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authorVineet Gupta <vgupta@synopsys.com>2014-12-15 16:33:39 +0530
committerVineet Gupta <vgupta@synopsys.com>2015-02-02 17:08:37 +0530
commit98edfab4c10343bd3ba1ca47d000544b9f964886 (patch)
tree7a7199204acacf79b6e5b933926a1bc3f73f5067 /arch/arc
parent4c86231c14a8a1e9838dcb013ded07ebd2f2a1a5 (diff)
ARC: add some more comments to ret_from_fork
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc')
-rw-r--r--arch/arc/kernel/entry.S14
1 files 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)