From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932329Ab3BIBPm (ORCPT ); Fri, 8 Feb 2013 20:15:42 -0500 Received: from va3ehsobe002.messaging.microsoft.com ([216.32.180.12]:15222 "EHLO va3outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932195Ab3BIBPk (ORCPT ); Fri, 8 Feb 2013 20:15:40 -0500 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: 0 X-BigFish: VS0(zz98dI936eI1432I4015Ib922lzz1f42h1ee6h1de0h1202h1e76h1d1ah1d2ahzz8275chz2dh2a8h668h839h944hd24he5bhf0ah1220h1288h12a5h12a9h12bdh137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1155h) Date: Fri, 8 Feb 2013 19:12:08 -0600 From: Kim Phillips To: Nicolas Pitre CC: "Woodhouse, David" , Russell King - ARM Linux , Borislav Petkov , Andrew Morton , Daniel Santos , David Rientjes , Rusty Russell , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Rob Herring Subject: Re: [RFC] arm: use built-in byte swap function Message-ID: <20130208191208.2ef3d78bda71aa7b44d00d7b@freescale.com> In-Reply-To: References: <20130129181046.GC25415@pd.tnic> <1359541333.3529.186.camel@shinybook.infradead.org> <20130130200900.9d7cf7908caeaef4ecee1d61@freescale.com> <20130131092801.GV23505@n2100.arm.linux.org.uk> <20130131145947.f62474a0600848df86548b96@freescale.com> <20130201011712.GF23505@n2100.arm.linux.org.uk> <1359703995.23531.6.camel@shinybook.infradead.org> <20130205210436.670c62e26d2121330e87af35@freescale.com> <1360141322.6066.4.camel@shinybook.infradead.org> <20130206191905.ac8eb6743e69425f30888704@freescale.com> <20130207181315.GM17833@n2100.arm.linux.org.uk> <1360344301.6066.263.camel@shinybook.infradead.org> <1360363233.6066.283.camel@shinybook.infradead.org> Organization: Freescale Semiconductor, Inc. X-Mailer: Sylpheed 3.2.0 (GTK+ 2.24.13; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 8 Feb 2013 17:47:33 -0500 Nicolas Pitre wrote: > On Fri, 8 Feb 2013, Woodhouse, David wrote: > > > On Fri, 2013-02-08 at 15:04 -0500, Nicolas Pitre wrote: > > > On Fri, 8 Feb 2013, Woodhouse, David wrote: > > > > > > > On Thu, 2013-02-07 at 18:13 +0000, Russell King - ARM Linux wrote: > > > > > > > > > > However, the biggest reason not to use libgcc is that we want to control > > > > > what gets used in the kernel - for example, no floating point, and no > > > > > use of 64 x 64bit division. > > > > > > > > Which is all very sensible. But there's no particular reason we couldn't > > > > add a __bswap[sd]i2 to the kernel's version of libgcc if we wanted to. > > > > > > Absolutely. > > > > And then ARM can just set ARCH_USE_BUILTIN_BSWAP like other > > architectures do, right? > > If that turns out to be beneficial over what we have now, then yes. > I didn't read back the whole thread to form an opinion though. The diff below implements __bswap[sd]i2 in arch/arm/lib, and results in the following savings in vmlinux size: column 1: name of defconfig column 2: text+data+bss, linux-next-20130207 vanilla, gcc 4.6.3 column 3: text+data+bss, linux-next-20130207+below diff, gcc 4.6.3 column 4: col. 3 - col. 2 (ie., -ve numbers represent savings) acs5k_tiny_defconfig: 2886048 2886016 -32 ag5evm_defconfig: 2767596 2767564 -32 am200epdkit_defconfig: 3283557 3283557 0 ap4evb_defconfig: 2059540 2059524 -16 armadillo800eva_defconfig: 4521440 4521200 -240 assabet_defconfig: 3562923 3562603 -320 at91_dt_defconfig: 4195020 4189164 -5856 at91rm9200_defconfig: 5804566 5803742 -824 at91sam9261_defconfig: 4726625 4725969 -656 at91sam9263_defconfig: 5115407 5114459 -948 at91sam9g20_defconfig: 4175306 4175138 -168 at91x40_defconfig: 1344264 1344256 -8 badge4_defconfig: 3359661 3359485 -176 bcm_defconfig: 3575901 3575757 -144 bonito_defconfig: 2221729 2221681 -48 cerfcube_defconfig: 3063610 3063370 -240 cns3420vb_defconfig: 2595667 2595651 -16 collie_defconfig: 3015148 3014972 -176 da8xx_omapl_defconfig: 4168517 4168165 -352 davinci_all_defconfig: 4060434 4060110 -324 dove_defconfig: 4940257 4939245 -1012 ebsa110_defconfig: 3236795 3236587 -208 ep93xx_defconfig: 4169466 4168986 -480 eseries_pxa_defconfig: 3090656 3090448 -208 exynos4_defconfig: 3008671 3008639 -32 ezx_defconfig: 10042035 10041835 -200 footbridge_defconfig: 3662497 3662369 -128 h3600_defconfig: 3471140 3470820 -320 h5000_defconfig: 2976046 2976030 -16 h7201_defconfig: 2158753 2158705 -48 h7202_defconfig: 3395888 3395520 -368 hackkit_defconfig: 3128690 3128578 -112 imote2_defconfig: 9916412 9916180 -232 imx_v4_v5_defconfig: 6866952 6866272 -680 imx_v6_v7_defconfig: 7672373 7667089 -5284 integrator_defconfig: 4224588 4224284 -304 iop13xx_defconfig: 5229604 5228468 -1136 iop32x_defconfig: 5616676 5615492 -1184 iop33x_defconfig: 4611219 4610835 -384 ixp4xx_defconfig: 4566094 4564238 -1856 jornada720_defconfig: 3140569 3140345 -224 kota2_defconfig: 3971280 3971280 0 kzm9d_defconfig: 3042784 3042784 0 kzm9g_defconfig: 4728939 4728907 -32 lart_defconfig: 2941150 2941054 -96 lpc32xx_defconfig: 5009215 5004619 -4596 mackerel_defconfig: 4687162 4686922 -240 mini2440_defconfig: 5095413 5095037 -376 msm_defconfig: 2920312 2920224 -88 multi_v7_defconfig: 3511744 3511712 -32 mvebu_defconfig: 3871035 3870931 -104 mxs_defconfig: 11091983 11095679 3696 netwinder_defconfig: 3814476 3814124 -352 nhk8815_defconfig: 4277138 4276778 -360 nuc910_defconfig: 2527988 2527956 -32 nuc950_defconfig: 2634352 2634312 -40 nuc960_defconfig: 2546592 2546552 -40 omap2plus_defconfig: 13801444 13800144 -1300 palmz72_defconfig: 3345726 3345758 32 pcm027_defconfig: 3634230 3634158 -72 pleb_defconfig: 2847643 2847515 -128 prima2_defconfig: 3080439 3080347 -92 pxa3xx_defconfig: 4266677 4266457 -220 realview_defconfig: 3891673 3891465 -208 realview-smp_defconfig: 4157253 4157045 -208 rpc_defconfig: 3974677 3974661 -16 s3c2410_defconfig: 5217336 5217000 -336 s3c6400_defconfig: 3209178 3209178 0 s5p64x0_defconfig: 2843307 2843275 -32 s5pc100_defconfig: 2696641 2696657 16 shannon_defconfig: 3586908 3586636 -272 shark_defconfig: 3565471 3565423 -48 simpad_defconfig: 3681433 3681161 -272 socfpga_defconfig: 4326480 4326408 -72 spear13xx_defconfig: 4062410 4062378 -32 spear6xx_defconfig: 3457392 3457360 -32 tct_hammer_defconfig: 2406856 2406824 -32 trizeps4_defconfig: 5869063 5868483 -580 u300_defconfig: 2627488 2627488 0 versatile_defconfig: 3789155 3788787 -368 vexpress_defconfig: 5105737 5105489 -248 viper_defconfig: 3309176 3308920 -256 xcep_defconfig: 2820463 2820367 -96 zeus_defconfig: 3775525 3775367 -158 gcc 4.7.3 runs haven't been as good across the board as gcc 4.6.3, however: acs5k_tiny_defconfig: 2873380 2873330 -50 ag5evm_defconfig: 2753016 2753128 112 am200epdkit_defconfig: 3274245 3274295 50 ap4evb_defconfig: 2051952 2051944 -8 armadillo800eva_defconfig: 4531864 4531718 -146 assabet_defconfig: 3540515 3540337 -178 at91_dt_defconfig: 4211064 4205394 -5670 at91rm9200_defconfig: 5785930 5785368 -562 at91sam9261_defconfig: 4705357 4705139 -218 at91sam9263_defconfig: 5098831 5098501 -330 at91sam9g20_defconfig: 4163686 4163576 -110 at91sam9g45_defconfig: 4675215 4669553 -5662 at91x40_defconfig: 1342256 1342192 -64 badge4_defconfig: 3338677 3338615 -62 bcm_defconfig: 3568365 3568259 -106 bonito_defconfig: 2225353 2225355 2 cerfcube_defconfig: 3043650 3043556 -94 cns3420vb_defconfig: 2589035 2589049 14 collie_defconfig: 2994100 2993972 -128 da8xx_omapl_defconfig: 4155189 4155047 -142 davinci_all_defconfig: 4043450 4043304 -146 dove_defconfig: 4902213 4901627 -586 ebsa110_defconfig: 3216131 3215953 -178 ep93xx_defconfig: 4154038 4153796 -242 eseries_pxa_defconfig: 3076688 3076610 -78 exynos4_defconfig: 3001451 3001465 14 ezx_defconfig: 10022647 10022553 -94 footbridge_defconfig: 3640857 3640763 -94 h3600_defconfig: 3453932 3453722 -210 h5000_defconfig: 2963034 2963036 2 h7201_defconfig: 2148969 2148987 18 h7202_defconfig: 3376072 3375894 -178 hackkit_defconfig: 3107994 3107916 -78 imote2_defconfig: 9899372 9899278 -94 imx_v4_v5_defconfig: 6834892 6834338 -554 imx_v6_v7_defconfig: 7637605 7636935 -670 integrator_defconfig: 4204944 4204674 -270 iop13xx_defconfig: 5193128 5192790 -338 iop32x_defconfig: 5576144 5575758 -386 iop33x_defconfig: 4584683 4584585 -98 ixp4xx_defconfig: 4546578 4545176 -1402 jornada720_defconfig: 3121377 3121299 -78 kota2_defconfig: 3951220 3951220 0 kzm9d_defconfig: 3055284 3055252 -32 kzm9g_defconfig: 4742195 4742161 -34 lart_defconfig: 2922550 2926600 4050 lpc32xx_defconfig: 5036722 5032072 -4650 mackerel_defconfig: 4660786 4660612 -174 mini2440_defconfig: 5074529 5074231 -298 msm_defconfig: 2911200 2911240 40 multi_v7_defconfig: 3502888 3502824 -64 mvebu_defconfig: 3853083 3853165 82 mxs_defconfig: 11071139 11070893 -246 netwinder_defconfig: 3791108 3790884 -224 netx_defconfig: 3951133 3950911 -222 nhk8815_defconfig: 4259910 4259696 -214 nuc910_defconfig: 2523448 2523408 -40 nuc950_defconfig: 2633644 2633604 -40 nuc960_defconfig: 2541916 2541876 -40 omap2plus_defconfig: 13770376 13770026 -350 palmz72_defconfig: 3335850 3335868 18 pcm027_defconfig: 3615962 3615896 -66 pleb_defconfig: 2828707 2828753 46 prima2_defconfig: 3021195 3021213 18 pxa3xx_defconfig: 4250245 4250135 -110 realview_defconfig: 3874745 3874791 46 realview-smp_defconfig: 4144973 4145051 78 rpc_defconfig: 3952749 3952831 82 s3c2410_defconfig: 5191024 5195006 3982 s3c6400_defconfig: 3208530 3208548 18 s5p64x0_defconfig: 2837611 2837625 14 s5pc100_defconfig: 2689877 2689895 18 shannon_defconfig: 3567412 3567234 -178 shark_defconfig: 3548103 3548149 46 simpad_defconfig: 3657889 3657763 -126 socfpga_defconfig: 4287524 4287610 86 spear13xx_defconfig: 4040898 4044932 4034 spear6xx_defconfig: 3446968 3446998 30 tct_hammer_defconfig: 2394112 2394126 14 trizeps4_defconfig: 5846883 5846505 -378 u300_defconfig: 2622856 2622934 78 versatile_defconfig: 3766635 3766409 -226 vexpress_defconfig: 5076237 5076279 42 viper_defconfig: 3293388 3293294 -94 xcep_defconfig: 2804423 2808549 4126 zeus_defconfig: 3760613 3760539 -74 Haven't looked at why. In any case, some questions I have are: (a) are the __bswap[sd]i2 implementations acceptable written in C, as in the diff? I don't speak ARM asm (yet at least). The generated code looks pretty optimal in both armv5 and 6+. (b) would adding __bswap[sd]i2 to the kernel build need to be disabled on armv6+? AFAICT, gcc doesn't emit calls - even for the 8-byte swap, even with -Os, on armv6+. (c) testing allyesconfigs is proving to be a pain - lots of breakeage - other than defconfig testing, is there any more I can do? Thanks, and for your patience, Kim diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 4265a26..5e8b735 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -58,6 +58,7 @@ config ARM select CLONE_BACKWARDS select OLD_SIGSUSPEND3 select OLD_SIGACTION + select ARCH_USE_BUILTIN_BSWAP help The ARM series is a line of low-power-consumption RISC chip designs licensed by ARM Ltd and targeted at embedded applications and diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index c9865f6..c225624 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -111,12 +111,12 @@ endif targets := vmlinux vmlinux.lds \ piggy.$(suffix_y) piggy.$(suffix_y).o \ - lib1funcs.o lib1funcs.S ashldi3.o ashldi3.S \ + lib1funcs.o lib1funcs.S ashldi3.o ashldi3.S bswapsdi2.o \ font.o font.c head.o misc.o $(OBJS) # Make sure files are removed during clean extra-y += piggy.gzip piggy.lzo piggy.lzma piggy.xzkern \ - lib1funcs.S ashldi3.S $(libfdt) $(libfdt_hdrs) + lib1funcs.S ashldi3.S bswapsdi2.o $(libfdt) $(libfdt_hdrs) ifeq ($(CONFIG_FUNCTION_TRACER),y) ORIG_CFLAGS := $(KBUILD_CFLAGS) @@ -158,6 +158,12 @@ ashldi3 = $(obj)/ashldi3.o $(obj)/ashldi3.S: $(srctree)/arch/$(SRCARCH)/lib/ashldi3.S $(call cmd,shipped) +# For __bswapsi2, __bswapdi2 +bswapsdi2 = $(obj)/bswapsdi2.o + +$(obj)/bswapsdi2.o: $(srctree)/arch/$(SRCARCH)/lib/bswapsdi2.o + $(call cmd,shipped) + # We need to prevent any GOTOFF relocs being used with references # to symbols in the .bss section since we cannot relocate them # independently from the rest at run time. This can be achieved by @@ -179,7 +185,8 @@ if [ $(words $(ZRELADDR)) -gt 1 -a "$(CONFIG_AUTO_ZRELADDR)" = "" ]; then \ fi $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.$(suffix_y).o \ - $(addprefix $(obj)/, $(OBJS)) $(lib1funcs) $(ashldi3) FORCE + $(addprefix $(obj)/, $(OBJS)) $(lib1funcs) $(ashldi3) \ + $(bswapsdi2) FORCE @$(check_for_multiple_zreladdr) $(call if_changed,ld) @$(check_for_bad_syms) diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c index 60d3b73..ba578f7 100644 --- a/arch/arm/kernel/armksyms.c +++ b/arch/arm/kernel/armksyms.c @@ -35,6 +35,8 @@ extern void __ucmpdi2(void); extern void __udivsi3(void); extern void __umodsi3(void); extern void __do_div64(void); +extern void __bswapsi2(void); +extern void __bswapdi2(void); extern void __aeabi_idiv(void); extern void __aeabi_idivmod(void); @@ -114,6 +116,8 @@ EXPORT_SYMBOL(__ucmpdi2); EXPORT_SYMBOL(__udivsi3); EXPORT_SYMBOL(__umodsi3); EXPORT_SYMBOL(__do_div64); +EXPORT_SYMBOL(__bswapsi2); +EXPORT_SYMBOL(__bswapdi2); #ifdef CONFIG_AEABI EXPORT_SYMBOL(__aeabi_idiv); diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile index af72969..5383df7 100644 --- a/arch/arm/lib/Makefile +++ b/arch/arm/lib/Makefile @@ -13,7 +13,7 @@ lib-y := backtrace.o changebit.o csumipv6.o csumpartial.o \ ashldi3.o ashrdi3.o lshrdi3.o muldi3.o \ ucmpdi2.o lib1funcs.o div64.o \ io-readsb.o io-writesb.o io-readsl.o io-writesl.o \ - call_with_stack.o + call_with_stack.o bswapsdi2.o mmu-y := clear_user.o copy_page.o getuser.o putuser.o diff --git a/arch/arm/lib/bswapsdi2.c b/arch/arm/lib/bswapsdi2.c new file mode 100644 index 0000000..1923b2f --- /dev/null +++ b/arch/arm/lib/bswapsdi2.c @@ -0,0 +1,19 @@ +unsigned int __bswapsi2(unsigned int x) +{ + return ((x & 0x000000ffUL) << 24) | + ((x & 0x0000ff00UL) << 8) | + ((x & 0x00ff0000UL) >> 8) | + ((x & 0xff000000UL) >> 24); +} + +unsigned long long __bswapdi2(unsigned long long x) +{ + return ((x & 0x00000000000000ffULL) << 56) | + ((x & 0x000000000000ff00ULL) << 40) | + ((x & 0x0000000000ff0000ULL) << 24) | + ((x & 0x00000000ff000000ULL) << 8) | + ((x & 0x000000ff00000000ULL) >> 8) | + ((x & 0x0000ff0000000000ULL) >> 24) | + ((x & 0x00ff000000000000ULL) >> 40) | + ((x & 0xff00000000000000ULL) >> 56); +}