linux-kernel - [patch V9 06/39] x86/idtentry: Switch to conditional RCU handling

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Date:   Thu, 21 May 2020 22:05:19 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        X86 ML <x86@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Wei Liu <wei.liu@...nel.org>,
        Michael Kelley <mikelley@...rosoft.com>,
        Jason Chen CJ <jason.cj.chen@...el.com>,
        Zhao Yakui <yakui.zhao@...el.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V9 06/39] x86/idtentry: Switch to conditional RCU handling

Switch all idtentry_enter/exit() users over to the new conditional RCU
handling scheme and make the user mode entries in #DB, #INT3 and #MCE use
the user mode idtentry functions.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V9: New patch
---
 arch/x86/include/asm/idtentry.h |   10 ++++++----
 arch/x86/kernel/cpu/mce/core.c  |    4 ++--
 arch/x86/kernel/traps.c         |   10 +++++-----
 3 files changed, 13 insertions(+), 11 deletions(-)

--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -61,11 +61,12 @@ static __always_inline void __##func(str
 									\
 __visible noinstr void func(struct pt_regs *regs)			\
 {									\
-	idtentry_enter(regs);						\
+	bool rcu_exit = idtentry_enter_cond_rcu(regs);			\
+									\
 	instrumentation_begin();					\
 	__##func (regs);						\
 	instrumentation_end();						\
-	idtentry_exit(regs);						\
+	idtentry_exit_cond_rcu(regs, rcu_exit);				\
 }									\
 									\
 static __always_inline void __##func(struct pt_regs *regs)
@@ -107,11 +108,12 @@ static __always_inline void __##func(str
 __visible noinstr void func(struct pt_regs *regs,			\
 			    unsigned long error_code)			\
 {									\
-	idtentry_enter(regs);						\
+	bool rcu_exit = idtentry_enter_cond_rcu(regs);			\
+									\
 	instrumentation_begin();					\
 	__##func (regs, error_code);					\
 	instrumentation_end();						\
-	idtentry_exit(regs);						\
+	idtentry_exit_cond_rcu(regs, rcu_exit);				\
 }									\
 									\
 static __always_inline void __##func(struct pt_regs *regs,		\
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1929,11 +1929,11 @@ static __always_inline void exc_machine_
 
 static __always_inline void exc_machine_check_user(struct pt_regs *regs)
 {
-	idtentry_enter(regs);
+	idtentry_enter_user(regs);
 	instrumentation_begin();
 	machine_check_vector(regs);
 	instrumentation_end();
-	idtentry_exit(regs);
+	idtentry_exit_user(regs);
 }
 
 #ifdef CONFIG_X86_64
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -619,18 +619,18 @@ DEFINE_IDTENTRY_RAW(exc_int3)
 		return;
 
 	/*
-	 * idtentry_enter() uses static_branch_{,un}likely() and therefore
+	 * idtentry_enter_user() uses static_branch_{,un}likely() and therefore
 	 * can trigger INT3, hence poke_int3_handler() must be done
 	 * before. If the entry came from kernel mode, then use nmi_enter()
 	 * because the INT3 could have been hit in any context including
 	 * NMI.
 	 */
 	if (user_mode(regs)) {
-		idtentry_enter(regs);
+		idtentry_enter_user(regs);
 		instrumentation_begin();
 		do_int3_user(regs);
 		instrumentation_end();
-		idtentry_exit(regs);
+		idtentry_exit_user(regs);
 	} else {
 		nmi_enter();
 		instrumentation_begin();
@@ -877,7 +877,7 @@ static __always_inline void exc_debug_ke
 static __always_inline void exc_debug_user(struct pt_regs *regs,
 					   unsigned long dr6)
 {
-	idtentry_enter(regs);
+	idtentry_enter_user(regs);
 	clear_thread_flag(TIF_BLOCKSTEP);
 
 	/*
@@ -886,7 +886,7 @@ static __always_inline void exc_debug_us
 	 * User wants a sigtrap for that.
 	 */
 	handle_debug(regs, dr6, !dr6);
-	idtentry_exit(regs);
+	idtentry_exit_user(regs);
 }
 
 #ifdef CONFIG_X86_64