linux-kernel - [RFC V1 23/31] um/mm: Enable ARCH_HAS_VM_GET_PAGE

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Date:   Mon, 24 Jan 2022 18:27:00 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, hch@...radead.org,
        akpm@...ux-foundation.org,
        Anshuman Khandual <anshuman.khandual@....com>,
        Jeff Dike <jdike@...toit.com>, linux-um@...ts.infradead.org
Subject: [RFC V1 23/31] um/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT

This defines and exports a platform specific custom vm_get_page_prot() via
subscribing ARCH_HAS_VM_GET_PAGE_PROT. Subsequently all __SXXX and __PXXX
macros can be dropped which are no longer needed.

Cc: Jeff Dike <jdike@...toit.com>
Cc: linux-um@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
 arch/um/Kconfig               |  1 +
 arch/um/include/asm/pgtable.h | 17 ---------------
 arch/um/kernel/mem.c          | 41 +++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 17 deletions(-)

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 4d398b80aea8..5836296868a8 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -9,6 +9,7 @@ config UML
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_STRNCPY_FROM_USER
 	select ARCH_HAS_STRNLEN_USER
+	select ARCH_HAS_VM_GET_PAGE_PROT
 	select ARCH_NO_PREEMPT
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_SECCOMP_FILTER
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index b9e20bbe2f75..d982622c0708 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -68,23 +68,6 @@ extern unsigned long end_iomem;
  * Also, write permissions imply read permissions. This is the closest we can
  * get..
  */
-#define __P000	PAGE_NONE
-#define __P001	PAGE_READONLY
-#define __P010	PAGE_COPY
-#define __P011	PAGE_COPY
-#define __P100	PAGE_READONLY
-#define __P101	PAGE_READONLY
-#define __P110	PAGE_COPY
-#define __P111	PAGE_COPY
-
-#define __S000	PAGE_NONE
-#define __S001	PAGE_READONLY
-#define __S010	PAGE_SHARED
-#define __S011	PAGE_SHARED
-#define __S100	PAGE_READONLY
-#define __S101	PAGE_READONLY
-#define __S110	PAGE_SHARED
-#define __S111	PAGE_SHARED
 
 /*
  * ZERO_PAGE is a global shared page that is always zero: used
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 15295c3237a0..1f53584ac361 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -197,3 +197,44 @@ void *uml_kmalloc(int size, int flags)
 {
 	return kmalloc(size, flags);
 }
+
+pgprot_t vm_get_page_prot(unsigned long vm_flags)
+{
+	switch (vm_flags & (VM_READ | VM_WRITE | VM_EXEC | VM_SHARED)) {
+	case VM_NONE:
+		return PAGE_NONE;
+	case VM_READ:
+		return PAGE_READONLY;
+	case VM_WRITE:
+		return PAGE_COPY;
+	case VM_READ | VM_WRITE:
+		return PAGE_COPY;
+	case VM_EXEC:
+		return PAGE_READONLY;
+	case VM_EXEC | VM_READ:
+		return PAGE_READONLY;
+	case VM_EXEC | VM_WRITE:
+		return PAGE_COPY;
+	case VM_EXEC | VM_READ | VM_WRITE:
+		return PAGE_COPY;
+	case VM_SHARED:
+		return PAGE_NONE;
+	case VM_SHARED | VM_READ:
+		return PAGE_READONLY;
+	case VM_SHARED | VM_WRITE:
+		return PAGE_SHARED;
+	case VM_SHARED | VM_READ | VM_WRITE:
+		return PAGE_SHARED;
+	case VM_SHARED | VM_EXEC:
+		return PAGE_READONLY;
+	case VM_SHARED | VM_EXEC | VM_READ:
+		return PAGE_READONLY;
+	case VM_SHARED | VM_EXEC | VM_WRITE:
+		return PAGE_SHARED;
+	case VM_SHARED | VM_EXEC | VM_READ | VM_WRITE:
+		return PAGE_SHARED;
+	default:
+		BUILD_BUG();
+	}
+}
+EXPORT_SYMBOL(vm_get_page_prot);
-- 
2.25.1