[PATCH] powerpc/mm: Fix build error with FLATMEM book3s64 config

[PATCH] powerpc/mm: Fix build error with FLATMEM book3s64 config

[Aneesh Kumar K.V]

The current value of MAX_PHYSMEM_BITS cannot work with 32 bit configs.
We used to have MAX_PHYSMEM_BITS not defined without SPARSEMEM and 32
bit configs never expected a value to be set for MAX_PHYSMEM_BITS.

Dependent code such as zsmalloc derived the right values based on other
fields. Instead of finding a value that works with different configs,
use new values only for book3s_64. For 64 bit booke, use the definition
of MAX_PHYSMEM_BITS as per commit a7df61a0e2b6 ("[PATCH] ppc64: Increase sparsemem defaults")
That change was done in 2005 and hopefully will work with book3e 64.

Fixes: 8bc086899816 ("powerpc/mm: Only define MAX_PHYSMEM_BITS in SPARSEMEM configurations")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/mmu.h | 15 +++++++++++++++
 arch/powerpc/include/asm/mmu.h           | 15 ---------------
 arch/powerpc/include/asm/nohash/64/mmu.h |  2 ++
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h
index 1ceee000c18d..a809bdd77322 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu.h
@@ -35,6 +35,21 @@ typedef pte_t *pgtable_t;
 
 #endif /* __ASSEMBLY__ */
 
+/*
+ * If we store section details in page->flags we can't increase the MAX_PHYSMEM_BITS
+ * if we increase SECTIONS_WIDTH we will not store node details in page->flags and
+ * page_to_nid does a page->section->node lookup
+ * Hence only increase for VMEMMAP. Further depending on SPARSEMEM_EXTREME reduce
+ * memory requirements with large number of sections.
+ * 51 bits is the max physical real address on POWER9
+ */
+#if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_SPARSEMEM_EXTREME) &&  \
+	defined(CONFIG_PPC_64K_PAGES)
+#define MAX_PHYSMEM_BITS 51
+#else
+#define MAX_PHYSMEM_BITS 46
+#endif
+
 /* 64-bit classic hash table MMU */
 #include <asm/book3s/64/mmu-hash.h>
 
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 598cdcdd1355..78d53c4396ac 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -341,21 +341,6 @@ static inline bool strict_kernel_rwx_enabled(void)
  */
 #define MMU_PAGE_COUNT	16
 
-/*
- * If we store section details in page->flags we can't increase the MAX_PHYSMEM_BITS
- * if we increase SECTIONS_WIDTH we will not store node details in page->flags and
- * page_to_nid does a page->section->node lookup
- * Hence only increase for VMEMMAP. Further depending on SPARSEMEM_EXTREME reduce
- * memory requirements with large number of sections.
- * 51 bits is the max physical real address on POWER9
- */
-#if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_SPARSEMEM_EXTREME) &&	\
-	defined (CONFIG_PPC_64K_PAGES)
-#define MAX_PHYSMEM_BITS        51
-#elif defined(CONFIG_SPARSEMEM)
-#define MAX_PHYSMEM_BITS        46
-#endif
-
 #ifdef CONFIG_PPC_BOOK3S_64
 #include <asm/book3s/64/mmu.h>
 #else /* CONFIG_PPC_BOOK3S_64 */
diff --git a/arch/powerpc/include/asm/nohash/64/mmu.h b/arch/powerpc/include/asm/nohash/64/mmu.h
index e6585480dfc4..81cf30c370e5 100644
--- a/arch/powerpc/include/asm/nohash/64/mmu.h
+++ b/arch/powerpc/include/asm/nohash/64/mmu.h
@@ -2,6 +2,8 @@
 #ifndef _ASM_POWERPC_NOHASH_64_MMU_H_
 #define _ASM_POWERPC_NOHASH_64_MMU_H_
 
+#define MAX_PHYSMEM_BITS        44
+
 /* Freescale Book-E software loaded TLB or Book-3e (ISA 2.06+) MMU */
 #include <asm/nohash/mmu-book3e.h>
 
-- 
2.20.1

Re: powerpc/mm: Fix build error with FLATMEM book3s64 config

[Michael Ellerman]

On Wed, 2019-04-03 at 06:05:14 UTC, "Aneesh Kumar K.V" wrote:
> The current value of MAX_PHYSMEM_BITS cannot work with 32 bit configs.
> We used to have MAX_PHYSMEM_BITS not defined without SPARSEMEM and 32
> bit configs never expected a value to be set for MAX_PHYSMEM_BITS.
> 
> Dependent code such as zsmalloc derived the right values based on other
> fields. Instead of finding a value that works with different configs,
> use new values only for book3s_64. For 64 bit booke, use the definition
> of MAX_PHYSMEM_BITS as per commit a7df61a0e2b6 ("[PATCH] ppc64: Increase sparsemem defaults")
> That change was done in 2005 and hopefully will work with book3e 64.
> 
> Fixes: 8bc086899816 ("powerpc/mm: Only define MAX_PHYSMEM_BITS in SPARSEMEM configurations")
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/6161a37307f3320808b5a7549593b991

cheers