linux-kernel - [PATCH] csky: Fixup io-range page attribute for mmap("/dev/mem")

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Date:   Wed, 30 Jan 2019 20:33:49 +0800
From:   guoren@...nel.org
To:     arnd@...db.de
Cc:     linux-kernel@...r.kernel.org, guoren@...nel.org,
        linux-arch@...r.kernel.org, xiaodong.fan@...ahualu.com,
        Guo Ren <ren_guo@...ky.com>
Subject: [PATCH] csky: Fixup io-range page attribute for mmap("/dev/mem")

From: Guo Ren <ren_guo@...ky.com>

Some user space drivers need accessing IO address and IO remap need
SO(strong order) page-attribute to make IO operation correct. So we
need add SO-page-attr for all non-memory address.

Signed-off-by: Guo Ren <ren_guo@...ky.com>
Reported-by: Fan Xiaodong <xiaodong.fan@...ahualu.com>
---
 arch/csky/include/asm/pgtable.h |  5 +++++
 arch/csky/mm/ioremap.c          | 14 ++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgtable.h
index af7a7fa..dcea277 100644
--- a/arch/csky/include/asm/pgtable.h
+++ b/arch/csky/include/asm/pgtable.h
@@ -241,6 +241,11 @@ static inline pte_t pte_mkyoung(pte_t pte)
 
 #define pgd_index(address)	((address) >> PGDIR_SHIFT)
 
+#define __HAVE_PHYS_MEM_ACCESS_PROT
+struct file;
+extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
+				     unsigned long size, pgprot_t vma_prot);
+
 /*
  * Macro to make mark a page protection value as "uncacheable".  Note
  * that "protection" is really a misnomer here as the protection value
diff --git a/arch/csky/mm/ioremap.c b/arch/csky/mm/ioremap.c
index cb7c03e..8473b6b 100644
--- a/arch/csky/mm/ioremap.c
+++ b/arch/csky/mm/ioremap.c
@@ -46,3 +46,17 @@ void iounmap(void __iomem *addr)
 	vunmap((void *)((unsigned long)addr & PAGE_MASK));
 }
 EXPORT_SYMBOL(iounmap);
+
+pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
+			      unsigned long size, pgprot_t vma_prot)
+{
+	if (!pfn_valid(pfn)) {
+		vma_prot.pgprot |= _PAGE_SO;
+		return pgprot_noncached(vma_prot);
+	} else if (file->f_flags & O_SYNC) {
+		return pgprot_noncached(vma_prot);
+	}
+
+	return vma_prot;
+}
+EXPORT_SYMBOL(phys_mem_access_prot);
-- 
2.7.4