From: Sinan Kaya <okaya@codeaurora.org>
Date: Tue, 3 Apr 2018 12:55:03 +0000 (-0400)
Subject: MIPS: io: Prevent compiler reordering writeX()
X-Git-Tag: Ubuntu-4.15.0-37.40~275
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=b72b2ba92daa7fa6aeec5ef84eb6f52b66837523;p=mirror_ubuntu-bionic-kernel.git

MIPS: io: Prevent compiler reordering writeX()

BugLink: http://bugs.launchpad.net/bugs/1794889

[ Upstream commit f6b7aeee8f167409195fbf1364d02988fecad1d0 ]

writeX() has strong ordering semantics with respect to memory updates.
In the absence of a write barrier or a compiler barrier, the compiler
can reorder register and memory update instructions. This breaks the
writeX() API.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/18997/
[jhogan@kernel.org: Tidy commit message]
Signed-off-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---

diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 0cbf3af37eca..fd00ddafb425 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -307,7 +307,7 @@ static inline void iounmap(const volatile void __iomem *addr)
 #if defined(CONFIG_CPU_CAVIUM_OCTEON) || defined(CONFIG_LOONGSON3_ENHANCEMENT)
 #define war_io_reorder_wmb()		wmb()
 #else
-#define war_io_reorder_wmb()		do { } while (0)
+#define war_io_reorder_wmb()		barrier()
 #endif
 
 #define __BUILD_MEMORY_SINGLE(pfx, bwlq, type, irq)			\