entry: Wire up syscall_work in common entry code

Prepare the common entry code to use the SYSCALL_WORK flags. They will
be defined in subsequent patches for each type of syscall
work. SYSCALL_WORK_ENTRY/EXIT are defined for the transition, as they
will replace the TIF_ equivalent defines.
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20201116174206.2639648-4-krisman@collabora.com

include/linux/entry-common.h

@@ -64,6 +64,9 @@
 	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT |			\
 	 _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
 
+#define SYSCALL_WORK_ENTER	(0)
+#define SYSCALL_WORK_EXIT	(0)
+
 /*
  * TIF flags handled in exit_to_user_mode_loop()
  */

kernel/entry/common.c

@@ -42,7 +42,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 }
 
 static long syscall_trace_enter(struct pt_regs *regs, long syscall,
-				unsigned long ti_work)
+				unsigned long ti_work, unsigned long work)
 {
 	long ret = 0;
 
@@ -74,11 +74,12 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
 static __always_inline long
 __syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	unsigned long ti_work;
 
 	ti_work = READ_ONCE(current_thread_info()->flags);
-	if (ti_work & SYSCALL_ENTER_WORK)
-		syscall = syscall_trace_enter(regs, syscall, ti_work);
+	if (work & SYSCALL_WORK_ENTER || ti_work & SYSCALL_ENTER_WORK)
+		syscall = syscall_trace_enter(regs, syscall, ti_work, work);
 
 	return syscall;
 }
@@ -225,7 +226,8 @@ static inline bool report_single_step(unsigned long ti_work)
 }
 #endif
 
-static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work)
+static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
+			      unsigned long work)
 {
 	bool step;
 
@@ -245,6 +247,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work)
  */
 static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	u32 cached_flags = READ_ONCE(current_thread_info()->flags);
 	unsigned long nr = syscall_get_nr(current, regs);
 
@@ -262,8 +265,8 @@ static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 	 * enabled, we want to run them exactly once per syscall exit with
 	 * interrupts enabled.
 	 */
-	if (unlikely(cached_flags & SYSCALL_EXIT_WORK))
-		syscall_exit_work(regs, cached_flags);
+	if (unlikely(work & SYSCALL_WORK_EXIT || cached_flags & SYSCALL_EXIT_WORK))
+		syscall_exit_work(regs, cached_flags, work);
 }
 
 __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)