[patch 01/16] x86/entry: Provide IDTENTRY_IST

From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>
Subject: [patch 01/16] x86/entry: Provide IDTENTRY_IST
Date: Tue, 25 Feb 2020 23:33:22 +0100	[thread overview]
Message-ID: <20200225224144.204871995@linutronix.de> (raw)
In-Reply-To: 20200225223321.231477305@linutronix.de

Same as IDTENTRY but for exceptions which run on Interrupt STacks (IST) on
64bit. For 32bit this maps to IDTENTRY.

There are 3 variants which will be used:
      IDTENTRY_MCE
      IDTENTRY_DB
      IDTENTRY_NMI

These map to IDTENTRY_IST, but only the MCE and DB variants are emitting
ASM code as the NMI entry needs hand crafted ASM still.

The function defines do not contain any idtenter/exit calls as these
exceptions need special treatment.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/idtentry.h |   70 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -111,6 +111,58 @@ NOKPROBE_SYMBOL(func);							\
 static __always_inline void __##func(struct pt_regs *regs,		\
 				     unsigned long error_code)
 
+#ifdef CONFIG_X86_64
+/**
+ * DECLARE_IDTENTRY_IST - Declare functions for IST handling IDT entry points
+ * @vector:	Vector number (ignored for C)
+ * @func:	Function name of the entry point
+ *
+ * Declares three functions:
+ * - The ASM entry point: asm_##func
+ * - The XEN PV trap entry point: xen_##func (maybe unused)
+ * - 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 func(struct pt_regs *regs)
+
+/**
+ * DEFINE_IDTENTRY_IST - Emit code for IST entry points
+ * @func:	Function name of the entry point
+ *
+ * This provides two entry points:
+ * - The real IST based entry
+ * - The regular stack based entry invoked when coming from user mode
+ *   or XEN_PV
+ */
+#define DEFINE_IDTENTRY_IST(func)					\
+static __always_inline void __##func(struct pt_regs *regs);		\
+									\
+__visible notrace void func(struct pt_regs *regs)			\
+{									\
+	__##func (regs);						\
+}									\
+NOKPROBE_SYMBOL(func);							\
+									\
+static __always_inline void __##func(struct pt_regs *regs)
+
+#else	/* CONFIG_X86_64 */
+/* Maps to a regular IDTENTRY on 32bit for now */
+# define DECLARE_IDTENTRY_IST		DECLARE_IDTENTRY
+# define DEFINE_IDTENTRY_IST		DEFINE_IDTENTRY
+#endif	/* !CONFIG_X86_64 */
+
+/* C-Code mapping */
+#define DECLARE_IDTENTRY_MCE		DECLARE_IDTENTRY_IST
+#define DEFINE_IDTENTRY_MCE		DEFINE_IDTENTRY_IST
+
+#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
+
 #else /* !__ASSEMBLY__ */
 
 /* Defines for ASM code to construct the IDT entries */
@@ -123,6 +175,24 @@ static __always_inline void __##func(str
 /* Special case for 32bit IRET 'trap'. Do not emit ASM code */
 #define DECLARE_IDTENTRY_SW(vector, func)
 
+#ifdef CONFIG_X86_64
+# define DECLARE_IDTENTRY_MCE(vector, func)			\
+	idtentry_mce_db vector asm_##func func
+
+# define DECLARE_IDTENTRY_DEBUG(vector, func)			\
+	idtentry_mce_db vector asm_##func func
+
+#else
+# define DECLARE_IDTENTRY_MCE(vector, func)			\
+	DECLARE_IDTENTRY(vector, func)
+
+# define DECLARE_IDTENTRY_DEBUG(vector, func)			\
+	DECLARE_IDTENTRY(vector, func)
+#endif
+
+/* No ASM code emitted for NMI */
+# define DECLARE_IDTENTRY_NMI(vector, func)
+
 #endif /* __ASSEMBLY__ */
 
 /* Simple exception entries: */

