From 98edfab4c10343bd3ba1ca47d000544b9f964886 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Mon, 15 Dec 2014 16:33:39 +0530 Subject: [PATCH] ARC: add some more comments to ret_from_fork Signed-off-by: Vineet Gupta --- arch/arc/kernel/entry.S | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S index 83a046a7cd06..d868289c5a26 100644 --- 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)