make seccomp zerocost in schedule
This follows a suggestion from Chuck Ebbert on how to make seccomp
absolutely zerocost in schedule too. The only remaining footprint of
seccomp is in terms of the bzImage size that becomes a few bytes (perhaps
even a few kbytes) larger, measure it if you care in the embedded.
Signed-off-by: Andrea Arcangeli <andrea@cpushare.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h
index 4cb0f91..54424e0 100644
--- a/include/asm-i386/thread_info.h
+++ b/include/asm-i386/thread_info.h
@@ -137,6 +137,7 @@
#define TIF_DEBUG 17 /* uses debug registers */
#define TIF_IO_BITMAP 18 /* uses I/O bitmap */
#define TIF_FREEZE 19 /* is freezing for suspend */
+#define TIF_NOTSC 20 /* TSC is not accessible in userland */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@@ -151,6 +152,7 @@
#define _TIF_DEBUG (1<<TIF_DEBUG)
#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
#define _TIF_FREEZE (1<<TIF_FREEZE)
+#define _TIF_NOTSC (1<<TIF_NOTSC)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
@@ -160,7 +162,8 @@
#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
/* flags to check in __switch_to() */
-#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP)
+#define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG)
+#define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC)
/*
* Thread-synchronous status.