From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj2-f12.google.com (mail-pj2-f12.google.com [74.125.227.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5318941D648 for ; Sat, 3 Oct 2026 12:26:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.140 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791030393; cv=none; b=MUUA46RE83exk20zyZOVk/SzMKkc1z40Q+ZoWufRbq7bUEbUSh8rxSOFAB7IY9ZaZZTMV46NbfOJgzcxqIAMvehoMUgv83jGorRn/FdfOg1YZvRiDnEkJf7CaeAH4xy1GBuwkDwc/6kQxO30PNOPPSb0B7vnXwYDN+uWUG05bFc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791030393; c=relaxed/simple; bh=tMNk9xXn/8/QLwLZhGeYbz3KTI0eZs3dJXEFJHR9kaI=; h=Content-Type:Date:Message-Id:Cc:Subject:From:To:In-Reply-To: References:MIME-Version; b=UProV442EgQmNnvUFII1qTlbB1fJkEuhqKCNp8Q5yLw/v7umirRuoPWUajw62JZ16/T79rPUehdtWP1bTAVmwpTCWK4uXZfOmoQ3sxBUcbmkYBCdcoW3FNxZC8o5VDiQoZDx9MWB3078bVqJw3JXuBN9s2t4pYwwokOCMgbRiyA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ilmqjpcY; arc=none smtp.client-ip=74.125.227.140 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ilmqjpcY" Received: by mail-pj2-f12.google.com with SMTP id 98e67ed59e1d1-396ccda24afso90525a91.3 for ; Sat, 03 Oct 2026 05:26:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1791030392; x=1791635192; darn=vger.kernel.org; h=mime-version:content-transfer-encoding:references:in-reply-to:to :from:subject:cc:message-id:date:content-type:from:to:cc:subject :date:message-id:reply-to:content-type; bh=KEFakFLXqE1dz/kBByjhcvN1VdcTzWWCXJmwn3Pv+m8=; b=ilmqjpcY9Zt2We9/oimBsO4wmplULLB+pMErBsJQVWjWJvVN8Upku4/+Yw+5B18kwf rb7XXTG/253VmdlrHPcL2kbhvVnUPiDDRqPu9zEyhmDH8M0KwF1lcOlKGQvzxjM+Cvf7 H5iYbI/I6lChrnGyt0MUhecH2hjOPAw4Vk6qF73SWedGpC71fagGWOSXVrU5RgmSi+eu BcOlOlI6wbX77Fv5LVTNFRp+pxqUPL4ZMKD4mr8Xos8MLLB1UpDAbdA9k/fOhLdmRuHt 6FjQZlzbvPIsj9Yy1T0AgdukhdZK0zokfH85iAnqOpMAQePyN2yWWo/7NPbEe56yJVcz A7LQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791030392; x=1791635192; h=mime-version:content-transfer-encoding:references:in-reply-to:to :from:subject:cc:message-id:date:content-type:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=KEFakFLXqE1dz/kBByjhcvN1VdcTzWWCXJmwn3Pv+m8=; b=lEfC2tkiocGgMO88Kk7BPeN1N70ve7Mo8pdLnwJQJvZ49KO9jSCtDJ1B1W+3wWzLxs rWXI2evXUOzgz+D8qtpHwly92FAklRbn3zUbq2iuVuNd9ZU2xqo73QWGNJlEa3x5qsdn VIsSPj1geG7FOrnAWI0Hw6NBe/boUEz6xazeYD7IG9NXHeVGs22bYm/7cImKYF5rGBwz 3VEmU0ZISuykgfws4ankSdZVB0OdJgcGPXqPIb/UxWE5hPHXu3axFSlf4L22Lr3haveI D0GikOa8alvgJ1QYWYLo1T2XYwGqRWro8qlHYC0si4J/1eh5UsXsHCeSdo5A0xBPEeF/ thxQ== X-Forwarded-Encrypted: i=1; AKwUvBzlrtWwqMCpIosoLb4NsLt1YeAc470tkLBnJjaABXpRri2OkRiHB3x5BTz3aaVh4nKkqWs=@vger.kernel.org X-Gm-Message-State: AFq9FYLG5mHPHQij3ye5SJtu2Ugg0R20MX2wsGDMlXr4OMavnKk0txdG mNcnkfHFdxd/5IRHpieO2kNTS/hO3d51FEiW34rNoBkJa02LjMAFC8QS X-Gm-Gg: AYBFou3LNaO1TDSyUXJFjxK+h22r/I74K/olaZMWNDtiYXBHS8D7aktg6CRaUE8zzVM 7aO744ZfHQ0idXu79nvYbcjjCtAiNYKl800g+a+aSM1lQnCRvM9oWi0YKqH8Ps2i1giz/W/LyzM uOt5RPjd1NDMgElmJbj8km9yQAmYJy4TjSe2fqlWFOFom+dEUXnozz20IeywrgGIa6PAygQbT10 +ttaFvTPT0PdkTaTdPosxPN+Dr32/1nwdDDh4/12eNrOD931mj3Oin3e99ftVUWyaeEZE5sceMv YKxPfBmZTgqoruqe7BplgDD4kpo2m1y9vAA5KE6QNzf/6ef01Pb5jIIwdWkXho4P00Tzc6vQzIh GW1SqVHd/jrNFqgvTVQv010/MH6iirvRpufCXwdWbW6cdDubZ7SQOosfx+7DH9bSRdU09aNEdUq YfD+rYeagKZooXvgbWNdXMQymM3BteiZ7BZ7GxGulatbropNIFfsRpn7ojnZBUmdV27uKbCOLPY b+ztXIOT6PGVI4Pp5VGSkvbTQh4zelogUZrSENDFxP2eiSUR9wHUugXpRZ6ZP9rhkTn1V+FP9zb dNg= X-Received: by 2002:a17:90b:3846:b0:3a0:c717:2db with SMTP id 98e67ed59e1d1-3a6ce7913eamr2502055a91.27.1791030391511; Sat, 03 Oct 2026 05:26:31 -0700 (PDT) Received: from localhost ([153.61.198.246]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a78d6610a2sm2991731a91.6.2026.10.03.05.26.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 03 Oct 2026 05:26:31 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Sat, 03 Oct 2026 12:26:30 +0000 Message-Id: Cc: "Andrii Nakryiko" , "Daniel Borkmann" , "Eduard Zingerman" , Subject: Re: [PATCH bpf-next v8 11/22] bpf: Dispatch cleanup pads by rewriting return addresses From: "Alexei Starovoitov" To: "Yonghong Song" , In-Reply-To: <20261001133103.1340994-1-yonghong.song@linux.dev> References: <20261001133006.1335369-1-yonghong.song@linux.dev> <20261001133103.1340994-1-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 Thu, Oct 01, 2026 at 06:31 AM Yonghong Song wrote: > + if (!bpf_prog_need_blind(prog)) { > + ret = bpf_exc_attach_main_prog(env, prog); > + if (ret) > + return ERR_PTR(ret); > return bpf_int_jit_compile(env, prog); > + } bpf-ci is right. The table of a prog without subprogs is never read. Drop bpf_exc_attach_main_prog() and these hunks. [...] > + rcu_read_lock(); > + prog = bpf_prog_ksym_find(ip); > + rcu_read_unlock(); > + if (!prog) > + return !ctx->cnt; fexit attached to a subprog in the chain stops the walk here. main -> A -> trampoline -> B -> C C calls bpf_unwind(). The return into B is rewritten. The next ip is in the trampoline, bpf_prog_ksym_find() returns NULL and the returns into A and main stay as they were. B returns 0 through the trampoline to A at callsite + 1. The verifier didn't see that path, or removed it as dead code.