ARC: add some more comments to ret_from_fork

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

diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 83a046a..d868289 100644 (file)
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -736,16 +736,20 @@ ENTRY(ret_from_fork)
        ; put last task in scheduler queue
        bl   @schedule_tail
 
-       ; If kernel thread, jump to its entry-point
        ld   r9, [sp, PT_status32]
        brne r9, 0, 1f
 
-       jl.d [r14]
-       mov  r0, r13            ; arg to payload
+       jl.d [r14]              ; kernel thread entry point
+       mov  r0, r13            ; (see PF_KTHREAD block in copy_thread)
 
 1:
-       ; special case of kernel_thread entry point returning back due to
-       ; kernel_execve() - pretend return from syscall to ret to userland
+       ; Return to user space
+       ; 1. Any forked task (Reach here via BRne above)
+       ; 2. First ever init task (Reach here via return from JL above)
+       ;    This is the historic "kernel_execve" use-case, to return to init
+       ;    user mode, in a round about way since that is always done from
+       ;    a kernel thread which is executed via JL above but always returns
+       ;    out whenever kernel_execve (now inline do_fork()) is involved
        b    ret_from_exception
 END(ret_from_fork)