Re: [PATCH v8 0/3] ARM: Implement MODULE_PLT support in FTRACE

From: Florian Fainelli <f.fainelli@gmail.com>
To: Qais Yousef <qais.yousef@arm.com>,
	Alexander Sverdlin <alexander.sverdlin@nokia.com>
Cc: linux-arm-kernel@lists.infradead.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH v8 0/3] ARM: Implement MODULE_PLT support in FTRACE
Date: Tue, 4 May 2021 12:11:01 -0700	[thread overview]
Message-ID: <761c79cf-8709-6da6-cdb7-9e03e25f0272@gmail.com> (raw)
In-Reply-To: <20210419223448.vummlz37nyc3a64i@e107158-lin.cambridge.arm.com>

On 4/19/21 3:34 PM, Qais Yousef wrote:
> On 04/19/21 14:54, Florian Fainelli wrote:
>>
>>
>> On 4/12/2021 4:08 AM, Qais Yousef wrote:
>>> Hi Alexander
>>>
>>> Fixing Ard's email as the Linaro one keeps bouncing back. Please fix that in
>>> your future postings.
>>>
>>> On 04/12/21 08:28, Alexander Sverdlin wrote:
>>>> Hi!
>>>>
>>>> On 09/04/2021 17:33, Qais Yousef wrote:
>>>>> I still think the ifdefery in patch 3 is ugly. Any reason my suggestion didn't
>>>>> work out for you? I struggle to see how this is better and why it was hard to
>>>>> incorporate my suggestion.
>>>>>
>>>>> For example
>>>>>
>>>>> 	-       old = ftrace_call_replace(ip, adjust_address(rec, addr));
>>>>> 	+#ifdef CONFIG_ARM_MODULE_PLTS
>>>>> 	+       /* mod is only supplied during module loading */
>>>>> 	+       if (!mod)
>>>>> 	+               mod = rec->arch.mod;
>>>>> 	+       else
>>>>> 	+               rec->arch.mod = mod;
>>>>> 	+#endif
>>>>> 	+
>>>>> 	+       old = ftrace_call_replace(ip, aaddr,
>>>>> 	+                                 !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod);
>>>>> 	+#ifdef CONFIG_ARM_MODULE_PLTS
>>>>> 	+       if (!old && mod) {
>>>>> 	+               aaddr = get_module_plt(mod, ip, aaddr);
>>>>> 	+               old = ftrace_call_replace(ip, aaddr, true);
>>>>> 	+       }
>>>>> 	+#endif
>>>>> 	+
>>>>>
>>>>> There's an ifdef, followed by a code that embeds
>>>>> !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) followed by another ifdef :-/
>>>>
>>>> No, it's actually two small ifdefed blocks added before and after an original call,
>>>> which parameters have been modified as well. The issue with arch.mod was explained
>>>> by Steven Rostedt, maybe you've missed his email.
>>>
>>> If you're referring to arch.mod having to be protected by the ifdef I did
>>> address that. Please look at my patch.
>>>
>>> My comment here refers to the ugliness of this ifdefery. Introducing 2 simple
>>> wrapper functions would address that as I've demonstrated in my
>>> suggestion/patch.
>>
>> What is the plan to move forward with this patch series, should v8 be
>> submitted into RMK's patch tracker and improved upon from there, or do
>> you feel like your suggestion needs to be addressed right away?
> 
> There's no objection from my side to submitting this and improve later.

OK, thanks! Alexander, do you mind sending these patches to RMK's patch
tracker: https://www.armlinux.org.uk/developer/patches/?

Thank you!
-- 
Florian