From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@alien8.de>,
        Brian Gerst <brgerst@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        David Laight <David.Laight@aculab.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Juergen Gross <jgross@suse.com>,
        Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>
Subject: [PATCH 4.14 018/146] x86/mm/pti: Map ESPFIX into user space
Date: Mon,  1 Jan 2018 15:36:49 +0100
Message-Id: <20180101140126.489063433@linuxfoundation.org>
In-Reply-To: <20180101140123.743014891@linuxfoundation.org>
References: <20180101140123.743014891@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@kernel.org>

commit 4b6bbe95b87966ba08999574db65c93c5e925a36 upstream.

Map the ESPFIX pages into user space when PTI is enabled.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/mm/pti.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -288,6 +288,16 @@ static void __init pti_clone_user_shared
 }
 
 /*
+ * Clone the ESPFIX P4D into the user space visinble page table
+ */
+static void __init pti_setup_espfix64(void)
+{
+#ifdef CONFIG_X86_ESPFIX64
+	pti_clone_p4d(ESPFIX_BASE_ADDR);
+#endif
+}
+
+/*
  * Clone the populated PMDs of the entry and irqentry text and force it RO.
  */
 static void __init pti_clone_entry_text(void)
@@ -308,4 +318,5 @@ void __init pti_init(void)
 
 	pti_clone_user_shared();
 	pti_clone_entry_text();
+	pti_setup_espfix64();
 }