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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	X86 ML <x86@kernel.org>, "Paul E. McKenney" <paulmck@kernel.org>,
	Alexandre Chartre <alexandre.chartre@oracle.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Petr Mladek <pmladek@suse.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>, Brian Gerst <brgerst@gmail.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Will Deacon <will@kernel.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Wei Liu <wei.liu@kernel.org>,
	Michael Kelley <mikelley@microsoft.com>,
	Jason Chen CJ <jason.cj.chen@intel.com>,
	Zhao Yakui <yakui.zhao@intel.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [patch V9 07/39] x86/entry: Cleanup idtentry_enter/exit() leftovers
Date: Thu, 21 May 2020 22:05:20 +0200
Message-ID: <20200521202117.473597954@linutronix.de> (raw)
In-Reply-To: <20200521200513.656533920@linutronix.de>

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 hit Linus tree.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V9: New patch
---
 arch/x86/entry/common.c         |   67 +++++++++++++++++-----------------------
 arch/x86/include/asm/idtentry.h |   12 -------
 2 files changed, 30 insertions(+), 49 deletions(-)

--- 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
@@ -545,12 +544,12 @@ 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();
 	} else {
-		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
@@ -605,52 +604,44 @@ void noinstr idtentry_exit_cond_rcu(stru
 	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();
 	}
--- 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


  parent reply index

Thread overview: 132+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-21 20:05 [patch V9 00/39] x86/entry: Rework leftovers (was part V) Thomas Gleixner
2020-05-21 20:05 ` [patch V9 01/39] nmi, tracing: Make hardware latency tracing noinstr safe Thomas Gleixner
2020-05-27  8:12   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 02/39] rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter() Thomas Gleixner
2020-05-21 21:03   ` Paul E. McKenney
2020-05-21 21:25     ` Thomas Gleixner
2020-05-26  8:14     ` Ingo Molnar
2020-05-26 15:34       ` Paul E. McKenney
2020-05-27  8:12   ` [tip: x86/entry] " tip-bot2 for Paul E. McKenney
2020-05-21 20:05 ` [patch V9 03/39] rcu: Provide rcu_irq_exit_check_preempt() Thomas Gleixner
2020-05-27  8:12   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 04/39] x86/entry: Provide idtentry_entry/exit_cond_rcu() Thomas Gleixner
2020-05-21 21:06   ` Paul E. McKenney
2020-05-26  8:23   ` Ingo Molnar
2020-05-26  8:58     ` Thomas Gleixner
2020-05-21 20:05 ` [patch V9 05/39] x86/entry: Provide idtentry_enter/exit_user() Thomas Gleixner
2020-05-27  8:12   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 06/39] x86/idtentry: Switch to conditional RCU handling Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` Thomas Gleixner [this message]
2020-05-27  8:11   ` [tip: x86/entry] x86/entry: Clean up idtentry_enter/exit() leftovers tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 08/39] genirq: Provide irq_enter/exit_rcu() Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 09/39] genirq: Provide __irq_enter/exit_raw() Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 10/39] x86/entry: Provide helpers for execute on irqstack Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] x86/entry: Provide helpers for executing on the irqstack tip-bot2 for Thomas Gleixner
2020-06-05 17:18   ` [patch V9 10/39] x86/entry: Provide helpers for execute on irqstack Qian Cai
2020-06-05 17:36     ` Peter Zijlstra
2020-06-05 17:52       ` Qian Cai
2020-06-07 11:59         ` Thomas Gleixner
2020-06-07 18:27           ` Qian Cai
2020-06-08 16:01       ` Qian Cai
2020-06-08 22:20         ` Thomas Gleixner
2020-06-09  2:32           ` Qian Cai
2020-06-09 20:33             ` Thomas Gleixner
2020-06-09 20:50               ` Thomas Gleixner
2020-06-10 12:38                 ` Qian Cai
2020-06-10 19:38                   ` Thomas Gleixner
2020-06-13 13:55                     ` Qian Cai
2020-06-13 14:03                       ` Thomas Gleixner
2020-06-13 21:41                         ` Qian Cai
2020-06-14  8:59                           ` Thomas Gleixner
2020-05-21 20:05 ` [patch V9 11/39] x86/entry/64: Move do_softirq_own_stack() to C Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 12/39] x86/entry: Split out idtentry_exit_cond_resched() Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 13/39] x86/entry: Switch XEN/PV hypercall entry to IDTENTRY Thomas Gleixner
2020-05-22 18:32   ` [patch V9-1 " Thomas Gleixner
2020-05-26  7:44     ` Jürgen Groß
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 14/39] x86/entry/64: Simplify idtentry_body Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 15/39] x86/entry: Switch page fault exception to IDTENTRY_RAW Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 16/39] x86/entry: Remove the transition leftovers Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 17/39] x86/entry: Change exit path of xen_failsafe_callback Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 18/39] x86/entry/64: Remove error_exit Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] x86/entry/64: Remove error_exit() tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 19/39] x86/entry/32: Remove common_exception Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] x86/entry/32: Remove common_exception() tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 20/39] x86/irq: Use generic irq_regs implementation Thomas Gleixner
2020-05-26 18:39   ` damian
2020-05-28  9:50     ` Thomas Gleixner
2020-05-28 20:20       ` damian
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 21/39] x86/irq: Convey vector as argument and not in ptregs Thomas Gleixner
2020-05-22 19:34   ` Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-08-24 17:29   ` [patch V9 21/39] " Alexander Graf
2020-08-25 10:28     ` Thomas Gleixner
2020-08-25 23:17       ` Alexander Graf
2020-08-25 23:41         ` Andy Lutomirski
2020-08-26  0:04           ` Alexander Graf
2020-08-26  1:03             ` Brian Gerst
2020-08-26  0:55           ` Thomas Gleixner
2020-05-21 20:05 ` [patch V9 22/39] x86/irq: Rework handle_irq() for 64bit Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] x86/irq: Rework handle_irq() for 64-bit tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 23/39] x86/entry: Add IRQENTRY_IRQ macro Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 24/39] x86/entry: Use idtentry for interrupts Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 25/39] x86/entry: Provide IDTENTRY_SYSVEC Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 26/39] x86/entry: Convert APIC interrupts to IDTENTRY_SYSVEC Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 27/39] x86/entry: Convert SMP system vectors " Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 28/39] x86/entry: Convert various system vectors Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 29/39] x86/entry: Convert KVM vectors to IDTENTRY_SYSVEC* Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 30/39] x86/entry: Convert various hypervisor vectors to IDTENTRY_SYSVEC Thomas Gleixner
2020-05-26  9:29   ` Wei Liu
2020-05-27  1:46   ` Boqun Feng
2020-05-27  8:38     ` Wei Liu
2020-05-27 12:09       ` Wei Liu
2020-05-27 23:06         ` Boqun Feng
2020-05-27 12:30       ` Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 31/39] x86/entry: Convert XEN hypercall vector " Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 32/39] x86/entry: Convert reschedule interrupt to IDTENTRY_SYSVEC_SIMPLE Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 33/39] x86/entry: Remove the apic/BUILD interrupt leftovers Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 34/39] x86/entry/64: Remove IRQ stack switching ASM Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 35/39] x86/entry: Make enter_from_user_mode() static Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 36/39] x86/entry/32: Remove redundant irq disable code Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 37/39] x86/entry/64: Remove TRACE_IRQS_*_DEBUG Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 38/39] x86/entry: Move paranoid irq tracing out of ASM code Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-21 20:05 ` [patch V9 39/39] x86/entry: Remove the TRACE_IRQS cruft Thomas Gleixner
2020-05-27  8:11   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-22  7:20 ` [patch V9 00/39] x86/entry: Rework leftovers (was part V) Andrew Cooper
2020-05-22 21:17   ` Peter Zijlstra
2020-06-03 19:18     ` Andrew Cooper
2020-06-04 13:25       ` Peter Zijlstra
2020-06-04 13:29         ` Paolo Bonzini
2020-06-04 13:35           ` Peter Zijlstra
2020-06-04 15:42             ` Andy Lutomirski
2020-06-04 15:55               ` Peter Zijlstra
2020-05-22 14:26 ` Boris Ostrovsky
2020-05-22 17:47   ` Thomas Gleixner
2020-05-22 18:08     ` Thomas Gleixner
2020-05-26  4:33 ` Andy Lutomirski

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