diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2020-07-23 00:00:07 +0200 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2020-07-24 15:05:00 +0200 |
commit | bdcd178ada90d2413bcc9df4211dcdd511a47586 (patch) | |
tree | f4e76cfb964331df2294b7dd8fd6dce6b185dc96 /arch/x86/entry | |
parent | 517e499227bed34acc69166691e2db5df3dc859a (diff) |
x86/entry: Use generic interrupt entry/exit code
Replace the x86 code with the generic variant. Use temporary defines for
idtentry_* which will be cleaned up in the next step.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200722220520.711492752@linutronix.de
Diffstat (limited to 'arch/x86/entry')
-rw-r--r-- | arch/x86/entry/common.c | 167 |
1 files changed, 1 insertions, 166 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index bc96eb8e055a..297e08ea9f87 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -198,171 +198,6 @@ SYSCALL_DEFINE0(ni_syscall) return -ENOSYS; } -/** - * idtentry_enter - Handle state tracking on ordinary idtentries - * @regs: Pointer to pt_regs of interrupted context - * - * Invokes: - * - lockdep irqflag state tracking as low level ASM entry disabled - * interrupts. - * - * - Context tracking if the exception hit user mode. - * - * - The hardirq tracer to keep the state consistent as low level ASM - * entry disabled interrupts. - * - * As a precondition, this requires that the entry came from user mode, - * idle, or a kernel context in which RCU is watching. - * - * For kernel mode entries RCU handling is done conditional. If RCU is - * watching then the only RCU requirement is to check whether the tick has - * to be restarted. If RCU is not watching then rcu_irq_enter() has to be - * invoked on entry and rcu_irq_exit() on exit. - * - * Avoiding the rcu_irq_enter/exit() calls is an optimization but also - * solves the problem of kernel mode pagefaults which can schedule, which - * is not possible after invoking rcu_irq_enter() without undoing it. - * - * For user mode entries irqentry_enter_from_user_mode() must be invoked to - * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit - * would not be possible. - * - * Returns: An opaque object that must be passed to idtentry_exit() - * - * The return value must be fed into the state argument of - * idtentry_exit(). - */ -idtentry_state_t noinstr idtentry_enter(struct pt_regs *regs) -{ - idtentry_state_t ret = { - .exit_rcu = false, - }; - - if (user_mode(regs)) { - irqentry_enter_from_user_mode(regs); - return ret; - } - - /* - * If this entry hit the idle task invoke rcu_irq_enter() whether - * RCU is watching or not. - * - * Interupts can nest when the first interrupt invokes softirq - * processing on return which enables interrupts. - * - * Scheduler ticks in the idle task can mark quiescent state and - * terminate a grace period, if and only if the timer interrupt is - * not nested into another interrupt. - * - * Checking for __rcu_is_watching() here would prevent the nesting - * interrupt to invoke rcu_irq_enter(). If that nested interrupt is - * the tick then rcu_flavor_sched_clock_irq() would wrongfully - * assume that it is the first interupt and eventually claim - * quiescient state and end grace periods prematurely. - * - * Unconditionally invoke rcu_irq_enter() so RCU state stays - * consistent. - * - * TINY_RCU does not support EQS, so let the compiler eliminate - * this part when enabled. - */ - if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) { - /* - * If RCU is not watching then the same careful - * sequence vs. lockdep and tracing is required - * as in irqentry_enter_from_user_mode(). - */ - lockdep_hardirqs_off(CALLER_ADDR0); - rcu_irq_enter(); - instrumentation_begin(); - trace_hardirqs_off_finish(); - instrumentation_end(); - - ret.exit_rcu = true; - return ret; - } - - /* - * If RCU is watching then RCU only wants to check whether it needs - * to restart the tick in NOHZ mode. rcu_irq_enter_check_tick() - * already contains a warning when RCU is not watching, so no point - * in having another one here. - */ - instrumentation_begin(); - rcu_irq_enter_check_tick(); - /* Use the combo lockdep/tracing function */ - trace_hardirqs_off(); - instrumentation_end(); - - return ret; -} - -static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched) -{ - if (may_sched && !preempt_count()) { - /* Sanity check RCU and thread stack */ - rcu_irq_exit_check_preempt(); - if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) - WARN_ON_ONCE(!on_thread_stack()); - if (need_resched()) - preempt_schedule_irq(); - } - /* Covers both tracing and lockdep */ - trace_hardirqs_on(); -} - -/** - * idtentry_exit - Handle return from exception that used idtentry_enter() - * @regs: Pointer to pt_regs (exception entry regs) - * @state: Return value from matching call to idtentry_enter() - * - * Depending on the return target (kernel/user) this runs the necessary - * preemption and work checks if possible and reguired and returns to - * the caller with interrupts disabled and no further work pending. - * - * This is the last action before returning to the low level ASM code which - * just needs to return to the appropriate context. - * - * Counterpart to idtentry_enter(). The return value of the entry - * function must be fed into the @state argument. - */ -void noinstr idtentry_exit(struct pt_regs *regs, idtentry_state_t state) -{ - lockdep_assert_irqs_disabled(); - - /* Check whether this returns to user mode */ - if (user_mode(regs)) { - irqentry_exit_to_user_mode(regs); - } else if (regs->flags & X86_EFLAGS_IF) { - /* - * If RCU was not watching on entry this needs to be done - * carefully and needs the same ordering of lockdep/tracing - * and RCU as the return to user mode path. - */ - if (state.exit_rcu) { - instrumentation_begin(); - /* Tell the tracer that IRET will enable interrupts */ - trace_hardirqs_on_prepare(); - lockdep_hardirqs_on_prepare(CALLER_ADDR0); - instrumentation_end(); - rcu_irq_exit(); - lockdep_hardirqs_on(CALLER_ADDR0); - return; - } - - instrumentation_begin(); - idtentry_exit_cond_resched(regs, IS_ENABLED(CONFIG_PREEMPTION)); - instrumentation_end(); - } else { - /* - * IRQ flags state is correct already. Just tell RCU if it - * was not watching on entry. - */ - if (state.exit_rcu) - rcu_irq_exit(); - } -} - #ifdef CONFIG_XEN_PV #ifndef CONFIG_PREEMPTION /* @@ -427,7 +262,7 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs) inhcall = get_and_clear_inhcall(); if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) { instrumentation_begin(); - idtentry_exit_cond_resched(regs, true); + irqentry_exit_cond_resched(); instrumentation_end(); restore_inhcall(inhcall); } else { |