sparc64: Document PGD and PMD layout.

We're going to be messing around with the PMD interpretation and layout
for the sake of transparent huge pages, so we better clearly document what
we're starting with.

Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 16 insertions, 8 deletions

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index a7b5091f3b1..af3cd7a9e9a 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -63,6 +63,14 @@
 #error Page table parameters do not cover virtual address space properly.
 #endif
 
+/* PMDs point to PTE tables which are 4K aligned.  */
+#define PMD_PADDR       _AC(0xfffffffe,UL)
+#define PMD_PADDR_SHIFT _AC(11,UL)
+
+/* PGDs point to PMD tables which are 8K aligned.  */
+#define PGD_PADDR       _AC(0xfffffffc,UL)
+#define PGD_PADDR_SHIFT _AC(11,UL)
+
 #ifndef __ASSEMBLY__
 
 #include <linux/sched.h>
@@ -581,14 +589,14 @@ static inline unsigned long pte_special(pte_t pte)
 }
 
 #define pmd_set(pmdp, ptep)     \
-        (pmd_val(*(pmdp)) = (__pa((unsigned long) (ptep)) >> 11UL))
+        (pmd_val(*(pmdp)) = (__pa((unsigned long) (ptep)) >> PMD_PADDR_SHIFT))
 #define pud_set(pudp, pmdp)     \
-        (pud_val(*(pudp)) = (__pa((unsigned long) (pmdp)) >> 11UL))
+        (pud_val(*(pudp)) = (__pa((unsigned long) (pmdp)) >> PGD_PADDR_SHIFT))
 #define __pmd_page(pmd)         \
-        ((unsigned long) __va((((unsigned long)pmd_val(pmd))<<11UL)))
+        ((unsigned long) __va((((unsigned long)pmd_val(pmd))<<PMD_PADDR_SHIFT)))
 #define pmd_page(pmd)                   virt_to_page((void *)__pmd_page(pmd))
 #define pud_page_vaddr(pud)             \
-        ((unsigned long) __va((((unsigned long)pud_val(pud))<<11UL)))
+        ((unsigned long) __va((((unsigned long)pud_val(pud))<<PGD_PADDR_SHIFT)))
 #define pud_page(pud)                   virt_to_page((void *)pud_page_vaddr(pud))
 #define pmd_none(pmd)                   (!pmd_val(pmd))
 #define pmd_bad(pmd)                    (0)
diff --git a/arch/sparc/include/asm/tsb.h b/arch/sparc/include/asm/tsb.h
index 6435924b451..ef8cd1a174f 100644
--- a/arch/sparc/include/asm/tsb.h
+++ b/arch/sparc/include/asm/tsb.h
@@ -147,13 +147,13 @@ extern struct tsb_phys_patch_entry __tsb_phys_patch, __tsb_phys_patch_end;
         brz,pn          REG1, FAIL_LABEL; \
          sllx           VADDR, 64 - (PMD_SHIFT + PMD_BITS), REG2; \
         srlx            REG2, 64 - PAGE_SHIFT, REG2; \
-        sllx            REG1, 11, REG1; \
+        sllx            REG1, PGD_PADDR_SHIFT, REG1; \
         andn            REG2, 0x3, REG2; \
         lduwa           [REG1 + REG2] ASI_PHYS_USE_EC, REG1; \
         brz,pn          REG1, FAIL_LABEL; \
          sllx           VADDR, 64 - PMD_SHIFT, REG2; \
         srlx            REG2, 64 - (PAGE_SHIFT - 1), REG2; \
-        sllx            REG1, 11, REG1; \
+        sllx            REG1, PMD_PADDR_SHIFT, REG1; \
         andn            REG2, 0x7, REG2; \
         add             REG1, REG2, REG1;
 
@@ -172,13 +172,13 @@ extern struct tsb_phys_patch_entry __tsb_phys_patch, __tsb_phys_patch_end;
         brz,pn          REG1, FAIL_LABEL; \
          sllx           VADDR, 64 - (PMD_SHIFT + PMD_BITS), REG2; \
         srlx            REG2, 64 - PAGE_SHIFT, REG2; \
-        sllx            REG1, 11, REG1; \
+        sllx            REG1, PGD_PADDR_SHIFT, REG1; \
         andn            REG2, 0x3, REG2; \
         lduwa           [REG1 + REG2] ASI_PHYS_USE_EC, REG1; \
         brz,pn          REG1, FAIL_LABEL; \
          sllx           VADDR, 64 - PMD_SHIFT, REG2; \
         srlx            REG2, 64 - (PAGE_SHIFT - 1), REG2; \
-        sllx            REG1, 11, REG1; \
+        sllx            REG1, PMD_PADDR_SHIFT, REG1; \
         andn            REG2, 0x7, REG2; \
         add             REG1, REG2, REG1;