kaiser: Set _PAGE_NX only if supported

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@chromium.org>
Signed-off-by: Lepton Wu <ytht.net@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c
index 8f8e5e0..a8ade08 100644 (file)
--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -197,6 +197,8 @@ static int kaiser_add_user_map(const void *__start_addr, unsigned long size,
         * 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);