Commit-ID: baa73d9e478ff32d62f3f9422822b59dd9a95a21 Gitweb: http://git.kernel.org/tip/baa73d9e478ff32d62f3f9422822b59dd9a95a21 Author: Nicolas Pitre <nicolas.pi...@linaro.org> AuthorDate: Fri, 11 Nov 2016 00:10:10 -0500 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Wed, 16 Nov 2016 09:26:35 +0100
posix-timers: Make them configurable Some embedded systems have no use for them. This removes about 25KB from the kernel binary size when configured out. Corresponding syscalls are routed to a stub logging the attempt to use those syscalls which should be enough of a clue if they were disabled without proper consideration. They are: timer_create, timer_gettime: timer_getoverrun, timer_settime, timer_delete, clock_adjtime, setitimer, getitimer, alarm. The clock_settime, clock_gettime, clock_getres and clock_nanosleep syscalls are replaced by simple wrappers compatible with CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only which should cover the vast majority of use cases with very little code. Signed-off-by: Nicolas Pitre <n...@linaro.org> Acked-by: Richard Cochran <richardcoch...@gmail.com> Acked-by: Thomas Gleixner <t...@linutronix.de> Acked-by: John Stultz <john.stu...@linaro.org> Reviewed-by: Josh Triplett <j...@joshtriplett.org> Cc: Paul Bolle <pebo...@tiscali.nl> Cc: linux-kbu...@vger.kernel.org Cc: net...@vger.kernel.org Cc: Michal Marek <mma...@suse.com> Cc: Edward Cree <ec...@solarflare.com> Link: http://lkml.kernel.org/r/1478841010-28605-7-git-send-email-nicolas.pi...@linaro.org Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- arch/alpha/kernel/osf_sys.c | 8 +++ drivers/char/Kconfig | 1 + drivers/ptp/Kconfig | 2 +- fs/exec.c | 2 + init/Kconfig | 17 ++++++ kernel/compat.c | 8 +++ kernel/exit.c | 11 +++- kernel/fork.c | 2 + kernel/signal.c | 6 +++ kernel/sys.c | 3 +- kernel/time/Makefile | 10 +++- kernel/time/alarmtimer.c | 6 ++- kernel/time/posix-stubs.c | 123 ++++++++++++++++++++++++++++++++++++++++++++ kernel/time/timer.c | 3 +- security/selinux/hooks.c | 11 ++-- 15 files changed, 200 insertions(+), 13 deletions(-) diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c index ffb93f49..56e427c 100644 --- a/arch/alpha/kernel/osf_sys.c +++ b/arch/alpha/kernel/osf_sys.c @@ -1029,11 +1029,16 @@ SYSCALL_DEFINE2(osf_settimeofday, struct timeval32 __user *, tv, return do_sys_settimeofday(tv ? &kts : NULL, tz ? &ktz : NULL); } +asmlinkage long sys_ni_posix_timers(void); + SYSCALL_DEFINE2(osf_getitimer, int, which, struct itimerval32 __user *, it) { struct itimerval kit; int error; + if (!IS_ENABLED(CONFIG_POSIX_TIMERS)) + return sys_ni_posix_timers(); + error = do_getitimer(which, &kit); if (!error && put_it32(it, &kit)) error = -EFAULT; @@ -1047,6 +1052,9 @@ SYSCALL_DEFINE3(osf_setitimer, int, which, struct itimerval32 __user *, in, struct itimerval kin, kout; int error; + if (!IS_ENABLED(CONFIG_POSIX_TIMERS)) + return sys_ni_posix_timers(); + if (in) { if (get_it32(&kin, in)) return -EFAULT; diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig index dcc0973..45ba878 100644 --- a/drivers/char/Kconfig +++ b/drivers/char/Kconfig @@ -542,6 +542,7 @@ config HANGCHECK_TIMER config MMTIMER tristate "MMTIMER Memory mapped RTC for SGI Altix" depends on IA64_GENERIC || IA64_SGI_SN2 + depends on POSIX_TIMERS default y help The mmtimer device allows direct userspace access to the diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig index 0f7492f..bdce332 100644 --- a/drivers/ptp/Kconfig +++ b/drivers/ptp/Kconfig @@ -6,7 +6,7 @@ menu "PTP clock support" config PTP_1588_CLOCK tristate "PTP clock support" - depends on NET + depends on NET && POSIX_TIMERS select PPS select NET_PTP_CLASSIFY help diff --git a/fs/exec.c b/fs/exec.c index 4e497b9..923c57d 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1169,8 +1169,10 @@ no_thread_group: /* we have changed execution domain */ tsk->exit_signal = SIGCHLD; +#ifdef CONFIG_POSIX_TIMERS exit_itimers(sig); flush_itimer_signals(); +#endif if (atomic_read(&oldsighand->count) != 1) { struct sighand_struct *newsighand; diff --git a/init/Kconfig b/init/Kconfig index 34407f1..456e0b8 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1445,6 +1445,23 @@ config SYSCTL_SYSCALL If unsure say N here. +config POSIX_TIMERS + bool "Posix Clocks & timers" if EXPERT + default y + help + This includes native support for POSIX timers to the kernel. + Some embedded systems have no use for them and therefore they + can be configured out to reduce the size of the kernel image. + + When this option is disabled, the following syscalls won't be + available: timer_create, timer_gettime: timer_getoverrun, + timer_settime, timer_delete, clock_adjtime, getitimer, + setitimer, alarm. Furthermore, the clock_settime, clock_gettime, + clock_getres and clock_nanosleep syscalls will be limited to + CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. + + If unsure say y. + config KALLSYMS bool "Load all symbols for debugging/ksymoops" if EXPERT default y diff --git a/kernel/compat.c b/kernel/compat.c index 333d364..b3a047f 100644 --- a/kernel/compat.c +++ b/kernel/compat.c @@ -307,12 +307,17 @@ static inline long put_compat_itimerval(struct compat_itimerval __user *o, __put_user(i->it_value.tv_usec, &o->it_value.tv_usec))); } +asmlinkage long sys_ni_posix_timers(void); + COMPAT_SYSCALL_DEFINE2(getitimer, int, which, struct compat_itimerval __user *, it) { struct itimerval kit; int error; + if (!IS_ENABLED(CONFIG_POSIX_TIMERS)) + return sys_ni_posix_timers(); + error = do_getitimer(which, &kit); if (!error && put_compat_itimerval(it, &kit)) error = -EFAULT; @@ -326,6 +331,9 @@ COMPAT_SYSCALL_DEFINE3(setitimer, int, which, struct itimerval kin, kout; int error; + if (!IS_ENABLED(CONFIG_POSIX_TIMERS)) + return sys_ni_posix_timers(); + if (in) { if (get_compat_itimerval(&kin, in)) return -EFAULT; diff --git a/kernel/exit.c b/kernel/exit.c index d16bcdd..684de01 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -92,11 +92,10 @@ static void __exit_signal(struct task_struct *tsk) lockdep_tasklist_lock_is_held()); spin_lock(&sighand->siglock); +#ifdef CONFIG_POSIX_TIMERS posix_cpu_timers_exit(tsk); if (group_dead) { posix_cpu_timers_exit_group(tsk); - tty = sig->tty; - sig->tty = NULL; } else { /* * This can only happen if the caller is de_thread(). @@ -105,7 +104,13 @@ static void __exit_signal(struct task_struct *tsk) */ if (unlikely(has_group_leader_pid(tsk))) posix_cpu_timers_exit_group(tsk); + } +#endif + if (group_dead) { + tty = sig->tty; + sig->tty = NULL; + } else { /* * If there is any task waiting for the group exit * then notify it: @@ -803,8 +808,10 @@ void __noreturn do_exit(long code) acct_update_integrals(tsk); group_dead = atomic_dec_and_test(&tsk->signal->live); if (group_dead) { +#ifdef CONFIG_POSIX_TIMERS hrtimer_cancel(&tsk->signal->real_timer); exit_itimers(tsk->signal); +#endif if (tsk->mm) setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); } diff --git a/kernel/fork.c b/kernel/fork.c index 623259f..17da35f 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1342,8 +1342,10 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) seqlock_init(&sig->stats_lock); prev_cputime_init(&sig->prev_cputime); +#ifdef CONFIG_POSIX_TIMERS hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); sig->real_timer.function = it_real_fn; +#endif task_lock(current->group_leader); memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); diff --git a/kernel/signal.c b/kernel/signal.c index 75761ac..29a4107 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -427,6 +427,7 @@ void flush_signals(struct task_struct *t) spin_unlock_irqrestore(&t->sighand->siglock, flags); } +#ifdef CONFIG_POSIX_TIMERS static void __flush_itimer_signals(struct sigpending *pending) { sigset_t signal, retain; @@ -460,6 +461,7 @@ void flush_itimer_signals(void) __flush_itimer_signals(&tsk->signal->shared_pending); spin_unlock_irqrestore(&tsk->sighand->siglock, flags); } +#endif void ignore_signals(struct task_struct *t) { @@ -567,6 +569,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) if (!signr) { signr = __dequeue_signal(&tsk->signal->shared_pending, mask, info); +#ifdef CONFIG_POSIX_TIMERS /* * itimer signal ? * @@ -590,6 +593,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) hrtimer_restart(tmr); } } +#endif } recalc_sigpending(); @@ -611,6 +615,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) */ current->jobctl |= JOBCTL_STOP_DEQUEUED; } +#ifdef CONFIG_POSIX_TIMERS if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) { /* * Release the siglock to ensure proper locking order @@ -622,6 +627,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) do_schedule_next_timer(info); spin_lock(&tsk->sighand->siglock); } +#endif return signr; } diff --git a/kernel/sys.c b/kernel/sys.c index 89d5be4..78c9fb7 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1416,7 +1416,8 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource, * applications, so we live with it */ if (!retval && new_rlim && resource == RLIMIT_CPU && - new_rlim->rlim_cur != RLIM_INFINITY) + new_rlim->rlim_cur != RLIM_INFINITY && + IS_ENABLED(CONFIG_POSIX_TIMERS)) update_rlimit_cpu(tsk, new_rlim->rlim_cur); out: read_unlock(&tasklist_lock); diff --git a/kernel/time/Makefile b/kernel/time/Makefile index 49eca0b..976840d 100644 --- a/kernel/time/Makefile +++ b/kernel/time/Makefile @@ -1,6 +1,12 @@ -obj-y += time.o timer.o hrtimer.o itimer.o posix-timers.o posix-cpu-timers.o +obj-y += time.o timer.o hrtimer.o obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o -obj-y += timeconv.o timecounter.o posix-clock.o alarmtimer.o +obj-y += timeconv.o timecounter.o alarmtimer.o + +ifeq ($(CONFIG_POSIX_TIMERS),y) + obj-y += posix-timers.o posix-cpu-timers.o posix-clock.o itimer.o +else + obj-y += posix-stubs.o +endif obj-$(CONFIG_GENERIC_CLOCKEVENTS) += clockevents.o tick-common.o ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y) diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 12dd190..a15caa3 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -846,8 +846,10 @@ static int __init alarmtimer_init(void) alarmtimer_rtc_timer_init(); - posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock); - posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock); + if (IS_ENABLED(CONFIG_POSIX_TIMERS)) { + posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock); + posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock); + } /* Initialize alarm bases */ alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME; diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c new file mode 100644 index 0000000..cd6716e --- /dev/null +++ b/kernel/time/posix-stubs.c @@ -0,0 +1,123 @@ +/* + * Dummy stubs used when CONFIG_POSIX_TIMERS=n + * + * Created by: Nicolas Pitre, July 2016 + * Copyright: (C) 2016 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/linkage.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/errno.h> +#include <linux/syscalls.h> +#include <linux/ktime.h> +#include <linux/timekeeping.h> +#include <linux/posix-timers.h> + +asmlinkage long sys_ni_posix_timers(void) +{ + pr_err_once("process %d (%s) attempted a POSIX timer syscall " + "while CONFIG_POSIX_TIMERS is not set\n", + current->pid, current->comm); + return -ENOSYS; +} + +#define SYS_NI(name) SYSCALL_ALIAS(sys_##name, sys_ni_posix_timers) + +SYS_NI(timer_create); +SYS_NI(timer_gettime); +SYS_NI(timer_getoverrun); +SYS_NI(timer_settime); +SYS_NI(timer_delete); +SYS_NI(clock_adjtime); +SYS_NI(getitimer); +SYS_NI(setitimer); +#ifdef __ARCH_WANT_SYS_ALARM +SYS_NI(alarm); +#endif + +/* + * We preserve minimal support for CLOCK_REALTIME and CLOCK_MONOTONIC + * as it is easy to remain compatible with little code. CLOCK_BOOTTIME + * is also included for convenience as at least systemd uses it. + */ + +SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock, + const struct timespec __user *, tp) +{ + struct timespec new_tp; + + if (which_clock != CLOCK_REALTIME) + return -EINVAL; + if (copy_from_user(&new_tp, tp, sizeof (*tp))) + return -EFAULT; + return do_sys_settimeofday(&new_tp, NULL); +} + +SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock, + struct timespec __user *,tp) +{ + struct timespec kernel_tp; + + switch (which_clock) { + case CLOCK_REALTIME: ktime_get_real_ts(&kernel_tp); break; + case CLOCK_MONOTONIC: ktime_get_ts(&kernel_tp); break; + case CLOCK_BOOTTIME: get_monotonic_boottime(&kernel_tp); break; + default: return -EINVAL; + } + if (copy_to_user(tp, &kernel_tp, sizeof (kernel_tp))) + return -EFAULT; + return 0; +} + +SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock, struct timespec __user *, tp) +{ + struct timespec rtn_tp = { + .tv_sec = 0, + .tv_nsec = hrtimer_resolution, + }; + + switch (which_clock) { + case CLOCK_REALTIME: + case CLOCK_MONOTONIC: + case CLOCK_BOOTTIME: + if (copy_to_user(tp, &rtn_tp, sizeof(rtn_tp))) + return -EFAULT; + return 0; + default: + return -EINVAL; + } +} + +SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags, + const struct timespec __user *, rqtp, + struct timespec __user *, rmtp) +{ + struct timespec t; + + switch (which_clock) { + case CLOCK_REALTIME: + case CLOCK_MONOTONIC: + case CLOCK_BOOTTIME: + if (copy_from_user(&t, rqtp, sizeof (struct timespec))) + return -EFAULT; + if (!timespec_valid(&t)) + return -EINVAL; + return hrtimer_nanosleep(&t, rmtp, flags & TIMER_ABSTIME ? + HRTIMER_MODE_ABS : HRTIMER_MODE_REL, + which_clock); + default: + return -EINVAL; + } +} + +#ifdef CONFIG_COMPAT +long clock_nanosleep_restart(struct restart_block *restart_block) +{ + return hrtimer_nanosleep_restart(restart_block); +} +#endif diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 42d27aa..e2892e4 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1601,7 +1601,8 @@ void update_process_times(int user_tick) irq_work_tick(); #endif scheduler_tick(); - run_posix_cpu_timers(p); + if (IS_ENABLED(CONFIG_POSIX_TIMERS)) + run_posix_cpu_timers(p); } /** diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 09fd610..38b79d7 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2525,7 +2525,8 @@ static void selinux_bprm_committing_creds(struct linux_binprm *bprm) rlim->rlim_cur = min(rlim->rlim_max, initrlim->rlim_cur); } task_unlock(current); - update_rlimit_cpu(current, rlimit(RLIMIT_CPU)); + if (IS_ENABLED(CONFIG_POSIX_TIMERS)) + update_rlimit_cpu(current, rlimit(RLIMIT_CPU)); } } @@ -2555,9 +2556,11 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm) */ rc = avc_has_perm(osid, sid, SECCLASS_PROCESS, PROCESS__SIGINH, NULL); if (rc) { - memset(&itimer, 0, sizeof itimer); - for (i = 0; i < 3; i++) - do_setitimer(i, &itimer, NULL); + if (IS_ENABLED(CONFIG_POSIX_TIMERS)) { + memset(&itimer, 0, sizeof itimer); + for (i = 0; i < 3; i++) + do_setitimer(i, &itimer, NULL); + } spin_lock_irq(¤t->sighand->siglock); if (!fatal_signal_pending(current)) { flush_sigqueue(¤t->pending);
