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Commit 76551468 authored by Eugeniy Paltsev's avatar Eugeniy Paltsev Committed by Vineet Gupta
Browse files

ARCv2: Add explcit unaligned access support (and ability to disable too) 



As of today we enable unaligned access unconditionally on ARCv2.
Do this under a Kconfig option to allow disable it for test, benchmarking
etc. Also while at it

  - Select HAVE_EFFICIENT_UNALIGNED_ACCESS
  - Although gcc defaults to unaligned access (since GNU 2018.03), add the
    right toggles for enabling or disabling as appropriate
  - update bootlog to prints both HW feature status (exists, enabled/disabled)
    and SW status (used / not used).
  - wire up the relaxed memcpy for unaligned access

Signed-off-by: default avatarEugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
[vgupta: squashed patches, handle gcc -mno-unaligned-access quick]
parent 4d1e7918

arch/arc/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -386,6 +386,15 @@ config ARC_HAS_SWAPE 


if ISA_ARCV2



config ARC_USE_UNALIGNED_MEM_ACCESS

	bool "Enable unaligned access in HW"

	default y

	select HAVE_EFFICIENT_UNALIGNED_ACCESS

	help

	  The ARC HS architecture supports unaligned memory access

	  which is disabled by default. Enable unaligned access in

	  hardware and use software to use it



config ARC_HAS_LL64

	bool "Insn: 64bit LDD/STD"

	help

arch/arc/Makefile

+6 −0
Original line number Diff line number Diff line
@@ -28,6 +28,12 @@ cflags-$(CONFIG_ARC_HAS_SWAPE) += -mswape 


ifdef CONFIG_ISA_ARCV2



ifdef CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS

cflags-y				+= -munaligned-access

else

cflags-y				+= -mno-unaligned-access

endif



ifndef CONFIG_ARC_HAS_LL64

cflags-y				+= -mno-ll64

endif

arch/arc/include/asm/arcregs.h

+1 −0
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ 
#define ECR_V_DTLB_MISS			0x05

#define ECR_V_PROTV			0x06

#define ECR_V_TRAP			0x09

#define ECR_V_MISALIGN			0x0d

#endif



/* DTLB Miss and Protection Violation Cause Codes */

arch/arc/include/asm/irqflags-arcv2.h

+7 −1
Original line number Diff line number Diff line
@@ -44,7 +44,13 @@ 
#define ARCV2_IRQ_DEF_PRIO	1



/* seed value for status register */

#define ISA_INIT_STATUS_BITS	(STATUS_IE_MASK | STATUS_AD_MASK | \

#ifdef CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS

#define __AD_ENB	STATUS_AD_MASK

#else

#define __AD_ENB	0

#endif



#define ISA_INIT_STATUS_BITS	(STATUS_IE_MASK | __AD_ENB | \

					(ARCV2_IRQ_DEF_PRIO << 1))



#ifndef __ASSEMBLY__

arch/arc/kernel/head.S

+5 −0
Original line number Diff line number Diff line
@@ -54,7 +54,12 @@ 
	; gcc 7.3.1 (ARC GNU 2018.03) onwards generates unaligned access

	; by default

	lr	r5, [status32]

#ifdef CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS

	bset	r5, r5, STATUS_AD_BIT

#else

	; Although disabled at reset, bootloader might have enabled it

	bclr	r5, r5, STATUS_AD_BIT

#endif

	kflag	r5

#endif

.endm