From patchwork Mon Oct 21 13:39:28 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13844164 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-170.mta1.migadu.com (out-170.mta1.migadu.com [95.215.58.170]) (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 8CBBE1F9400 for ; Mon, 21 Oct 2024 13:39:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729517985; cv=none; b=RAqaxnXDBtFDGRCp6sfGvpovN3IlTWFLPZfqwbztW6bqf9d4j7/+rIw9VPzS2NVUiJr8+32LeKtkm0cySimr9oPg/54be5YbnwWIfMK41P9FG0jYTJ9ClRpRveW8Pe38vRKNaF2+1bsmfg7kDskjtleyqH0U5eEURdEa1iT3BLA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729517985; c=relaxed/simple; bh=y1MhfUHbW9bFrohLvIqKd4pYEJhEqFvhfNmn1YVgCDs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=E4HMwI32/mKtv4u3hdz6cyuXejAnEiFtk7dw/ovNfimd5w8Bl8e2VHmrChzNFVQw5AElk6p9pyz5sfP9/jTDlr0fsQqvjjLr+MxWpSolxXG+1OzYaspeJlRgjZPl+v7GUNQusCjXEeaad/+Ef17m39hZcew3oS3U3zYORb5XBQ4= 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=aAE/BQ5u; arc=none smtp.client-ip=95.215.58.170 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="aAE/BQ5u" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1729517980; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eWCoRxD2VEdzF1sLzKyFXuJE1yx+GR1ex+u/p/I/GH8=; b=aAE/BQ5uepzzaCKtYMMpsYvXQY74D+pFhXMc3HsJWU1ujBxJppIcaB4G/DtzMmtsDtrNCh lI+BFa6bpH498A+IUPMJDBGddeJTLf52e6LcCAPnwGqcaToGeN3foWmOC9GXvf/+57GMuN snOGjuHKGagkZ+RvNLNG/dE/vEO7Zm8= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, jolsa@kernel.org, eddyz87@gmail.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next 1/2] bpf, x64: Propagate tailcall info only for tail_call_reachable subprogs Date: Mon, 21 Oct 2024 21:39:28 +0800 Message-ID: <20241021133929.67782-2-leon.hwang@linux.dev> In-Reply-To: <20241021133929.67782-1-leon.hwang@linux.dev> References: <20241021133929.67782-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net In the x86_64 JIT, when calling a function, tailcall info is propagated if the program is tail_call_reachable, regardless of whether the function is a subprog, helper, or kfunc. However, this propagation is unnecessary for not-tail_call_reachable subprogs, helpers, or kfuncs. The verifier can determine if a subprog is tail_call_reachable. Therefore, it can be optimized to only propagate tailcall info when the callee is subprog and the subprog is actually tail_call_reachable. Signed-off-by: Leon Hwang --- arch/x86/net/bpf_jit_comp.c | 4 +++- kernel/bpf/verifier.c | 6 ++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 06b080b61aa57..6ad6886ecfc88 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2124,10 +2124,12 @@ st: if (is_imm8(insn->off)) /* call */ case BPF_JMP | BPF_CALL: { + bool pseudo_call = src_reg == BPF_PSEUDO_CALL; + bool subprog_tail_call_reachable = dst_reg; u8 *ip = image + addrs[i - 1]; func = (u8 *) __bpf_call_base + imm32; - if (tail_call_reachable) { + if (pseudo_call && subprog_tail_call_reachable) { LOAD_TAIL_CALL_CNT_PTR(bpf_prog->aux->stack_depth); ip += 7; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f514247ba8ba8..6e7e42c7bc7b1 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19990,6 +19990,12 @@ static int jit_subprogs(struct bpf_verifier_env *env) insn[0].imm = (u32)addr; insn[1].imm = addr >> 32; } + + if (bpf_pseudo_call(insn)) + /* In the x86_64 JIT, tailcall information can only be + * propagated if the subprog is tail_call_reachable. + */ + insn->dst_reg = env->subprog_info[subprog].tail_call_reachable; } err = bpf_prog_alloc_jited_linfo(prog); From patchwork Mon Oct 21 13:39:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13844165 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (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 A8D351F9418 for ; Mon, 21 Oct 2024 13:39:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729517986; cv=none; b=N7MdWkH+k9Nn0KJCW4M+dt+AX6AoToBz4+3423pqglTpfsO4E0+NLbde5Nh2/6MIIAVQndsd8y1Jgv3yIouTWPVOVV8FwIB+7uIQoNeknKu9kbgrSzXi57XThD1MiNpVcR97IA6T9UMYqyNeIzr2VaPFKo2AmTy4djeJSV9d0yE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729517986; c=relaxed/simple; bh=H2A1+JYWKknofAA4jRCsvWtKXIjXKWUD6kTdfZtv0Cg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jbcnYcGvfq+LxilBWonhB135wpaXl5KoMbSrrOnzSSjizKZ99Ncv5iBeI3TjRHxXawXR4Zvv0u7wn0JtuVY1Y0UAQZ4ClS7a16XGWpDY3+iiWQZv/Eg8RvmcLJPWE4+JD0lQVWgms+akf7aMrrG0UVmCCnYAw10iZAI8DnNzAOM= 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=gjt8jVAz; arc=none smtp.client-ip=95.215.58.181 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="gjt8jVAz" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1729517982; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PgLLvH0slcXFg5B1Nm6mKktt/JEYcQ52/xEyV27bsLg=; b=gjt8jVAzBxKRQSjHUsCV3GihIxXd8E4SMO7PDfESpxHlg98+ZG5dw0xTSZ0XBjUyKlG431 HZ5v0MFrXnvA8Xh80xmH3O+7PYRquTUqXCVYgsCbxQkZkp/IT4PHOSO+9vjTJI0M7zYcUE RKgdEcVsHKCvF1H8t7/ZerZSCLlc3PU= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, jolsa@kernel.org, eddyz87@gmail.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next 2/2] bpf, verifier: Check trampoline target is tail_call_reachable subprog Date: Mon, 21 Oct 2024 21:39:29 +0800 Message-ID: <20241021133929.67782-3-leon.hwang@linux.dev> In-Reply-To: <20241021133929.67782-1-leon.hwang@linux.dev> References: <20241021133929.67782-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net In the x86_64 JIT, tailcall info is propagated through the trampoline when the target program is tail_call_reachable. However, this propagation is unnecessary if the target is a main prog, or a subprog that is not tail_call_reachable. Since the verifier can determine if a subprog is tail_call_reachable, it should only propagate tailcall info when the target is subprog and the subprog is actually tail_call_reachable. Signed-off-by: Leon Hwang --- include/linux/bpf.h | 1 + kernel/bpf/verifier.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0c216e71cec76..32b56a759d788 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1220,6 +1220,7 @@ struct bpf_attach_target_info { struct module *tgt_mod; const char *tgt_name; const struct btf_type *tgt_type; + bool tgt_tail_call_reachable; }; #define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6e7e42c7bc7b1..9a09621a8832c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -21916,6 +21916,8 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, bpf_log(log, "Subprog %s doesn't exist\n", tname); return -EINVAL; } + tgt_info->tgt_tail_call_reachable = subprog && + aux->func[subprog]->aux->tail_call_reachable; if (aux->func && aux->func[subprog]->aux->exception_cb) { bpf_log(log, "%s programs cannot attach to exception callback\n", @@ -22285,7 +22287,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) if (!tr) return -ENOMEM; - if (tgt_prog && tgt_prog->aux->tail_call_reachable) + if (tgt_prog && tgt_info.tgt_tail_call_reachable) tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX; prog->aux->dst_trampoline = tr;