[PATCH] kexec: x86 kexec core
This is the i386 implementation of kexec.
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 31567f4d..0f391cb 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -953,6 +953,23 @@
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.
+
endmenu
diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index 51ecd51..4cc83b3 100644
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -24,6 +24,7 @@
obj-$(CONFIG_X86_LOCAL_APIC) += apic.o nmi.o
obj-$(CONFIG_X86_IO_APIC) += io_apic.o
obj-$(CONFIG_X86_REBOOTFIXUPS) += reboot_fixups.o
+obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
obj-$(CONFIG_X86_NUMAQ) += numaq.o
obj-$(CONFIG_X86_SUMMIT_NUMA) += summit.o
obj-$(CONFIG_KPROBES) += kprobes.o
diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c
new file mode 100644
index 0000000..fa27a6c
--- /dev/null
+++ b/arch/i386/kernel/crash.c
@@ -0,0 +1,42 @@
+/*
+ * Architecture specific (i386) 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 <linux/irq.h>
+#include <linux/delay.h>
+#include <linux/elf.h>
+#include <linux/elfcore.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.
+ */
+}
diff --git a/arch/i386/kernel/machine_kexec.c b/arch/i386/kernel/machine_kexec.c
new file mode 100644
index 0000000..67188041
--- /dev/null
+++ b/arch/i386/kernel/machine_kexec.c
@@ -0,0 +1,220 @@
+/*
+ * 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 <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>
+
+static inline unsigned long read_cr3(void)
+{
+ unsigned long cr3;
+ asm volatile("movl %%cr3,%0": "=r"(cr3));
+ return cr3;
+}
+
+#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
+
+#define L0_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
+#define L1_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
+#define L2_ATTR (_PAGE_PRESENT)
+
+#define LEVEL0_SIZE (1UL << 12UL)
+
+#ifndef CONFIG_X86_PAE
+#define LEVEL1_SIZE (1UL << 22UL)
+static u32 pgtable_level1[1024] PAGE_ALIGNED;
+
+static void identity_map_page(unsigned long address)
+{
+ unsigned long level1_index, level2_index;
+ u32 *pgtable_level2;
+
+ /* Find the current page table */
+ pgtable_level2 = __va(read_cr3());
+
+ /* Find the indexes of the physical address to identity map */
+ level1_index = (address % LEVEL1_SIZE)/LEVEL0_SIZE;
+ level2_index = address / LEVEL1_SIZE;
+
+ /* Identity map the page table entry */
+ pgtable_level1[level1_index] = address | L0_ATTR;
+ pgtable_level2[level2_index] = __pa(pgtable_level1) | L1_ATTR;
+
+ /* Flush the tlb so the new mapping takes effect.
+ * Global tlb entries are not flushed but that is not an issue.
+ */
+ load_cr3(pgtable_level2);
+}
+
+#else
+#define LEVEL1_SIZE (1UL << 21UL)
+#define LEVEL2_SIZE (1UL << 30UL)
+static u64 pgtable_level1[512] PAGE_ALIGNED;
+static u64 pgtable_level2[512] PAGE_ALIGNED;
+
+static void identity_map_page(unsigned long address)
+{
+ unsigned long level1_index, level2_index, level3_index;
+ u64 *pgtable_level3;
+
+ /* Find the current page table */
+ pgtable_level3 = __va(read_cr3());
+
+ /* Find the indexes of the physical address to identity map */
+ level1_index = (address % LEVEL1_SIZE)/LEVEL0_SIZE;
+ level2_index = (address % LEVEL2_SIZE)/LEVEL1_SIZE;
+ level3_index = address / LEVEL2_SIZE;
+
+ /* Identity map the page table entry */
+ pgtable_level1[level1_index] = address | L0_ATTR;
+ pgtable_level2[level2_index] = __pa(pgtable_level1) | L1_ATTR;
+ set_64bit(&pgtable_level3[level3_index], __pa(pgtable_level2) | L2_ATTR);
+
+ /* Flush the tlb so the new mapping takes effect.
+ * Global tlb entries are not flushed but that is not an issue.
+ */
+ load_cr3(pgtable_level3);
+}
+#endif
+
+
+static void set_idt(void *newidt, __u16 limit)
+{
+ unsigned char curidt[6];
+
+ /* ia32 supports unaliged loads & stores */
+ (*(__u16 *)(curidt)) = limit;
+ (*(__u32 *)(curidt +2)) = (unsigned long)(newidt);
+
+ __asm__ __volatile__ (
+ "lidt %0\n"
+ : "=m" (curidt)
+ );
+};
+
+
+static void set_gdt(void *newgdt, __u16 limit)
+{
+ unsigned char curgdt[6];
+
+ /* ia32 supports unaligned loads & stores */
+ (*(__u16 *)(curgdt)) = limit;
+ (*(__u32 *)(curgdt +2)) = (unsigned long)(newgdt);
+
+ __asm__ __volatile__ (
+ "lgdt %0\n"
+ : "=m" (curgdt)
+ );
+};
+
+static void load_segments(void)
+{
+#define __STR(X) #X
+#define STR(X) __STR(X)
+
+ __asm__ __volatile__ (
+ "\tljmp $"STR(__KERNEL_CS)",$1f\n"
+ "\t1:\n"
+ "\tmovl $"STR(__KERNEL_DS)",%eax\n"
+ "\tmovl %eax,%ds\n"
+ "\tmovl %eax,%es\n"
+ "\tmovl %eax,%fs\n"
+ "\tmovl %eax,%gs\n"
+ "\tmovl %eax,%ss\n"
+ );
+#undef STR
+#undef __STR
+}
+
+typedef asmlinkage NORET_TYPE void (*relocate_new_kernel_t)(
+ unsigned long indirection_page, unsigned long reboot_code_buffer,
+ unsigned long start_address, unsigned int has_pae) ATTRIB_NORET;
+
+const extern unsigned char relocate_new_kernel[];
+extern void relocate_new_kernel_end(void);
+const extern unsigned int relocate_new_kernel_size;
+
+/*
+ * A architecture hook called to validate the
+ * proposed image and prepare the control pages
+ * as needed. The pages for KEXEC_CONTROL_CODE_SIZE
+ * have been allocated, but the segments have yet
+ * been copied into the kernel.
+ *
+ * Do what every setup is needed on image and the
+ * reboot code buffer to allow us to avoid allocations
+ * later.
+ *
+ * Currently nothing.
+ */
+int machine_kexec_prepare(struct kimage *image)
+{
+ return 0;
+}
+
+/*
+ * Undo anything leftover by machine_kexec_prepare
+ * when an image is freed.
+ */
+void machine_kexec_cleanup(struct kimage *image)
+{
+}
+
+/*
+ * 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 reboot_code_buffer;
+ relocate_new_kernel_t rnk;
+
+ /* Interrupts aren't acceptable while we reboot */
+ local_irq_disable();
+
+ /* Compute some offsets */
+ reboot_code_buffer = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
+ page_list = image->head;
+
+ /* Set up an identity mapping for the reboot_code_buffer */
+ identity_map_page(reboot_code_buffer);
+
+ /* copy it out */
+ memcpy((void *)reboot_code_buffer, relocate_new_kernel, relocate_new_kernel_size);
+
+ /* 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 you set the segment to a different selector.
+ *
+ * The more common model is 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) reboot_code_buffer;
+ (*rnk)(page_list, reboot_code_buffer, image->start, cpu_has_pae);
+}
diff --git a/arch/i386/kernel/relocate_kernel.S b/arch/i386/kernel/relocate_kernel.S
new file mode 100644
index 0000000..d312616
--- /dev/null
+++ b/arch/i386/kernel/relocate_kernel.S
@@ -0,0 +1,120 @@
+/*
+ * relocate_kernel.S - put the kernel image in place to boot
+ * 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/linkage.h>
+
+ /*
+ * Must be relocatable PIC code callable as a C function, that once
+ * it starts can not use the previous processes stack.
+ */
+ .globl relocate_new_kernel
+relocate_new_kernel:
+ /* read the arguments and say goodbye to the stack */
+ movl 4(%esp), %ebx /* page_list */
+ movl 8(%esp), %ebp /* reboot_code_buffer */
+ movl 12(%esp), %edx /* start address */
+ movl 16(%esp), %ecx /* cpu_has_pae */
+
+ /* zero out flags, and disable interrupts */
+ pushl $0
+ popfl
+
+ /* set a new stack at the bottom of our page... */
+ lea 4096(%ebp), %esp
+
+ /* store the parameters back on the stack */
+ pushl %edx /* store the start address */
+
+ /* Set cr0 to a known state:
+ * 31 0 == Paging disabled
+ * 18 0 == Alignment check disabled
+ * 16 0 == Write protect disabled
+ * 3 0 == No task switch
+ * 2 0 == Don't do FP software emulation.
+ * 0 1 == Proctected mode enabled
+ */
+ movl %cr0, %eax
+ andl $~((1<<31)|(1<<18)|(1<<16)|(1<<3)|(1<<2)), %eax
+ orl $(1<<0), %eax
+ movl %eax, %cr0
+
+ /* clear cr4 if applicable */
+ testl %ecx, %ecx
+ jz 1f
+ /* Set cr4 to a known state:
+ * Setting everything to zero seems safe.
+ */
+ movl %cr4, %eax
+ andl $0, %eax
+ movl %eax, %cr4
+
+ jmp 1f
+1:
+
+ /* Flush the TLB (needed?) */
+ xorl %eax, %eax
+ movl %eax, %cr3
+
+ /* Do the copies */
+ movl %ebx, %ecx
+ jmp 1f
+
+0: /* top, read another word from the indirection page */
+ movl (%ebx), %ecx
+ addl $4, %ebx
+1:
+ testl $0x1, %ecx /* is it a destination page */
+ jz 2f
+ movl %ecx, %edi
+ andl $0xfffff000, %edi
+ jmp 0b
+2:
+ testl $0x2, %ecx /* is it an indirection page */
+ jz 2f
+ movl %ecx, %ebx
+ andl $0xfffff000, %ebx
+ jmp 0b
+2:
+ testl $0x4, %ecx /* is it the done indicator */
+ jz 2f
+ jmp 3f
+2:
+ testl $0x8, %ecx /* is it the source indicator */
+ jz 0b /* Ignore it otherwise */
+ movl %ecx, %esi /* For every source page do a copy */
+ andl $0xfffff000, %esi
+
+ movl $1024, %ecx
+ rep ; movsl
+ jmp 0b
+
+3:
+
+ /* To be certain of avoiding problems with self-modifying code
+ * I need to execute a serializing instruction here.
+ * So I flush the TLB, it's handy, and not processor dependent.
+ */
+ xorl %eax, %eax
+ movl %eax, %cr3
+
+ /* set all of the registers to known values */
+ /* leave %esp alone */
+
+ xorl %eax, %eax
+ xorl %ebx, %ebx
+ xorl %ecx, %ecx
+ xorl %edx, %edx
+ xorl %esi, %esi
+ xorl %edi, %edi
+ xorl %ebp, %ebp
+ ret
+relocate_new_kernel_end:
+
+ .globl relocate_new_kernel_size
+relocate_new_kernel_size:
+ .long relocate_new_kernel_end - relocate_new_kernel
diff --git a/arch/i386/kernel/syscall_table.S b/arch/i386/kernel/syscall_table.S
index d408afa..442a6e9 100644
--- a/arch/i386/kernel/syscall_table.S
+++ b/arch/i386/kernel/syscall_table.S
@@ -283,7 +283,7 @@
.long sys_mq_timedreceive /* 280 */
.long sys_mq_notify
.long sys_mq_getsetattr
- .long sys_ni_syscall /* reserved for kexec */
+ .long sys_kexec_load
.long sys_waitid
.long sys_ni_syscall /* 285 */ /* available */
.long sys_add_key