linux-kernel - [PATCH 4.4 62/87] kaiser: Set _PAGE

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Message-Id: <20180115123355.962115950@linuxfoundation.org>
Date:   Mon, 15 Jan 2018 13:35:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <groeck@...omium.org>,
        Lepton Wu <ytht.net@...il.com>
Subject: [PATCH 4.4 62/87] kaiser: Set _PAGE_NX only if supported

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Lepton Wu <ytht.net@...il.com>

This finally resolve crash if loaded under qemu + haxm. Haitao Shan pointed
out that the reason of that crash is that NX bit get set for page tables.
It seems we missed checking if _PAGE_NX is supported in kaiser_add_user_map

Link: https://www.spinics.net/lists/kernel/msg2689835.html

Reviewed-by: Guenter Roeck <groeck@...omium.org>
Signed-off-by: Lepton Wu <ytht.net@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/mm/kaiser.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -198,6 +198,8 @@ static int kaiser_add_user_map(const voi
 	 * requires that not to be #defined to 0): so mask it off here.
 	 */
 	flags &= ~_PAGE_GLOBAL;
+	if (!(__supported_pte_mask & _PAGE_NX))
+		flags &= ~_PAGE_NX;
 
 	for (; address < end_addr; address += PAGE_SIZE) {
 		target_address = get_pa_from_mapping(address);