[patch V4 part 4 18/24] x86/entry: Provide IDTRENTRY_NOIST variants for #DB and #MC

From: Thomas Gleixner
Date: Tue May 05 2020 - 10:16:33 EST


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@xxxxxxxxxxxxx>
---
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