Christophe Leroy <christophe.le...@c-s.fr> writes: > Hi Santosh, > > Le 26/08/2019 à 07:44, Santosh Sivaraj a écrit : >> Hi Christophe, >> >> Christophe Leroy <christophe.le...@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.le...@c-s.fr> >>> --- >>> arch/powerpc/kernel/vdso32/cacheflush.S | 10 +++++----- >>> arch/powerpc/kernel/vdso32/datapage.S | 29 >>> ++++------------------------- >>> arch/powerpc/kernel/vdso32/datapage.h | 11 +++++++++++ >>> arch/powerpc/kernel/vdso32/gettimeofday.S | 13 ++++++------- >>> 4 files changed, 26 insertions(+), 37 deletions(-) >>> create mode 100644 arch/powerpc/kernel/vdso32/datapage.h >> >> The datapage.h file should ideally be moved under include/asm, then we can >> use >> the same for powerpc64 too. > > I have a more ambitious project indeed. > > Most of the VDSO code is duplicated between vdso32 and vdso64. I'm > aiming at merging everything into a single source code. > > This means we would have to generate vdso32.so and vdso64.so out of the > same source files. Any idea on how to do that ? I'm not too good at > creating Makefiles. I guess we would have everything in > arch/powerpc/kernel/vdso/ and would have to build the objects twice, > once in arch/powerpc/kernel/vdso32/ and once in arch/powerpc/kernel/vdso64/
Should we need to build the objects twice? For 64 bit config it is going to be a 64 bit build else a 32 bit build. It should suffice to get the single source code compile for both, maybe with macros or (!)CONFIG_PPC64 conditional compilation. Am I missing something when you say build twice? Thanks, Santosh
