This is a note to let you know that I've just added the patch titled
ARC: Add missing io barriers to io{read,write}{16,32}be()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arc-add-missing-io-barriers-to-io-read-write-16-32-be.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e5bc0478ab6cf565619224536d75ecb2aedca43b Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Date: Thu, 5 May 2016 13:32:34 +0530
Subject: ARC: Add missing io barriers to io{read,write}{16,32}be()
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
commit e5bc0478ab6cf565619224536d75ecb2aedca43b upstream.
While reviewing a different change to asm-generic/io.h Arnd spotted that
ARC ioread32 and ioread32be both of which come from asm-generic versions
are not symmetrical in terms of calling the io barriers.
generic ioread32 -> ARC readl() [ has barriers]
generic ioread32be -> __be32_to_cpu(__raw_readl()) [ lacks barriers]
While generic ioread32be is being remediated to call readl(), that involves
a swab32(), causing double swaps on ioread32be() on Big Endian systems.
So provide our versions of big endian IO accessors to ensure io barrier
calls while also keeping them optimal
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arc/include/asm/io.h | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
--- a/arch/arc/include/asm/io.h
+++ b/arch/arc/include/asm/io.h
@@ -13,6 +13,15 @@
#include <asm/byteorder.h>
#include <asm/page.h>
+#ifdef CONFIG_ISA_ARCV2
+#include <asm/barrier.h>
+#define __iormb() rmb()
+#define __iowmb() wmb()
+#else
+#define __iormb() do { } while (0)
+#define __iowmb() do { } while (0)
+#endif
+
extern void __iomem *ioremap(unsigned long physaddr, unsigned long size);
extern void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
unsigned long flags);
@@ -22,6 +31,15 @@ extern void iounmap(const void __iomem *
#define ioremap_wc(phy, sz) ioremap(phy, sz)
#define ioremap_wt(phy, sz) ioremap(phy, sz)
+/*
+ * io{read,write}{16,32}be() macros
+ */
+#define ioread16be(p) ({ u16 __v = be16_to_cpu((__force __be16)__raw_readw(p)); __iormb(); __v; })
+#define ioread32be(p) ({ u32 __v = be32_to_cpu((__force __be32)__raw_readl(p)); __iormb(); __v; })
+
+#define iowrite16be(v,p) ({ __iowmb(); __raw_writew((__force u16)cpu_to_be16(v), p); })
+#define iowrite32be(v,p) ({ __iowmb(); __raw_writel((__force u32)cpu_to_be32(v), p); })
+
/* Change struct page to physical address */
#define page_to_phys(page) (page_to_pfn(page) << PAGE_SHIFT)
@@ -99,15 +117,6 @@ static inline void __raw_writel(u32 w, v
}
-#ifdef CONFIG_ISA_ARCV2
-#include <asm/barrier.h>
-#define __iormb() rmb()
-#define __iowmb() wmb()
-#else
-#define __iormb() do { } while (0)
-#define __iowmb() do { } while (0)
-#endif
-
/*
* MMIO can also get buffered/optimized in micro-arch, so barriers needed
* Based on ARM model for the typical use case
Patches currently in stable-queue which might be from vgupta@xxxxxxxxxxxx are
queue-4.4/arc-add-missing-io-barriers-to-io-read-write-16-32-be.patch
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