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From:   =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>
To:     Song Shuai <suagrfillet@gmail.com>, paul.walmsley@sifive.com,
        palmer@dabbelt.com, aou@eecs.berkeley.edu, rostedt@goodmis.org,
        mhiramat@kernel.org, mark.rutland@arm.com, guoren@kernel.org,
        suagrfillet@gmail.com, jszhang@kernel.org, e.shatokhin@yadro.com,
        bjorn@rivosinc.com
Cc:     linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH V10 3/4] riscv: ftrace: Add
 DYNAMIC_FTRACE_WITH_DIRECT_CALLS support
In-Reply-To: <20230511093234.3123181-4-suagrfillet@gmail.com>
References: <20230511093234.3123181-1-suagrfillet@gmail.com>
 <20230511093234.3123181-4-suagrfillet@gmail.com>
Date:   Thu, 11 May 2023 21:42:03 +0200
Message-ID: <87zg6ad59w.fsf@all.your.base.are.belong.to.us>
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Song Shuai <suagrfillet@gmail.com> writes:

> This patch adds DYNAMIC_FTRACE_WITH_DIRECT_CALLS support for RISC-V.
>
> select the DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide the
> register_ftrace_direct[_multi] interfaces allowing users to register
> the customed trampoline (direct_caller) as the mcount for one or
> more target functions. And modify_ftrace_direct[_multi] are also
> provided for modifying direct_caller.
>
> To make the direct_caller and the other ftrace hooks (eg. function/fgraph
> tracer, k[ret]probes) co-exist, a temporary register is nominated to
> store the address of direct_caller in ftrace_regs_caller. After the
> setting of the address direct_caller by direct_ops->func and the
> RESTORE_REGS in ftrace_regs_caller, direct_caller will be jumped to
> by the `jr` inst.
>
> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> Tested-by: Guo Ren <guoren@kernel.org>
> Signed-off-by: Guo Ren <guoren@kernel.org>

Thank you for addressing my comments, and for your work on
WITH_DIRECT_CALLS!

Acked-by: Bj=C3=B6rn T=C3=B6pel <bjorn@rivosinc.com>