linux-kernel - [PATCH 3.16 154/204] MIPS: Fix CM region target definitions

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Message-ID: <lsq.1514480744.561600054@decadent.org.uk>
Date:   Thu, 28 Dec 2017 17:05:44 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, linux-mips@...ux-mips.org,
        "Matt Redfearn" <matt.redfearn@...s.com>,
        "James Hogan" <jhogan@...nel.org>,
        "Ralf Baechle" <ralf@...ux-mips.org>,
        "Paul Burton" <paul.burton@...s.com>
Subject: [PATCH 3.16 154/204] MIPS: Fix CM region target definitions

3.16.52-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Burton <paul.burton@...s.com>

commit 6a6cba1d945a7511cdfaf338526871195e420762 upstream.

The default CM target field in the GCR_BASE register is encoded with 0
meaning memory & 1 being reserved. However the definitions we use for
those bits effectively get these two values backwards - likely because
they were copied from the definitions for the CM regions where the
target is encoded differently. This results in use setting up GCR_BASE
with the reserved target value by default, rather than targeting memory
as intended. Although we currently seem to get away with this it's not a
great idea to rely upon.

Fix this by changing our macros to match the documentated target values.

The incorrect encoding became used as of commit 9f98f3dd0c51 ("MIPS: Add
generic CM probe & access code") in the Linux v3.15 cycle, and was
likely carried forwards from older but unused code introduced by
commit 39b8d5254246 ("[MIPS] Add support for MIPS CMP platform.") in the
v2.6.26 cycle.

Fixes: 9f98f3dd0c51 ("MIPS: Add generic CM probe & access code")
Signed-off-by: Paul Burton <paul.burton@...s.com>
Reported-by: Matt Redfearn <matt.redfearn@...s.com>
Reviewed-by: James Hogan <jhogan@...nel.org>
Cc: Matt Redfearn <matt.redfearn@...s.com>
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: linux-mips@...ux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17562/
Signed-off-by: James Hogan <jhogan@...nel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/mips/include/asm/mips-cm.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/mips/include/asm/mips-cm.h
+++ b/arch/mips/include/asm/mips-cm.h
@@ -173,8 +173,8 @@ BUILD_CM_Cx_R_(tcid_8_priority,	0x80)
 #define CM_GCR_BASE_GCRBASE_MSK			(_ULCAST_(0x1ffff) << 15)
 #define CM_GCR_BASE_CMDEFTGT_SHF		0
 #define CM_GCR_BASE_CMDEFTGT_MSK		(_ULCAST_(0x3) << 0)
-#define  CM_GCR_BASE_CMDEFTGT_DISABLED		0
-#define  CM_GCR_BASE_CMDEFTGT_MEM		1
+#define  CM_GCR_BASE_CMDEFTGT_MEM		0
+#define  CM_GCR_BASE_CMDEFTGT_RESERVED		1
 #define  CM_GCR_BASE_CMDEFTGT_IOCU0		2
 #define  CM_GCR_BASE_CMDEFTGT_IOCU1		3