linux-kernel - [patch 07/16] x86/entry: Provide IDTRENTRY

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Date:   Tue, 25 Feb 2020 23:33:28 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: [patch 07/16] 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 |   17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -117,14 +117,16 @@ static __always_inline void __##func(str
  * @vector:	Vector number (ignored for C)
  * @func:	Function name of the entry point
  *
- * Declares three functions:
+ * Declares four functions:
  * - The ASM entry point: asm_##func
  * - The XEN PV trap entry point: xen_##func (maybe unused)
+ * - The NOIST C handler called from the ASM entry point on user mode entry
  * - The C handler called from the ASM entry point
  */
 #define DECLARE_IDTENTRY_IST(vector, func)				\
 	asmlinkage void asm_##func(void);				\
 	asmlinkage void xen_asm_##func(void);				\
+	__visible void noist_##func(struct pt_regs *regs);		\
 	__visible void func(struct pt_regs *regs)
 
 /**
@@ -147,6 +149,17 @@ NOKPROBE_SYMBOL(func);							\
 									\
 static __always_inline void __##func(struct pt_regs *regs)
 
+/**
+ * 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().
+ */
+#define DEFINE_IDTENTRY_NOIST(func)					\
+	DEFINE_IDTENTRY(noist_##func)
+
 #else	/* CONFIG_X86_64 */
 /* Maps to a regular IDTENTRY on 32bit for now */
 # define DECLARE_IDTENTRY_IST		DECLARE_IDTENTRY
@@ -156,12 +169,14 @@ 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