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[192.26.29.3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a97c42b3c1sm10695605e9.6.2026.10.27.19.15.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 19:15:20 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bot+bpf-ci@kernel.org Cc: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, emil@etsalapatis.com, ihor.solodrai@linux.dev, kkd@meta.com, kernel-team@meta.com, martin.lau@kernel.org, yonghong.song@linux.dev, mason@kernel.org Subject: Re: [RFC PATCH bpf-next v1 01/11] bpf: Give a helper a way to call its callback with a pad Date: Wed, 28 Oct 2026 03:15:19 +0100 Message-ID: <20261028021519.1203900-8-memxor@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <81df2f63249021a13160d155eccab3bbd591e464d05db9765a15427c3cc97650@mail.kernel.org> References: <03d6c53ccdf3eb0f5503eae9f9ffa5e6570549c3.1793147364.git.memxor@gmail.com> <81df2f63249021a13160d155eccab3bbd591e464d05db9765a15427c3cc97650@mail.kernel.org> X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Wed Oct 28, 2026 at 2:39 AM CET, bot+bpf-ci wrote: > [...] > TL;DR: > - bpf_unwind_leave() may misbehave if the helper is ftrace/kretprobe/fexit > traced: unwind lost, pointer or reference treated as scalar Right. Every function with a pad is notrace and no kprobe target in the next version, as the verifier lets only fentry attach to a subprog that unwinds, with a test that fexit on bpf_loop() is refused. > - With gcc, bpf_call_cb() register variables may be clobbered by KASAN/KCSAN > calls, possibly jumping to a bad address Right, for a call in the evaluation of a later argument, which the compiler does not keep the register variables across. The next version evaluates every argument into a temporary first. > [...]