--- /dev/null
+/*
+ * machine_kexec.c - handle transition of Linux booting another kernel
+ * Copyright (C) 2002-2004 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/delay.h>
+#include <linux/string.h>
+#include <linux/reboot.h>
+#include <asm/pda.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
+#include <asm/io.h>
+#include <asm/apic.h>
+#include <asm/cpufeature.h>
+#include <asm/hw_irq.h>
+
+#define LEVEL0_SIZE (1UL << 12UL)
+#define LEVEL1_SIZE (1UL << 21UL)
+#define LEVEL2_SIZE (1UL << 30UL)
+#define LEVEL3_SIZE (1UL << 39UL)
+#define LEVEL4_SIZE (1UL << 48UL)
+
+#define L0_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
+#define L1_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_PSE)
+#define L2_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
+#define L3_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
+
+static void init_level2_page(
+ uint64_t *level2p, unsigned long addr)
+{
+ unsigned long end_addr;
+ addr &= PAGE_MASK;
+ end_addr = addr + LEVEL2_SIZE;
+ while(addr < end_addr) {
+ *(level2p++) = addr | L1_ATTR;
+ addr += LEVEL1_SIZE;
+ }
+}
+
+static int init_level3_page(struct kimage *image,
+ uint64_t *level3p, unsigned long addr, unsigned long last_addr)
+{
+ unsigned long end_addr;
+ int result;
+ result = 0;
+ addr &= PAGE_MASK;
+ end_addr = addr + LEVEL3_SIZE;
+ while((addr < last_addr) && (addr < end_addr)) {
+ struct page *page;
+ uint64_t *level2p;
+ page = kimage_alloc_control_pages(image, 0);
+ if (!page) {
+ result = -ENOMEM;
+ goto out;
+ }
+ level2p = (uint64_t *)page_address(page);
+ init_level2_page(level2p, addr);
+ *(level3p++) = __pa(level2p) | L2_ATTR;
+ addr += LEVEL2_SIZE;
+ }
+ /* clear the unused entries */
+ while(addr < end_addr) {
+ *(level3p++) = 0;
+ addr += LEVEL2_SIZE;
+ }
+out:
+ return result;
+}
+
+
+static int init_level4_page(struct kimage *image,
+ uint64_t *level4p, unsigned long addr, unsigned long last_addr)
+{
+ unsigned long end_addr;
+ int result;
+ result = 0;
+ addr &= PAGE_MASK;
+ end_addr = addr + LEVEL4_SIZE;
+ while((addr < last_addr) && (addr < end_addr)) {
+ struct page *page;
+ uint64_t *level3p;
+ page = kimage_alloc_control_pages(image, 0);
+ if (!page) {
+ result = -ENOMEM;
+ goto out;
+ }
+ level3p = (uint64_t *)page_address(page);
+ result = init_level3_page(image, level3p, addr, last_addr);
+ if (result) {
+ goto out;
+ }
+ *(level4p++) = __pa(level3p) | L3_ATTR;
+ addr += LEVEL3_SIZE;
+ }
+ /* clear the unused entries */
+ while(addr < end_addr) {
+ *(level4p++) = 0;
+ addr += LEVEL3_SIZE;
+ }
+ out:
+ return result;
+}
+
+
+static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
+{
+ uint64_t *level4p;
+ level4p = (uint64_t *)__va(start_pgtable);
+ return init_level4_page(image, level4p, 0, end_pfn << PAGE_SHIFT);
+}
+
+static void set_idt(void *newidt, __u16 limit)
+{
+ unsigned char curidt[10];
+
+ /* x86-64 supports unaliged loads & stores */
+ (*(__u16 *)(curidt)) = limit;
+ (*(__u64 *)(curidt +2)) = (unsigned long)(newidt);
+
+ __asm__ __volatile__ (
+ "lidt %0\n"
+ : "=m" (curidt)
+ );
+};
+
+
+static void set_gdt(void *newgdt, __u16 limit)
+{
+ unsigned char curgdt[10];
+
+ /* x86-64 supports unaligned loads & stores */
+ (*(__u16 *)(curgdt)) = limit;
+ (*(__u64 *)(curgdt +2)) = (unsigned long)(newgdt);
+
+ __asm__ __volatile__ (
+ "lgdt %0\n"
+ : "=m" (curgdt)
+ );
+};
+
+static void load_segments(void)
+{
+ __asm__ __volatile__ (
+ "\tmovl $"STR(__KERNEL_DS)",%eax\n"
+ "\tmovl %eax,%ds\n"
+ "\tmovl %eax,%es\n"
+ "\tmovl %eax,%ss\n"
+ "\tmovl %eax,%fs\n"
+ "\tmovl %eax,%gs\n"
+ );
+#undef STR
+#undef __STR
+}
+
+typedef void (*relocate_new_kernel_t)(
+ unsigned long indirection_page, unsigned long control_code_buffer,
+ unsigned long start_address, unsigned long pgtable);
+
+const extern unsigned char relocate_new_kernel[];
+extern void relocate_new_kernel_end(void);
+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 + 4096UL;
+
+ /* 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.
+ */
+void machine_kexec(struct kimage *image)
+{
+ unsigned long indirection_page;
+ 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 */
+ indirection_page = image->head & PAGE_MASK;
+ start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
+ control_code_buffer = start_pgtable + 4096UL;
+
+ /* 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((void *)read_pda(level4_pgt), __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)(indirection_page, control_code_buffer, image->start, start_pgtable);
+}
git://git.onelab.eu / linux-2.6.git / blobdiff