From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1AA51C433DF for ; Fri, 3 Jul 2020 17:03:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E072520870 for ; Fri, 3 Jul 2020 17:03:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593795795; bh=aoOg10QirbcC8zOGZUWIfDtYifxpxqzURqnegZXBqPI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vnhP0xlVgeBbv63qJWGshQLyNi2yqXQYCAW0vycUFWNMqXPI7/qxm/SKD3Ob4Mapp fUJNR6S32R9Hjjp4iQ9GimSwZS4E70iT6oS/ltWmpOhhs19gLXwQuhM7jepfK0LXHL PpZpXLxFc+FsRxG5T1bXitoHVQ5ZMuGlQsreW1ro= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726832AbgGCRDM (ORCPT ); Fri, 3 Jul 2020 13:03:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:32812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726148AbgGCRDH (ORCPT ); Fri, 3 Jul 2020 13:03:07 -0400 Received: from localhost (c-67-180-165-146.hsd1.ca.comcast.net [67.180.165.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AAAA1208E4; Fri, 3 Jul 2020 17:03:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593795785; bh=aoOg10QirbcC8zOGZUWIfDtYifxpxqzURqnegZXBqPI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rGNmRlJk3p0RNxMg0O2FsFuxmT+WwBgpDn6okIzGDzgqaIoiKXIUvmQyL+dCNuGwq LOQCDZR4+ahfDdmEkMX2Ovq4IwsvlBB3KyHCQNU1SBIEA1H9vPmJDt5C/ntcchwsx3 Q8ceEN9anjeNm6eJlwWBVkUCP41HDX0fSJmBFSp0= From: Andy Lutomirski To: x86@kernel.org Cc: Andrew Cooper , Juergen Gross , LKML , Andy Lutomirski Subject: [PATCH entry v2 6/6] x86/entry: Rename idtentry_enter/exit_cond_rcu() to idtentry_enter/exit() Date: Fri, 3 Jul 2020 10:02:58 -0700 Message-Id: <247fc67685263e0b673e1d7f808182d28ff80359.1593795633.git.luto@kernel.org> X-Mailer: git-send-email 2.25.4 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org They were originally called _cond_rcu because they were special versions with conditional RCU handling. Now they're the standard entry and exit path, so the _cond_rcu part is just confusing. Drop it. Also change the signature to make them more extensible and more foolproof. This patch makes no functional change -- it's pure refactoring. Signed-off-by: Andy Lutomirski --- arch/x86/entry/common.c | 50 ++++++++++++++++++--------------- arch/x86/include/asm/idtentry.h | 28 ++++++++++-------- arch/x86/kernel/kvm.c | 6 ++-- arch/x86/kernel/traps.c | 6 ++-- arch/x86/mm/fault.c | 6 ++-- kernel/time/tick-sched.c | 1 + 6 files changed, 54 insertions(+), 43 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index e83b3f14897c..0521546022cb 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -559,8 +559,7 @@ SYSCALL_DEFINE0(ni_syscall) } /** - * idtentry_enter_cond_rcu - Handle state tracking on idtentry with conditional - * RCU handling + * idtentry_enter - Handle state tracking on ordinary idtentries * @regs: Pointer to pt_regs of interrupted context * * Invokes: @@ -572,6 +571,9 @@ SYSCALL_DEFINE0(ni_syscall) * - 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 @@ -585,18 +587,21 @@ SYSCALL_DEFINE0(ni_syscall) * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit * would not be possible. * - * Returns: True if RCU has been adjusted on a kernel entry - * False otherwise + * Returns: An opaque object that must be passed to idtentry_exit() * - * The return value must be fed into the rcu_exit argument of - * idtentry_exit_cond_rcu(). + * The return value must be fed into the state argument of + * idtentry_exit(). */ -bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs) +idtentry_state_t noinstr idtentry_enter(struct pt_regs *regs) { + idtentry_state_t ret = { + .exit_rcu = false, + }; + if (user_mode(regs)) { check_user_regs(regs); enter_from_user_mode(); - return false; + return ret; } /* @@ -634,7 +639,8 @@ bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs) trace_hardirqs_off_finish(); instrumentation_end(); - return true; + ret.exit_rcu = true; + return ret; } /* @@ -649,7 +655,7 @@ bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs) trace_hardirqs_off(); instrumentation_end(); - return false; + return ret; } static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched) @@ -667,10 +673,9 @@ static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched) } /** - * idtentry_exit_cond_rcu - Handle return from exception with conditional RCU - * handling + * idtentry_exit - Handle return from exception that used idtentry_enter() * @regs: Pointer to pt_regs (exception entry regs) - * @rcu_exit: Invoke rcu_irq_exit() if true + * @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 @@ -679,10 +684,10 @@ static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched) * 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_cond_rcu(). The return value of the entry - * function must be fed into the @rcu_exit argument. + * Counterpart to idtentry_enter(). The return value of the entry + * function must be fed into the @state argument. */ -void noinstr idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit) +void noinstr idtentry_exit(struct pt_regs *regs, idtentry_state_t state) { lockdep_assert_irqs_disabled(); @@ -695,7 +700,7 @@ void noinstr idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit) * carefully and needs the same ordering of lockdep/tracing * and RCU as the return to user mode path. */ - if (rcu_exit) { + if (state.exit_rcu) { instrumentation_begin(); /* Tell the tracer that IRET will enable interrupts */ trace_hardirqs_on_prepare(); @@ -714,7 +719,7 @@ void noinstr idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit) * IRQ flags state is correct already. Just tell RCU if it * was not watching on entry. */ - if (rcu_exit) + if (state.exit_rcu) rcu_irq_exit(); } } @@ -800,9 +805,10 @@ static void __xen_pv_evtchn_do_upcall(void) __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs) { struct pt_regs *old_regs; - bool inhcall, rcu_exit; + bool inhcall; + idtentry_state_t state; - rcu_exit = idtentry_enter_cond_rcu(regs); + state = idtentry_enter(regs); old_regs = set_irq_regs(regs); instrumentation_begin(); @@ -812,13 +818,13 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs) set_irq_regs(old_regs); inhcall = get_and_clear_inhcall(); - if (inhcall && !WARN_ON_ONCE(rcu_exit)) { + if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) { instrumentation_begin(); idtentry_exit_cond_resched(regs, true); instrumentation_end(); restore_inhcall(inhcall); } else { - idtentry_exit_cond_rcu(regs, rcu_exit); + idtentry_exit(regs, state); } } #endif /* CONFIG_XEN_PV */ diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index eeac6dc2adaa..7227225cf45d 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -13,8 +13,12 @@ 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); -void idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit); +typedef struct idtentry_state { + bool exit_rcu; +} idtentry_state_t; + +idtentry_state_t idtentry_enter(struct pt_regs *regs); +void idtentry_exit(struct pt_regs *regs, idtentry_state_t state); /** * DECLARE_IDTENTRY - Declare functions for simple IDT entry points @@ -54,12 +58,12 @@ static __always_inline void __##func(struct pt_regs *regs); \ \ __visible noinstr void func(struct pt_regs *regs) \ { \ - bool rcu_exit = idtentry_enter_cond_rcu(regs); \ + idtentry_state_t state = idtentry_enter(regs); \ \ instrumentation_begin(); \ __##func (regs); \ instrumentation_end(); \ - idtentry_exit_cond_rcu(regs, rcu_exit); \ + idtentry_exit(regs, state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs) @@ -101,12 +105,12 @@ static __always_inline void __##func(struct pt_regs *regs, \ __visible noinstr void func(struct pt_regs *regs, \ unsigned long error_code) \ { \ - bool rcu_exit = idtentry_enter_cond_rcu(regs); \ + idtentry_state_t state = idtentry_enter(regs); \ \ instrumentation_begin(); \ __##func (regs, error_code); \ instrumentation_end(); \ - idtentry_exit_cond_rcu(regs, rcu_exit); \ + idtentry_exit(regs, state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs, \ @@ -199,7 +203,7 @@ static __always_inline void __##func(struct pt_regs *regs, u8 vector); \ __visible noinstr void func(struct pt_regs *regs, \ unsigned long error_code) \ { \ - bool rcu_exit = idtentry_enter_cond_rcu(regs); \ + idtentry_state_t state = idtentry_enter(regs); \ \ instrumentation_begin(); \ irq_enter_rcu(); \ @@ -207,7 +211,7 @@ __visible noinstr void func(struct pt_regs *regs, \ __##func (regs, (u8)error_code); \ irq_exit_rcu(); \ instrumentation_end(); \ - idtentry_exit_cond_rcu(regs, rcu_exit); \ + idtentry_exit(regs, state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs, u8 vector) @@ -241,7 +245,7 @@ static void __##func(struct pt_regs *regs); \ \ __visible noinstr void func(struct pt_regs *regs) \ { \ - bool rcu_exit = idtentry_enter_cond_rcu(regs); \ + idtentry_state_t state = idtentry_enter(regs); \ \ instrumentation_begin(); \ irq_enter_rcu(); \ @@ -249,7 +253,7 @@ __visible noinstr void func(struct pt_regs *regs) \ run_on_irqstack_cond(__##func, regs, regs); \ irq_exit_rcu(); \ instrumentation_end(); \ - idtentry_exit_cond_rcu(regs, rcu_exit); \ + idtentry_exit(regs, state); \ } \ \ static noinline void __##func(struct pt_regs *regs) @@ -270,7 +274,7 @@ static __always_inline void __##func(struct pt_regs *regs); \ \ __visible noinstr void func(struct pt_regs *regs) \ { \ - bool rcu_exit = idtentry_enter_cond_rcu(regs); \ + idtentry_state_t state = idtentry_enter(regs); \ \ instrumentation_begin(); \ __irq_enter_raw(); \ @@ -278,7 +282,7 @@ __visible noinstr void func(struct pt_regs *regs) \ __##func (regs); \ __irq_exit_raw(); \ instrumentation_end(); \ - idtentry_exit_cond_rcu(regs, rcu_exit); \ + idtentry_exit(regs, state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index df63786e7bfa..3f78482d9496 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -233,7 +233,7 @@ EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags); noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) { u32 reason = kvm_read_and_reset_apf_flags(); - bool rcu_exit; + idtentry_state_t state; switch (reason) { case KVM_PV_REASON_PAGE_NOT_PRESENT: @@ -243,7 +243,7 @@ noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) return false; } - rcu_exit = idtentry_enter_cond_rcu(regs); + state = idtentry_enter(regs); instrumentation_begin(); /* @@ -264,7 +264,7 @@ noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) } instrumentation_end(); - idtentry_exit_cond_rcu(regs, rcu_exit); + idtentry_exit(regs, state); return true; } diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 6ed8cc5fbe8f..de75e531cdd2 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -218,7 +218,7 @@ static inline void handle_invalid_op(struct pt_regs *regs) DEFINE_IDTENTRY_RAW(exc_invalid_op) { - bool rcu_exit; + idtentry_state_t state; /* * Handle BUG/WARN like NMIs instead of like normal idtentries: @@ -251,11 +251,11 @@ DEFINE_IDTENTRY_RAW(exc_invalid_op) */ } - rcu_exit = idtentry_enter_cond_rcu(regs); + state = idtentry_enter(regs); instrumentation_begin(); handle_invalid_op(regs); instrumentation_end(); - idtentry_exit_cond_rcu(regs, rcu_exit); + idtentry_exit(regs, state); } DEFINE_IDTENTRY(exc_coproc_segment_overrun) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 1ead568c0101..5e41949453cc 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1377,7 +1377,7 @@ handle_page_fault(struct pt_regs *regs, unsigned long error_code, DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault) { unsigned long address = read_cr2(); - bool rcu_exit; + idtentry_state_t state; prefetchw(¤t->mm->mmap_lock); @@ -1412,11 +1412,11 @@ DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault) * code reenabled RCU to avoid subsequent wreckage which helps * debugability. */ - rcu_exit = idtentry_enter_cond_rcu(regs); + state = idtentry_enter(regs); instrumentation_begin(); handle_page_fault(regs, error_code, address); instrumentation_end(); - idtentry_exit_cond_rcu(regs, rcu_exit); + idtentry_exit(regs, state); } diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 3e2dc9b8858c..6aa0daca0dd2 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -921,6 +921,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { pr_warn("NOHZ: local_softirq_pending %02x\n", (unsigned int) local_softirq_pending()); + WARN_ON_ONCE(1); ratelimit++; } return false; -- 2.25.4