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From:   Krishna Chaitanya <chaitanya.mgit@gmail.com>
Date:   Tue, 20 Apr 2021 18:26:35 +0530
Message-ID: <CABPxzYKjxW+P_cMLmZgtQN7nbCB3zzksYQWpChC70tbVb6VJCA@mail.gmail.com>
Subject: Module versioning + Missing CRC in symvers + export tracepoints
To:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Hi,

I am seeing an issue of no CRC being generated in the Module.symvers for a
driver module even when CONFIG_MODVERSIONS Is enabled, this causes
modpost warnings about missing versioning.

The module in questions only exports tracepoint related symbols (as
struct tracepoint is
part of the module CRC), I have seen this with other modules also e.g.
iwlwifi with CONFIG_MODVERSIONS.

Though I am trying on 5.12.-rc2, also, seeing this issue with older kernels with
CONFIG_MODVERSIONS enabled e.g. 4.15.0, Below are a couple of snippets
to demonstrate the issue.

modpost warnings
===============

WARNING: modpost: EXPORT symbol "__tracepoint_iwlwifi_dev_ucode_event"
[drivers/net/wireless/intel/iwlwifi//iwlwifi.ko] version generation
failed, symbol will not be versioned.
WARNING: modpost: EXPORT symbol "iwl_remove_notification"
[drivers/net/wireless/intel/iwlwifi//iwlwifi.ko] version generation
failed, symbol will not be versioned.


Module.symvers (after modpost)
==============
0x00000000      iwl_remove_notification
drivers/net/wireless/intel/iwlwifi//iwlwifi     EXPORT_SYMBOL_GPL
0x00000000      __tracepoint_iwlwifi_dev_ucode_event
drivers/net/wireless/intel/iwlwifi//iwlwifi     EXPORT_SYMBOL

Any ideas?