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authorMichael Ellerman <michael@ellerman.id.au>2008-07-31 16:54:28 +1000
committerPaul Mackerras <paulus@samba.org>2008-08-20 09:50:21 +1000
commit7230ced4925b07c259a62b515d8278c6bb1ad98c (patch)
tree7d1afdc5dac4ccc3481a8a22b86d2bb2f548bd4d
parentd82bf490948eaf10023ff850d0b5c70e49e0ba76 (diff)
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 <michael@ellerman.id.au> Signed-off-by: Sachin Sant <sachinp@in.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--arch/powerpc/kernel/crash_dump.c31
1 files changed, 22 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index e0debcca0bfa..a323c9b32ee1 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;
}

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