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Message-id: <alpine.LFD.2.03.1302222139170.6419@syhkavp.arg> Date: Fri, 22 Feb 2013 21:40:17 -0500 (EST) From: Nicolas Pitre <nico@...xnic.net> To: Kim Phillips <kim.phillips@...escale.com> Cc: "Woodhouse, David" <david.woodhouse@...el.com>, Russell King - ARM Linux <linux@....linux.org.uk>, Borislav Petkov <bp@...en8.de>, Andrew Morton <akpm@...ux-foundation.org>, Daniel Santos <daniel.santos@...ox.com>, David Rientjes <rientjes@...gle.com>, Rusty Russell <rusty@...tcorp.com.au>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Rob Herring <robherring2@...il.com> Subject: Re: [PATCH v6] arm: use built-in byte swap function On Fri, 22 Feb 2013, Kim Phillips wrote: > On Thu, 21 Feb 2013 22:40:08 -0500 > Nicolas Pitre <nico@...xnic.net> wrote: > > > On Thu, 21 Feb 2013, Kim Phillips wrote: > > > > > Here's the asm version I'm working on now, based on compiler > > > output of the C version. Haven't tested beyond defconfig builds, > > > which pass ok. > > > > > > Is there anything I have to do for thumb mode? If so, how to test? > > > > You just need to pick a config that uses some ARMv7 processor, and > > enable CONFIG_THUMB2_KERNEL. I don't see any problem with your patch > > wrt Thumb2. > > ok, I've addressed your comments and tested both pre-armv6 and armv6 > + bswapsi2s on i.mx hardware with CONFIG_CC_OPTIMIZE_FOR_SIZE and > CONFIG_THUMB2_KERNEL set: > > >From c22f4050174d8da71fdddba2cf67ae40c00ca5cc Mon Sep 17 00:00:00 2001 > From: Kim Phillips <kim.phillips@...escale.com> > Date: Tue, 19 Feb 2013 17:16:11 -0600 > Subject: [PATCH] arm: use built-in byte swap function > > Enable the compiler intrinsic for byte swapping on arch ARM. This > allows the compiler to detect and be able to optimize out byte > swappings, and has a tiny benefit on vmlinux size (Linaro gcc 4.7.3): > > text data bss dec hex filename > 2754100 121144 56520 2931764 2cbc34 vmlinux-lart #orig > 2754050 121144 56520 2931714 2cbc02 vmlinux-lart #builtin-bswap > 6282699 307852 5578076 12168627 b9adb3 vmlinux-mxs #orig > 6282241 307832 5578076 12168149 b9abd5 vmlinux-mxs #builtin-bswap > 7200193 364180 361748 7926121 78f169 vmlinux-imx_v6_v7 #orig > 7199515 364188 361748 7925451 78eecb vmlinux-imx_v6_v7 #builtin-bswap > > Signed-off-by: Kim Phillips <kim.phillips@...escale.com> Reviewed-by: Nicolas Pitre <nico@...aro.org> > --- > akin to: http://comments.gmane.org/gmane.linux.kernel.cross-arch/16016 > > based on linux-next-20130221. > > changes from last diff: > - addressed Nicolas' comments > - updated commit text figures and reformatted as a patch > > changes from diff before that: > - 1st asm version > > changes from diff before that: > - enforce -O2 for bswapsdi2.o > - fix building out-of-source tree > > changes from diff before that: > - implement custom __bswap[sd]i2 in arch/arm/lib/bswapsdi2.c > > v5: re-work based on new gcc version test data: > - moved outside armv6 protection > - check for gcc 4.6+ demoted to gcc 4.5+ with: > !defined(CONFIG_CC_OPTIMIZE_FOR_SIZE) > > v4: > - undo v2-2's addition of ARCH_DEFINES_BUILTIN_BSWAP per Boris > and David - object is to find arches that define _HAVE_BSWAP > and clean it up in the future: patch is much less intrusive. :) > > v3: > - moved out of uapi swab.h into arch/arm/include/asm/swab.h > - moved ARCH_DEFINES_BUILTIN_BSWAP help text into commit message > - moved GCC_VERSION >= 40800 ifdef into GCC_VERSION >= 40600 block > > v2: > - at91 and lpd270 builds fixed by limiting to ARMv6 and above > (i.e., ARM cores that have support for the 'rev' instruction). > Otherwise, the compiler emits calls to libgcc's __bswapsi2 on > these ARMv4/v5 builds (and arch ARM doesn't link with libgcc). > All ARM defconfigs now have the same build status as they did > without this patch (some are broken on linux-next). > > - move ARM check from generic compiler.h to arch ARM's swab.h. > - pretty sure it should be limited to __KERNEL__ builds > > - add new ARCH_DEFINES_BUILTIN_BSWAP (see Kconfig help). > - if set, generic compiler header does not set HAVE_BUILTIN_BSWAPxx > - not too sure about this having to be a new CONFIG_, but it's hard > to find a place for it given linux/compiler.h doesn't include any > arch-specific files. > > - move new selects to end of CONFIG_ARM's Kconfig select list, > as is done in David Woodhouse's original patchseries for ppc/x86. > > arch/arm/Kconfig | 1 + > arch/arm/boot/compressed/Makefile | 15 +++++++++++---- > arch/arm/kernel/armksyms.c | 4 ++++ > arch/arm/lib/Makefile | 2 +- > arch/arm/lib/bswapsdi2.S | 36 ++++++++++++++++++++++++++++++++++++ > 5 files changed, 53 insertions(+), 5 deletions(-) > create mode 100644 arch/arm/lib/bswapsdi2.S > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index dedf02b..e8a41d0 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -59,6 +59,7 @@ 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 5cad8a6..d9b5ee5 100644 > --- a/arch/arm/boot/compressed/Makefile > +++ b/arch/arm/boot/compressed/Makefile > @@ -108,12 +108,12 @@ endif > > targets := vmlinux vmlinux.lds \ > piggy.$(suffix_y) piggy.$(suffix_y).o \ > - lib1funcs.o lib1funcs.S ashldi3.o ashldi3.S \ > - font.o font.c head.o misc.o $(OBJS) > + lib1funcs.o lib1funcs.S ashldi3.o ashldi3.S bswapsdi2.o \ > + bswapsdi2.S 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.S $(libfdt) $(libfdt_hdrs) > > ifeq ($(CONFIG_FUNCTION_TRACER),y) > ORIG_CFLAGS := $(KBUILD_CFLAGS) > @@ -155,6 +155,12 @@ 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.S: $(srctree)/arch/$(SRCARCH)/lib/bswapsdi2.S > + $(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 > @@ -176,7 +182,8 @@ 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.S b/arch/arm/lib/bswapsdi2.S > new file mode 100644 > index 0000000..2ba43a0 > --- /dev/null > +++ b/arch/arm/lib/bswapsdi2.S > @@ -0,0 +1,36 @@ > +#include <linux/linkage.h> > + > +#if __LINUX_ARM_ARCH__ >= 6 > +ENTRY(__bswapsi2) > + rev r0, r0 > + bx lr > +ENDPROC(__bswapsi2) > + > +ENTRY(__bswapdi2) > + rev r3, r0 > + rev r0, r1 > + mov r1, r3 > + bx lr > +ENDPROC(__bswapdi2) > +#else > +ENTRY(__bswapsi2) > + eor r3, r0, r0, ror #16 > + mov r3, r3, lsr #8 > + bic r3, r3, #0xff00 > + eor r0, r3, r0, ror #8 > + mov pc, lr > +ENDPROC(__bswapsi2) > + > +ENTRY(__bswapdi2) > + mov ip, r1 > + eor r3, ip, ip, ror #16 > + eor r1, r0, r0, ror #16 > + mov r1, r1, lsr #8 > + mov r3, r3, lsr #8 > + bic r3, r3, #0xff00 > + bic r1, r1, #0xff00 > + eor r1, r1, r0, ror #8 > + eor r0, r3, ip, ror #8 > + mov pc, lr > +ENDPROC(__bswapdi2) > +#endif > -- > 1.8.1.4 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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