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Subject[PATCH 2/2] timers: retpoline mitigation for time funcs
From
Adds indirect call exports for clock reads from tsc, apic,
hrtimer, via clock-event, timekeeper & posix interfaces.

Signed-off-by: Pete Swain <swine@google.com>
---
arch/x86/kernel/apic/apic.c | 8 +++++---
arch/x86/kernel/tsc.c | 3 ++-
include/linux/hrtimer.h | 19 ++++++++++++++++---
kernel/time/clockevents.c | 9 ++++++---
kernel/time/hrtimer.c | 3 ++-
kernel/time/posix-cpu-timers.c | 4 ++--
kernel/time/posix-timers.c | 3 ++-
kernel/time/timekeeping.c | 2 +-
8 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index b70344bf6600..523a569dd35e 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -463,15 +463,17 @@ EXPORT_SYMBOL_GPL(setup_APIC_eilvt);
/*
* Program the next event, relative to now
*/
-static int lapic_next_event(unsigned long delta,
+INDIRECT_CALLABLE_SCOPE
+int lapic_next_event(unsigned long delta,
struct clock_event_device *evt)
{
apic_write(APIC_TMICT, delta);
return 0;
}

-static int lapic_next_deadline(unsigned long delta,
- struct clock_event_device *evt)
+INDIRECT_CALLABLE_SCOPE
+int lapic_next_deadline(unsigned long delta,
+ struct clock_event_device *evt)
{
u64 tsc;

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index a698196377be..ff2868d5ddea 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1090,7 +1090,8 @@ static void tsc_resume(struct clocksource *cs)
* checking the result of read_tsc() - cycle_last for being negative.
* That works because CLOCKSOURCE_MASK(64) does not mask out any bit.
*/
-static u64 read_tsc(struct clocksource *cs)
+INDIRECT_CALLABLE_SCOPE
+u64 read_tsc(struct clocksource *cs)
{
return (u64)rdtsc_ordered();
}
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 0ee140176f10..9d2d110f0b8c 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -20,6 +20,7 @@
#include <linux/seqlock.h>
#include <linux/timer.h>
#include <linux/timerqueue.h>
+#include <linux/indirect_call_wrapper.h>

struct hrtimer_clock_base;
struct hrtimer_cpu_base;
@@ -297,14 +298,17 @@ static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
return ktime_to_ns(timer->node.expires);
}

+INDIRECT_CALLABLE_DECLARE(extern ktime_t ktime_get(void));
+
static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
{
- return ktime_sub(timer->node.expires, timer->base->get_time());
+ return ktime_sub(timer->node.expires,
+ INDIRECT_CALL_1(timer->base->get_time, ktime_get));
}

static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
{
- return timer->base->get_time();
+ return INDIRECT_CALL_1(timer->base->get_time, ktime_get);
}

static inline int hrtimer_is_hres_active(struct hrtimer *timer)
@@ -503,7 +507,9 @@ hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
static inline u64 hrtimer_forward_now(struct hrtimer *timer,
ktime_t interval)
{
- return hrtimer_forward(timer, timer->base->get_time(), interval);
+ return hrtimer_forward(timer,
+ INDIRECT_CALL_1(timer->base->get_time, ktime_get),
+ interval);
}

/* Precise sleep: */
@@ -536,4 +542,11 @@ int hrtimers_dead_cpu(unsigned int cpu);
#define hrtimers_dead_cpu NULL
#endif

+struct clock_event_device;
+INDIRECT_CALLABLE_DECLARE(extern __weak u64 read_tsc(struct clocksource *cs));
+INDIRECT_CALLABLE_DECLARE(extern int thread_cpu_clock_get(
+ const clockid_t which_clock, struct timespec64 *tp));
+INDIRECT_CALLABLE_DECLARE(extern __weak int lapic_next_deadline(
+ unsigned long delta, struct clock_event_device *evt));
+
#endif
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 003ccf338d20..ac15412e87c4 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -245,7 +245,8 @@ static int clockevents_program_min_delta(struct clock_event_device *dev)

dev->retries++;
clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
- if (dev->set_next_event((unsigned long) clc, dev) == 0)
+ if (INDIRECT_CALL_1(dev->set_next_event, lapic_next_deadline,
+ (unsigned long) clc, dev) == 0)
return 0;

if (++i > 2) {
@@ -284,7 +285,8 @@ static int clockevents_program_min_delta(struct clock_event_device *dev)

dev->retries++;
clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
- if (dev->set_next_event((unsigned long) clc, dev) == 0)
+ if (INDIRECT_CALL_1(dev->set_next_event, lapic_next_deadline,
+ (unsigned long) clc, dev) == 0)
return 0;
}
return -ETIME;
@@ -331,7 +333,8 @@ int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
delta = max(delta, (int64_t) dev->min_delta_ns);

clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
- rc = dev->set_next_event((unsigned long) clc, dev);
+ rc = INDIRECT_CALL_1(dev->set_next_event, lapic_next_deadline,
+ (unsigned long) clc, dev);

return (rc && force) ? clockevents_program_min_delta(dev) : rc;
}
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 0ea8702eb516..e1e17fdfcd18 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1241,7 +1241,8 @@ static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
remove_hrtimer(timer, base, true, force_local);

if (mode & HRTIMER_MODE_REL)
- tim = ktime_add_safe(tim, base->get_time());
+ tim = ktime_add_safe(tim,
+ INDIRECT_CALL_1(base->get_time, ktime_get));

tim = hrtimer_update_lowres(timer, tim, mode);

diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 96b4e7810426..d8bf325fa84e 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1596,8 +1596,8 @@ static int thread_cpu_clock_getres(const clockid_t which_clock,
{
return posix_cpu_clock_getres(THREAD_CLOCK, tp);
}
-static int thread_cpu_clock_get(const clockid_t which_clock,
- struct timespec64 *tp)
+INDIRECT_CALLABLE_SCOPE
+int thread_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp)
{
return posix_cpu_clock_get(THREAD_CLOCK, tp);
}
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 1cd10b102c51..35eac10ee796 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1089,7 +1089,8 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
if (!kc)
return -EINVAL;

- error = kc->clock_get_timespec(which_clock, &kernel_tp);
+ error = INDIRECT_CALL_1(kc->clock_get_timespec, thread_cpu_clock_get,
+ which_clock, &kernel_tp);

if (!error && put_timespec64(&kernel_tp, tp))
error = -EFAULT;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index dcdcb85121e4..2b1a3b146614 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -190,7 +190,7 @@ static inline u64 tk_clock_read(const struct tk_read_base *tkr)
{
struct clocksource *clock = READ_ONCE(tkr->clock);

- return clock->read(clock);
+ return INDIRECT_CALL_1(clock->read, read_tsc, clock);
}

#ifdef CONFIG_DEBUG_TIMEKEEPING
--
2.35.1.473.g83b2b277ed-goog
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