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Date:   Sat, 06 Apr 2019 22:52:47 +0530
From:   "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Subject: Re: [PATCH] kprobes: fix compilation when KPROBE_EVENTS is enabled
 without kretpobes
To:     linux-kernel@vger.kernel.org, Sven Schnelle <svens@stackframe.org>
Cc:     Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Masami Hiramatsu <mhiramat@kernel.org>
References: <20190406155543.15353-1-svens@stackframe.org>
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Sven Schnelle wrote:
> While implementing kprobes on PA-RISC (without kretprobes) compilation
> fails when CONFIG_KPROBE_EVENTS is enabled:

Thanks for working on that! Is there a specific reason kretprobes is not 
being enabled on parisc?

> 
> kernel/trace/trace_kprobe.o: in function `trace_kprobe_create':
> kernel/trace/trace_kprobe.c:666: undefined reference to `kprobe_on_func_entry'
> kernel/trace/trace_kprobe.o: in function `trace_kprobe_on_func_entry':
> kernel/trace/trace_kprobe.c:167: undefined reference to `kprobe_on_func_entry'
> kernel/trace/trace_kprobe.c:167: undefined reference to `kprobe_on_func_entry'
> make: *** [Makefile:1029: vmlinux] Error 1
> 
> Given the fact that these functions have no dependencies on kretprobes i think
> they should be moved out of the #ifdef CONFIG_KRETPROBES block.
> 
> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> ---
>  kernel/kprobes.c | 39 ++++++++++++++++++++-------------------
>  1 file changed, 20 insertions(+), 19 deletions(-)

These functions were originally added only for kretprobes, but have 
taken on newer uses since then. So, for this patch:
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

However, I wonder if we should simply remove CONFIG_KRETPROBES 
altogether. All architectures supporting kprobes today also support 
kretprobes. I don't see why anyone would want to only disable 
kretprobes.


- Naveen