Re: [PATCH v3 1/2] kretprobe: produce sane stack traces

On 2018-11-02, Aleksa Sarai [off-list ref] wrote:

Unfortunately, I'm having a lot of trouble understanding how the current
ftrace hooking works -- ORC has a couple of ftrace hooks that seem
reasonable on the surface but I don't understand (for instance) how
HAVE_FUNCTION_GRAPH_RET_ADDR_PTR *actually* works. Though your comment
appears to indicate that it doesn't work for stack traces?

Sorry, I just figured out how it works! (To make sure I actually
understand -- retp is a pointer to the place in the stack where the
return address is stored, so it uniquely specifies what each trampoline
actually points to -- this trick could also be used for kretprobes).

-- 
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>