powerpc: Replace kmap_atomic with kmap in pte_offset_map

The pte_offset_map/pte_offset_map_nested use kmap_atomic to get the
virtual address for the pte table, but kmap_atomic will disable preempt.
Hence there will be call trace if we acquire a spin lock after invoking
pte_offset_map/pte_offset_map_nested in preempt-rt.  To fix it, I've
replaced kmap_atomic with kmap in these macros.

Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
LKML-Reference: <ffaf532c138188b526a8c623ed3c7f5067da6d68.1267566249.git.paul.gortmaker@windriver.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/pgtable-ppc32.h b/arch/powerpc/include/asm/pgtable-ppc32.h
index 55646adfa843..a83809916f28 100644
--- a/arch/powerpc/include/asm/pgtable-ppc32.h
+++ b/arch/powerpc/include/asm/pgtable-ppc32.h
@@ -307,6 +307,17 @@ static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
         (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 #define pte_offset_kernel(dir, addr)    \
         ((pte_t *) pmd_page_vaddr(*(dir)) + pte_index(addr))
+#ifdef CONFIG_PREEMPT_RT
+#define pte_offset_map(dir, addr)               \
+        ((pte_t *) kmap(pmd_page(*(dir))) + pte_index(addr))
+#define pte_offset_map_nested(dir, addr)        \
+        ((pte_t *) kmap(pmd_page(*(dir))) + pte_index(addr))
+
+#define pte_unmap(pte)  \
+        kunmap((struct page *)_ALIGN_DOWN((unsigned int)pte, PAGE_SIZE))
+#define pte_unmap_nested(pte)   \
+        kunmap((struct page *)_ALIGN_DOWN((unsigned int)pte, PAGE_SIZE))
+#else
 #define pte_offset_map(dir, addr)               \
         ((pte_t *) kmap_atomic(pmd_page(*(dir)), KM_PTE0) + pte_index(addr))
 #define pte_offset_map_nested(dir, addr)        \
@@ -314,6 +325,7 @@ static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
 
 #define pte_unmap(pte)          kunmap_atomic(pte, KM_PTE0)
 #define pte_unmap_nested(pte)   kunmap_atomic(pte, KM_PTE1)
+#endif
 
 /*
  * Encode and decode a swap entry.