Message-Id: <20170515203213.25080-1-hch@lst.de>
Date:   Mon, 15 May 2017 22:32:13 +0200
From:   Christoph Hellwig <hch@....de>
To:     tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] kernel: mark all struct k_clock instances const

And keep a pointer to it instead of a copy in the posix_clocks array.

Based on similar changes in the Grsecurity patchset, but redone from
scratch including a few tweaks.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/char/mmtimer.c         |   4 +-
 include/linux/posix-timers.h   |   7 +-
 kernel/time/alarmtimer.c       |  19 +++---
 kernel/time/posix-clock.c      |   2 +-
 kernel/time/posix-cpu-timers.c |  29 ++++----
 kernel/time/posix-timers.c     | 150 ++++++++++++++++++++++-------------------
 6 files changed, 111 insertions(+), 100 deletions(-)

diff --git a/drivers/char/mmtimer.c b/drivers/char/mmtimer.c
index 0e7fcb04f01e..e501403dd860 100644
--- a/drivers/char/mmtimer.c
+++ b/drivers/char/mmtimer.c
@@ -53,7 +53,7 @@ MODULE_LICENSE("GPL");
 
 #define RTC_BITS 55 /* 55 bits for this implementation */
 
-static struct k_clock sgi_clock;
+static const struct k_clock sgi_clock;
 
 extern unsigned long sn_rtc_cycles_per_second;
 
@@ -772,7 +772,7 @@ static int sgi_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 	return 0;
 }
 
-static struct k_clock sgi_clock = {
+static const struct k_clock sgi_clock = {
 	.clock_set	= sgi_clock_set,
 	.clock_get	= sgi_clock_get,
 	.clock_getres	= sgi_clock_getres,
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 8c1e43ab14a9..5166393e19d7 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -105,10 +105,11 @@ struct k_clock {
 			   struct itimerspec64 *cur_setting);
 };
 
-extern struct k_clock clock_posix_cpu;
-extern struct k_clock clock_posix_dynamic;
+extern const struct k_clock clock_posix_cpu;
+extern const struct k_clock clock_posix_dynamic;
 
-void posix_timers_register_clock(const clockid_t clock_id, struct k_clock *new_clock);
+void posix_timers_register_clock(const clockid_t clock_id,
+		const struct k_clock *new_clock);
 
 /* function to call to trigger timer event */
 int posix_timer_event(struct k_itimer *timr, int si_private);
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 5cb5b0008d97..3a5206ee50c1 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -860,6 +860,16 @@ static struct platform_driver alarmtimer_driver = {
 	}
 };
 
+static const struct k_clock alarm_clock = {
+	.clock_getres	= alarm_clock_getres,
+	.clock_get	= alarm_clock_get,
+	.timer_create	= alarm_timer_create,
+	.timer_set	= alarm_timer_set,
+	.timer_del	= alarm_timer_del,
+	.timer_get	= alarm_timer_get,
+	.nsleep		= alarm_timer_nsleep,
+};
+
 /**
  * alarmtimer_init - Initialize alarm timer code
  *
@@ -871,15 +881,6 @@ static int __init alarmtimer_init(void)
 	struct platform_device *pdev;
 	int error = 0;
 	int i;
-	struct k_clock alarm_clock = {
-		.clock_getres	= alarm_clock_getres,
-		.clock_get	= alarm_clock_get,
-		.timer_create	= alarm_timer_create,
-		.timer_set	= alarm_timer_set,
-		.timer_del	= alarm_timer_del,
-		.timer_get	= alarm_timer_get,
-		.nsleep		= alarm_timer_nsleep,
-	};
 
 	alarmtimer_rtc_timer_init();
 
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index 31d588d37a17..7e453005e078 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -434,7 +434,7 @@ static int pc_timer_settime(struct k_itimer *kit, int flags,
 	return err;
 }
 
-struct k_clock clock_posix_dynamic = {
+const struct k_clock clock_posix_dynamic = {
 	.clock_getres	= pc_clock_getres,
 	.clock_set	= pc_clock_settime,
 	.clock_get	= pc_clock_gettime,
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 1370f067fb51..ba79aa955137 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1413,7 +1413,7 @@ static int thread_cpu_timer_create(struct k_itimer *timer)
 	return posix_cpu_timer_create(timer);
 }
 
-struct k_clock clock_posix_cpu = {
+const struct k_clock clock_posix_cpu = {
 	.clock_getres	= posix_cpu_clock_getres,
 	.clock_set	= posix_cpu_clock_set,
 	.clock_get	= posix_cpu_clock_get,
@@ -1425,21 +1425,22 @@ struct k_clock clock_posix_cpu = {
 	.timer_get	= posix_cpu_timer_get,
 };
 
+static const struct k_clock process = {
+	.clock_getres	= process_cpu_clock_getres,
+	.clock_get	= process_cpu_clock_get,
+	.timer_create	= process_cpu_timer_create,
+	.nsleep		= process_cpu_nsleep,
+	.nsleep_restart	= process_cpu_nsleep_restart,
+};
+
+static const struct k_clock thread = {
+	.clock_getres	= thread_cpu_clock_getres,
+	.clock_get	= thread_cpu_clock_get,
+	.timer_create	= thread_cpu_timer_create,
+};
+
 static __init int init_posix_cpu_timers(void)
 {
-	struct k_clock process = {
-		.clock_getres	= process_cpu_clock_getres,
-		.clock_get	= process_cpu_clock_get,
-		.timer_create	= process_cpu_timer_create,
-		.nsleep		= process_cpu_nsleep,
-		.nsleep_restart	= process_cpu_nsleep_restart,
-	};
-	struct k_clock thread = {
-		.clock_getres	= thread_cpu_clock_getres,
-		.clock_get	= thread_cpu_clock_get,
-		.timer_create	= thread_cpu_timer_create,
-	};
-
 	posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
 	posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
 
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 4d7b2ce09c27..5e01120897fe 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -125,7 +125,7 @@ static DEFINE_SPINLOCK(hash_lock);
  *	    which we beg off on and pass to do_sys_settimeofday().
  */
 
-static struct k_clock posix_clocks[MAX_CLOCKS];
+static const struct k_clock *posix_clocks[MAX_CLOCKS];
 
 /*
  * These ones are defined below.
@@ -280,66 +280,73 @@ static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
 	return 0;
 }
 
+
+static const struct k_clock clock_realtime = {
+	.clock_getres	= posix_get_hrtimer_res,
+	.clock_get	= posix_clock_realtime_get,
+	.clock_set	= posix_clock_realtime_set,
+	.clock_adj	= posix_clock_realtime_adj,
+	.nsleep		= common_nsleep,
+	.nsleep_restart	= hrtimer_nanosleep_restart,
+	.timer_create	= common_timer_create,
+	.timer_set	= common_timer_set,
+	.timer_get	= common_timer_get,
+	.timer_del	= common_timer_del,
+};
+
+static const struct k_clock clock_monotonic = {
+	.clock_getres	= posix_get_hrtimer_res,
+	.clock_get	= posix_ktime_get_ts,
+	.nsleep		= common_nsleep,
+	.nsleep_restart	= hrtimer_nanosleep_restart,
+	.timer_create	= common_timer_create,
+	.timer_set	= common_timer_set,
+	.timer_get	= common_timer_get,
+	.timer_del	= common_timer_del,
+};
+
+static const struct k_clock clock_monotonic_raw = {
+	.clock_getres	= posix_get_hrtimer_res,
+	.clock_get	= posix_get_monotonic_raw,
+};
+
+static const struct k_clock clock_realtime_coarse = {
+	.clock_getres	= posix_get_coarse_res,
+	.clock_get	= posix_get_realtime_coarse,
+};
+
+static const struct k_clock clock_monotonic_coarse = {
+	.clock_getres	= posix_get_coarse_res,
+	.clock_get	= posix_get_monotonic_coarse,
+};
+
+static const struct k_clock clock_tai = {
+	.clock_getres	= posix_get_hrtimer_res,
+	.clock_get	= posix_get_tai,
+	.nsleep		= common_nsleep,
+	.nsleep_restart	= hrtimer_nanosleep_restart,
+	.timer_create	= common_timer_create,
+	.timer_set	= common_timer_set,
+	.timer_get	= common_timer_get,
+	.timer_del	= common_timer_del,
+};
+
+static const struct k_clock clock_boottime = {
+	.clock_getres	= posix_get_hrtimer_res,
+	.clock_get	= posix_get_boottime,
+	.nsleep		= common_nsleep,
+	.nsleep_restart	= hrtimer_nanosleep_restart,
+	.timer_create	= common_timer_create,
+	.timer_set	= common_timer_set,
+	.timer_get	= common_timer_get,
+	.timer_del	= common_timer_del,
+};
+
 /*
  * Initialize everything, well, just everything in Posix clocks/timers ;)
  */
 static __init int init_posix_timers(void)
 {
-	struct k_clock clock_realtime = {
-		.clock_getres	= posix_get_hrtimer_res,
-		.clock_get	= posix_clock_realtime_get,
-		.clock_set	= posix_clock_realtime_set,
-		.clock_adj	= posix_clock_realtime_adj,
-		.nsleep		= common_nsleep,
-		.nsleep_restart	= hrtimer_nanosleep_restart,
-		.timer_create	= common_timer_create,
-		.timer_set	= common_timer_set,
-		.timer_get	= common_timer_get,
-		.timer_del	= common_timer_del,
-	};
-	struct k_clock clock_monotonic = {
-		.clock_getres	= posix_get_hrtimer_res,
-		.clock_get	= posix_ktime_get_ts,
-		.nsleep		= common_nsleep,
-		.nsleep_restart	= hrtimer_nanosleep_restart,
-		.timer_create	= common_timer_create,
-		.timer_set	= common_timer_set,
-		.timer_get	= common_timer_get,
-		.timer_del	= common_timer_del,
-	};
-	struct k_clock clock_monotonic_raw = {
-		.clock_getres	= posix_get_hrtimer_res,
-		.clock_get	= posix_get_monotonic_raw,
-	};
-	struct k_clock clock_realtime_coarse = {
-		.clock_getres	= posix_get_coarse_res,
-		.clock_get	= posix_get_realtime_coarse,
-	};
-	struct k_clock clock_monotonic_coarse = {
-		.clock_getres	= posix_get_coarse_res,
-		.clock_get	= posix_get_monotonic_coarse,
-	};
-	struct k_clock clock_tai = {
-		.clock_getres	= posix_get_hrtimer_res,
-		.clock_get	= posix_get_tai,
-		.nsleep		= common_nsleep,
-		.nsleep_restart	= hrtimer_nanosleep_restart,
-		.timer_create	= common_timer_create,
-		.timer_set	= common_timer_set,
-		.timer_get	= common_timer_get,
-		.timer_del	= common_timer_del,
-	};
-	struct k_clock clock_boottime = {
-		.clock_getres	= posix_get_hrtimer_res,
-		.clock_get	= posix_get_boottime,
-		.nsleep		= common_nsleep,
-		.nsleep_restart	= hrtimer_nanosleep_restart,
-		.timer_create	= common_timer_create,
-		.timer_set	= common_timer_set,
-		.timer_get	= common_timer_get,
-		.timer_del	= common_timer_del,
-	};
-
 	posix_timers_register_clock(CLOCK_REALTIME, &clock_realtime);
 	posix_timers_register_clock(CLOCK_MONOTONIC, &clock_monotonic);
 	posix_timers_register_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
@@ -522,7 +529,7 @@ static struct pid *good_sigevent(sigevent_t * event)
 }
 
 void posix_timers_register_clock(const clockid_t clock_id,
-				 struct k_clock *new_clock)
+				 const struct k_clock *new_clock)
 {
 	if ((unsigned) clock_id >= MAX_CLOCKS) {
 		printk(KERN_WARNING "POSIX clock register failed for clock_id %d\n",
@@ -541,7 +548,7 @@ void posix_timers_register_clock(const clockid_t clock_id,
 		return;
 	}
 
-	posix_clocks[clock_id] = *new_clock;
+	posix_clocks[clock_id] = new_clock;
 }
 EXPORT_SYMBOL_GPL(posix_timers_register_clock);
 
@@ -581,15 +588,16 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
 	call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
 }
 
-static struct k_clock *clockid_to_kclock(const clockid_t id)
+static const struct k_clock *clockid_to_kclock(const clockid_t id)
 {
 	if (id < 0)
 		return (id & CLOCKFD_MASK) == CLOCKFD ?
 			&clock_posix_dynamic : &clock_posix_cpu;
 
-	if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)
+	if (id >= MAX_CLOCKS || !posix_clocks[id] ||
+	    !posix_clocks[id]->clock_getres)
 		return NULL;
-	return &posix_clocks[id];
+	return posix_clocks[id];
 }
 
 static int common_timer_create(struct k_itimer *new_timer)
@@ -604,7 +612,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
 		struct sigevent __user *, timer_event_spec,
 		timer_t __user *, created_timer_id)
 {
-	struct k_clock *kc = clockid_to_kclock(which_clock);
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct k_itimer *new_timer;
 	int error, new_timer_id;
 	sigevent_t event;
@@ -781,7 +789,7 @@ SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
 	struct itimerspec64 cur_setting64;
 	struct itimerspec cur_setting;
 	struct k_itimer *timr;
-	struct k_clock *kc;
+	const struct k_clock *kc;
 	unsigned long flags;
 	int ret = 0;
 
@@ -890,7 +898,7 @@ SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
 	struct itimerspec new_spec, old_spec;
 	struct k_itimer *timr;
 	unsigned long flag;
-	struct k_clock *kc;
+	const struct k_clock *kc;
 	int error = 0;
 
 	if (!new_setting)
@@ -939,7 +947,7 @@ static int common_timer_del(struct k_itimer *timer)
 
 static inline int timer_delete_hook(struct k_itimer *timer)
 {
-	struct k_clock *kc = clockid_to_kclock(timer->it_clock);
+	const struct k_clock *kc = clockid_to_kclock(timer->it_clock);
 
 	if (WARN_ON_ONCE(!kc || !kc->timer_del))
 		return -EINVAL;
@@ -1018,7 +1026,7 @@ void exit_itimers(struct signal_struct *sig)
 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 		const struct timespec __user *, tp)
 {
-	struct k_clock *kc = clockid_to_kclock(which_clock);
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 new_tp64;
 	struct timespec new_tp;
 
@@ -1035,7 +1043,7 @@ SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 		struct timespec __user *,tp)
 {
-	struct k_clock *kc = clockid_to_kclock(which_clock);
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 kernel_tp64;
 	struct timespec kernel_tp;
 	int error;
@@ -1055,7 +1063,7 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
 		struct timex __user *, utx)
 {
-	struct k_clock *kc = clockid_to_kclock(which_clock);
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timex ktx;
 	int err;
 
@@ -1078,7 +1086,7 @@ SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
 		struct timespec __user *, tp)
 {
-	struct k_clock *kc = clockid_to_kclock(which_clock);
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 rtn_tp64;
 	struct timespec rtn_tp;
 	int error;
@@ -1110,7 +1118,7 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 		const struct timespec __user *, rqtp,
 		struct timespec __user *, rmtp)
 {
-	struct k_clock *kc = clockid_to_kclock(which_clock);
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
 	struct timespec64 t64;
 	struct timespec t;
 
@@ -1136,7 +1144,7 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 long clock_nanosleep_restart(struct restart_block *restart_block)
 {
 	clockid_t which_clock = restart_block->nanosleep.clockid;
-	struct k_clock *kc = clockid_to_kclock(which_clock);
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
 
 	if (WARN_ON_ONCE(!kc || !kc->nsleep_restart))
 		return -EINVAL;
-- 
2.11.0

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