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[RFC] Simplify pte_offset_map() on 32 bits

To: linux-mips <linux-mips@linux-mips.org>
Subject: [RFC] Simplify pte_offset_map() on 32 bits
From: Franck Bui-Huu <vagabon.xyz@gmail.com>
Date: Fri, 23 Mar 2007 14:00:28 +0100
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Looking its implementation, I'm wondering why this macro and its
sister "pte_offset_map_nested()" are so complex.

I changed their implementations as the following patch shows and my
tiny 32 bits machine still boot fine.

Code size is a little bit decreased:

        vmlinux  =>  vmlinux~patched
         text:  3045700  3044664    -1036  0%
         data:   155756   155756        0  0%
          bss:  2269216  2269216        0  0%
        total:  5470672  5469636    -1036  0%


Could anybody have a look and tell me if I'm missing something ?

Thanks,
                Franck
-- >8 --

diff --git a/include/asm-mips/pgtable-32.h b/include/asm-mips/pgtable-32.h
index 2fbd47e..a0e76e4 100644
--- a/include/asm-mips/pgtable-32.h
+++ b/include/asm-mips/pgtable-32.h
@@ -143,6 +143,7 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 #define __pgd_offset(address)  pgd_index(address)
 #define __pud_offset(address)  (((address) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
 #define __pmd_offset(address)  (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
+#define __pte_offset(address)  (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE-1))
 
 /* to find an entry in a kernel page-table-directory */
 #define pgd_offset_k(address) pgd_offset(&init_mm, address)
@@ -153,17 +154,15 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 #define pgd_offset(mm,addr)    ((mm)->pgd + pgd_index(addr))
 
 /* Find an entry in the third-level page table.. */
-#define __pte_offset(address)                                          \
-       (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 #define pte_offset(dir, address)                                       \
        ((pte_t *) pmd_page_vaddr(*(dir)) + __pte_offset(address))
 #define pte_offset_kernel(dir, address)                                        
\
        ((pte_t *) pmd_page_vaddr(*(dir)) + __pte_offset(address))
 
 #define pte_offset_map(dir, address)                                    \
-       ((pte_t *)page_address(pmd_page(*(dir))) + __pte_offset(address))
+       ((pte_t *) pmd_page_vaddr(*(dir)) + __pte_offset(address))
 #define pte_offset_map_nested(dir, address)                             \
-       ((pte_t *)page_address(pmd_page(*(dir))) + __pte_offset(address))
+       ((pte_t *) pmd_page_vaddr(*(dir)) + __pte_offset(address))
 #define pte_unmap(pte) ((void)(pte))
 #define pte_unmap_nested(pte) ((void)(pte))
 
diff --git a/mm/memory.c b/mm/memory.c


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