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Sun, 26 Oct 2025 13:27:36 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Sun, 26 Oct 2025 21:27:34 +0100 To: Song Liu Cc: Song Liu , "bpf@vger.kernel.org" , "linux-trace-kernel@vger.kernel.org" , "live-patching@vger.kernel.org" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "rostedt@goodmis.org" , "andrey.grodzovsky@crowdstrike.com" , "mhiramat@kernel.org" , Kernel Team , "olsajiri@gmail.com" Subject: Re: [PATCH v2 bpf 0/3] Fix ftrace for livepatch + BPF fexit programs Message-ID: References: <20251024182901.3247573-1-song@kernel.org> <8412F9AA-FEC6-4EFA-BACD-8B1579B90177@meta.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8412F9AA-FEC6-4EFA-BACD-8B1579B90177@meta.com> On Fri, Oct 24, 2025 at 08:47:08PM +0000, Song Liu wrote: > > > > On Oct 24, 2025, at 11:28 AM, Song Liu wrote: > > > > livepatch and BPF trampoline are two special users of ftrace. livepatch > > uses ftrace with IPMODIFY flag and BPF trampoline uses ftrace direct > > functions. When livepatch and BPF trampoline with fexit programs attach to > > the same kernel function, BPF trampoline needs to call into the patched > > version of the kernel function. > > > > 1/3 and 2/3 of this patchset fix two issues with livepatch + fexit cases, > > one in the register_ftrace_direct path, the other in the > > modify_ftrace_direct path. > > > > 3/3 adds selftests for both cases. > > AI has a good point on this: > > https://github.com/kernel-patches/bpf/pull/10088#issuecomment-3444465504 makes sense, I think it'll make the code easier to read jirka > > > I will wait a bit more for human to chime in before sending v3 with the > suggestion by AI. > > Thanks, > Song >