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author | Nathan Lynch <nathan_lynch@mentor.com> | 2015-08-07 21:03:23 -0500 |
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committer | Catalin Marinas <catalin.marinas@arm.com> | 2015-08-10 15:37:45 +0100 |
commit | 878854a374620a3f5e8c0a3c418e82a429bc2cff (patch) | |
tree | edcf287f8f7829e25067bdda041cdcb53ef473ef /arch | |
parent | f7644cbfcdf03528f0f450f3940c4985b2291f49 (diff) | |
download | linux-878854a374620a3f5e8c0a3c418e82a429bc2cff.tar.gz |
arm64: VDSO: fix coarse clock monotonicity regression
Since 906c55579a63 ("timekeeping: Copy the shadow-timekeeper over the real timekeeper last") it has become possible on arm64 to: - Obtain a CLOCK_MONOTONIC_COARSE or CLOCK_REALTIME_COARSE timestamp via syscall. - Subsequently obtain a timestamp for the same clock ID via VDSO which predates the first timestamp (by one jiffy). This is because arm64's update_vsyscall is deriving the coarse time using the __current_kernel_time interface, when it should really be using the timekeeper object provided to it by the timekeeping core. It happened to work before only because __current_kernel_time would access the same timekeeper object which had been passed to update_vsyscall. This is no longer the case. Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/arm64/kernel/vdso.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index ec37ab3f524f..97bc68f4c689 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -199,16 +199,15 @@ up_fail: */ void update_vsyscall(struct timekeeper *tk) { - struct timespec xtime_coarse; u32 use_syscall = strcmp(tk->tkr_mono.clock->name, "arch_sys_counter"); ++vdso_data->tb_seq_count; smp_wmb(); - xtime_coarse = __current_kernel_time(); vdso_data->use_syscall = use_syscall; - vdso_data->xtime_coarse_sec = xtime_coarse.tv_sec; - vdso_data->xtime_coarse_nsec = xtime_coarse.tv_nsec; + vdso_data->xtime_coarse_sec = tk->xtime_sec; + vdso_data->xtime_coarse_nsec = tk->tkr_mono.xtime_nsec >> + tk->tkr_mono.shift; vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec; vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec; |