Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 13 Nov 2002 08:22:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 13 Nov 2002 08:22:59 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:25677 "EHLO frodo.biederman.org") by vger.kernel.org with ESMTP id ; Wed, 13 Nov 2002 08:22:35 -0500 To: Andy Pfiffer Cc: Linus Torvalds , Alan Cox , Werner Almesberger , Suparna Bhattacharya , Jeff Garzik , "Matt D. Robinson" , Rusty Russell , Linux Kernel Mailing List , Mike Galbraith , "Martin J. Bligh" Subject: Kexec for v2.5.47-bk2 References: <1037055149.13304.47.camel@andyp> <1037148514.13280.97.camel@andyp> From: ebiederm@xmission.com (Eric W. Biederman) Date: 13 Nov 2002 06:26:29 -0700 In-Reply-To: <1037148514.13280.97.camel@andyp> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.1 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 32636 Lines: 1153 O.k. and now a version that applies cleanly to v2.5.47-bk2 aka ChangeSet@1.845 I killed all of the locks and used xchg. That is what I really wanted anyway. Linus care to comment on anything you see wrong? Eric MAINTAINERS | 7 arch/i386/Kconfig | 17 arch/i386/kernel/Makefile | 1 arch/i386/kernel/entry.S | 1 arch/i386/kernel/machine_kexec.c | 142 ++++++++ arch/i386/kernel/relocate_kernel.S | 99 +++++ include/asm-i386/kexec.h | 25 + include/asm-i386/unistd.h | 1 include/linux/kexec.h | 45 ++ include/linux/reboot.h | 2 kernel/Makefile | 1 kernel/kexec.c | 640 +++++++++++++++++++++++++++++++++++++ kernel/sys.c | 23 + 13 files changed, 1004 insertions diff -uNr linux-2.5.47-bk2/MAINTAINERS linux-2.5.47-bk2.x86kexec/MAINTAINERS --- linux-2.5.47-bk2/MAINTAINERS Mon Nov 11 00:22:33 2002 +++ linux-2.5.47-bk2.x86kexec/MAINTAINERS Wed Nov 13 06:08:52 2002 @@ -968,6 +968,13 @@ W: http://www.cse.unsw.edu.au/~neilb/patches/linux-devel/ S: Maintained +KEXEC +P: Eric Biederman +M: ebiederm@xmission.com +M: ebiederman@lnxi.com +L: linux-kernel@vger.kernel.org +S: Maintained + LANMEDIA WAN CARD DRIVER P: Andrew Stanley-Jones M: asj@lanmedia.com diff -uNr linux-2.5.47-bk2/arch/i386/Kconfig linux-2.5.47-bk2.x86kexec/arch/i386/Kconfig --- linux-2.5.47-bk2/arch/i386/Kconfig Wed Nov 13 06:08:11 2002 +++ linux-2.5.47-bk2.x86kexec/arch/i386/Kconfig Wed Nov 13 06:08:52 2002 @@ -784,6 +784,23 @@ depends on (SMP || PREEMPT) && X86_CMPXCHG default y +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 on an going 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 -uNr linux-2.5.47-bk2/arch/i386/kernel/Makefile linux-2.5.47-bk2.x86kexec/arch/i386/kernel/Makefile --- linux-2.5.47-bk2/arch/i386/kernel/Makefile Wed Nov 13 06:08:11 2002 +++ linux-2.5.47-bk2.x86kexec/arch/i386/kernel/Makefile Wed Nov 13 06:09:36 2002 @@ -24,6 +24,7 @@ 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-$(CONFIG_SOFTWARE_SUSPEND) += suspend.o suspend_asm.o obj-$(CONFIG_X86_NUMAQ) += numaq.o obj-$(CONFIG_PROFILING) += profile.o diff -uNr linux-2.5.47-bk2/arch/i386/kernel/entry.S linux-2.5.47-bk2.x86kexec/arch/i386/kernel/entry.S --- linux-2.5.47-bk2/arch/i386/kernel/entry.S Wed Nov 13 06:08:11 2002 +++ linux-2.5.47-bk2.x86kexec/arch/i386/kernel/entry.S Wed Nov 13 06:08:52 2002 @@ -743,6 +743,7 @@ .long sys_epoll_ctl /* 255 */ .long sys_epoll_wait .long sys_remap_file_pages + .long sys_kexec_load .rept NR_syscalls-(.-sys_call_table)/4 diff -uNr linux-2.5.47-bk2/arch/i386/kernel/machine_kexec.c linux-2.5.47-bk2.x86kexec/arch/i386/kernel/machine_kexec.c --- linux-2.5.47-bk2/arch/i386/kernel/machine_kexec.c Wed Dec 31 17:00:00 1969 +++ linux-2.5.47-bk2.x86kexec/arch/i386/kernel/machine_kexec.c Wed Nov 13 06:08:52 2002 @@ -0,0 +1,142 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +/* + * machine_kexec + * ======================= + */ + + +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 unaliged 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 +} + +static void identity_map_page(unsigned long address) +{ + /* This code is x86 specific... + * general purpose code must be more carful + * of caches and tlbs... + */ + pgd_t *pgd; + pmd_t *pmd; + struct mm_struct *mm = current->mm; + spin_lock(&mm->page_table_lock); + + pgd = pgd_offset(mm, address); + pmd = pmd_alloc(mm, pgd, address); + + if (pmd) { + pte_t *pte = pte_alloc_map(mm, pmd, address); + if (pte) { + set_pte(pte, + mk_pte(virt_to_page(phys_to_virt(address)), + PAGE_SHARED)); + __flush_tlb_one(address); + } + } + spin_unlock(&mm->page_table_lock); +} + + +typedef void (*relocate_new_kernel_t)( + unsigned long indirection_page, unsigned long reboot_code_buffer, + unsigned long start_address); + +const extern unsigned char relocate_new_kernel[]; +extern void relocate_new_kernel_end(void); +const extern unsigned int relocate_new_kernel_size; + +void machine_kexec(struct kimage *image) +{ + unsigned long *indirection_page; + void *reboot_code_buffer; + relocate_new_kernel_t rnk; + + /* Interrupts aren't acceptable while we reboot */ + local_irq_disable(); + reboot_code_buffer = image->reboot_code_buffer; + indirection_page = phys_to_virt(image->head & PAGE_MASK); + + identity_map_page(virt_to_phys(reboot_code_buffer)); + + /* copy it out */ + memcpy(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) virt_to_phys(reboot_code_buffer); + (*rnk)(virt_to_phys(indirection_page), virt_to_phys(reboot_code_buffer), + image->start); +} + diff -uNr linux-2.5.47-bk2/arch/i386/kernel/relocate_kernel.S linux-2.5.47-bk2.x86kexec/arch/i386/kernel/relocate_kernel.S --- linux-2.5.47-bk2/arch/i386/kernel/relocate_kernel.S Wed Dec 31 17:00:00 1969 +++ linux-2.5.47-bk2.x86kexec/arch/i386/kernel/relocate_kernel.S Wed Nov 13 06:08:52 2002 @@ -0,0 +1,99 @@ +#include +#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 */ + + /* 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 + 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 -uNr linux-2.5.47-bk2/include/asm-i386/kexec.h linux-2.5.47-bk2.x86kexec/include/asm-i386/kexec.h --- linux-2.5.47-bk2/include/asm-i386/kexec.h Wed Dec 31 17:00:00 1969 +++ linux-2.5.47-bk2.x86kexec/include/asm-i386/kexec.h Wed Nov 13 06:08:52 2002 @@ -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 (FIXADDR_START - PAGE_OFFSET) +/* Maximum address we can reach in physical address mode */ +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL) + +#define KEXEC_REBOOT_CODE_SIZE 4096 +#define KEXEC_REBOOT_CODE_ALIGN 0 + + +#endif /* _I386_KEXEC_H */ diff -uNr linux-2.5.47-bk2/include/asm-i386/unistd.h linux-2.5.47-bk2.x86kexec/include/asm-i386/unistd.h --- linux-2.5.47-bk2/include/asm-i386/unistd.h Tue Nov 5 19:03:51 2002 +++ linux-2.5.47-bk2.x86kexec/include/asm-i386/unistd.h Wed Nov 13 06:08:52 2002 @@ -262,6 +262,7 @@ #define __NR_sys_epoll_ctl 255 #define __NR_sys_epoll_wait 256 #define __NR_remap_file_pages 257 +#define __NR_sys_kexec_load 258 /* user-visible error numbers are in the range -1 - -124: see */ diff -uNr linux-2.5.47-bk2/include/linux/kexec.h linux-2.5.47-bk2.x86kexec/include/linux/kexec.h --- linux-2.5.47-bk2/include/linux/kexec.h Wed Dec 31 17:00:00 1969 +++ linux-2.5.47-bk2.x86kexec/include/linux/kexec.h Wed Nov 13 06:08:52 2002 @@ -0,0 +1,45 @@ +#ifndef LINUX_KEXEC_H +#define LINUX_KEXEC_H + +#if CONFIG_KEXEC +#include +#include + +/* + * This structure is used to hold the arguments that are used when loading + * kernel binaries. + */ + +typedef unsigned long kimage_entry_t; +#define IND_DESTINATION 0x1 +#define IND_INDIRECTION 0x2 +#define IND_DONE 0x4 +#define IND_SOURCE 0x8 + +struct kimage { + kimage_entry_t head; + kimage_entry_t *entry; + kimage_entry_t *last_entry; + + unsigned long destination; + unsigned long offset; + + unsigned long start; + void *reboot_code_buffer; +}; + +struct kexec_segment { + void *buf; + size_t bufsz; + void *mem; + size_t memsz; +}; + +/* kexec interface functions */ +extern void machine_kexec(struct kimage *image); +extern asmlinkage long sys_kexec(unsigned long entry, long nr_segments, + struct kexec_segment *segments); +extern struct kimage *kexec_image; +#endif +#endif /* LINUX_KEXEC_H */ + diff -uNr linux-2.5.47-bk2/include/linux/reboot.h linux-2.5.47-bk2.x86kexec/include/linux/reboot.h --- linux-2.5.47-bk2/include/linux/reboot.h Fri Oct 11 22:22:47 2002 +++ linux-2.5.47-bk2.x86kexec/include/linux/reboot.h Wed Nov 13 06:08:52 2002 @@ -21,6 +21,7 @@ * POWER_OFF Stop OS and remove all power from system, if possible. * RESTART2 Restart system using given command string. * SW_SUSPEND Suspend system using Software Suspend if compiled in + * KEXEC Restart the system using a different kernel. */ #define LINUX_REBOOT_CMD_RESTART 0x01234567 @@ -30,6 +31,7 @@ #define LINUX_REBOOT_CMD_POWER_OFF 0x4321FEDC #define LINUX_REBOOT_CMD_RESTART2 0xA1B2C3D4 #define LINUX_REBOOT_CMD_SW_SUSPEND 0xD000FCE2 +#define LINUX_REBOOT_CMD_KEXEC 0x45584543 #ifdef __KERNEL__ diff -uNr linux-2.5.47-bk2/kernel/Makefile linux-2.5.47-bk2.x86kexec/kernel/Makefile --- linux-2.5.47-bk2/kernel/Makefile Wed Nov 13 06:08:13 2002 +++ linux-2.5.47-bk2.x86kexec/kernel/Makefile Wed Nov 13 06:08:52 2002 @@ -21,6 +21,7 @@ obj-$(CONFIG_CPU_FREQ) += cpufreq.o obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o obj-$(CONFIG_SOFTWARE_SUSPEND) += suspend.o +obj-$(CONFIG_KEXEC) += kexec.o ifneq ($(CONFIG_IA64),y) # According to Alan Modra , the -fno-omit-frame-pointer is diff -uNr linux-2.5.47-bk2/kernel/kexec.c linux-2.5.47-bk2.x86kexec/kernel/kexec.c --- linux-2.5.47-bk2/kernel/kexec.c Wed Dec 31 17:00:00 1969 +++ linux-2.5.47-bk2.x86kexec/kernel/kexec.c Wed Nov 13 06:08:52 2002 @@ -0,0 +1,640 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* As designed kexec can only use the memory that you don't + * need to use kmap to access. Memory that you can use virt_to_phys() + * on an call get_free_page to allocate. + * + * In the best case you need one page for the transition from + * virtual to physical memory. And this page must be identity + * mapped. Which pretty much leaves you with pages < PAGE_OFFSET + * as you can only mess with user pages. + * + * As the only subset of memory that it is easy to restrict allocation + * to is the physical memory mapped into the kernel, I do that + * with get_free_page and hope it is enough. + * + * I don't know of a good way to do this calcuate which pages get_free_page + * will return independent of architecture so I depend on + * to properly set + * KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DESTINATION_MEMORY_LIMIT + * + */ + +static struct kimage *kimage_alloc(void) +{ + struct kimage *image; + image = kmalloc(sizeof(*image), GFP_KERNEL); + if (!image) + return 0; + memset(image, 0, sizeof(*image)); + image->head = 0; + image->entry = &image->head; + image->last_entry = &image->head; + return image; +} +static int kimage_add_entry(struct kimage *image, kimage_entry_t entry) +{ + if (image->offset != 0) { + image->entry++; + } + if (image->entry == image->last_entry) { + kimage_entry_t *ind_page; + ind_page = (void *)__get_free_page(GFP_KERNEL); + if (!ind_page) { + return -ENOMEM; + } + *image->entry = virt_to_phys(ind_page) | IND_INDIRECTION; + image->entry = ind_page; + image->last_entry = + ind_page + ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1); + } + *image->entry = entry; + image->entry++; + image->offset = 0; + return 0; +} + +static int kimage_verify_destination(unsigned long destination) +{ + int result; + + /* Assume the page is bad unless we pass the checks */ + result = -EADDRNOTAVAIL; + + if (destination >= KEXEC_DESTINATION_MEMORY_LIMIT) { + goto out; + } + + /* NOTE: The caller is responsible for making certain we + * don't attempt to load the new image into invalid or + * reserved areas of RAM. + */ + result = 0; +out: + return result; +} + +static int kimage_set_destination( + struct kimage *image, unsigned long destination) +{ + int result; + destination &= PAGE_MASK; + result = kimage_verify_destination(destination); + if (result) { + return result; + } + result = kimage_add_entry(image, destination | IND_DESTINATION); + if (result == 0) { + image->destination = destination; + } + return result; +} + + +static int kimage_add_page(struct kimage *image, unsigned long page) +{ + int result; + page &= PAGE_MASK; + result = kimage_verify_destination(image->destination); + if (result) { + return result; + } + result = kimage_add_entry(image, page | IND_SOURCE); + if (result == 0) { + image->destination += PAGE_SIZE; + } + return result; +} + + +static int kimage_terminate(struct kimage *image) +{ + int result; + result = kimage_add_entry(image, IND_DONE); + if (result == 0) { + /* Point at the terminating element */ + image->entry--; + } + return result; +} + +#define for_each_kimage_entry(image, ptr, entry) \ + for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \ + ptr = (entry & IND_INDIRECTION)? \ + phys_to_virt((entry & PAGE_MASK)): ptr +1) + +static void kimage_free(struct kimage *image) +{ + kimage_entry_t *ptr, entry; + kimage_entry_t ind = 0; + if (!image) + return; + for_each_kimage_entry(image, ptr, entry) { + if (entry & IND_INDIRECTION) { + /* Free the previous indirection page */ + if (ind & IND_INDIRECTION) { + free_page((unsigned long)phys_to_virt(ind & PAGE_MASK)); + } + /* Save this indirection page until we are + * done with it. + */ + ind = entry; + } + else if (entry & IND_SOURCE) { + free_page((unsigned long)phys_to_virt(entry & PAGE_MASK)); + } + } + kfree(image); +} + +static int kimage_is_destination_page( + struct kimage *image, unsigned long page) +{ + kimage_entry_t *ptr, entry; + unsigned long destination; + destination = 0; + page &= PAGE_MASK; + for_each_kimage_entry(image, ptr, entry) { + if (entry & IND_DESTINATION) { + destination = entry & PAGE_MASK; + } + else if (entry & IND_SOURCE) { + if (page == destination) { + return 1; + } + destination += PAGE_SIZE; + } + } + return 0; +} + +static int kimage_get_unused_area( + struct kimage *image, unsigned long size, unsigned long align, + unsigned long *area) +{ + /* Walk through mem_map and find the first chunk of + * ununsed memory that is at least size bytes long. + */ + /* Since the kernel plays with Page_Reseved mem_map is less + * than ideal for this purpose, but it will give us a correct + * conservative estimate of what we need to do. + */ + /* For now we take advantage of the fact that all kernel pages + * are marked with PG_resereved to allocate a large + * contiguous area for the reboot code buffer. + */ + unsigned long addr; + unsigned long start, end; + unsigned long mask; + mask = ((1 << align) -1); + start = end = PAGE_SIZE; + for(addr = PAGE_SIZE; addr < KEXEC_SOURCE_MEMORY_LIMIT; addr += PAGE_SIZE) { + struct page *page; + unsigned long aligned_start; + page = virt_to_page(phys_to_virt(addr)); + if (PageReserved(page) || + kimage_is_destination_page(image, addr)) { + /* The current page is reserved so the start & + * end of the next area must be atleast at the + * next page. + */ + start = end = addr + PAGE_SIZE; + } + else { + /* O.k. The current page isn't reserved + * so push up the end of the area. + */ + end = addr; + } + aligned_start = (start + mask) & ~mask; + if (aligned_start > start) { + continue; + } + if (aligned_start > end) { + continue; + } + if (end - aligned_start >= size) { + *area = aligned_start; + return 0; + } + } + *area = 0; + return -ENOSPC; +} + +static kimage_entry_t *kimage_dst_conflict( + struct kimage *image, unsigned long page, kimage_entry_t *limit) +{ + kimage_entry_t *ptr, entry; + unsigned long destination = 0; + for_each_kimage_entry(image, ptr, entry) { + if (ptr == limit) { + return 0; + } + else if (entry & IND_DESTINATION) { + destination = entry & PAGE_MASK; + } + else if (entry & IND_SOURCE) { + if (page == destination) { + return ptr; + } + destination += PAGE_SIZE; + } + } + return 0; +} + +static kimage_entry_t *kimage_src_conflict( + struct kimage *image, unsigned long destination, kimage_entry_t *limit) +{ + kimage_entry_t *ptr, entry; + for_each_kimage_entry(image, ptr, entry) { + unsigned long page; + if (ptr == limit) { + return 0; + } + else if (entry & IND_DESTINATION) { + /* nop */ + } + else if (entry & IND_DONE) { + /* nop */ + } + else { + /* SOURCE & INDIRECTION */ + page = entry & PAGE_MASK; + if (page == destination) { + return ptr; + } + } + } + return 0; +} + +static int kimage_get_off_destination_pages(struct kimage *image) +{ + kimage_entry_t *ptr, *cptr, entry; + unsigned long buffer, page; + unsigned long destination = 0; + + /* Here we implement safe guards to insure that + * a source page is not copied to it's destination + * page before the data on the destination page is + * no longer useful. + * + * To make it work we actually wind up with a + * stronger condition. For every page considered + * it is either it's own destination page or it is + * not a destination page of any page considered. + * + * Invariants + * 1. buffer is not a destination of a previous page. + * 2. page is not a destination of a previous page. + * 3. destination is not a previous source page. + * + * Result: Either a source page and a destination page + * are the same or the page is not a destination page. + * + * These checks could be done when we allocate the pages, + * but doing it as a final pass allows us more freedom + * on how we allocate pages. + * + * Also while the checks are necessary, in practice nothing + * happens. The destination kernel wants to sit in the + * same physical addresses as the current kernel so we never + * actually allocate a destination page. + * + * BUGS: This is a O(N^2) algorithm. + */ + + + buffer = __get_free_page(GFP_KERNEL); + if (!buffer) { + return -ENOMEM; + } + buffer = virt_to_phys((void *)buffer); + for_each_kimage_entry(image, ptr, entry) { + /* Here we check to see if an allocated page */ + kimage_entry_t *limit; + if (entry & IND_DESTINATION) { + destination = entry & PAGE_MASK; + } + else if (entry & IND_INDIRECTION) { + /* Indirection pages must include all of their + * contents in limit checking. + */ + limit = phys_to_virt(page + PAGE_SIZE - sizeof(*limit)); + } + if (!((entry & IND_SOURCE) | (entry & IND_INDIRECTION))) { + continue; + } + page = entry & PAGE_MASK; + limit = ptr; + + /* See if a previous page has the current page as it's + * destination. + * i.e. invariant 2 + */ + cptr = kimage_dst_conflict(image, page, limit); + if (cptr) { + unsigned long cpage; + kimage_entry_t centry; + centry = *cptr; + cpage = centry & PAGE_MASK; + memcpy(phys_to_virt(buffer), phys_to_virt(page), PAGE_SIZE); + memcpy(phys_to_virt(page), phys_to_virt(cpage), PAGE_SIZE); + *cptr = page | (centry & ~PAGE_MASK); + *ptr = buffer | (entry & ~PAGE_MASK); + buffer = cpage; + } + if (!(entry & IND_SOURCE)) { + continue; + } + + /* See if a previous page is our destination page. + * If so claim it now. + * i.e. invariant 3 + */ + cptr = kimage_src_conflict(image, destination, limit); + if (cptr) { + unsigned long cpage; + kimage_entry_t centry; + centry = *cptr; + cpage = centry & PAGE_MASK; + memcpy(phys_to_virt(buffer), phys_to_virt(cpage), PAGE_SIZE); + memcpy(phys_to_virt(cpage), phys_to_virt(page), PAGE_SIZE); + *cptr = buffer | (centry & ~PAGE_MASK); + *ptr = cpage | ( entry & ~PAGE_MASK); + buffer = page; + } + /* If the buffer is my destination page do the copy now + * i.e. invariant 3 & 1 + */ + if (buffer == destination) { + memcpy(phys_to_virt(buffer), phys_to_virt(page), PAGE_SIZE); + *ptr = buffer | (entry & ~PAGE_MASK); + buffer = page; + } + } + free_page((unsigned long)phys_to_virt(buffer)); + return 0; +} + +static int kimage_add_empty_pages(struct kimage *image, + unsigned long len) +{ + unsigned long pos; + int result; + for(pos = 0; pos < len; pos += PAGE_SIZE) { + char *page; + result = -ENOMEM; + page = (void *)__get_free_page(GFP_KERNEL); + if (!page) { + goto out; + } + result = kimage_add_page(image, virt_to_phys(page)); + if (result) { + goto out; + } + } + result = 0; + out: + return result; +} + + +static int kimage_load_segment(struct kimage *image, + struct kexec_segment *segment) +{ + unsigned long mstart; + int result; + unsigned long offset; + unsigned long offset_end; + unsigned char *buf; + + result = 0; + buf = segment->buf; + mstart = (unsigned long)segment->mem; + + offset_end = segment->memsz; + + result = kimage_set_destination(image, mstart); + if (result < 0) { + goto out; + } + for(offset = 0; offset < segment->memsz; offset += PAGE_SIZE) { + char *page; + size_t size, leader; + page = (char *)__get_free_page(GFP_KERNEL); + if (page == 0) { + result = -ENOMEM; + goto out; + } + result = kimage_add_page(image, virt_to_phys(page)); + if (result < 0) { + goto out; + } + if (segment->bufsz < offset) { + /* We are past the end zero the whole page */ + memset(page, 0, PAGE_SIZE); + continue; + } + size = PAGE_SIZE; + leader = 0; + if ((offset == 0)) { + leader = mstart & ~PAGE_MASK; + } + if (leader) { + /* We are on the first page zero the unused portion */ + memset(page, 0, leader); + size -= leader; + page += leader; + } + if (size > (segment->bufsz - offset)) { + size = segment->bufsz - offset; + } + result = copy_from_user(page, buf + offset, size); + if (result) { + result = (result < 0)?result : -EIO; + goto out; + } + if (size < (PAGE_SIZE - leader)) { + /* zero the trailing part of the page */ + memset(page + size, 0, (PAGE_SIZE - leader) - size); + } + } + out: + return result; +} + + +/* do_kexec executes a new kernel + */ +static int do_kexec(unsigned long start, unsigned long nr_segments, + struct kexec_segment *arg_segments, struct kimage *image) +{ + struct kexec_segment *segments; + size_t segment_bytes; + int i; + + int result; + unsigned long reboot_code_buffer; + kimage_entry_t *end; + + /* Initialize variables */ + segments = 0; + + segment_bytes = nr_segments * sizeof(*segments); + segments = kmalloc(GFP_KERNEL, segment_bytes); + if (segments == 0) { + result = -ENOMEM; + goto out; + } + result = copy_from_user(segments, arg_segments, segment_bytes); + if (result) { + goto out; + } + + /* Read in the data from user space */ + image->start = start; + for(i = 0; i < nr_segments; i++) { + result = kimage_load_segment(image, &segments[i]); + if (result) { + goto out; + } + } + + /* Terminate early so I can get a place holder. */ + result = kimage_terminate(image); + if (result) + goto out; + end = image->entry; + + /* Usage of the reboot code buffer is subtle. We first + * find a continguous area of ram, that is not one + * of our destination pages. We do not allocate the ram. + * + * The algorithm to make certain we do not have address + * conflicts requires each destination region to have some + * backing store so we allocate abitrary source pages. + * + * Later in machine_kexec when we copy data to the + * reboot_code_buffer it still may be allocated for other + * purposes, but we do know there are no source or destination + * pages in that area. And since the rest of the kernel + * is already shutdown those pages are free for use, + * regardless of their page->count values. + * + * The kernel mapping is of the reboot code buffer is passed to + * the machine dependent code. If it needs something else + * it is free to set that up. + */ + result = kimage_get_unused_area( + image, KEXEC_REBOOT_CODE_SIZE, KEXEC_REBOOT_CODE_ALIGN, + &reboot_code_buffer); + if (result) + goto out; + + /* Allocating pages we should never need is silly but the + * code won't work correctly unless we have dummy pages to + * work with. + */ + result = kimage_set_destination(image, reboot_code_buffer); + if (result) + goto out; + result = kimage_add_empty_pages(image, KEXEC_REBOOT_CODE_SIZE); + if (result) + goto out; + image->reboot_code_buffer = phys_to_virt(reboot_code_buffer); + + result = kimage_terminate(image); + if (result) + goto out; + + result = kimage_get_off_destination_pages(image); + if (result) + goto out; + + /* Now hide the extra source pages for the reboot code buffer. + */ + image->entry = end; + result = kimage_terminate(image); + if (result) + goto out; + + result = 0; + out: + /* cleanup and exit */ + if (segments) kfree(segments); + return result; +} + + +/* + * Exec Kernel system call: for obvious reasons only root may call it. + * + * This call breaks up into three pieces. + * - A generic part which loads the new kernel from the current + * address space, and very carefully places the data in the + * allocated pages. + * + * - A generic part that interacts with the kernel and tells all of + * the devices to shut down. Preventing on-going dmas, and placing + * the devices in a consistent state so a later kernel can + * reinitialize them. + * + * - A machine specific part that includes the syscall number + * and the copies the image to it's final destination. And + * jumps into the image at entry. + * + * kexec does not sync, or unmount filesystems so if you need + * that to happen you need to do that yourself. + */ +struct kimage *kexec_image = 0; + +asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments, + struct kexec_segment *segments, unsigned long flags) +{ + /* Am I using to much stack space here? */ + struct kimage *image, *old_image; + int result; + + /* We only trust the superuser with rebooting the system. */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* In case we need just a little bit of special behavior for + * reboot on panic + */ + if (flags != 0) + return -EINVAL; + + image = 0; + if (nr_segments > 0) { + image = kimage_alloc(); + if (!image) { + return -ENOMEM; + } + result = do_kexec(entry, nr_segments, segments, image); + if (result) { + kimage_free(image); + return result; + } + } + + old_image = xchg(&kexec_image, image); + + kimage_free(old_image); + return 0; +} diff -uNr linux-2.5.47-bk2/kernel/sys.c linux-2.5.47-bk2.x86kexec/kernel/sys.c --- linux-2.5.47-bk2/kernel/sys.c Wed Nov 13 06:08:13 2002 +++ linux-2.5.47-bk2.x86kexec/kernel/sys.c Wed Nov 13 06:08:52 2002 @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -206,6 +207,7 @@ cond_syscall(sys_lookup_dcookie) cond_syscall(sys_swapon) cond_syscall(sys_swapoff) +cond_syscall(sys_kexec_load) cond_syscall(sys_init_module) cond_syscall(sys_delete_module) @@ -416,6 +418,27 @@ machine_restart(buffer); break; +#ifdef CONFIG_KEXEC + case LINUX_REBOOT_CMD_KEXEC: + { + struct kimage *image; + if (arg) { + unlock_kernel(); + return -EINVAL; + } + image = xchg(&kexec_image, 0); + if (!image) { + unlock_kernel(); + return -EINVAL; + } + notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL); + system_running = 0; + device_shutdown(); + printk(KERN_EMERG "Starting new kernel\n"); + machine_kexec(image); + break; + } +#endif #ifdef CONFIG_SOFTWARE_SUSPEND case LINUX_REBOOT_CMD_SW_SUSPEND: if (!software_suspend_enabled) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/