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From:   Joerg Roedel <joro@8bytes.org>
To:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        "H . Peter Anvin" <hpa@zytor.com>
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        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
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        Peter Zijlstra <peterz@infradead.org>,
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        Brian Gerst <brgerst@gmail.com>,
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        Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>,
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        jroedel@suse.de, joro@8bytes.org
Subject: [PATCH 30/39] x86/mm/pti: Clone entry-text again in pti_finalize()
Date:   Wed, 18 Jul 2018 11:41:07 +0200
Message-Id: <1531906876-13451-31-git-send-email-joro@8bytes.org>
In-Reply-To: <1531906876-13451-1-git-send-email-joro@8bytes.org>
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From: Joerg Roedel <jroedel@suse.de>

The mapping for entry-text might have changed in the kernel
after it was cloned to the user page-table. Clone again
to update the user page-table to bring the mapping in sync
with the kernel again.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/mm/pti.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 1825f30..b879ccd 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -404,7 +404,7 @@ static void __init pti_setup_espfix64(void)
 /*
  * Clone the populated PMDs of the entry and irqentry text and force it RO.
  */
-static void __init pti_clone_entry_text(void)
+static void pti_clone_entry_text(void)
 {
 	pti_clone_pmds((unsigned long) __entry_text_start,
 			(unsigned long) __irqentry_text_end,
@@ -528,13 +528,18 @@ void __init pti_init(void)
 }
 
 /*
- * Finalize the kernel mappings in the userspace page-table.
+ * Finalize the kernel mappings in the userspace page-table. Some of the
+ * mappings for the kernel image might have changed since pti_init()
+ * cloned them. This is because parts of the kernel image have been
+ * mapped RO and/or NX.  These changes need to be cloned again to the
+ * userspace page-table.
  */
 void pti_finalize(void)
 {
 	/*
-	 * Do this after all of the manipulation of the
-	 * kernel text page tables are complete.
+	 * We need to clone everything (again) that maps parts of the
+	 * kernel image.
 	 */
+	pti_clone_entry_text();
 	pti_clone_kernel_text();
 }
-- 
2.7.4