From 7230ced4925b07c259a62b515d8278c6bb1ad98c Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 31 Jul 2008 16:54:28 +1000 Subject: [PATCH] powerpc: Fix /dev/oldmem interface for kdump A change to __ioremap() broke reading /dev/oldmem because we're no longer able to ioremap pfn 0 (d177c207, "[PATCH] powerpc: IOMMU: don't ioremap null addresses"). We actually don't need to ioremap for anything that's part of the linear mapping, so just read it directly. Also make sure we're only reading one page or less at a time. Signed-off-by: Michael Ellerman Signed-off-by: Sachin Sant Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/crash_dump.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c index e0debcca0b..a323c9b32e 100644 --- a/arch/powerpc/kernel/crash_dump.c +++ b/arch/powerpc/kernel/crash_dump.c @@ -86,6 +86,19 @@ static int __init parse_savemaxmem(char *p) } __setup("savemaxmem=", parse_savemaxmem); + +static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize, + unsigned long offset, int userbuf) +{ + if (userbuf) { + if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) + return -EFAULT; + } else + memcpy(buf, (vaddr + offset), csize); + + return csize; +} + /** * copy_oldmem_page - copy one page from "oldmem" * @pfn: page frame number to be copied @@ -107,16 +120,16 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, if (!csize) return 0; - vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); + csize = min(csize, PAGE_SIZE); - if (userbuf) { - if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) { - iounmap(vaddr); - return -EFAULT; - } - } else - memcpy(buf, (vaddr + offset), csize); + if (pfn < max_pfn) { + vaddr = __va(pfn << PAGE_SHIFT); + csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); + } else { + vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0); + csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); + iounmap(vaddr); + } - iounmap(vaddr); return csize; } -- 2.39.5