Commit b4171fd0 authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Arnd Bergmann
Browse files

ARC: Always use SWAPE instructions for __arch_swab32() 



Since commit 67a697e7576 ("ARC: retire ARC750 support") all supported
CPUs have the 'swape' instruction.

Always use the implementation of __arch_swabe() which uses 'swape'.
ARCH_USE_BUILTIN_BSWAP can not be used as that results on libcalls on
-mcpu=arc700.

As as side-effect, remove a leak of an internal kconfig symbol through
the UAPI headers.

Suggested-by: default avatarArnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/0ae2688a-5a22-405b-adaf-9b5ad712b245@app.fastmail.com/


Suggested-by: default avatarVineet Gupta <vgupta@kernel.org>
Link: https://lore.kernel.org/lkml/a033a402-e3c5-4982-9fff-b6a4c55817ae@kernel.org/


Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent eed444d0

arch/arc/Kconfig

+0 −5
Original line number Diff line number Diff line
@@ -121,7 +121,6 @@ choice 
config ARC_CPU_770

	bool "ARC770"

	depends on ISA_ARCOMPACT

	select ARC_HAS_SWAPE

	help

	  Support for ARC770 core introduced with Rel 4.10 (Summer 2011)

	  This core has a bunch of cool new features:
@@ -340,10 +339,6 @@ config ARC_HAS_LLSC 
	default y

	depends on !ARC_CANT_LLSC



config ARC_HAS_SWAPE

	bool "Insn: SWAPE (endian-swap)"

	default y



if ISA_ARCV2



config ARC_USE_UNALIGNED_MEM_ACCESS

arch/arc/Makefile

+1 −2
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ ifeq ($(CROSS_COMPILE),) 
CROSS_COMPILE := $(call cc-cross-prefix, arc-linux- arceb-linux- arc-linux-gnu-)

endif



cflags-y	+= -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__

cflags-y	+= -fno-common -pipe -fno-builtin -mmedium-calls -mswape -D__linux__



tune-mcpu-def-$(CONFIG_ISA_ARCOMPACT)	:= -mcpu=arc700

tune-mcpu-def-$(CONFIG_ISA_ARCV2)	:= -mcpu=hs38
@@ -41,7 +41,6 @@ endif 
cflags-y				+= -fsection-anchors



cflags-$(CONFIG_ARC_HAS_LLSC)		+= -mlock

cflags-$(CONFIG_ARC_HAS_SWAPE)		+= -mswape



ifdef CONFIG_ISA_ARCV2

arch/arc/include/uapi/asm/swab.h

+0 −63
Original line number Diff line number Diff line
@@ -19,9 +19,6 @@ 


#include <linux/types.h>



/* Native single cycle endian swap insn */

#ifdef CONFIG_ARC_HAS_SWAPE



#define __arch_swab32(x)		\

({					\

	unsigned int tmp = x;		\
@@ -32,66 +29,6 @@ 
	tmp;				\

})



#else



/* Several ways of Endian-Swap Emulation for ARC

 * 0: kernel generic

 * 1: ARC optimised "C"

 * 2: ARC Custom instruction

 */

#define ARC_BSWAP_TYPE	1



#if (ARC_BSWAP_TYPE == 1)		/******* Software only ********/



/* The kernel default implementation of htonl is

 *		return  x<<24 | x>>24 |

 *		 (x & (__u32)0x0000ff00UL)<<8 | (x & (__u32)0x00ff0000UL)>>8;

 *

 * This generates 9 instructions on ARC (excluding the ld/st)

 *

 * 8051fd8c:	ld     r3,[r7,20]	; Mem op : Get the value to be swapped

 * 8051fd98:	asl    r5,r3,24		; get  3rd Byte

 * 8051fd9c:	lsr    r2,r3,24		; get  0th Byte

 * 8051fda0:	and    r4,r3,0xff00

 * 8051fda8:	asl    r4,r4,8		; get 1st Byte

 * 8051fdac:	and    r3,r3,0x00ff0000

 * 8051fdb4:	or     r2,r2,r5		; combine 0th and 3rd Bytes

 * 8051fdb8:	lsr    r3,r3,8		; 2nd Byte at correct place in Dst Reg

 * 8051fdbc:	or     r2,r2,r4		; combine 0,3 Bytes with 1st Byte

 * 8051fdc0:	or     r2,r2,r3		; combine 0,3,1 Bytes with 2nd Byte

 * 8051fdc4:	st     r2,[r1,20]	; Mem op : save result back to mem

 *

 * Joern suggested a better "C" algorithm which is great since

 * (1) It is portable to any architecture

 * (2) At the same time it takes advantage of ARC ISA (rotate intrns)

 */



#define __arch_swab32(x)					\

({	unsigned long __in = (x), __tmp;			\

	__tmp = __in << 8 | __in >> 24; /* ror tmp,in,24 */	\

	__in = __in << 24 | __in >> 8; /* ror in,in,8 */	\

	__tmp ^= __in;						\

	__tmp &= 0xff00ff;					\

	__tmp ^ __in;						\

})



#elif (ARC_BSWAP_TYPE == 2)	/* Custom single cycle bswap instruction */



#define __arch_swab32(x)						\

({									\

	unsigned int tmp = x;						\

	__asm__(							\

	"	.extInstruction	bswap, 7, 0x00, SUFFIX_NONE, SYNTAX_2OP	\n"\

	"	bswap  %0, %1						\n"\

	: "=r" (tmp)							\

	: "r" (tmp));							\

	tmp;								\

})



#endif /* ARC_BSWAP_TYPE=zzz */



#endif /* CONFIG_ARC_HAS_SWAPE */



#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)

#define __SWAB_64_THRU_32__

#endif

scripts/headers_install.sh

+0 −1
Original line number Diff line number Diff line
@@ -70,7 +70,6 @@ configs=$(sed -e ' 
#

# The format is <file-name>:<CONFIG-option> in each line.

config_leak_ignores="

arch/arc/include/uapi/asm/swab.h:CONFIG_ARC_HAS_SWAPE

arch/arm/include/uapi/asm/ptrace.h:CONFIG_CPU_ENDIAN_BE8

arch/nios2/include/uapi/asm/swab.h:CONFIG_NIOS2_CI_SWAB_NO

arch/nios2/include/uapi/asm/swab.h:CONFIG_NIOS2_CI_SWAB_SUPPORT