The following commit has been merged into the x86/entry branch of tip: Commit-ID: 1951bc04047a0ca5c88146c4b19b296d40e489ef Gitweb: https://git.kernel.org/tip/1951bc04047a0ca5c88146c4b19b296d40e489ef Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Thu, 21 May 2020 22:05:20 +02:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 26 May 2020 19:06:27 +02:00 x86/entry: Clean up idtentry_enter/exit() leftovers Now that everything is converted to conditional RCU handling remove idtentry_enter/exit() and tidy up the conditional functions. This does not remove rcu_irq_exit_preempt(), to avoid conflicts with the RCU tree. Will be removed once all of this hits Linus's tree. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> Link: https://lore.kernel.org/r/20200521202117.473597954@xxxxxxxxxxxxx --- arch/x86/entry/common.c | 67 +++++++++++++------------------- arch/x86/include/asm/idtentry.h | 12 +------ 2 files changed, 30 insertions(+), 49 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index b7fcb13..2a80e4e 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -515,7 +515,6 @@ SYSCALL_DEFINE0(ni_syscall) * idtentry_enter_cond_rcu - Handle state tracking on idtentry with conditional * RCU handling * @regs: Pointer to pt_regs of interrupted context - * @cond_rcu: Invoke rcu_irq_enter() only if RCU is not watching * * Invokes: * - lockdep irqflag state tracking as low level ASM entry disabled @@ -545,14 +544,14 @@ SYSCALL_DEFINE0(ni_syscall) * The return value must be fed into the rcu_exit argument of * idtentry_exit_cond_rcu(). */ -bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs, bool cond_rcu) +bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs) { if (user_mode(regs)) { enter_from_user_mode(); return false; } - if (!cond_rcu || !__rcu_is_watching()) { + if (!__rcu_is_watching()) { /* * If RCU is not watching then the same careful * sequence vs. lockdep and tracing is required @@ -608,52 +607,44 @@ void noinstr idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit) if (user_mode(regs)) { prepare_exit_to_usermode(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 (rcu_exit) { + 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(); + /* Check kernel preemption, if enabled */ if (IS_ENABLED(CONFIG_PREEMPTION)) { - /* - * This needs to be done very carefully. - * idtentry_enter() invoked rcu_irq_enter(). This - * needs to be undone before scheduling. - * - * Preemption is disabled inside of RCU idle - * sections. When the task returns from - * preempt_schedule_irq(), RCU is still watching. - * - * rcu_irq_exit_preempt() has additional state - * checking if CONFIG_PROVE_RCU=y - */ if (!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()); - instrumentation_begin(); - if (rcu_exit) - rcu_irq_exit_preempt(); if (need_resched()) preempt_schedule_irq(); - /* Covers both tracing and lockdep */ - trace_hardirqs_on(); - instrumentation_end(); - return; } } - /* - * If preemption is disabled then this needs to be done - * carefully with respect to RCU. The exception might come - * from a RCU idle section in the idle task due to the fact - * that safe_halt() enables interrupts. So this needs the - * same ordering of lockdep/tracing and RCU as the return - * to user mode path. - */ - instrumentation_begin(); - /* Tell the tracer that IRET will enable interrupts */ - trace_hardirqs_on_prepare(); - lockdep_hardirqs_on_prepare(CALLER_ADDR0); + /* Covers both tracing and lockdep */ + trace_hardirqs_on(); + instrumentation_end(); - if (rcu_exit) - rcu_irq_exit(); - lockdep_hardirqs_on(CALLER_ADDR0); } else { - /* IRQ flags state is correct already. Just tell RCU. */ + /* + * IRQ flags state is correct already. Just tell RCU if it + * was not watching on entry. + */ if (rcu_exit) rcu_irq_exit(); } diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 0f974e5..b056889 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -10,19 +10,9 @@ void idtentry_enter_user(struct pt_regs *regs); void idtentry_exit_user(struct pt_regs *regs); -bool idtentry_enter_cond_rcu(struct pt_regs *regs, bool cond_rcu); +bool idtentry_enter_cond_rcu(struct pt_regs *regs); void idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit); -static __always_inline void idtentry_enter(struct pt_regs *regs) -{ - idtentry_enter_cond_rcu(regs, false); -} - -static __always_inline void idtentry_exit(struct pt_regs *regs) -{ - idtentry_exit_cond_rcu(regs, true); -} - /** * DECLARE_IDTENTRY - Declare functions for simple IDT entry points * No error code pushed by hardware
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