On Mon, Jul 05, 2021 at 02:03:54AM +0200, Martin Fäcknitz wrote:
> Accessing raw timers (currently only CLOCK_MONOTONIC_RAW) through VDSO doesn't
> return the correct time when using the GIC as clock source. The address of the
> GIC mapped page is in this case not calculated correctly. The GIC mapped page
> is calculated from the VDSO data by subtracting PAGE_SIZE:
>
> void *get_gic(const struct vdso_data *data) {
> return (void __iomem *)data - PAGE_SIZE;
> }
>
> However, the data pointer is not page aligned for raw clock sources. This is
> because the VDSO data for raw clock sources (CS_RAW = 1) is stored after the
> VDSO data for coarse clock sources (CS_HRES_COARSE = 0). Therefore, only the
> VDSO data for CS_HRES_COARSE is page aligned:
>
> +--------------------+
> | |
> | vd[CS_RAW] | ---+
> | vd[CS_HRES_COARSE] | |
> +--------------------+ | -PAGE_SIZE
> | | |
> | GIC mapped page | <--+
> | |
> +--------------------+
>
> When __arch_get_hw_counter() is called with &vd[CS_RAW], get_gic returns the
> wrong address (somewhere inside the GIC mapped page). The GIC counter values
> are not returned which results in an invalid time.
>
> Signed-off-by: Martin Fäcknitz <faecknitz@xxxxxxxxxxxx>
applied to mips-next.
I've fixed subject and commit log formating. Please use checkpatch before
submitting next time. I also added
Fixes: a7f4df4e21dd ("MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()")
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
