x86/asm/entry: Remove user_mode_ignore_vm86()
user_mode_ignore_vm86() can be used instead of user_mode(), in
places where we have already done a v8086_mode() security
check of ptregs.
But doing this check in the wrong place would be a bug that
could result in security problems, and also the naming still
isn't very clear.
Furthermore, it only affects 32-bit kernels, while most
development happens on 64-bit kernels.
If we replace them with user_mode() checks then the cost is only
a very minor increase in various slowpaths:
text data bss dec hex filename
10573391 703562 1753042 13029995 c6d26b vmlinux.o.before
10573423 703562 1753042 13030027 c6d28b vmlinux.o.after
So lets get rid of this distinction once and for all.
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150329090233.GA1963@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index c8eb469..6751c5c 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -207,7 +207,7 @@
return -1;
}
- if (!user_mode_ignore_vm86(regs)) {
+ if (!user_mode(regs)) {
if (!fixup_exception(regs)) {
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = trapnr;
@@ -468,7 +468,7 @@
}
tsk = current;
- if (!user_mode_ignore_vm86(regs)) {
+ if (!user_mode(regs)) {
if (fixup_exception(regs))
goto exit;
@@ -685,7 +685,7 @@
* We already checked v86 mode above, so we can check for kernel mode
* by just checking the CPL of CS.
*/
- if ((dr6 & DR_STEP) && !user_mode_ignore_vm86(regs)) {
+ if ((dr6 & DR_STEP) && !user_mode(regs)) {
tsk->thread.debugreg6 &= ~DR_STEP;
set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
regs->flags &= ~X86_EFLAGS_TF;