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arm64: arch_timer: Enable CNTVCT_EL0 trap if workaround is enabled 

Userspace being allowed to use read CNTVCT_EL0 anytime (and not
only in the VDSO), we need to enable trapping whenever a cntvct
workaround is enabled on a given CPU.

Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2017-02-01 12:07:15 +00:00
parent bee67c53a9
commit a86bd139f2
1 changed files with 32 additions and 13 deletions
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45
drivers/clocksource/arm_arch_timer.c
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@ -83,6 +83,7 @@ static enum ppi_nr arch_timer_uses_ppi = VIRT_PPI;
static bool arch_timer_c3stop;
static bool arch_timer_mem_use_virtual;
static bool arch_counter_suspend_stop;
static bool vdso_default = true;
static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
@ -383,6 +384,17 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa
}
static_branch_enable(&arch_timer_read_ool_enabled);
/*
* Don't use the vdso fastpath if errata require using the
* out-of-line counter accessor. We may change our mind pretty
* late in the game (with a per-CPU erratum, for example), so
* change both the default value and the vdso itself.
*/
if (wa->read_cntvct_el0) {
clocksource_counter.archdata.vdso_direct = false;
vdso_default = false;
}
}
static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type type,
@ -443,11 +455,19 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
__val; \
})
static bool arch_timer_this_cpu_has_cntvct_wa(void)
{
const struct arch_timer_erratum_workaround *wa;
wa = __this_cpu_read(timer_unstable_counter_workaround);
return wa && wa->read_cntvct_el0;
}
#else
#define arch_timer_check_ool_workaround(t,a) do { } while(0)
#define erratum_set_next_event_tval_virt(...) ({BUG(); 0;})
#define erratum_set_next_event_tval_phys(...) ({BUG(); 0;})
#define erratum_handler(fn, r, ...) ({false;})
#define arch_timer_this_cpu_has_cntvct_wa() ({false;})
#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */
static __always_inline irqreturn_t timer_handler(const int access,
@ -660,15 +680,23 @@ static void arch_counter_set_user_access(void)
{
u32 cntkctl = arch_timer_get_cntkctl();
/* Disable user access to the timers and the physical counter */
/* Disable user access to the timers and both counters */
/* Also disable virtual event stream */
cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
| ARCH_TIMER_USR_VT_ACCESS_EN
| ARCH_TIMER_USR_VCT_ACCESS_EN
| ARCH_TIMER_VIRT_EVT_EN
| ARCH_TIMER_USR_PCT_ACCESS_EN);
/* Enable user access to the virtual counter */
cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
/*
* Enable user access to the virtual counter if it doesn't
* need to be workaround. The vdso may have been already
* disabled though.
*/
if (arch_timer_this_cpu_has_cntvct_wa())
pr_info("CPU%d: Trapping CNTVCT access\n", smp_processor_id());
else
cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
arch_timer_set_cntkctl(cntkctl);
}
@ -791,16 +819,7 @@ static void __init arch_counter_register(unsigned type)
else
arch_timer_read_counter = arch_counter_get_cntpct;
clocksource_counter.archdata.vdso_direct = true;
#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
/*
* Don't use the vdso fastpath if errata require using
* the out-of-line counter accessor.
*/
if (static_branch_unlikely(&arch_timer_read_ool_enabled))
clocksource_counter.archdata.vdso_direct = false;
#endif
clocksource_counter.archdata.vdso_direct = vdso_default;
} else {
arch_timer_read_counter = arch_counter_get_cntvct_mem;
}