Messages in this thread | | | Date | Thu, 21 Feb 2013 22:40:08 -0500 (EST) | From | Nicolas Pitre <> | Subject | Re: [RFC] arm: use built-in byte swap function |
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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.
Still, I have minor comments below.
> 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..a277e97 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 \ > + lib1funcs.o lib1funcs.S ashldi3.o ashldi3.S bswapsdi2.o \
Should be both 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.o $(libfdt) $(libfdt_hdrs)
Should be bswapsdi2.S.
> ifeq ($(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..e9c8ca7 > --- /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 > + lsr r3, r3, #8
Some older binutils used with pre ARMv6 platforms don't understand the latest unified syntax. So in this case it is better to use:
mov r3, r3, lsr #8
> + bic r3, r3, #65280 @ 0xff00
Please use #0xff00 directly rather than keeping it as a comment.
> + 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 > + lsr r1, r1, #8 > + lsr r3, r3, #8 > + bic r3, r3, #65280 @ 0xff00 > + bic r1, r1, #65280 @ 0xff00
Same comments for the 4 instructions above.
> + eor r1, r1, r0, ror #8 > + eor r0, r3, ip, ror #8 > + mov pc, lr > +ENDPROC(__bswapdi2) > +#endif > > Thanks, > > Kim >
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