semantics of KSTK_ESP and friends

From: Vineet Gupta
Date: Thu Feb 12 2015 - 02:10:24 EST


Is KSTK_ESP supposed to return the kernel mode SP of a sleeping task or is it supposed to provide the user mode SP at the time of last kernel entry ?

The 2 non arch users of the API expect the user mode SP semantics:
* vm_is_stack_for_task() - to annotate /proc/<pid>/maps stack vma - which is shere Alexey noted this.
* do_task_stat()

ARC port uses these for unwinding the task of a sleeping task (hence kernel mode SP semantics).
metag (from the looks of it) also seem to provide kernel mode value, while most others seem to provide the user mode variant.

I can fix ARC to work with expectation of generic code, but wanted to understand anyways.

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