linux-kernel - [tip:x86/urgent] x86/idt: Load idt early in start

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Message-ID: <tip-d632044a53571267034f430a5433f048ff8168da@git.kernel.org>
Date:   Mon, 27 Nov 2017 15:35:09 -0800
From:   tip-bot for Chunyu Hu <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de, hpa@...or.com,
        chuhu@...hat.com, mingo@...nel.org
Subject: [tip:x86/urgent] x86/idt: Load idt early in start_secondary

Commit-ID:  d632044a53571267034f430a5433f048ff8168da
Gitweb:     https://git.kernel.org/tip/d632044a53571267034f430a5433f048ff8168da
Author:     Chunyu Hu <chuhu@...hat.com>
AuthorDate: Mon, 27 Nov 2017 22:21:39 +0800
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 28 Nov 2017 00:28:56 +0100

x86/idt: Load idt early in start_secondary

On a secondary, idt is first loaded in cpu_init() with load_current_idt(),
i.e. no exceptions can be handled before that point.

The conversion of WARN() to use UD requires the IDT being loaded earlier as
any warning between start_secondary() and load_curren_idt() in cpu_init()
will result in an unhandled @UD exception and therefore fail the bringup of
the CPU.

Install the IDT handlers right in start_secondary() before calling cpu_init().

[ tglx: Massaged changelog ]

Signed-off-by: Chunyu Hu <chuhu@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: peterz@...radead.org
Cc: bp@...en8.de
Cc: rostedt@...dmis.org
Cc: luto@...nel.org
Link: https://lkml.kernel.org/r/1511792499-4073-1-git-send-email-chuhu@redhat.com

---
 arch/x86/kernel/smpboot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3d01df7..05a97d5 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -237,7 +237,7 @@ static void notrace start_secondary(void *unused)
 	load_cr3(swapper_pg_dir);
 	__flush_tlb_all();
 #endif
-
+	load_current_idt();
 	cpu_init();
 	x86_cpuinit.early_percpu_clock_init();
 	preempt_disable();