[PATCH] kexec: x86_64 kexec implementation (5234f5eb) · Commits · EulixOS / Software / Kernel

arch/x86_64/Kconfig

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		@@ -380,6 +380,23 @@ config PHYSICAL_START

		Don't change this unless you know what you are doing.

		config KEXEC
		bool "kexec system call (EXPERIMENTAL)"
		depends on EXPERIMENTAL
		help
		kexec is a system call that implements the ability to shutdown your
		current kernel, and to start another kernel. It is like a reboot
		but it is indepedent of the system firmware. And like a reboot
		you can start any kernel with it, not just Linux.

		The name comes from the similiarity to the exec system call.

		It is an ongoing process to be certain the hardware in a machine
		is properly shutdown, so do not be surprised if this code does not
		initially work for you. It may help to enable device hotplugging
		support. As of this writing the exact hardware interface is
		strongly in flux, so no good recommendation can be made.

		config SECCOMP
		bool "Enable seccomp to safely compute untrusted bytecode"
		depends on PROC_FS

arch/x86_64/ia32/ia32entry.S

+1 −1

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		@@ -589,7 +589,7 @@ ia32_sys_call_table:
		.quad compat_sys_mq_timedreceive /* 280 */
		.quad compat_sys_mq_notify
		.quad compat_sys_mq_getsetattr
		.quad quiet_ni_syscall /* reserved for kexec */
		.quad compat_sys_kexec_load /* reserved for kexec */
		.quad compat_sys_waitid
		.quad quiet_ni_syscall /* sys_altroot */
		.quad sys_add_key

arch/x86_64/kernel/Makefile

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		@@ -20,6 +20,7 @@ obj-$(CONFIG_SMP) += smp.o smpboot.o trampoline.o
		obj-$(CONFIG_X86_LOCAL_APIC) += apic.o nmi.o
		obj-$(CONFIG_X86_IO_APIC) += io_apic.o mpparse.o \
		genapic.o genapic_cluster.o genapic_flat.o
		obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
		obj-$(CONFIG_PM) += suspend.o
		obj-$(CONFIG_SOFTWARE_SUSPEND) += suspend_asm.o
		obj-$(CONFIG_CPU_FREQ) += cpufreq/

arch/x86_64/kernel/crash.c

0 → 100644

+38 −0

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		/*
		* Architecture specific (x86_64) functions for kexec based crash dumps.
		*
		* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
		*
		* Copyright (C) IBM Corporation, 2004. All rights reserved.
		*
		*/

		#include <linux/init.h>
		#include <linux/types.h>
		#include <linux/kernel.h>
		#include <linux/smp.h>
		#include <linux/irq.h>
		#include <linux/reboot.h>
		#include <linux/kexec.h>

		#include <asm/processor.h>
		#include <asm/hardirq.h>
		#include <asm/nmi.h>
		#include <asm/hw_irq.h>

		#define MAX_NOTE_BYTES 1024
		typedef u32 note_buf_t[MAX_NOTE_BYTES/4];

		note_buf_t crash_notes[NR_CPUS];

		void machine_crash_shutdown(void)
		{
		/* This function is only called after the system
		* has paniced or is otherwise in a critical state.
		* The minimum amount of code to allow a kexec'd kernel
		* to run successfully needs to happen here.
		*
		* In practice this means shooting down the other cpus in
		* an SMP system.
		*/
		}

arch/x86_64/kernel/machine_kexec.c

0 → 100644

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Original line number	Diff line number	Diff line
		/*
		* 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/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(
		u64 *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,
		u64 *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;
		u64 *level2p;
		page = kimage_alloc_control_pages(image, 0);
		if (!page) {
		result = -ENOMEM;
		goto out;
		}
		level2p = (u64 *)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,
		u64 *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;
		u64 *level3p;
		page = kimage_alloc_control_pages(image, 0);
		if (!page) {
		result = -ENOMEM;
		goto out;
		}
		level3p = (u64 *)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)
		{
		u64 *level4p;
		level4p = (u64 *)__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 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 + 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.
		*/
		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 + 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(__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);
		}