Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH v3 4/8] powerpc/vdso32: inline __get_datapage() | From | Christophe Leroy <> | Date | Wed, 27 Nov 2019 15:47:56 +0100 |
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Hi Michael,
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 ?
Christophe
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