From: Eric W. Biederman This is the i386 implementation of kexec. Signed-off-by: Andrew Morton --- 25-akpm/arch/i386/Kconfig | 17 ++ 25-akpm/arch/i386/kernel/Makefile | 1 25-akpm/arch/i386/kernel/entry.S | 2 25-akpm/arch/i386/kernel/machine_kexec.c | 208 +++++++++++++++++++++++++++++ 25-akpm/arch/i386/kernel/relocate_kernel.S | 118 ++++++++++++++++ 25-akpm/include/asm-i386/kexec.h | 25 +++ 6 files changed, 370 insertions(+), 1 deletion(-) diff -puN arch/i386/Kconfig~kexec-kexeci386 arch/i386/Kconfig --- 25/arch/i386/Kconfig~kexec-kexeci386 2004-09-02 21:04:59.354299080 -0700 +++ 25-akpm/arch/i386/Kconfig 2004-09-02 21:04:59.361298016 -0700 @@ -866,6 +866,23 @@ config REGPARM source "drivers/perfctr/Kconfig" +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 -puN arch/i386/kernel/entry.S~kexec-kexeci386 arch/i386/kernel/entry.S --- 25/arch/i386/kernel/entry.S~kexec-kexeci386 2004-09-02 21:04:59.355298928 -0700 +++ 25-akpm/arch/i386/kernel/entry.S 2004-09-02 21:04:59.362297864 -0700 @@ -936,7 +936,7 @@ ENTRY(sys_call_table) .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_perfctr_info .long sys_vperfctr_open diff -puN /dev/null arch/i386/kernel/machine_kexec.c --- /dev/null 2003-09-15 06:40:47.000000000 -0700 +++ 25-akpm/arch/i386/kernel/machine_kexec.c 2004-09-02 21:04:59.363297712 -0700 @@ -0,0 +1,208 @@ +/* + * machine_kexec.c - handle transition of Linux booting another kernel + * Copyright (C) 2002-2004 Eric Biederman + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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 void (*relocate_new_kernel_t)( + unsigned long indirection_page, unsigned long reboot_code_buffer, + unsigned long start_address, unsigned int has_pae); + +const extern unsigned char relocate_new_kernel[]; +extern void relocate_new_kernel_end(void); +const extern unsigned int relocate_new_kernel_size; + +/* + * 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; +} + +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. + */ +void machine_kexec(struct kimage *image) +{ + unsigned long indirection_page; + 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; + indirection_page = image->head & PAGE_MASK; + + /* 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)(indirection_page, reboot_code_buffer, image->start, cpu_has_pae); +} diff -puN arch/i386/kernel/Makefile~kexec-kexeci386 arch/i386/kernel/Makefile --- 25/arch/i386/kernel/Makefile~kexec-kexeci386 2004-09-02 21:04:59.357298624 -0700 +++ 25-akpm/arch/i386/kernel/Makefile 2004-09-02 21:04:59.364297560 -0700 @@ -24,6 +24,7 @@ obj-$(CONFIG_X86_TRAMPOLINE) += trampoli obj-$(CONFIG_X86_MPPARSE) += mpparse.o obj-$(CONFIG_X86_LOCAL_APIC) += apic.o nmi.o obj-$(CONFIG_X86_IO_APIC) += io_apic.o +obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o obj-$(CONFIG_X86_NUMAQ) += numaq.o obj-$(CONFIG_X86_SUMMIT_NUMA) += summit.o obj-$(CONFIG_KPROBES) += kprobes.o diff -puN /dev/null arch/i386/kernel/relocate_kernel.S --- /dev/null 2003-09-15 06:40:47.000000000 -0700 +++ 25-akpm/arch/i386/kernel/relocate_kernel.S 2004-09-02 21:04:59.364297560 -0700 @@ -0,0 +1,118 @@ +/* + * relocate_kernel.S - put the kernel image in place to boot + * Copyright (C) 2002-2004 Eric Biederman + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ + +#include + + /* + * 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 /* indirection_page */ + 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 */ + cld +0: /* top, read another word for the indirection page */ + movl %ebx, %ecx + movl (%ebx), %ecx + addl $4, %ebx + testl $0x1, %ecx /* is it a destination page */ + jz 1f + movl %ecx, %edi + andl $0xfffff000, %edi + jmp 0b +1: + testl $0x2, %ecx /* is it an indirection page */ + jz 1f + movl %ecx, %ebx + andl $0xfffff000, %ebx + jmp 0b +1: + testl $0x4, %ecx /* is it the done indicator */ + jz 1f + jmp 2f +1: + 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 + +2: + + /* 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 -puN /dev/null include/asm-i386/kexec.h --- /dev/null 2003-09-15 06:40:47.000000000 -0700 +++ 25-akpm/include/asm-i386/kexec.h 2004-09-02 21:04:59.365297408 -0700 @@ -0,0 +1,25 @@ +#ifndef _I386_KEXEC_H +#define _I386_KEXEC_H + +#include + +/* + * KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return. + * I.e. Maximum page that is mapped directly into kernel memory, + * and kmap is not required. + * + * Someone correct me if FIXADDR_START - PAGEOFFSET is not the correct + * calculation for the amount of memory directly mappable into the + * kernel memory space. + */ + +/* Maximum physical address we can use pages from */ +#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL) +/* Maximum address we can reach in physical address mode */ +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL) +/* Maximum address we can use for the control code buffer */ +#define KEXEC_CONTROL_MEMORY_LIMIT TASK_SIZE + +#define KEXEC_CONTROL_CODE_SIZE 4096 + +#endif /* _I386_KEXEC_H */ _