[PATCH] csky: Fixup wrong update_mmu_cache implementation

[guoren]

From: Guo Ren <ren_...@c-sky.com>

In our stress test, we found some crash problem caused by:

if (!(vma->vm_flags & VM_EXEC))
        return;

in update_mmu_cache().

Seems current update_mmu_cache implementation is wrong and we retread
to the conservative implementation.

Also the usage of kmap_atomic in update_mmu_cache is risky, page-virtual
may be scheduled out and changed, so we must use preempt_disable &
pagefault_disable which is called by kmap_atomic().

Signed-off-by: Guo Ren <ren_...@c-sky.com>
Cc: Arnd Bergmann <a...@arndb.de>
---
 arch/csky/abiv2/cacheflush.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/arch/csky/abiv2/cacheflush.c b/arch/csky/abiv2/cacheflush.c
index d22c95f..5bb887b 100644
--- a/arch/csky/abiv2/cacheflush.c
+++ b/arch/csky/abiv2/cacheflush.c
@@ -34,10 +34,6 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned 
long address,
 {
        unsigned long addr, pfn;
        struct page *page;
-       void *va;
-
-       if (!(vma->vm_flags & VM_EXEC))
-               return;
 
        pfn = pte_pfn(*pte);
        if (unlikely(!pfn_valid(pfn)))
@@ -47,14 +43,9 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned 
long address,
        if (page == ZERO_PAGE(0))
                return;
 
-       va = page_address(page);
-       addr = (unsigned long) va;
-
-       if (va == NULL && PageHighMem(page))
-               addr = (unsigned long) kmap_atomic(page);
+       addr = (unsigned long) kmap_atomic(page);
 
        cache_wbinv_range(addr, addr + PAGE_SIZE);
 
-       if (va == NULL && PageHighMem(page))
-               kunmap_atomic((void *) addr);
+       kunmap_atomic((void *) addr);
 }
-- 
2.7.4