From 48e08d0fb265b007ebbb29a72297ff7e40938969 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 11 Nov 2014 12:49:41 -0800 Subject: [PATCH] x86, entry: Switch stacks on a paranoid entry from userspace This causes all non-NMI, non-double-fault kernel entries from userspace to run on the normal kernel stack. Double-fault is exempt to minimize confusion if we double-fault directly from userspace due to a bad kernel stack. This is, suprisingly, simpler and shorter than the current code. It removes the IMO rather frightening paranoid_userspace path, and it make sync_regs much simpler. There is no risk of stack overflow due to this change -- the kernel stack that we switch to is empty. This will also enable us to create non-atomic sections within machine checks from userspace, which will simplify memory failure handling. It will also allow the upcoming fsgsbase code to be simplified, because it doesn't need to worry about usergs when scheduling in paranoid_exit, as that code no longer exists. Cc: Oleg Nesterov Cc: Andi Kleen Cc: Tony Luck Acked-by: Borislav Petkov Signed-off-by: Andy Lutomirski --- Reading git-format-patch failed