Messages in this thread | | | Subject | Re: [PATCH v3 4/8] powerpc/vdso32: inline __get_datapage() | From | Christophe Leroy <> | Date | Mon, 2 Dec 2019 08:02:11 +0000 |
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On 11/28/2019 05:31 AM, Michael Ellerman wrote: > Christophe Leroy <christophe.leroy@c-s.fr> writes: >> Le 22/11/2019 à 07:38, Michael Ellerman a écrit : >>> Michael Ellerman <mpe@ellerman.id.au> writes: >>>> Christophe Leroy <christophe.leroy@c-s.fr> writes: >>>>> __get_datapage() is only a few instructions to retrieve the >>>>> address of the page where the kernel stores data to the VDSO. >>>>> >>>>> By inlining this function into its users, a bl/blr pair and >>>>> a mflr/mtlr pair is avoided, plus a few reg moves. >>>>> >>>>> The improvement is noticeable (about 55 nsec/call on an 8xx) >>>>> >>>>> vdsotest before the patch: >>>>> gettimeofday: vdso: 731 nsec/call >>>>> clock-gettime-realtime-coarse: vdso: 668 nsec/call >>>>> clock-gettime-monotonic-coarse: vdso: 745 nsec/call >>>>> >>>>> vdsotest after the patch: >>>>> gettimeofday: vdso: 677 nsec/call >>>>> clock-gettime-realtime-coarse: vdso: 613 nsec/call >>>>> clock-gettime-monotonic-coarse: vdso: 690 nsec/call >>>>> >>>>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> >>>> >>>> This doesn't build with gcc 4.6.3: >>>> >>>> /linux/arch/powerpc/kernel/vdso32/gettimeofday.S: Assembler messages: >>>> /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:41: Error: unsupported relocation against __kernel_datapage_offset >>>> /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:86: Error: unsupported relocation against __kernel_datapage_offset >>>> /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:213: Error: unsupported relocation against __kernel_datapage_offset >>>> /linux/arch/powerpc/kernel/vdso32/gettimeofday.S:247: Error: unsupported relocation against __kernel_datapage_offset >>>> make[4]: *** [arch/powerpc/kernel/vdso32/gettimeofday.o] Error 1 >>> >>> Actually I guess it's binutils, which is v2.22 in this case. >>> >>> Needed this: >>> >>> diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h >>> index 12785f72f17d..0048db347ddf 100644 >>> --- a/arch/powerpc/include/asm/vdso_datapage.h >>> +++ b/arch/powerpc/include/asm/vdso_datapage.h >>> @@ -117,7 +117,7 @@ extern struct vdso_data *vdso_data; >>> .macro get_datapage ptr, tmp >>> bcl 20, 31, .+4 >>> mflr \ptr >>> - addi \ptr, \ptr, __kernel_datapage_offset - (.-4) >>> + addi \ptr, \ptr, (__kernel_datapage_offset - (.-4))@l >>> lwz \tmp, 0(\ptr) >>> add \ptr, \tmp, \ptr >>> .endm >>> >> >> Are you still planning to getting this series merged ? Do you need any >> help / rebase / re-spin ? > > Not sure. I'll possibly send a 2nd pull request next week with it > included. >
v3 conflicts with 2038 cleanup series from Arnd merged yesterday by Linus (ceb307474506 ("Merge tag 'y2038-cleanups-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground"))
Not seen your Ack in that series.
I sent out v4 of my series, rebased on top of 2038 cleanup series.
Christophe
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