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Fri, 18 Sep 2026 22:02:44 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Sat, 19 Sep 2026 05:02:43 +0000 Message-Id: To: "Yonghong Song" , Cc: "Andrii Nakryiko" , "Daniel Borkmann" , "Eduard Zingerman" , Subject: Re: [PATCH bpf-next 11/20] bpf, x86: Dispatch exception cleanup pads at run time From: "Alexei Starovoitov" In-Reply-To: <20260917055742.3932170-1-yonghong.song@linux.dev> References: <20260917055645.3926444-1-yonghong.song@linux.dev> <20260917055742.3932170-1-yonghong.song@linux.dev> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, Sep 16, 2026 at 10:57 PM Yonghong Song wrote: > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c > index d4a980140b48..9d0dd54773e8 100644 > --- a/arch/x86/net/bpf_jit_comp.c > +++ b/arch/x86/net/bpf_jit_comp.c [...] > + if (bpf_is_unwind_resume_kfunc(insn)) { > + emit_return(&prog, image + addrs[i - 1] + (prog - temp)); > + break; > + } > + > func = (u8 *) __bpf_call_base + imm32; bpf_is_unwind_resume_kfunc() matches imm == btf_id && off == 0, but by now bpf_fixup_kfunc_call() has rewritten every other kfunc's imm to an offset from __bpf_call_base. A vmlinux kfunc that happens to sit btf_id bytes after __bpf_call_base gets JITed as a bare ret in the middle of a normal prog. Looks incorrect.