[PATCH 4.4-stable] kaiser: Set _PAGE_NX only if supported

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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

See https://www.spinics.net/lists/kernel/msg2689835.html for details.

Signed-off-by: Lepton Wu <ytht.net@xxxxxxxxx>
---
 arch/x86/mm/kaiser.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c
index 6a7a77929a8c..936672f71139 100644
--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -198,6 +198,10 @@ 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 CPU doesn't support NX, don't set it. */
+        if (!(__supported_pte_mask & _PAGE_NX))
+		flags &= ~_PAGE_NX;
+
 
 	for (; address < end_addr; address += PAGE_SIZE) {
 		target_address = get_pa_from_mapping(address);
-- 
2.16.0.rc1.238.g530d649a79-goog




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]