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Fri, 13 Sep 2024 06:03:52 +0000 (GMT) From: Sven Schnelle To: Masami Hiramatsu (Google) Cc: Steven Rostedt , Mark Rutland , Mathieu Desnoyers , Paul Walmsley , Palmer Dabbelt , Albert Ou , Guo Ren , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-csky@vger.kernel.org Subject: Re: [PATCH 0/7] add function arguments to ftrace In-Reply-To: (Sven Schnelle's message of "Mon, 09 Sep 2024 09:52:21 +0200") References: <20240904065908.1009086-1-svens@linux.ibm.com> <20240905111620.5211d9f8@gandalf.local.home> <20240906100738.2526cffd@gandalf.local.home> <20240908222830.01a01b10d62d59ed73dcb676@kernel.org> Date: Fri, 13 Sep 2024 08:03:51 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 7nToZDWGKNT9QZOOlyB71xBhYhClmsHN X-Proofpoint-GUID: 7nToZDWGKNT9QZOOlyB71xBhYhClmsHN X-Proofpoint-UnRewURL: 0 URL was un-rewritten Precedence: bulk X-Mailing-List: linux-csky@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-13_03,2024-09-12_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 priorityscore=1501 bulkscore=0 spamscore=0 phishscore=0 lowpriorityscore=0 mlxscore=0 mlxlogscore=858 impostorscore=0 clxscore=1015 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2408220000 definitions=main-2409130042 Sven Schnelle writes: > Masami Hiramatsu (Google) writes: > >> On Fri, 6 Sep 2024 10:07:38 -0400 >> Steven Rostedt wrote: >> >>> On Fri, 06 Sep 2024 08:18:02 +0200 >>> Sven Schnelle wrote: >>> >>> >>> > One thing i learned after submitting the series is that struct >>> > ftrace_regs depends on CONFIG_FUNCTION_TRACER, so it cannot be used >>> > with the graph tracer. >> >> Yeah, this is solved by my series [1]. >> >> [1] https://patchwork.kernel.org/project/linux-trace-kernel/patch/172398532480.293426.13232399076477198126.stgit@devnote2/ >> >> So I think this series is easier to apply after my series, which >> passes fgraph_regs in return handler. > > Thanks, i'll rebase my changes on top of your patches then. While doing so i noticed that i completely forgot about arguments located on the stack. The current patchset tries to read from the current kernel stack, which is obviously wrong. So either the tracer needs to save the stack frame in the ringbuffer (which would be quite a lot of data), or ftrace only prints arguments located in registers. Also not nice. Opinions? Thanks Sven