From: Vivek Goyal Date: Tue, 10 Jan 2006 04:51:50 +0000 (-0800) Subject: [PATCH] kdump: read previous kernel's memory X-Git-Tag: v2.6.16-rc1~629 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ae362be509306eafa6441603686d33fefe321c1;p=linux-2.6 [PATCH] kdump: read previous kernel's memory - Moving the crash_dump.c file to arch dependent part as kmap_atomic_pfn is specific to i386 and highmem may not exist in other archs. - Use ioremap for x86_64 to map the previous kernel memory. - In copy_oldmem_page(), we now directly copy to the user/kernel buffer and avoid the unneccesary copy to a kmalloc'd page. Signed-off-by: Rachita Kothiyal Signed-off-by: Vivek Goyal Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile index be1880bb75..60c3f76dfc 100644 --- a/arch/i386/kernel/Makefile +++ b/arch/i386/kernel/Makefile @@ -25,6 +25,7 @@ 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-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_X86_NUMAQ) += numaq.o obj-$(CONFIG_X86_SUMMIT_NUMA) += summit.o obj-$(CONFIG_KPROBES) += kprobes.o diff --git a/arch/i386/kernel/crash_dump.c b/arch/i386/kernel/crash_dump.c new file mode 100644 index 0000000000..3f532df488 --- /dev/null +++ b/arch/i386/kernel/crash_dump.c @@ -0,0 +1,74 @@ +/* + * kernel/crash_dump.c - Memory preserving reboot related code. + * + * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) + * Copyright (C) IBM Corporation, 2004. All rights reserved + */ + +#include +#include +#include + +#include + +static void *kdump_buf_page; + +/** + * copy_oldmem_page - copy one page from "oldmem" + * @pfn: page frame number to be copied + * @buf: target memory address for the copy; this can be in kernel address + * space or user address space (see @userbuf) + * @csize: number of bytes to copy + * @offset: offset in bytes into the page (based on pfn) to begin the copy + * @userbuf: if set, @buf is in user address space, use copy_to_user(), + * otherwise @buf is in kernel address space, use memcpy(). + * + * Copy a page from "oldmem". For this page, there is no pte mapped + * in the current kernel. We stitch up a pte, similar to kmap_atomic. + * + * Calling copy_to_user() in atomic context is not desirable. Hence first + * copying the data to a pre-allocated kernel page and then copying to user + * space in non-atomic context. + */ +ssize_t copy_oldmem_page(unsigned long pfn, char *buf, + size_t csize, unsigned long offset, int userbuf) +{ + void *vaddr; + + if (!csize) + return 0; + + vaddr = kmap_atomic_pfn(pfn, KM_PTE0); + + if (!userbuf) { + memcpy(buf, (vaddr + offset), csize); + kunmap_atomic(vaddr, KM_PTE0); + } else { + if (!kdump_buf_page) { + printk(KERN_WARNING "Kdump: Kdump buffer page not" + " allocated\n"); + return -EFAULT; + } + copy_page(kdump_buf_page, vaddr); + kunmap_atomic(vaddr, KM_PTE0); + if (copy_to_user(buf, (kdump_buf_page + offset), csize)) + return -EFAULT; + } + + return csize; +} + +static int __init kdump_buf_page_init(void) +{ + int ret = 0; + + kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!kdump_buf_page) { + printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer" + " page\n"); + ret = -ENOMEM; + } + + return ret; +} +arch_initcall(kdump_buf_page_init); diff --git a/arch/x86_64/kernel/Makefile b/arch/x86_64/kernel/Makefile index fe4cbd1c4b..12bc54005e 100644 --- a/arch/x86_64/kernel/Makefile +++ b/arch/x86_64/kernel/Makefile @@ -22,6 +22,7 @@ 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_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_PM) += suspend.o obj-$(CONFIG_SOFTWARE_SUSPEND) += suspend_asm.o obj-$(CONFIG_CPU_FREQ) += cpufreq/ diff --git a/kernel/crash_dump.c b/arch/x86_64/kernel/crash_dump.c similarity index 60% rename from kernel/crash_dump.c rename to arch/x86_64/kernel/crash_dump.c index fccb27dbc6..942deac4d4 100644 --- a/kernel/crash_dump.c +++ b/arch/x86_64/kernel/crash_dump.c @@ -5,21 +5,12 @@ * Copyright (C) IBM Corporation, 2004. All rights reserved */ -#include #include -#include -#include -#include #include -#include #include -#include - -/* Stores the physical address of elf header of crash image. */ -unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; +#include -#ifndef HAVE_ARCH_COPY_OLDMEM_PAGE /** * copy_oldmem_page - copy one page from "oldmem" * @pfn: page frame number to be copied @@ -34,31 +25,23 @@ unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; * in the current kernel. We stitch up a pte, similar to kmap_atomic. */ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) + size_t csize, unsigned long offset, int userbuf) { - void *page, *vaddr; + void *vaddr; if (!csize) return 0; - page = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!page) - return -ENOMEM; - - vaddr = kmap_atomic_pfn(pfn, KM_PTE0); - copy_page(page, vaddr); - kunmap_atomic(vaddr, KM_PTE0); + vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE); if (userbuf) { - if (copy_to_user(buf, (page + offset), csize)) { - kfree(page); + if (copy_to_user(buf, (vaddr + offset), csize)) { + iounmap(vaddr); return -EFAULT; } - } else { - memcpy(buf, (page + offset), csize); - } + } else + memcpy(buf, (vaddr + offset), csize); - kfree(page); + iounmap(vaddr); return csize; } -#endif diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 3b2e7b69e6..5378d7c784 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -35,6 +35,9 @@ static size_t elfcorebuf_sz; /* Total size of vmcore file. */ static u64 vmcore_size; +/* Stores the physical address of elf header of crash image. */ +unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; + struct proc_dir_entry *proc_vmcore = NULL; /* Reads a page from the oldmem device from given offset. */ diff --git a/kernel/Makefile b/kernel/Makefile index a940bac028..1e039700c0 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -30,7 +30,6 @@ obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_SYSFS) += ksysfs.o obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ -obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o