From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DDCC7125D0 for ; Thu, 5 Feb 2026 02:21:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770258075; cv=none; b=Y+VnEzd71S5WMRRAzHGQOCr3wudWPZouCo75YRcGjvZnHN237HMgw5JsqSPVfadBJuh/3jUjZheW4stgyDi0UtG03U+lAHQFudtXSHqAEs/WeYGJ6HXkiVptwfb1U6Jb+eTA3dBHy+4YhWODYQbRUG66cjQkSl7DeGc6IO6NVGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770258075; c=relaxed/simple; bh=2XE8HbfhFXMkSTQ1DjZ0dz3yRk4XRucvW0j10qt/2c8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cWpdGQ6OUF8foLHgOvxI2Guy7su2cOHtmWIfQWPCL1R2VjIyffRK2QpLCQW/3Y46gnQPojSbE/3h+3gBEuVUX53bCacG63SZn050dm9miQ9kEc9d+UXu8bQ913dyN+OzJjHVwCltczLARroeoLzkUeCOj4GQWKY/db2QcHbywDM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=p66kndHN; arc=none smtp.client-ip=91.218.175.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="p66kndHN" Message-ID: <8ff3384a-24a2-4833-b614-16d2c7227b5e@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1770258062; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oNWaH+3MFLvOh6Xfm+sXWjDEBIlfcpUNTm0CfSMiejg=; b=p66kndHNUsxax//oN/L/DwtqYmNC9orbMSlZws0UL5XF1SkdIFwfKWopH1SAWTT3jIe2MI OzLF+cjOpRIbhHhcJyHfu4gGgl4K7XBR1RpO6W84rbXW3jeHHdEqslAA0E2WOuZH8xjMrD WUb1VYLes3LwcjNLrOrJJLfJhPIXsmE= Date: Thu, 5 Feb 2026 10:20:44 +0800 Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v9 3/9] bpf: Refactor reporting log_true_size for prog_load Content-Language: en-US To: Andrii Nakryiko Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Christian Brauner , Seth Forshee , Yuichiro Tsuji , Andrey Albershteyn , Willem de Bruijn , Jason Xing , Tao Chen , Mykyta Yatsenko , Kumar Kartikeya Dwivedi , Anton Protopopov , Amery Hung , Rong Tao , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com References: <20260202144046.30651-1-leon.hwang@linux.dev> <20260202144046.30651-4-leon.hwang@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Leon Hwang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 5/2/26 03:48, Andrii Nakryiko wrote: > On Mon, Feb 2, 2026 at 6:42 AM Leon Hwang wrote: >> >> The next commit will add support for reporting logs via extended common >> attributes, including 'log_true_size'. >> >> To prepare for that, refactor the 'log_true_size' reporting logic by >> introducing a new struct bpf_log_attr to encapsulate log-related behavior: >> >> * bpf_prog_load_log_attr_init(): initialize the log fields, which will >> support extended common attributes in the next commit. >> * bpf_log_attr_finalize(): handle log finalization and write back >> 'log_true_size' to userspace. >> >> Signed-off-by: Leon Hwang >> --- >> include/linux/bpf.h | 4 +++- >> include/linux/bpf_verifier.h | 10 ++++++++++ >> kernel/bpf/log.c | 35 +++++++++++++++++++++++++++++++++++ >> kernel/bpf/syscall.c | 8 +++++--- >> kernel/bpf/verifier.c | 13 +++---------- >> 5 files changed, 56 insertions(+), 14 deletions(-) >> >> diff --git a/include/linux/bpf.h b/include/linux/bpf.h >> index cd9b96434904..d4dbcc7ad156 100644 >> --- a/include/linux/bpf.h >> +++ b/include/linux/bpf.h >> @@ -2913,7 +2913,9 @@ int bpf_check_uarg_tail_zero(bpfptr_t uaddr, size_t expected_size, >> size_t actual_size); >> >> /* verify correctness of eBPF program */ >> -int bpf_check(struct bpf_prog **fp, union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size); >> +struct bpf_log_attr; >> +int bpf_check(struct bpf_prog **fp, union bpf_attr *attr, bpfptr_t uattr, >> + struct bpf_log_attr *attr_log); >> >> #ifndef CONFIG_BPF_JIT_ALWAYS_ON >> void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth); >> diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h >> index 8355b585cd18..c805b85b6f7a 100644 >> --- a/include/linux/bpf_verifier.h >> +++ b/include/linux/bpf_verifier.h >> @@ -631,6 +631,16 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) >> return log && log->level; >> } >> >> +struct bpf_log_attr { >> + u32 offsetof_true_size; >> + u32 uattr_size; >> + bpfptr_t uattr; >> +}; >> + >> +int bpf_prog_load_log_attr_init(struct bpf_log_attr *attr_log, union bpf_attr *attr, >> + bpfptr_t uattr, u32 size); >> +int bpf_log_attr_finalize(struct bpf_log_attr *attr, struct bpf_verifier_log *log); >> + >> #define BPF_MAX_SUBPROGS 256 >> >> struct bpf_subprog_arg_info { >> diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c >> index a0c3b35de2ce..ff579fcba36f 100644 >> --- a/kernel/bpf/log.c >> +++ b/kernel/bpf/log.c >> @@ -863,3 +863,38 @@ void print_insn_state(struct bpf_verifier_env *env, const struct bpf_verifier_st >> } >> print_verifier_state(env, vstate, frameno, false); >> } >> + >> +static void bpf_log_attr_init(struct bpf_log_attr *attr_log, int offsetof_true_size, bpfptr_t uattr, >> + u32 uattr_size) >> +{ >> + memset(attr_log, 0, sizeof(*attr_log)); >> + attr_log->offsetof_true_size = offsetof_true_size; >> + attr_log->uattr_size = uattr_size; >> + attr_log->uattr = uattr; >> +} >> + >> +int bpf_prog_load_log_attr_init(struct bpf_log_attr *attr_log, union bpf_attr *attr, >> + bpfptr_t uattr, u32 size) >> +{ >> + bpf_log_attr_init(attr_log, offsetof(union bpf_attr, log_true_size), uattr, size); >> + return 0; >> +} >> + >> +int bpf_log_attr_finalize(struct bpf_log_attr *attr, struct bpf_verifier_log *log) >> +{ >> + u32 log_true_size; >> + size_t size; >> + int err; >> + >> + if (!log) >> + return 0; > > can this ever happen? why guard against this? > In patch #7, 'log' can be NULL when users do not provide 'log_buf'. However, bpf_vlog_finalize() already guards against this case, so I'll drop this check. >> + >> + err = bpf_vlog_finalize(log, &log_true_size); >> + >> + size = sizeof(log_true_size); >> + if (attr->uattr_size >= attr->offsetof_true_size + size && >> + copy_to_bpfptr_offset(attr->uattr, attr->offsetof_true_size, &log_true_size, size)) >> + err = -EFAULT; > > minor nit: return -EFAULT; > Ack. Thanks, Leon