ARC: Add support for irqflags tracing and lockdep

Lockdep required a small fix to stacktrace API which was incorrectly
unwindign out of __switch_to for the current call frame.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

2 files changed, 14 insertions, 1 deletions

diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index daa0e7990270..47d09d07f093 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -250,6 +250,14 @@ ARC_ENTRY handle_interrupt_level1
         lr  r0, [icause1]
         and r0, r0, 0x1f
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+        ; icause1 needs to be read early, before calling tracing, which
+        ; can clobber scratch regs, hence use of stack to stash it
+        push r0
+        TRACE_ASM_IRQ_DISABLE
+        pop  r0
+#endif
+
         bl.d  @arch_do_IRQ
         mov r1, sp
 
@@ -570,6 +578,7 @@ resume_user_mode_begin:
         ; --- (Slow Path #2) pending signal  ---
         mov r0, sp      ; pt_regs for arg to do_signal()/do_notify_resume()
 
+        GET_CURR_THR_INFO_FLAGS   r9
         bbit0  r9, TIF_SIGPENDING, .Lchk_notify_resume
 
         ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs
@@ -635,6 +644,8 @@ resume_kernel_mode:
 
 restore_regs :
 
+        TRACE_ASM_IRQ_ENABLE
+
         lr      r10, [status32]
 
         ; Restore REG File. In case multiple Events outstanding,
diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index f8b7d880304d..ab97b034922f 100644
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -237,11 +237,13 @@ unsigned int get_wchan(struct task_struct *tsk)
  */
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
+        /* Assumes @tsk is sleeping so unwinds from __switch_to */
         arc_unwind_core(tsk, NULL, __collect_all_but_sched, trace);
 }
 
 void save_stack_trace(struct stack_trace *trace)
 {
-        arc_unwind_core(current, NULL, __collect_all, trace);
+        /* Pass NULL for task so it unwinds the current call frame */
+        arc_unwind_core(NULL, NULL, __collect_all, trace);
 }
 #endif