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Mon, 27 Oct 2025 01:47:11 -0700 (PDT) Received: from krava ([2a02:8308:a00c:e200::b44f]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-475dd489e6dsm123106415e9.6.2025.10.27.01.47.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Oct 2025 01:47:11 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Mon, 27 Oct 2025 09:47:09 +0100 To: Song Liu Cc: 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@meta.com, olsajiri@gmail.com Subject: Re: [PATCH v3 bpf 0/3] Fix ftrace for livepatch + BPF fexit programs Message-ID: References: <20251026205445.1639632-1-song@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251026205445.1639632-1-song@kernel.org> On Sun, Oct 26, 2025 at 01:54:42PM -0700, 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. > > --- > > Changes v2 => v3: > 1. Incorporate feedback by AI, which also fixes build error reported by > Steven and kernel test robot. Reviewed-by: Jiri Olsa thanks, jirka > > v2: https://lore.kernel.org/bpf/20251024182901.3247573-1-song@kernel.org/ > > Changes v1 => v2: > 1. Target bpf tree. (Alexei) > 2. Bring back the FTRACE_WARN_ON in __ftrace_hash_update_ipmodify > for valid code paths. (Steven) > 3. Update selftests with cleaner way to find livepatch-sample.ko. > (offlline discussion with Ihor) > > v1: https://lore.kernel.org/bpf/20251024071257.3956031-1-song@kernel.org/ > > Song Liu (3): > ftrace: Fix BPF fexit with livepatch > ftrace: bpf: Fix IPMODIFY + DIRECT in modify_ftrace_direct() > selftests/bpf: Add tests for livepatch + bpf trampoline > > kernel/bpf/trampoline.c | 5 - > kernel/trace/ftrace.c | 46 ++++++-- > tools/testing/selftests/bpf/config | 3 + > .../bpf/prog_tests/livepatch_trampoline.c | 107 ++++++++++++++++++ > .../bpf/progs/livepatch_trampoline.c | 30 +++++ > 5 files changed, 177 insertions(+), 14 deletions(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/livepatch_trampoline.c > create mode 100644 tools/testing/selftests/bpf/progs/livepatch_trampoline.c > > -- > 2.47.3