This patch fixes the /dev/oldmem interface for kdump on ppc64.
The patch originally came from Michael Ellerman hence have
retained the signed-off line. I just rediffed/tested against
latest git. Michael has ack'ed this patch.
Ben this is not a must for 2.6.27 but would be good if it's
included.
Thanks
-Sachin
Signed-off-by : Michael Ellerman <[EMAIL PROTECTED]>
Acked-by : Michael Ellerman <[EMAIL PROTECTED]>
---
Fix /dev/oldmem for kdump
A change to __ioremap() broke reading /dev/oldmem because we're no
longer able to ioremap pfn 0 (d177c207ba16b1db31283e2d1fee7ad4a863584b).
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 <[EMAIL PROTECTED]>
---
diff -Naurp 1/arch/powerpc/kernel/crash_dump.c 2/arch/powerpc/kernel/crash_dump.c
--- 1/arch/powerpc/kernel/crash_dump.c 2008-07-31 11:55:39.000000000 +0530
+++ 2/arch/powerpc/kernel/crash_dump.c 2008-07-31 12:09:49.000000000 +0530
@@ -86,6 +86,19 @@ static int __init parse_savemaxmem(char
}
__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 p
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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