clock_getres in the vDSO library has to preserve the same behaviour
of posix_get_hrtimer_res().
In particular, posix_get_hrtimer_res() does:
sec = 0;
ns = hrtimer_resolution;
and hrtimer_resolution depends on the enablement of the high
resolution timers that can happen either at compile or at run time.
A possible fix is to change the vdso implementation of clock_getres,
keeping a copy of hrtimer_resolution in vdso data and using that
directly [1].
This patchset implements the proposed fix for arm64, powerpc, s390,
nds32 and adds a test to verify that the syscall and the vdso library
implementation of clock_getres return the same values.
[1] https://marc.info/?l=linux-arm-kernel&m=155110381930196&w=2
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Martin Schwidefsky <schwidef...@de.ibm.com>
Cc: Heiko Carstens <heiko.carst...@de.ibm.com>
Cc: Greentime Hu <green...@gmail.com>
Cc: Vincent Chen <deanbo...@gmail.com>
Cc: Shuah Khan <sh...@kernel.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Arnd Bergmann <a...@arndb.de>
Signed-off-by: Vincenzo Frascino <vincenzo.frasc...@arm.com>
Vincenzo Frascino (5):
arm64: Fix vDSO clock_getres()
powerpc: Fix vDSO clock_getres()
s390: Fix vDSO clock_getres()
nds32: Fix vDSO clock_getres()
kselftest: Extend vDSO selftest to clock_getres
arch/arm64/include/asm/vdso_datapage.h | 1 +
arch/arm64/kernel/asm-offsets.c | 2 +-
arch/arm64/kernel/vdso.c | 2 +
arch/arm64/kernel/vdso/gettimeofday.S | 25 ++--
arch/nds32/include/asm/vdso_datapage.h | 1 +
arch/nds32/kernel/vdso.c | 1 +
arch/nds32/kernel/vdso/gettimeofday.c | 4 +-
arch/powerpc/include/asm/vdso_datapage.h | 2 +
arch/powerpc/kernel/asm-offsets.c | 2 +-
arch/powerpc/kernel/time.c | 1 +
arch/powerpc/kernel/vdso32/gettimeofday.S | 22 ++--
arch/powerpc/kernel/vdso64/gettimeofday.S | 22 ++--
arch/s390/include/asm/vdso.h | 1 +
arch/s390/kernel/asm-offsets.c | 2 +-
arch/s390/kernel/time.c | 1 +
arch/s390/kernel/vdso32/clock_getres.S | 17 ++-
arch/s390/kernel/vdso64/clock_getres.S | 15 ++-
tools/testing/selftests/vDSO/Makefile | 2 +
.../selftests/vDSO/vdso_clock_getres.c | 107 ++++++++++++++++++
19 files changed, 191 insertions(+), 39 deletions(-)
create mode 100644 tools/testing/selftests/vDSO/vdso_clock_getres.c
--
2.21.0
