arch/tile: adopt prepare_exit_to_usermode() model from x86
This change is a prerequisite change for TASK_ISOLATION but also
stands on its own for readability and maintainability. The existing
tile do_work_pending() was called in a loop from assembly on
the slow path; this change moves the loop into C code as well.
For the x86 version see commit c5c46f59e4e7 ("x86/entry: Add new,
comprehensible entry and exit handlers written in C").
This change exposes a pre-existing bug on the older tilepro platform;
the singlestep processing is done last, but on tilepro (unlike tilegx)
we enable interrupts while doing that processing, so we could in
theory miss a signal or other asynchronous event. A future change
could fix this by breaking the singlestep work into a "prepare"
step done in the main loop, and a "trigger" step done after exiting
the loop. Since this change is intended as purely a restructuring
change, we call out the bug explicitly now, but don't yet fix it.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index 139dfde..0684e88 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -212,7 +212,7 @@
/* Nothing for now */
}
-extern int do_work_pending(struct pt_regs *regs, u32 flags);
+extern void prepare_exit_to_usermode(struct pt_regs *regs, u32 flags);
/*
diff --git a/arch/tile/include/asm/thread_info.h b/arch/tile/include/asm/thread_info.h
index dc1fb28..4b7cef9 100644
--- a/arch/tile/include/asm/thread_info.h
+++ b/arch/tile/include/asm/thread_info.h
@@ -140,10 +140,14 @@
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_NOHZ (1<<TIF_NOHZ)
+/* Work to do as we loop to exit to user space. */
+#define _TIF_WORK_MASK \
+ (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+ _TIF_ASYNC_TLB | _TIF_NOTIFY_RESUME)
+
/* Work to do on any return to user space. */
#define _TIF_ALLWORK_MASK \
- (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_SINGLESTEP | \
- _TIF_ASYNC_TLB | _TIF_NOTIFY_RESUME | _TIF_NOHZ)
+ (_TIF_WORK_MASK | _TIF_SINGLESTEP | _TIF_NOHZ)
/* Work to do at syscall entry. */
#define _TIF_SYSCALL_ENTRY_WORK \