oprofile: use KM_NMI slot for kmap_atomic

Orabug: 10369933

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.

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>

--- a/arch/i386/oprofile/backtrace.c
+++ b/arch/i386/oprofile/backtrace.c
@@ -40,9 +40,9 @@ copy_from_user_nmi(void *to, const void 
 		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;
--- a/include/asm-i386/kmap_types.h
+++ b/include/asm-i386/kmap_types.h
@@ -22,7 +22,12 @@ D(9)	KM_IRQ0,
 D(10)	KM_IRQ1,
 D(11)	KM_SOFTIRQ0,
 D(12)	KM_SOFTIRQ1,
+#if !defined(__GENKSYMS__)
+D(13)	KM_NMI,
+D(14)	KM_TYPE_NR
+#else
 D(13)	KM_TYPE_NR
+#endif
 };
 
 #undef D
--- a/include/asm-x86_64/kmap_types.h
+++ b/include/asm-x86_64/kmap_types.h
@@ -13,6 +13,9 @@ enum km_type {
 	KM_IRQ1,
 	KM_SOFTIRQ0,
 	KM_SOFTIRQ1,
+#if !defined(__GENKSYMS__)
+	KM_NMI,
+#endif
 	KM_TYPE_NR
 };