linux-kernel - [PATCH 7/7] RISC-V: Implement pte

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Date:   Wed, 27 Mar 2019 15:36:43 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Cc:     Stephen Bates <sbates@...thlin.com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Christoph Hellwig <hch@....de>,
        Albert Ou <aou@...s.berkeley.edu>,
        Logan Gunthorpe <logang@...tatee.com>,
        Laurent Dufour <ldufour@...ux.vnet.ibm.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Anup Patel <anup.patel@....com>, Zong Li <zong@...estech.com>,
        Guo Ren <ren_guo@...ky.com>,
        "Stefan O'Rear" <sorear2@...il.com>
Subject: [PATCH 7/7] RISC-V: Implement pte_devmap()

Use the 2nd software bit in the PTE as the devmap bit and add the
appropriate accessors.

This also allows us to set ARCH_HAS_ZONE_DEVICE.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Cc: Palmer Dabbelt <palmer@...ive.com>
Cc: Albert Ou <aou@...s.berkeley.edu>
Cc: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
Cc: Mike Rapoport <rppt@...ux.vnet.ibm.com>
Cc: Anup Patel <anup.patel@....com>
Cc: Zong Li <zong@...estech.com>
Cc: Guo Ren <ren_guo@...ky.com>
Cc: "Stefan O'Rear" <sorear2@...il.com>
---
 arch/riscv/Kconfig                    |  1 +
 arch/riscv/include/asm/pgtable-bits.h |  8 ++++++--
 arch/riscv/include/asm/pgtable.h      | 10 ++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 2cb39b4d6d6b..d365d7e17ed2 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -49,6 +49,7 @@ config RISCV
 	select GENERIC_IRQ_MULTI_HANDLER
 	select ARCH_HAS_PTE_SPECIAL
 	select HAVE_EBPF_JIT if 64BIT
+	select ARCH_HAS_ZONE_DEVICE
 
 config MMU
 	def_bool y
diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h
index 470755cb7558..9555d419a46f 100644
--- a/arch/riscv/include/asm/pgtable-bits.h
+++ b/arch/riscv/include/asm/pgtable-bits.h
@@ -30,9 +30,11 @@
 #define _PAGE_GLOBAL    (1 << 5)    /* Global */
 #define _PAGE_ACCESSED  (1 << 6)    /* Set by hardware on any access */
 #define _PAGE_DIRTY     (1 << 7)    /* Set by hardware on any write */
-#define _PAGE_SOFT      (1 << 8)    /* Reserved for software */
+#define _PAGE_SOFT1     (1 << 8)    /* Reserved for software */
+#define _PAGE_SOFT2     (1 << 9)    /* Reserved for software */
 
-#define _PAGE_SPECIAL   _PAGE_SOFT
+#define _PAGE_SPECIAL   _PAGE_SOFT1
+#define _PAGE_DEVMAP	_PAGE_SOFT2
 #define _PAGE_TABLE     _PAGE_PRESENT
 
 /*
@@ -41,6 +43,8 @@
  */
 #define _PAGE_PROT_NONE _PAGE_READ
 
+#define __HAVE_ARCH_PTE_DEVMAP
+
 #define _PAGE_PFN_SHIFT 10
 
 /* Set of bits to preserve across pte_modify() */
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index e071e2be3a6c..a0e6a5f8bbb5 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -248,6 +248,11 @@ static inline int pte_special(pte_t pte)
 	return pte_val(pte) & _PAGE_SPECIAL;
 }
 
+static inline int pte_devmap(pte_t pte)
+{
+	return pte_val(pte) & _PAGE_DEVMAP;
+}
+
 /* static inline pte_t pte_rdprotect(pte_t pte) */
 
 static inline pte_t pte_wrprotect(pte_t pte)
@@ -289,6 +294,11 @@ static inline pte_t pte_mkspecial(pte_t pte)
 	return __pte(pte_val(pte) | _PAGE_SPECIAL);
 }
 
+static inline pte_t pte_mkdevmap(pte_t pte)
+{
+	return __pte(pte_val(pte) | _PAGE_SPECIAL | _PAGE_DEVMAP);
+}
+
 /* Modify page protection bits */
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
-- 
2.20.1