[OpenWrt-Devel] [PATCH] arc770: enable unaligned access handling simulation in software

[Alexey Brodkin]

This enables misaligned access handling by software in Linux kernel.

With some wireless drivers (ath9k-htc and mt7601u for example) we see
misaligned accesses here and there and to cope with that without
fixing stuff in the drivers we're just gracefully handling it on ARC.

Signed-off-by: Alexey Brodkin <abrodkin at synopsys.com>
---
 target/linux/arc770/config-4.4                     |  5 ++--
 ...rc-enable-unaligned-access-in-kernel-mode.patch | 31 ++++++++++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 target/linux/generic/patches-4.4/333-arc-enable-unaligned-access-in-kernel-mode.patch

diff --git a/target/linux/arc770/config-4.4 b/target/linux/arc770/config-4.4
index c8f021d..87fd7e3 100644
--- a/target/linux/arc770/config-4.4
+++ b/target/linux/arc770/config-4.4
@@ -19,7 +19,7 @@ CONFIG_ARC_DBG=y
 # CONFIG_ARC_DBG_TLB_MISS_COUNT is not set
 # CONFIG_ARC_DBG_TLB_PARANOIA is not set
 CONFIG_ARC_DW2_UNWIND=y
-# CONFIG_ARC_EMUL_UNALIGNED is not set
+CONFIG_ARC_EMUL_UNALIGNED=y
 # CONFIG_ARC_FPU_SAVE_RESTORE is not set
 CONFIG_ARC_HAS_DCACHE=y
 # CONFIG_ARC_HAS_DCCM is not set
@@ -162,7 +162,8 @@ CONFIG_SRCU=y
 CONFIG_STACKTRACE=y
 CONFIG_STMMAC_ETH=y
 CONFIG_STMMAC_PLATFORM=y
-# CONFIG_SUNXI_SRAM is not set
+CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW=y
+CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN=y
 CONFIG_TICK_CPU_ACCOUNTING=y
 CONFIG_UNINLINE_SPIN_UNLOCK=y
 CONFIG_USB_SUPPORT=y
diff --git a/target/linux/generic/patches-4.4/333-arc-enable-unaligned-access-in-kernel-mode.patch b/target/linux/generic/patches-4.4/333-arc-enable-unaligned-access-in-kernel-mode.patch
new file mode 100644
index 0000000..76a9ce8
--- /dev/null
+++ b/target/linux/generic/patches-4.4/333-arc-enable-unaligned-access-in-kernel-mode.patch
@@ -0,0 +1,31 @@
+From af737b55fc7c61f17da9ae89fba536e0a9338e98 Mon Sep 17 00:00:00 2001
+From: Alexey Brodkin <abrodkin at synopsys.com>
+Date: Mon, 14 Mar 2016 17:26:34 +0300
+Subject: [PATCH] arc: enable unaligned access in kernel mode
+
+This enables misaligned access handling even in kernel mode.
+Some wireless drivers (ath9k-htc and mt7601u) use misaligned accesses
+here and there and to cope with that without fixing stuff in the drivers
+we're just gracefully handling it on ARC.
+
+Signed-off-by: Alexey Brodkin <abrodkin at synopsys.com>
+---
+ arch/arc/kernel/unaligned.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c
+index abd961f..0b0cc97 100644
+--- a/arch/arc/kernel/unaligned.c
++++ b/arch/arc/kernel/unaligned.c
+@@ -206,7 +206,7 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs,
+ 	char buf[TASK_COMM_LEN];
+ 
+ 	/* handle user mode only and only if enabled by sysadmin */
+-	if (!user_mode(regs) || !unaligned_enabled)
++	if (!unaligned_enabled)
+ 		return 1;
+ 
+ 	if (no_unaligned_warning) {
+-- 
+2.5.0
+
-- 
2.5.0
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