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

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: 2bfd65e45e87 ("powerpc/mm/radix: Add radix callbacks for early init routines")
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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 937d4e247ac3..df294224e280 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -228,5 +228,20 @@ 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_tree_size(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 227b2a6c4544..196222227e82 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_tree_size();
         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 c939e6e57a9e..e58707deef5c 100644
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c
@@ -160,9 +160,8 @@ 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_tree_size();
         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
@@ -176,10 +175,8 @@ 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_tree_size();
 
         BUILD_BUG_ON_MSG((PATB_SIZE_SHIFT > 24), "Partition table size too large.");
         partition_tb = early_alloc_pgtable(1UL << PATB_SIZE_SHIFT);