Re: [RFC PATCH] riscv: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS

From: "Björn Töpel" <bjorn@kernel.org>
To: Puranjay Mohan <puranjay12@gmail.com>
Cc: "Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	"Masami Hiramatsu" <mhiramat@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Sami Tolvanen" <samitolvanen@google.com>,
	"Guo Ren" <guoren@kernel.org>,
	"Ley Foon Tan" <leyfoon.tan@starfivetech.com>,
	"Deepak Gupta" <debug@rivosinc.com>,
	"Sia Jee Heng" <jeeheng.sia@starfivetech.com>,
	"Björn Töpel" <bjorn@rivosinc.com>,
	"Song Shuai" <suagrfillet@gmail.com>,
	"Clément Léger" <cleger@rivosinc.com>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Jisheng Zhang" <jszhang@kernel.org>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] riscv: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
Date: Fri, 08 Mar 2024 16:15:04 +0100	[thread overview]
Message-ID: <87edckkb5z.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <CANk7y0jpKb8XUycKxHbsrJGEWcTvVDYFjM+A2VUe0JeZ2Y-Zbw@mail.gmail.com>

Puranjay Mohan <puranjay12@gmail.com> writes:

>> Now, I think a better approach for RISC-V would be implementing what x86
>> has (arch_ftrace_update_trampoline()), rather than CALL_OPS for RISC-V.
>>
>> Thoughts?
>
> I am going to spin some patches for implementing
> arch_ftrace_update_trampoline() for
> RISC-V, then we can compare the two approaches and see which is
> better. But I agree
> that arch_ftrace_update_trampoline() is a better approach given that
> we can jump anywhere
> with auipc/jalr.

Yup, and the text size wont blow up.

Cheers,
Björn