linux/kexec.h>
+#include <linux/string.h>
+#include <linux/reboot.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
+#include <asm/io.h>
+
+static void init_level2_page(pmd_t *level2p, unsigned long addr)
+{
+	unsigned long end_addr;
+
+	addr &= PAGE_MASK;
+	end_addr = addr + PUD_SIZE;
+	while (addr < end_addr) {
+		set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
+		addr += PMD_SIZE;
+	}
+}
+
+static int init_level3_page(struct kimage *image, pud_t *level3p,
+				unsigned long addr, unsigned long last_addr)
+{
+	unsigned long end_addr;
+	int result;
+
+	result = 0;
+	addr &= PAGE_MASK;
+	end_addr = addr + PGDIR_SIZE;
+	while ((addr < last_addr) && (addr < end_addr)) {
+		struct page *page;
+		pmd_t *level2p;
+
+		page = kimage_alloc_control_pages(image, 0);
+		if (!page) {
+			result = -ENOMEM;
+			goto out;
+		}
+		level2p = (pmd_t *)page_address(page);
+		init_level2_page(level2p, addr);
+		set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
+		addr += PUD_SIZE;
+	}
+	/* clear the unused entries */
+	while (addr < end_addr) {
+		pud_clear(level3p++);
+		addr += PUD_SIZE;
+	}
+out:
+	return result;
+}
+
+
+static int init_level4_page(struct kimage *image, pgd_t *level4p,
+				unsigned long addr, unsigned long last_addr)
+{
+	unsigned long end_addr;
+	int result;
+
+	result = 0;
+	addr &= PAGE_MASK;
+	end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
+	while ((addr < last_addr) && (addr < end_addr)) {
+		struct page *page;
+		pud_t *level3p;
+
+		page = kimage_alloc_control_pages(image, 0);
+		if (!page) {
+			result = -ENOMEM;
+			goto out;
+		}
+		level3p = (pud_t *)page_address(page);
+		result = init_level3_page(image, level3p, addr, last_addr);
+		if (result) {
+			goto out;
+		}
+		set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
+		addr += PGDIR_SIZE;
+	}
+	/* clear the unused entries */
+	while (addr < end_addr) {
+		pgd_clear(level4p++);
+		addr += PGDIR_SIZE;
+	}
+out:
+	return result;
+}
+
+
+static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
+{
+	pgd_t *level4p;
+	level4p = (pgd_t *)__va(start_pgtable);
+ 	return init_level4_page(image, level4p, 0, end_pfn << PAGE_SHIFT);
+}
+
+static void set_idt(void *newidt, u16 limit)
+{
+	struct desc_ptr curidt;
+
+	/* x86-64 supports unaliged loads & stores */
+	curidt.size    = limit;
+	curidt.address = (unsigned long)newidt;
+
+	__asm__ __volatile__ (
+		"lidtq %0\n"
+		: : "m" (curidt)
+		);
+};
+
+
+static void set_gdt(void *newgdt, u16 limit)
+{
+	struct desc_ptr curgdt;
+
+	/* x86-64 supports unaligned loads & stores */
+	curgdt.size    = limit;
+	curgdt.address = (unsigned long)newgdt;
+
+	__asm__ __volatile__ (
+		"lgdtq %0\n"
+		: : "m" (curgdt)
+		);
+};
+
+static void load_segments(void)
+{
+	__asm__ __volatile__ (
+		"\tmovl %0,%%ds\n"
+		"\tmovl %0,%%es\n"
+		"\tmovl %0,%%ss\n"
+		"\tmovl %0,%%fs\n"
+		"\tmovl %0,%%gs\n"
+		: : "a" (__KERNEL_DS)
+		);
+}
+
+typedef NORET_TYPE void (*relocate_new_kernel_t)(unsigned long indirection_page,
+					unsigned long control_code_buffer,
+					unsigned long start_address,
+					unsigned long pgtable) ATTRIB_NORET;
+
+const extern unsigned char relocate_new_kernel[];
+const extern unsigned long relocate_new_kernel_size;
+
+int machine_kexec_prepare(struct kimage *image)
+{
+	unsigned long start_pgtable, control_code_buffer;
+	int result;
+
+	/* Calculate the offsets */
+	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
+	control_code_buffer = start_pgtable + PAGE_SIZE;
+
+	/* Setup the identity mapped 64bit page table */
+	result = init_pgtable(image, start_pgtable);
+	if (result)
+		return result;
+
+	/* Place the code in the reboot code buffer */
+	memcpy(__va(control_code_buffer), relocate_new_kernel,
+						relocate_new_kernel_size);
+
+	return 0;
+}
+
+void machine_kexec_cleanup(struct kimage *image)
+{
+	return;
+}
+
+/*
+ * Do not allocate memory (or fail in any way) in machine_kexec().
+ * We are past the point of no return, committed to rebooting now.
+ */
+NORET_TYPE void machine_kexec(struct kimage *image)
+{
+	unsigned long page_list;
+	unsigned long control_code_buffer;
+	unsigned long start_pgtable;
+	relocate_new_kernel_t rnk;
+
+	/* Interrupts aren't acceptable while we reboot */
+	local_irq_disable();
+
+	/* Calculate the offsets */
+	page_list = image->head;
+	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
+	control_code_buffer = start_pgtable + PAGE_SIZE;
+
+	/* Set the low half of the page table to my identity mapped
+	 * page table for kexec.  Leave the high half pointing at the
+	 * kernel pages.   Don't bother to flush the global pages
+	 * as that will happen when I fully switch to my identity mapped
+	 * page table anyway.
+	 */
+	memcpy(__va(read_cr3()), __va(start_pgtable), PAGE_SIZE/2);
+	__flush_tlb();
+
+
+	/* The segment registers are funny things, they are
+	 * automatically loaded from a table, in memory wherever you
+	 * set them to a specific selector, but this table is never
+	 * accessed again unless you set the segment to a different selector.
+	 *
+	 * The more common model are caches where the behide
+	 * the scenes work is done, but is also dropped at arbitrary
+	 * times.
+	 *
+	 * I take advantage of this here by force loading the
+	 * segments, before I zap the gdt with an invalid value.
+	 */
+	load_segments();
+	/* The gdt & idt are now invalid.
+	 * If you want to load them you must set up your own idt & gdt.
+	 */
+	set_gdt(phys_to_virt(0),0);
+	set_idt(phys_to_virt(0),0);
+	/* now call it */
+	rnk = (relocate_new_kernel_t) control_code_buffer;
+	(*rnk)(page_list, control_code_buffer, image->start, start_pgtable);
+}