powerpc/44x: Support 16K/64K base page sizes on 44x

This adds support for 16k and 64k page sizes on PowerPC 44x processors.

The PGDIR table is much smaller than a page when using 16k or 64k
pages (512 and 32 bytes respectively) so we allocate the PGDIR with
kzalloc() instead of __get_free_pages().

One PTE table covers rather a large memory area when using 16k or 64k
pages (32MB or 512MB respectively), so we can easily put FIXMAP and
PKMAP in the area covered by one PTE table.

Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
Signed-off-by: Vladimir Panfilov <pvr@emcraft.com>
Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h
index d77072a32cc..1458d950038 100644
--- a/arch/powerpc/include/asm/page_32.h
+++ b/arch/powerpc/include/asm/page_32.h
@@ -19,6 +19,8 @@
 #define PTE_FLAGS_OFFSET        0
 #endif
 
+#define PTE_SHIFT       (PAGE_SHIFT - PTE_T_LOG2)       /* full page */
+
 #ifndef __ASSEMBLY__
 /*
  * The basic type of a PTE - 64 bits for those CPUs with > 32 bit
@@ -26,10 +28,8 @@
  */
 #ifdef CONFIG_PTE_64BIT
 typedef unsigned long long pte_basic_t;
-#define PTE_SHIFT       (PAGE_SHIFT - 3)        /* 512 ptes per page */
 #else
 typedef unsigned long pte_basic_t;
-#define PTE_SHIFT       (PAGE_SHIFT - 2)        /* 1024 ptes per page */
 #endif
 
 struct page;
@@ -39,6 +39,9 @@ extern void copy_page(void *to, void *from);
 
 #include <asm-generic/page.h>
 
+#define PGD_T_LOG2      (__builtin_ffs(sizeof(pgd_t)) - 1)
+#define PTE_T_LOG2      (__builtin_ffs(sizeof(pte_t)) - 1)
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_PAGE_32_H */