[oprof-cvs] [PATCH] oprofile: use KM_NMI slot for kmap_atomic

[Junxiao Bi <jun...@or...>]

If one kernel path is using KM_USER0 slot and is interrupted by
the oprofile nmi, then in copy_from_user_nmi(), the KM_USER0 slot
will be overwrite and cleared to zero at last, when the control
return to the original kernel path, it will access an invalid
virtual address and trigger a crash.

Cc: Robert Richter <rob...@am...>
Cc: Greg KH <gr...@li...>
Cc: st...@vg...
Signed-off-by: Junxiao Bi <jun...@or...>

Hi, Please review this patch.

It is for linux-2.6.32.y stable branch not for mainline.

Thanks,
Junxiao.
---
 arch/x86/oprofile/backtrace.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index 829edf0..b50a280 100644
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -71,9 +71,9 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
 		offset = addr & (PAGE_SIZE - 1);
 		size = min(PAGE_SIZE - offset, n - len);
 
-		map = kmap_atomic(page, KM_USER0);
+		map = kmap_atomic(page, KM_NMI);
 		memcpy(to, map+offset, size);
-		kunmap_atomic(map, KM_USER0);
+		kunmap_atomic(map, KM_NMI);
 		put_page(page);
 
 		len  += size;
-- 
1.7.9.5