Re: [PATCH v19 10/11] tracing/wprobe: Support BTF typecast in fetchargs

[sashiko-bot@kernel.org]

> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> Allow BTF typecast syntax (STRUCT)FETCHARG->MEMBER in wprobe event
> fetchargs. Previously, handle_typecast() rejected any probe context
> that was not a function entry/return or tracepoint event probe.
> 
> Wprobe events use $addr (the accessed address) and $value (the value
> at that address). By enabling BTF typecast, users can now cast these
> to a concrete struct type and access its fields directly. For example:
> 
>   echo 'w:watch rw@-1:8 dflag=(dentry)$addr->d_flags' >> dynamic_events
> 
> With a set_wprobe trigger pointing the watchpoint at a dentry address,
> the resulting trace shows d_flags being accessed at that location.
> 
> Note that $addr and $value are restricted to kernel-space memory,
> which is consistent with the existing TPARG_FL_KERNEL flag used when
> parsing wprobe fetchargs.
> 
> Assisted-by: LLM
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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