MIPS: mm: Fix MIPS32 36b physical addressing (alchemy, netlogic)

There are 2 distinct cases in which a kernel for a MIPS32 CPU
(CONFIG_CPU_MIPS32=y) may use 64 bit physical addresses
(CONFIG_PHYS_ADDR_T_64BIT=y):

  - 36 bit physical addressing as used by RMI Alchemy & Netlogic XLP/XLR
    CPUs.

  - MIPS32r5 eXtended Physical Addressing (XPA).

These 2 cases are distinct in that they require different behaviour from
the kernel - the EntryLo registers have different formats. Until Linux
v4.1 we only supported the first case, with code conditional upon the 2
aforementioned Kconfig variables being set. Commit c5b367835cfc ("MIPS:
Add support for XPA.") added support for the second case, but did so by
modifying the code that existed for the first case rather than treating
the 2 cases as distinct. Since the EntryLo registers have different
formats this breaks the 36 bit Alchemy/XLP/XLR case. Fix this by
splitting the 2 cases, with XPA cases now being conditional upon
CONFIG_XPA and the non-XPA case matching the code as it existed prior to
commit c5b367835cfc ("MIPS: Add support for XPA.").

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reported-by: Manuel Lauss <manuel.lauss@gmail.com>
Tested-by: Manuel Lauss <manuel.lauss@gmail.com>
Fixes: c5b367835cfc ("MIPS: Add support for XPA.")
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: stable@vger.kernel.org # v4.1+
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13119/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 25 insertions, 2 deletions

diff --git a/arch/mips/include/asm/pgtable-32.h b/arch/mips/include/asm/pgtable-32.h
index 181bd8e7db7d..d21f3da7bdb6 100644
--- a/arch/mips/include/asm/pgtable-32.h
+++ b/arch/mips/include/asm/pgtable-32.h
@@ -103,7 +103,7 @@ static inline void pmd_clear(pmd_t *pmdp)
 	pmd_val(*pmdp) = ((unsigned long) invalid_pte_table);
 }
 
-#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
+#if defined(CONFIG_XPA)
 
 #define pte_pfn(x)		(((unsigned long)((x).pte_high >> _PFN_SHIFT)) | (unsigned long)((x).pte_low << _PAGE_PRESENT_SHIFT))
 static inline pte_t
@@ -118,6 +118,20 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 	return pte;
 }
 
+#elif defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
+
+#define pte_pfn(x)		((unsigned long)((x).pte_high >> 6))
+
+static inline pte_t pfn_pte(unsigned long pfn, pgprot_t prot)
+{
+	pte_t pte;
+
+	pte.pte_high = (pfn << 6) | (pgprot_val(prot) & 0x3f);
+	pte.pte_low = pgprot_val(prot);
+
+	return pte;
+}
+
 #else
 
 #ifdef CONFIG_CPU_VR41XX
@@ -166,7 +180,7 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 
 #else
 
-#if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
+#if defined(CONFIG_XPA)
 
 /* Swap entries must have VALID and GLOBAL bits cleared. */
 #define __swp_type(x)			(((x).val >> 4) & 0x1f)
@@ -175,6 +189,15 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 #define __pte_to_swp_entry(pte)		((swp_entry_t) { (pte).pte_high })
 #define __swp_entry_to_pte(x)		((pte_t) { 0, (x).val })
 
+#elif defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
+
+/* Swap entries must have VALID and GLOBAL bits cleared. */
+#define __swp_type(x)			(((x).val >> 2) & 0x1f)
+#define __swp_offset(x)			 ((x).val >> 7)
+#define __swp_entry(type, offset)	((swp_entry_t)  { ((type) << 2) | ((offset) << 7) })
+#define __pte_to_swp_entry(pte)		((swp_entry_t) { (pte).pte_high })
+#define __swp_entry_to_pte(x)		((pte_t) { 0, (x).val })
+
 #else
 /*
  * Constraints: