Commit 034bda1c authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 vdso updates from Ingo Molnar:
 "Two main changes:

   - Cleanups, simplifications and CLOCK_TAI support (Thomas Gleixner)

   - Improve code generation (Andy Lutomirski)"

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso: Rearrange do_hres() to improve code generation
  x86/vdso: Document vgtod_ts better
  x86/vdso: Remove "memory" clobbers in the vDSO syscall fallbacks
  x66/vdso: Add CLOCK_TAI support
  x86/vdso: Move cycle_last handling into the caller
  x86/vdso: Simplify the invalid vclock case
  x86/vdso: Replace the clockid switch case
  x86/vdso: Collapse coarse functions
  x86/vdso: Collapse high resolution functions
  x86/vdso: Introduce and use vgtod_ts
  x86/vdso: Use unsigned int consistently for vsyscall_gtod_data:: Seq
  x86/vdso: Enforce 64bit clocksource
  x86/time: Implement clocksource_arch_init()
  clocksource: Provide clocksource_arch_init()
parents d82924c3 99c19e6a
......@@ -48,6 +48,7 @@ config X86
select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
select ANON_INODES
select ARCH_CLOCKSOURCE_DATA
select ARCH_CLOCKSOURCE_INIT
select ARCH_DISCARD_MEMBLOCK
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_DEBUG_VIRTUAL
......
......@@ -45,21 +45,10 @@ notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
long ret;
asm ("syscall" : "=a" (ret), "=m" (*ts) :
"0" (__NR_clock_gettime), "D" (clock), "S" (ts) :
"memory", "rcx", "r11");
"rcx", "r11");
return ret;
}
notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)
{
long ret;
asm ("syscall" : "=a" (ret), "=m" (*tv), "=m" (*tz) :
"0" (__NR_gettimeofday), "D" (tv), "S" (tz) :
"memory", "rcx", "r11");
return ret;
}
#else
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
......@@ -73,22 +62,7 @@ notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
"mov %%edx, %%ebx \n"
: "=a" (ret), "=m" (*ts)
: "0" (__NR_clock_gettime), [clock] "g" (clock), "c" (ts)
: "memory", "edx");
return ret;
}
notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)
{
long ret;
asm (
"mov %%ebx, %%edx \n"
"mov %[tv], %%ebx \n"
"call __kernel_vsyscall \n"
"mov %%edx, %%ebx \n"
: "=a" (ret), "=m" (*tv), "=m" (*tz)
: "0" (__NR_gettimeofday), [tv] "g" (tv), "c" (tz)
: "memory", "edx");
: "edx");
return ret;
}
......@@ -100,12 +74,11 @@ static notrace const struct pvclock_vsyscall_time_info *get_pvti0(void)
return (const struct pvclock_vsyscall_time_info *)&pvclock_page;
}
static notrace u64 vread_pvclock(int *mode)
static notrace u64 vread_pvclock(void)
{
const struct pvclock_vcpu_time_info *pvti = &get_pvti0()->pvti;
u64 ret;
u64 last;
u32 version;
u64 ret;
/*
* Note: The kernel and hypervisor must guarantee that cpu ID
......@@ -132,175 +105,112 @@ static notrace u64 vread_pvclock(int *mode)
do {
version = pvclock_read_begin(pvti);
if (unlikely(!(pvti->flags & PVCLOCK_TSC_STABLE_BIT))) {
*mode = VCLOCK_NONE;
return 0;
}
if (unlikely(!(pvti->flags & PVCLOCK_TSC_STABLE_BIT)))
return U64_MAX;
ret = __pvclock_read_cycles(pvti, rdtsc_ordered());
} while (pvclock_read_retry(pvti, version));
/* refer to vread_tsc() comment for rationale */
last = gtod->cycle_last;
if (likely(ret >= last))
return ret;
return last;
}
#endif
#ifdef CONFIG_HYPERV_TSCPAGE
static notrace u64 vread_hvclock(int *mode)
static notrace u64 vread_hvclock(void)
{
const struct ms_hyperv_tsc_page *tsc_pg =
(const struct ms_hyperv_tsc_page *)&hvclock_page;
u64 current_tick = hv_read_tsc_page(tsc_pg);
if (current_tick != U64_MAX)
return current_tick;
*mode = VCLOCK_NONE;
return 0;
return hv_read_tsc_page(tsc_pg);
}
#endif
notrace static u64 vread_tsc(void)
{
u64 ret = (u64)rdtsc_ordered();
u64 last = gtod->cycle_last;
if (likely(ret >= last))
return ret;
/*
* GCC likes to generate cmov here, but this branch is extremely
* predictable (it's just a function of time and the likely is
* very likely) and there's a data dependence, so force GCC
* to generate a branch instead. I don't barrier() because
* we don't actually need a barrier, and if this function
* ever gets inlined it will generate worse code.
*/
asm volatile ("");
return last;
}
notrace static inline u64 vgetsns(int *mode)
notrace static inline u64 vgetcyc(int mode)
{
u64 v;
cycles_t cycles;
if (gtod->vclock_mode == VCLOCK_TSC)
cycles = vread_tsc();
if (mode == VCLOCK_TSC)
return (u64)rdtsc_ordered();
#ifdef CONFIG_PARAVIRT_CLOCK
else if (gtod->vclock_mode == VCLOCK_PVCLOCK)
cycles = vread_pvclock(mode);
else if (mode == VCLOCK_PVCLOCK)
return vread_pvclock();
#endif
#ifdef CONFIG_HYPERV_TSCPAGE
else if (gtod->vclock_mode == VCLOCK_HVCLOCK)
cycles = vread_hvclock(mode);
else if (mode == VCLOCK_HVCLOCK)
return vread_hvclock();
#endif
else
return 0;
v = (cycles - gtod->cycle_last) & gtod->mask;
return v * gtod->mult;
}
/* Code size doesn't matter (vdso is 4k anyway) and this is faster. */
notrace static int __always_inline do_realtime(struct timespec *ts)
{
unsigned long seq;
u64 ns;
int mode;
do {
seq = gtod_read_begin(gtod);
mode = gtod->vclock_mode;
ts->tv_sec = gtod->wall_time_sec;
ns = gtod->wall_time_snsec;
ns += vgetsns(&mode);
ns >>= gtod->shift;
} while (unlikely(gtod_read_retry(gtod, seq)));
ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
ts->tv_nsec = ns;
return mode;
return U64_MAX;
}
notrace static int __always_inline do_monotonic(struct timespec *ts)
notrace static int do_hres(clockid_t clk, struct timespec *ts)
{
unsigned long seq;
u64 ns;
int mode;
struct vgtod_ts *base = &gtod->basetime[clk];
u64 cycles, last, sec, ns;
unsigned int seq;
do {
seq = gtod_read_begin(gtod);
mode = gtod->vclock_mode;
ts->tv_sec = gtod->monotonic_time_sec;
ns = gtod->monotonic_time_snsec;
ns += vgetsns(&mode);
cycles = vgetcyc(gtod->vclock_mode);
ns = base->nsec;
last = gtod->cycle_last;
if (unlikely((s64)cycles < 0))
return vdso_fallback_gettime(clk, ts);
if (cycles > last)
ns += (cycles - last) * gtod->mult;
ns >>= gtod->shift;
sec = base->sec;
} while (unlikely(gtod_read_retry(gtod, seq)));
ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
/*
* Do this outside the loop: a race inside the loop could result
* in __iter_div_u64_rem() being extremely slow.
*/
ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
ts->tv_nsec = ns;
return mode;
return 0;
}
notrace static void do_realtime_coarse(struct timespec *ts)
notrace static void do_coarse(clockid_t clk, struct timespec *ts)
{
unsigned long seq;
do {
seq = gtod_read_begin(gtod);
ts->tv_sec = gtod->wall_time_coarse_sec;
ts->tv_nsec = gtod->wall_time_coarse_nsec;
} while (unlikely(gtod_read_retry(gtod, seq)));
}
struct vgtod_ts *base = &gtod->basetime[clk];
unsigned int seq;
notrace static void do_monotonic_coarse(struct timespec *ts)
{
unsigned long seq;
do {
seq = gtod_read_begin(gtod);
ts->tv_sec = gtod->monotonic_time_coarse_sec;
ts->tv_nsec = gtod->monotonic_time_coarse_nsec;
ts->tv_sec = base->sec;
ts->tv_nsec = base->nsec;
} while (unlikely(gtod_read_retry(gtod, seq)));
}
notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
{
switch (clock) {
case CLOCK_REALTIME:
if (do_realtime(ts) == VCLOCK_NONE)
goto fallback;
break;
case CLOCK_MONOTONIC:
if (do_monotonic(ts) == VCLOCK_NONE)
goto fallback;
break;
case CLOCK_REALTIME_COARSE:
do_realtime_coarse(ts);
break;
case CLOCK_MONOTONIC_COARSE:
do_monotonic_coarse(ts);
break;
default:
goto fallback;
}
unsigned int msk;
/* Sort out negative (CPU/FD) and invalid clocks */
if (unlikely((unsigned int) clock >= MAX_CLOCKS))
return vdso_fallback_gettime(clock, ts);
/*
* Convert the clockid to a bitmask and use it to check which
* clocks are handled in the VDSO directly.
*/
msk = 1U << clock;
if (likely(msk & VGTOD_HRES)) {
return do_hres(clock, ts);
} else if (msk & VGTOD_COARSE) {
do_coarse(clock, ts);
return 0;
fallback:
}
return vdso_fallback_gettime(clock, ts);
}
int clock_gettime(clockid_t, struct timespec *)
__attribute__((weak, alias("__vdso_clock_gettime")));
notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
{
if (likely(tv != NULL)) {
if (unlikely(do_realtime((struct timespec *)tv) == VCLOCK_NONE))
return vdso_fallback_gtod(tv, tz);
struct timespec *ts = (struct timespec *) tv;
do_hres(CLOCK_REALTIME, ts);
tv->tv_usec /= 1000;
}
if (unlikely(tz != NULL)) {
......@@ -320,7 +230,7 @@ int gettimeofday(struct timeval *, struct timezone *)
notrace time_t __vdso_time(time_t *t)
{
/* This is atomic on x86 so we don't need any locks. */
time_t result = READ_ONCE(gtod->wall_time_sec);
time_t result = READ_ONCE(gtod->basetime[CLOCK_REALTIME].sec);
if (t)
*t = result;
......
......@@ -31,6 +31,8 @@ void update_vsyscall(struct timekeeper *tk)
{
int vclock_mode = tk->tkr_mono.clock->archdata.vclock_mode;
struct vsyscall_gtod_data *vdata = &vsyscall_gtod_data;
struct vgtod_ts *base;
u64 nsec;
/* Mark the new vclock used. */
BUILD_BUG_ON(VCLOCK_MAX >= 32);
......@@ -45,34 +47,37 @@ void update_vsyscall(struct timekeeper *tk)
vdata->mult = tk->tkr_mono.mult;
vdata->shift = tk->tkr_mono.shift;
vdata->wall_time_sec = tk->xtime_sec;
vdata->wall_time_snsec = tk->tkr_mono.xtime_nsec;
base = &vdata->basetime[CLOCK_REALTIME];
base->sec = tk->xtime_sec;
base->nsec = tk->tkr_mono.xtime_nsec;
vdata->monotonic_time_sec = tk->xtime_sec
+ tk->wall_to_monotonic.tv_sec;
vdata->monotonic_time_snsec = tk->tkr_mono.xtime_nsec
+ ((u64)tk->wall_to_monotonic.tv_nsec
<< tk->tkr_mono.shift);
while (vdata->monotonic_time_snsec >=
(((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
vdata->monotonic_time_snsec -=
((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
vdata->monotonic_time_sec++;
}
base = &vdata->basetime[CLOCK_TAI];
base->sec = tk->xtime_sec + (s64)tk->tai_offset;
base->nsec = tk->tkr_mono.xtime_nsec;
vdata->wall_time_coarse_sec = tk->xtime_sec;
vdata->wall_time_coarse_nsec = (long)(tk->tkr_mono.xtime_nsec >>
tk->tkr_mono.shift);
base = &vdata->basetime[CLOCK_MONOTONIC];
base->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
nsec = tk->tkr_mono.xtime_nsec;
nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
nsec -= ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
base->sec++;
}
base->nsec = nsec;
vdata->monotonic_time_coarse_sec =
vdata->wall_time_coarse_sec + tk->wall_to_monotonic.tv_sec;
vdata->monotonic_time_coarse_nsec =
vdata->wall_time_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
base = &vdata->basetime[CLOCK_REALTIME_COARSE];
base->sec = tk->xtime_sec;
base->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
while (vdata->monotonic_time_coarse_nsec >= NSEC_PER_SEC) {
vdata->monotonic_time_coarse_nsec -= NSEC_PER_SEC;
vdata->monotonic_time_coarse_sec++;
base = &vdata->basetime[CLOCK_MONOTONIC_COARSE];
base->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
nsec += tk->wall_to_monotonic.tv_nsec;
while (nsec >= NSEC_PER_SEC) {
nsec -= NSEC_PER_SEC;
base->sec++;
}
base->nsec = nsec;
gtod_write_end(vdata);
}
......@@ -5,17 +5,38 @@
#include <linux/compiler.h>
#include <linux/clocksource.h>
#include <uapi/linux/time.h>
#ifdef BUILD_VDSO32_64
typedef u64 gtod_long_t;
#else
typedef unsigned long gtod_long_t;
#endif
/*
* There is one of these objects in the vvar page for each
* vDSO-accelerated clockid. For high-resolution clocks, this encodes
* the time corresponding to vsyscall_gtod_data.cycle_last. For coarse
* clocks, this encodes the actual time.
*
* To confuse the reader, for high-resolution clocks, nsec is left-shifted
* by vsyscall_gtod_data.shift.
*/
struct vgtod_ts {
u64 sec;
u64 nsec;
};
#define VGTOD_BASES (CLOCK_TAI + 1)
#define VGTOD_HRES (BIT(CLOCK_REALTIME) | BIT(CLOCK_MONOTONIC) | BIT(CLOCK_TAI))
#define VGTOD_COARSE (BIT(CLOCK_REALTIME_COARSE) | BIT(CLOCK_MONOTONIC_COARSE))
/*
* vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time
* so be carefull by modifying this structure.
*/
struct vsyscall_gtod_data {
unsigned seq;
unsigned int seq;
int vclock_mode;
u64 cycle_last;
......@@ -23,15 +44,7 @@ struct vsyscall_gtod_data {
u32 mult;
u32 shift;
/* open coded 'struct timespec' */
u64 wall_time_snsec;
gtod_long_t wall_time_sec;
gtod_long_t monotonic_time_sec;
u64 monotonic_time_snsec;
gtod_long_t wall_time_coarse_sec;
gtod_long_t wall_time_coarse_nsec;
gtod_long_t monotonic_time_coarse_sec;
gtod_long_t monotonic_time_coarse_nsec;
struct vgtod_ts basetime[VGTOD_BASES];
int tz_minuteswest;
int tz_dsttime;
......@@ -44,9 +57,9 @@ static inline bool vclock_was_used(int vclock)
return READ_ONCE(vclocks_used) & (1 << vclock);
}
static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
static inline unsigned int gtod_read_begin(const struct vsyscall_gtod_data *s)
{
unsigned ret;
unsigned int ret;
repeat:
ret = READ_ONCE(s->seq);
......@@ -59,7 +72,7 @@ static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
}
static inline int gtod_read_retry(const struct vsyscall_gtod_data *s,
unsigned start)
unsigned int start)
{
smp_rmb();
return unlikely(s->seq != start);
......
......@@ -10,6 +10,7 @@
*
*/
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
......@@ -105,3 +106,24 @@ void __init time_init(void)
{
late_time_init = x86_late_time_init;
}
/*
* Sanity check the vdso related archdata content.
*/
void clocksource_arch_init(struct clocksource *cs)
{
if (cs->archdata.vclock_mode == VCLOCK_NONE)
return;
if (cs->archdata.vclock_mode > VCLOCK_MAX) {
pr_warn("clocksource %s registered with invalid vclock_mode %d. Disabling vclock.\n",
cs->name, cs->archdata.vclock_mode);
cs->archdata.vclock_mode = VCLOCK_NONE;
}
if (cs->mask != CLOCKSOURCE_MASK(64)) {
pr_warn("clocksource %s registered with invalid mask %016llx. Disabling vclock.\n",
cs->name, cs->mask);
cs->archdata.vclock_mode = VCLOCK_NONE;
}
}
......@@ -241,6 +241,11 @@ static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz
__clocksource_update_freq_scale(cs, 1000, khz);
}
#ifdef CONFIG_ARCH_CLOCKSOURCE_INIT
extern void clocksource_arch_init(struct clocksource *cs);
#else
static inline void clocksource_arch_init(struct clocksource *cs) { }
#endif
extern int timekeeping_notify(struct clocksource *clock);
......
......@@ -12,6 +12,10 @@ config CLOCKSOURCE_WATCHDOG
config ARCH_CLOCKSOURCE_DATA
bool
# Architecture has extra clocksource init called from registration
config ARCH_CLOCKSOURCE_INIT
bool
# Clocksources require validation of the clocksource against the last
# cycle update - x86/TSC misfeature
config CLOCKSOURCE_VALIDATE_LAST_CYCLE
......
......@@ -937,6 +937,8 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
{
unsigned long flags;
clocksource_arch_init(cs);
/* Initialize mult/shift and max_idle_ns */
__clocksource_update_freq_scale(cs, scale, freq);
......
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