[PATCH] powerpc/mm/radix: Update Radix tree size as per ISA 3.0

[Aneesh Kumar K.V]

ISA 3.0 updated it to be encoded as Radix tree size = 2^(RTS + 31). We
have it encoded as 2^(RTS + 28). Add a helper with the correct encoding
and use it instead of opencoding.

Fixes commit 2bfd65e45e87 ("powerpc/mm/radix: Add radix callbacks for
early init routine ")

Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/radix.h | 15 +++++++++++++++
 arch/powerpc/mm/mmu_context_book3s64.c     |  2 +-
 arch/powerpc/mm/pgtable-radix.c            |  9 +++------
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/radix.h 
b/arch/powerpc/include/asm/book3s/64/radix.h
index 0d980de55c40..cdf791af8ab2 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -260,5 +260,20 @@ extern void radix__vmemmap_remove_mapping(unsigned long 
start,
 
 extern int radix__map_kernel_page(unsigned long ea, unsigned long pa,
                                 pgprot_t flags, unsigned int psz);
+
+static inline unsigned long radix__get_rts_value(void)
+{
+       unsigned long rts_field;
+       /*
+        * we support 52 bits, hence 52-31 = 21, 0b10101
+        * RTS encoding details
+        * bits 0 - 3 of rts -> bits 6 - 8 unsigned long
+        * bits 4 - 5 of rts -> bits 62 - 63 of unsigned long
+        */
+       rts_field = (0x5UL << 5); /* 6 - 8 bits */
+       rts_field |= (0x2UL << 61);
+
+       return rts_field;
+}
 #endif /* __ASSEMBLY__ */
 #endif
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c 
b/arch/powerpc/mm/mmu_context_book3s64.c
index 78ebc3877530..d48067bf4b24 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -65,7 +65,7 @@ static int radix__init_new_context(struct mm_struct *mm, int 
index)
        /*
         * set the process table entry,
         */
-       rts_field = 3ull << PPC_BITLSHIFT(2);
+       rts_field = radix__get_rts_value();
        process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | 
RADIX_PGD_INDEX_SIZE);
        return 0;
 }
diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
index 85da0212b276..8a25877b96bc 100644
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c
@@ -181,9 +181,8 @@ redo:
        process_tb = early_alloc_pgtable(1UL << PRTB_SIZE_SHIFT);
        /*
         * Fill in the process table.
-        * we support 52 bits, hence 52-28 = 24, 11000
         */
-       rts_field = 3ull << PPC_BITLSHIFT(2);
+       rts_field = radix__get_rts_value();
        process_tb->prtb0 = cpu_to_be64(rts_field | __pa(init_mm.pgd) | 
RADIX_PGD_INDEX_SIZE);
        /*
         * Fill in the partition table. We are suppose to use effective address
@@ -197,10 +196,8 @@ redo:
 static void __init radix_init_partition_table(void)
 {
        unsigned long rts_field;
-       /*
-        * we support 52 bits, hence 52-28 = 24, 11000
-        */
-       rts_field = 3ull << PPC_BITLSHIFT(2);
+
+       rts_field = radix__get_rts_value();
 
        BUILD_BUG_ON_MSG((PATB_SIZE_SHIFT > 24), "Partition table size too 
large.");
        partition_tb = early_alloc_pgtable(1UL << PATB_SIZE_SHIFT);
-- 
2.7.4

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