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Subject[RFC PATCH v2 00/10] powerpc/32: switch VDSO to C implementation.
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This is a second tentative to switch powerpc/32 vdso to generic C implementation.

It will likely not work on 64 bits or even build properly at the moment.

powerpc is a bit special for VDSO as well as system calls in the
way that it requires setting CR SO bit which cannot be done in C.
Therefore, entry/exit and fallback needs to be performed in ASM.

To allow that, the fallback calls are moved out of the common code
and left to the arches.

A few other changes in the common code have allowed performance improvement.

The performance has improved since first RFC, but it is still lower than
current assembly VDSO.

On a powerpc8xx, with current powerpc/32 ASM VDSO:

gettimeofday: vdso: 737 nsec/call
clock-getres-realtime: vdso: 475 nsec/call
clock-gettime-realtime: vdso: 892 nsec/call
clock-getres-monotonic: vdso: 475 nsec/call
clock-gettime-monotonic: vdso: 1014 nsec/call

First try of C implementation:

gettimeofday: vdso: 1533 nsec/call
clock-getres-realtime: vdso: 853 nsec/call
clock-gettime-realtime: vdso: 1570 nsec/call
clock-getres-monotonic: vdso: 835 nsec/call
clock-gettime-monotonic: vdso: 1605 nsec/call

With this series:

gettimeofday: vdso: 1016 nsec/call
clock-getres-realtime: vdso: 560 nsec/call
clock-gettime-realtime: vdso: 1192 nsec/call
clock-getres-monotonic: vdso: 560 nsec/call
clock-gettime-monotonic: vdso: 1192 nsec/call


Changes made to other arches are untested, not even compiled.


Christophe Leroy (10):
lib: vdso: ensure all arches have 32bit fallback
lib: vdso: move call to fallback out of common code.
lib: vdso: Change __cvdso_clock_gettime/getres_common() to
__cvdso_clock_gettime/getres()
lib: vdso: get pointer to vdso data from the arch
lib: vdso: inline do_hres()
lib: vdso: make do_coarse() return 0
lib: vdso: don't use READ_ONCE() in __c_kernel_time()
lib: vdso: Avoid duplication in __cvdso_clock_getres()
powerpc/vdso32: inline __get_datapage()
powerpc/32: Switch VDSO to C implementation.

arch/arm/include/asm/vdso/gettimeofday.h | 26 +++
arch/arm/vdso/vgettimeofday.c | 32 ++-
arch/arm64/include/asm/vdso/compat_gettimeofday.h | 2 -
arch/arm64/include/asm/vdso/gettimeofday.h | 26 +++
arch/arm64/kernel/vdso/vgettimeofday.c | 24 +-
arch/arm64/kernel/vdso32/vgettimeofday.c | 39 +++-
arch/mips/include/asm/vdso/gettimeofday.h | 28 ++-
arch/mips/vdso/vgettimeofday.c | 56 ++++-
arch/powerpc/Kconfig | 2 +
arch/powerpc/include/asm/vdso/gettimeofday.h | 45 ++++
arch/powerpc/include/asm/vdso/vsyscall.h | 27 +++
arch/powerpc/include/asm/vdso_datapage.h | 28 +--
arch/powerpc/kernel/asm-offsets.c | 23 +-
arch/powerpc/kernel/time.c | 92 +-------
arch/powerpc/kernel/vdso.c | 19 +-
arch/powerpc/kernel/vdso32/Makefile | 19 +-
arch/powerpc/kernel/vdso32/cacheflush.S | 9 +-
arch/powerpc/kernel/vdso32/datapage.S | 28 +--
arch/powerpc/kernel/vdso32/gettimeofday.S | 265 +++-------------------
arch/powerpc/kernel/vdso32/vgettimeofday.c | 32 +++
arch/x86/entry/vdso/vclock_gettime.c | 52 ++++-
arch/x86/include/asm/vdso/gettimeofday.h | 28 ++-
lib/vdso/gettimeofday.c | 100 +++-----
23 files changed, 505 insertions(+), 497 deletions(-)
create mode 100644 arch/powerpc/include/asm/vdso/gettimeofday.h
create mode 100644 arch/powerpc/include/asm/vdso/vsyscall.h
create mode 100644 arch/powerpc/kernel/vdso32/vgettimeofday.c

--
2.13.3

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