| Message ID | 20200701161824.1346732-2-maz@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Allow the compat vdso to be disabled at runtime | expand |
On Wed, Jul 01, 2020 at 05:18:22PM +0100, Marc Zyngier wrote: > We have a class of errata (grouped under the ARM64_WORKAROUND_1418040 > banner) that force the trapping of counter access from 32bit EL0. > > We would normally disable the whole vdso for such defect, except that > it would disable it for 64bit userspace as well, which is a shame. > > Instead, add a new vdso_clock_mode, which signals that the vdso > isn't usable for compat tasks. This gets checked in the new > vdso_clocksource_ok() helper, now provided for the 32bit vdso. > > Signed-off-by: Marc Zyngier <maz@kernel.org> As-is this looks sound to me. It's not entirely clear to me how this will compose with VDSO_CLOCKMODE_TIMENS, but given this series is fixing an existing brokenness I think this has higher priority. Minor comment below, but regardless: Acked-by: Mark Rutland <mark.rutland@arm.com> > --- > arch/arm64/include/asm/vdso/clocksource.h | 7 +++++-- > arch/arm64/include/asm/vdso/compat_gettimeofday.h | 8 +++++++- > 2 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/vdso/clocksource.h b/arch/arm64/include/asm/vdso/clocksource.h > index df6ea65c1dec..b054d9febfb5 100644 > --- a/arch/arm64/include/asm/vdso/clocksource.h > +++ b/arch/arm64/include/asm/vdso/clocksource.h > @@ -2,7 +2,10 @@ > #ifndef __ASM_VDSOCLOCKSOURCE_H > #define __ASM_VDSOCLOCKSOURCE_H > > -#define VDSO_ARCH_CLOCKMODES \ > - VDSO_CLOCKMODE_ARCHTIMER > +#define VDSO_ARCH_CLOCKMODES \ > + /* vdso clocksource for both 32 and 64bit tasks */ \ > + VDSO_CLOCKMODE_ARCHTIMER, \ > + /* vdso clocksource for 64bit tasks only */ \ > + VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT > > #endif > diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h > index b6907ae78e53..9a625e8947ff 100644 > --- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h > +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h > @@ -111,7 +111,7 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) > * update. Return something. Core will do another round and then > * see the mode change and fallback to the syscall. > */ > - if (clock_mode == VDSO_CLOCKMODE_NONE) > + if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER) > return 0; > > /* > @@ -152,6 +152,12 @@ static __always_inline const struct vdso_data *__arch_get_vdso_data(void) > return ret; > } > > +static inline bool vdso_clocksource_ok(const struct vdso_data *vd) > +{ > + return vd->clock_mode == VDSO_CLOCKMODE_ARCHTIMER; > +} > +#define vdso_clocksource_ok vdso_clocksource_ok Existing issue, but it's a shame this doesn't take the clock mode directly, then we wouldn't have to duplicate the conditions (as above, inverted). Mark.
diff --git a/arch/arm64/include/asm/vdso/clocksource.h b/arch/arm64/include/asm/vdso/clocksource.h index df6ea65c1dec..b054d9febfb5 100644 --- a/arch/arm64/include/asm/vdso/clocksource.h +++ b/arch/arm64/include/asm/vdso/clocksource.h @@ -2,7 +2,10 @@ #ifndef __ASM_VDSOCLOCKSOURCE_H #define __ASM_VDSOCLOCKSOURCE_H -#define VDSO_ARCH_CLOCKMODES \ - VDSO_CLOCKMODE_ARCHTIMER +#define VDSO_ARCH_CLOCKMODES \ + /* vdso clocksource for both 32 and 64bit tasks */ \ + VDSO_CLOCKMODE_ARCHTIMER, \ + /* vdso clocksource for 64bit tasks only */ \ + VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT #endif diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h index b6907ae78e53..9a625e8947ff 100644 --- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h @@ -111,7 +111,7 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) * update. Return something. Core will do another round and then * see the mode change and fallback to the syscall. */ - if (clock_mode == VDSO_CLOCKMODE_NONE) + if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER) return 0; /* @@ -152,6 +152,12 @@ static __always_inline const struct vdso_data *__arch_get_vdso_data(void) return ret; } +static inline bool vdso_clocksource_ok(const struct vdso_data *vd) +{ + return vd->clock_mode == VDSO_CLOCKMODE_ARCHTIMER; +} +#define vdso_clocksource_ok vdso_clocksource_ok + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_VDSO_GETTIMEOFDAY_H */
We have a class of errata (grouped under the ARM64_WORKAROUND_1418040 banner) that force the trapping of counter access from 32bit EL0. We would normally disable the whole vdso for such defect, except that it would disable it for 64bit userspace as well, which is a shame. Instead, add a new vdso_clock_mode, which signals that the vdso isn't usable for compat tasks. This gets checked in the new vdso_clocksource_ok() helper, now provided for the 32bit vdso. Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/include/asm/vdso/clocksource.h | 7 +++++-- arch/arm64/include/asm/vdso/compat_gettimeofday.h | 8 +++++++- 2 files changed, 12 insertions(+), 3 deletions(-)