Messages in this thread Patch in this message | | | Date | Fri, 22 Feb 2013 19:40:32 -0600 | From | Kim Phillips <> | Subject | [PATCH v6] arm: use built-in byte swap function |
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On Thu, 21 Feb 2013 22:40:08 -0500 Nicolas Pitre <nico@fluxnic.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@freescale.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@freescale.com> --- 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
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