linux-kernel - [patch V4 part 4 18/24] x86/entry: Provide IDTRENTRY

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Date:   Tue, 05 May 2020 15:49:44 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...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>
Subject: [patch V4 part 4 18/24] x86/entry: Provide IDTRENTRY_NOIST variants
 for #DB and #MC

Provide NOIST entry point macros which allows to implement NOIST variants
of the C entry points. These are invoked when #DB or #MC enter from user
space. This allows explicit handling of the difference between user mode
and kernel mode entry later.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/include/asm/idtentry.h |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -138,10 +138,12 @@ static __always_inline void __##func(str
  * @vector:	Vector number (ignored for C)
  * @func:	Function name of the entry point
  *
- * Maps to DECLARE_IDTENTRY_RAW
+ * Maps to DECLARE_IDTENTRY_RAW, but declares also the NOIST C handler
+ * which is called from the ASM entry point on user mode entry
  */
 #define DECLARE_IDTENTRY_IST(vector, func)				\
-	DECLARE_IDTENTRY_RAW(vector, func)
+	DECLARE_IDTENTRY_RAW(vector, func);				\
+	__visible void noist_##func(struct pt_regs *regs)
 
 /**
  * DEFINE_IDTENTRY_IST - Emit code for IST entry points
@@ -152,6 +154,17 @@ static __always_inline void __##func(str
 #define DEFINE_IDTENTRY_IST(func)					\
 	DEFINE_IDTENTRY_RAW(func)
 
+/**
+ * DEFINE_IDTENTRY_NOIST - Emit code for NOIST entry points which
+ *			   belong to a IST entry point (MCE, DB)
+ * @func:	Function name of the entry point. Must be the same as
+ *		the function name of the corresponding IST variant
+ *
+ * Maps to DEFINE_IDTENTRY_RAW().
+ */
+#define DEFINE_IDTENTRY_NOIST(func)					\
+	DEFINE_IDTENTRY_RAW(noist_##func)
+
 #else	/* CONFIG_X86_64 */
 /* Maps to a regular IDTENTRY on 32bit for now */
 # define DECLARE_IDTENTRY_IST		DECLARE_IDTENTRY
@@ -161,12 +174,14 @@ static __always_inline void __##func(str
 /* C-Code mapping */
 #define DECLARE_IDTENTRY_MCE		DECLARE_IDTENTRY_IST
 #define DEFINE_IDTENTRY_MCE		DEFINE_IDTENTRY_IST
+#define DEFINE_IDTENTRY_MCE_USER	DEFINE_IDTENTRY_NOIST
 
 #define DECLARE_IDTENTRY_NMI		DECLARE_IDTENTRY_IST
 #define DEFINE_IDTENTRY_NMI		DEFINE_IDTENTRY_IST
 
 #define DECLARE_IDTENTRY_DEBUG		DECLARE_IDTENTRY_IST
 #define DEFINE_IDTENTRY_DEBUG		DEFINE_IDTENTRY_IST
+#define DEFINE_IDTENTRY_DEBUG_USER	DEFINE_IDTENTRY_NOIST
 
 /**
  * DECLARE_IDTENTRY_XEN - Declare functions for XEN redirect IDT entry points