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: Mon, 19 Apr 2021 14:54:30 -0700	[thread overview]
Message-ID: <b26651f2-a5ca-ff5d-23e4-05b7eb7d9583@gmail.com> (raw)
In-Reply-To: <20210412110810.t7pqkwawn5zmqbca@e107158-lin.cambridge.arm.com>


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?
-- 
Florian

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