From 71ed49d8fb33023f242419a77ecb1141c029cac4 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 12 Jun 2020 14:02:27 +0200
Subject: [PATCH] x86/entry: Make NMI use IDTENTRY_RAW
For no reason other than beginning brainmelt, IDTENTRY_NMI was mapped to
IDTENTRY_IST.
This is not a problem on 64bit because the IST default entry point maps to
IDTENTRY_RAW which does not any entry handling. The surplus function
declaration for the noist C entry point is unused and as there is no ASM
code emitted for NMI this went unnoticed.
On 32bit IDTENTRY_IST maps to a regular IDTENTRY which does the normal
entry handling. That is clearly the wrong thing to do for NMI.
Map it to IDTENTRY_RAW to unbreak it. The IDTENTRY_NMI mapping needs to
stay to avoid emitting ASM code.
Fixes: 6271fef00b34 ("x86/entry: Convert NMI to IDTENTRY_NMI")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Debugged-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/CA+G9fYvF3cyrY+-iw_SZtpN-i2qA2BruHg4M=QYECU2-dNdsMw@mail.gmail.com
---
arch/x86/include/asm/idtentry.h | 4 ++--
arch/x86/kernel/nmi.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 2fc6b0c583413..cf51c50eb356d 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -391,8 +391,8 @@ __visible noinstr void func(struct pt_regs *regs, \
#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_NMI DECLARE_IDTENTRY_RAW
+#define DEFINE_IDTENTRY_NMI DEFINE_IDTENTRY_RAW
#define DECLARE_IDTENTRY_DEBUG DECLARE_IDTENTRY_IST
#define DEFINE_IDTENTRY_DEBUG DEFINE_IDTENTRY_IST
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 3a98ff36f4115..2de365f15684c 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -476,7 +476,7 @@ static DEFINE_PER_CPU(enum nmi_states, nmi_state);
static DEFINE_PER_CPU(unsigned long, nmi_cr2);
static DEFINE_PER_CPU(unsigned long, nmi_dr7);
-DEFINE_IDTENTRY_NMI(exc_nmi)
+DEFINE_IDTENTRY_RAW(exc_nmi)
{
if (IS_ENABLED(CONFIG_SMP) && cpu_is_offline(smp_processor_id()))
return;
--
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