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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 BA808C433DF for ; Fri, 16 Oct 2020 12:55:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 56CE5207DE for ; Fri, 16 Oct 2020 12:55:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="SNrpEftL"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="iwKyGQXN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407911AbgJPMzZ (ORCPT ); Fri, 16 Oct 2020 08:55:25 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:44424 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395281AbgJPMzZ (ORCPT ); Fri, 16 Oct 2020 08:55:25 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1602852921; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=IFWVugT+dTTDWBodFUMTGKF6FcevqFcG4mwU/SJ4v3Y=; b=SNrpEftLssya9LMStEuqL5omNeFMJKimnual6z3+V6aJAqwaUJ7YhPr4HzoDb5wJNKmhRa ERXtUA+56vN9HATCTKMxDnfdtRHBWpx51mO+jg65f8EUy0e8KQSw9VR/MgAZeIF2yb4pIJ I8n7wZQnZwcr+K19jvygnHDNq4Jk/L0IBKQg2QRt/1nxF+GrNzUTrIIeEE/5W9iFdWRaC8 lUCpqI+kFsLqt/pBhvB4Tb9aeb+1JzLwvWXgr0Nn+pnOmqqfBQEZLUJDWw7Riu+RZAobpx u2dPba2xPUPusgwNKAatKpyuyYl0UYBTxqbdxYuQCB+X8rh00DTnvQrUQEncLg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1602852921; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=IFWVugT+dTTDWBodFUMTGKF6FcevqFcG4mwU/SJ4v3Y=; b=iwKyGQXNsIU0MpOOMuSbEs4FgUEjJn4OHYUpcfwCy4h0dcT5Zw7jZ+W1pdwzI3jGgKmLmi IWRicg8gEqquLqBg== To: Peter Zijlstra , ira.weiny@intel.com Cc: Ingo Molnar , Borislav Petkov , Andy Lutomirski , x86@kernel.org, Dave Hansen , Dan Williams , Andrew Morton , Fenghua Yu , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC V3 6/9] x86/entry: Pass irqentry_state_t by reference In-Reply-To: <20201016114510.GO2611@hirez.programming.kicks-ass.net> References: <20201009194258.3207172-1-ira.weiny@intel.com> <20201009194258.3207172-7-ira.weiny@intel.com> <20201016114510.GO2611@hirez.programming.kicks-ass.net> Date: Fri, 16 Oct 2020 14:55:21 +0200 Message-ID: <87lfg6tjnq.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 16 2020 at 13:45, Peter Zijlstra wrote: > On Fri, Oct 09, 2020 at 12:42:55PM -0700, ira.weiny@intel.com wrote: >> @@ -238,7 +236,7 @@ noinstr void idtentry_exit_nmi(struct pt_regs *regs, bool restore) >> >> rcu_nmi_exit(); >> lockdep_hardirq_exit(); >> - if (restore) >> + if (irq_state->exit_rcu) >> lockdep_hardirqs_on(CALLER_ADDR0); >> __nmi_exit(); >> } > > That's not nice.. The NMI path is different from the IRQ path and has a > different variable. Yes, this works, but *groan*. > > Maybe union them if you want to avoid bloating the structure, but the > above makes it really hard to read. Right, and also that nmi entry thing should not be in x86. Something like the untested below as first cleanup. Thanks, tglx ---- Subject: x86/entry: Move nmi entry/exit into common code From: Thomas Gleixner Date: Fri, 11 Sep 2020 10:09:56 +0200 Add blurb here. Signed-off-by: Thomas Gleixner --- arch/x86/entry/common.c | 34 ---------------------------------- arch/x86/include/asm/idtentry.h | 3 --- arch/x86/kernel/cpu/mce/core.c | 6 +++--- arch/x86/kernel/nmi.c | 6 +++--- arch/x86/kernel/traps.c | 13 +++++++------ include/linux/entry-common.h | 20 ++++++++++++++++++++ kernel/entry/common.c | 36 ++++++++++++++++++++++++++++++++++++ 7 files changed, 69 insertions(+), 49 deletions(-) --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -209,40 +209,6 @@ SYSCALL_DEFINE0(ni_syscall) return -ENOSYS; } -noinstr bool idtentry_enter_nmi(struct pt_regs *regs) -{ - bool irq_state = lockdep_hardirqs_enabled(); - - __nmi_enter(); - lockdep_hardirqs_off(CALLER_ADDR0); - lockdep_hardirq_enter(); - rcu_nmi_enter(); - - instrumentation_begin(); - trace_hardirqs_off_finish(); - ftrace_nmi_enter(); - instrumentation_end(); - - return irq_state; -} - -noinstr void idtentry_exit_nmi(struct pt_regs *regs, bool restore) -{ - instrumentation_begin(); - ftrace_nmi_exit(); - if (restore) { - trace_hardirqs_on_prepare(); - lockdep_hardirqs_on_prepare(CALLER_ADDR0); - } - instrumentation_end(); - - rcu_nmi_exit(); - lockdep_hardirq_exit(); - if (restore) - lockdep_hardirqs_on(CALLER_ADDR0); - __nmi_exit(); -} - #ifdef CONFIG_XEN_PV #ifndef CONFIG_PREEMPTION /* --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -11,9 +11,6 @@ #include -bool idtentry_enter_nmi(struct pt_regs *regs); -void idtentry_exit_nmi(struct pt_regs *regs, bool irq_state); - /** * DECLARE_IDTENTRY - Declare functions for simple IDT entry points * No error code pushed by hardware --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1983,7 +1983,7 @@ void (*machine_check_vector)(struct pt_r static __always_inline void exc_machine_check_kernel(struct pt_regs *regs) { - bool irq_state; + irqentry_state_t irq_state; WARN_ON_ONCE(user_mode(regs)); @@ -1995,7 +1995,7 @@ static __always_inline void exc_machine_ mce_check_crashing_cpu()) return; - irq_state = idtentry_enter_nmi(regs); + irq_state = irqentry_nmi_enter(regs); /* * The call targets are marked noinstr, but objtool can't figure * that out because it's an indirect call. Annotate it. @@ -2006,7 +2006,7 @@ static __always_inline void exc_machine_ if (regs->flags & X86_EFLAGS_IF) trace_hardirqs_on_prepare(); instrumentation_end(); - idtentry_exit_nmi(regs, irq_state); + irqentry_nmi_exit(regs, irq_state); } static __always_inline void exc_machine_check_user(struct pt_regs *regs) --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -475,7 +475,7 @@ static DEFINE_PER_CPU(unsigned long, nmi DEFINE_IDTENTRY_RAW(exc_nmi) { - bool irq_state; + irqentry_state_t irq_state; /* * Re-enable NMIs right here when running as an SEV-ES guest. This might @@ -502,14 +502,14 @@ DEFINE_IDTENTRY_RAW(exc_nmi) this_cpu_write(nmi_dr7, local_db_save()); - irq_state = idtentry_enter_nmi(regs); + irq_state = irqentry_nmi_enter(regs); inc_irq_stat(__nmi_count); if (!ignore_nmis) default_do_nmi(regs); - idtentry_exit_nmi(regs, irq_state); + irqentry_nmi_exit(regs, irq_state); local_db_restore(this_cpu_read(nmi_dr7)); --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -405,7 +405,7 @@ DEFINE_IDTENTRY_DF(exc_double_fault) } #endif - idtentry_enter_nmi(regs); + irqentry_nmi_enter(regs); instrumentation_begin(); notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV); @@ -651,12 +651,13 @@ DEFINE_IDTENTRY_RAW(exc_int3) instrumentation_end(); irqentry_exit_to_user_mode(regs); } else { - bool irq_state = idtentry_enter_nmi(regs); + irqentry_state_t irq_state = irqentry_nmi_enter(regs); + instrumentation_begin(); if (!do_int3(regs)) die("int3", regs, 0); instrumentation_end(); - idtentry_exit_nmi(regs, irq_state); + irqentry_nmi_exit(regs, irq_state); } } @@ -864,7 +865,7 @@ static __always_inline void exc_debug_ke * includes the entry stack is excluded for everything. */ unsigned long dr7 = local_db_save(); - bool irq_state = idtentry_enter_nmi(regs); + irqentry_state_t irq_state = irqentry_nmi_enter(regs); instrumentation_begin(); /* @@ -907,7 +908,7 @@ static __always_inline void exc_debug_ke regs->flags &= ~X86_EFLAGS_TF; out: instrumentation_end(); - idtentry_exit_nmi(regs, irq_state); + irqentry_nmi_exit(regs, irq_state); local_db_restore(dr7); } @@ -925,7 +926,7 @@ static __always_inline void exc_debug_us /* * NB: We can't easily clear DR7 here because - * idtentry_exit_to_usermode() can invoke ptrace, schedule, access + * irqentry_exit_to_usermode() can invoke ptrace, schedule, access * user memory, etc. This means that a recursive #DB is possible. If * this happens, that #DB will hit exc_debug_kernel() and clear DR7. * Since we're not on the IST stack right now, everything will be --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -343,6 +343,7 @@ void irqentry_exit_to_user_mode(struct p #ifndef irqentry_state typedef struct irqentry_state { bool exit_rcu; + bool lockdep; } irqentry_state_t; #endif @@ -402,4 +403,23 @@ void irqentry_exit_cond_resched(void); */ void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state); +/** + * irqentry_nmi_enter - Handle NMI entry + * @regs: Pointer to currents pt_regs + * + * Similar to irqentry_enter() but taking care of the NMI constraints. + */ +irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs); + +/** + * irqentry_nmi_exit - Handle return from NMI handling + * @regs: Pointer to pt_regs (NMI entry regs) + * @state: Return value from matching call to irqentry_nmi_enter() + * + * Last action before returning to the low level assmenbly code. + * + * Counterpart to irqentry_nmi_enter(). + */ +void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state); + #endif --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -398,3 +398,39 @@ noinstr void irqentry_exit(struct pt_reg rcu_irq_exit(); } } + +irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) +{ + irqentry_state_t irq_state; + + irq_state.lockdep = lockdep_hardirqs_enabled(); + + __nmi_enter(); + lockdep_hardirqs_off(CALLER_ADDR0); + lockdep_hardirq_enter(); + rcu_nmi_enter(); + + instrumentation_begin(); + trace_hardirqs_off_finish(); + ftrace_nmi_enter(); + instrumentation_end(); + + return irq_state; +} + +void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state) +{ + instrumentation_begin(); + ftrace_nmi_exit(); + if (irq_state.lockdep) { + trace_hardirqs_on_prepare(); + lockdep_hardirqs_on_prepare(CALLER_ADDR0); + } + instrumentation_end(); + + rcu_nmi_exit(); + lockdep_hardirq_exit(); + if (irq_state.lockdep) + lockdep_hardirqs_on(CALLER_ADDR0); + __nmi_exit(); +}