From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) (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 2993023A984 for ; Mon, 29 Dec 2025 19:58:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767038289; cv=none; b=Za8JlNf39Dlg684RQNAp30n0hlqflQiS5HsfiMo6ijjlPnXGJpnT0YzPWwiNJlHghhVcNzv/C95WL2NzpEAEg35mRYGAkASNO+avuabJZ4leP3Sv5DKPmOS4Zfwf0Nf9HopUvKnRz34HHLbx25dPKpCKGKx5hYMuvdE/eCQICjM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767038289; c=relaxed/simple; bh=ILOnzjB6omPzsTjFaR5p7kIAmLgY60kDToG8kB6uAvw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=dwWK/EbM2zo1gcpaTyth5PCPS2k5aSN5/NqgMwWCgfWBlFeG8ikHhpcJevCfogbO+rdX/DWFCLbBZg/IlsvAWNmy3l5RsGxD+wnvgqHpdGAmTfh5/8DBZghXE8JICg6EFUBX6wlonnGS95yjredbJQcKVqzeGFcS9M/W2r7JqQk= 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=ZYThaZjB; arc=none smtp.client-ip=209.85.210.179 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="ZYThaZjB" Received: by mail-pf1-f179.google.com with SMTP id d2e1a72fcca58-803474aaa8bso3236519b3a.0 for ; Mon, 29 Dec 2025 11:58:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1767038286; x=1767643086; darn=vger.kernel.org; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:from:to:cc:subject :date:message-id:reply-to; bh=Xko4XQ8K4/4/p+5qf10V0z8LE3R9sFv1la/WwKpKg8w=; b=ZYThaZjBxgHPLg/ru2oZZkkkGV9I+IQ40v7BeSRjUsjFg8NWfReiJwLQlrKmnUqHLA rvkVXYMB6uxFjEseJU4LblqV3xz3tL12y51GumsjIc6cyS6zleoKH96pr/Tu3MCKuh6z 1dkPwxdpY+D6+VQ7nF03YfwSISSL9p0H/3y7TtvjKIMmnjgr5ZS7B38Ulg/fPpmOCF/C mzs007TEjxUXjZWR40SZsreLbn7Jhf2pb0ZW/kFXs1QmTYbCo3paFgYLhanP+ceAWCdo Ud7A7P4dtNPgw8WyCtxZZmpBMyv54oRfhGuAZ+FKsKVJkhdrbHIGLMTgVMUxRxwk+/qG 7PcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767038286; x=1767643086; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Xko4XQ8K4/4/p+5qf10V0z8LE3R9sFv1la/WwKpKg8w=; b=wdz7uhjfsJ5wrwD1eO7YvJs26ACZWt/EQvPexlD0NeEkX0OoPx5PzZe4qbwntsKfJT i9Kg1Ok0pc/5zWFbILl1B2U8NZSOHdJWprfHkvXLqzJKSPZz0PfjibPkTxZsBQYOa5D1 KwsbTFyvOfPK7k0U/8McZtvGMEsMXIjXUrHtF+oKggEHTZHSAmPbp/P+x1WqGh0HR0sM 57AzKDoOoQ7z5CiHNmJpCeSzUmQNjqXUd6D0pKwl+b/CBqiVR2Bk1w61F7+KkyX2M8hy 6q9QVlBvaTTY+dZ/In/++yFuDAZwfICnfDCiYGxeIKDtCWh76e1dNRH8lBQSpTHWDIjy +jbg== X-Forwarded-Encrypted: i=1; AJvYcCVRpTImV/0nvzPvj+arAuz8TJy4rgma4N+8jT+3uAyKNY2wp1NJVXWcqJNIDFX2VApr5Skm3GI=@vger.kernel.org X-Gm-Message-State: AOJu0YxVPTvkzLJHXoKMikEIrMEpKvC7qQqCZ8agh4mGID3DVx7wbYTQ L/U0+hC0Tp2nTdhnRfwl7/Qeh9rkslsID+D+WbPX+CC3WsbC+5MqzlWh X-Gm-Gg: AY/fxX6iWYw6TDo/e+jfM2qLPpK5l/mvvPM77XFj9or1JkvqdaTVv8XRl/tJ1ZI28ba oFunmhX4MWts36nnbxpQLqkFSjXTBcawLWS7oex+RR2IK99l88AkqmPLgnasOgU+o6/VsXXbyTw CAplTJr6DjDnngTmkzVlRfWiPPgNwwIuLy+01UO8VuKkQyJrBgmJTDzx8omH0SGyC7OmvKzDu9C soKvibkhLswNvSEzEdTRYZFCDXDnoBdP/zOuHvxTpRKLQKMxOaUnNwUDPqEeOZbIhBhOPlPtRMO IW6Syar/QN8bSTI61+Y4wTmnZ0zAh+owCKZ7/873Gw9SzmybmjqWsXMZeaNBERJYWM4BmusP5on A61qKLn3dc1FHLjlEJJSnooOQ9FwuRS8zqm2yrZiYHZmJnoaGu3Hk+VtZDVX8H8gbm2jtgC83wY 7fVOmzfuLiK8j8qOtiEk4npGCtj4zaautV8X1rbY6Q9fXetoY= X-Google-Smtp-Source: AGHT+IFClYfhXcvzYGUEAeGNRFFMkUwqOYUjfX2LyOlUE6PEoi9FZ13hia7PJghTWywP+YG21UqZAQ== X-Received: by 2002:a05:6a20:7f81:b0:366:14b0:4b1c with SMTP id adf61e73a8af0-3769ff1c33fmr28383151637.39.1767038286311; Mon, 29 Dec 2025 11:58:06 -0800 (PST) Received: from ?IPv6:2a03:83e0:115c:1:ac6b:d5ad:83fe:6cca? ([2620:10d:c090:500::2:1bc9]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7ff7dfac28fsm30215140b3a.32.2025.12.29.11.58.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Dec 2025 11:58:06 -0800 (PST) Message-ID: <0f0bd124a42723acf87b427cc69356a0e4b1e339.camel@gmail.com> Subject: Re: [PATCH bpf-next] bpf, x86: inline bpf_get_current_task() for x86_64 From: Eduard Zingerman To: Menglong Dong , ast@kernel.org Cc: davem@davemloft.net, dsahern@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, jiang.biao@linux.dev, x86@kernel.org, hpa@zytor.com, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 29 Dec 2025 11:58:03 -0800 In-Reply-To: <20251225104459.204104-1-dongml2@chinatelecom.cn> References: <20251225104459.204104-1-dongml2@chinatelecom.cn> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2025-12-25 at 18:44 +0800, Menglong Dong wrote: > Inline bpf_get_current_task() and bpf_get_current_task_btf() for x86_64 > to obtain better performance. The instruction we use here is: >=20 > 65 48 8B 04 25 [offset] // mov rax, gs:[offset] >=20 > Not sure if there is any side effect here. >=20 > Signed-off-by: Menglong Dong > --- The change makes sense to me. Could you please address the compilation error reported by kernel test robo= t? Could you please also add a tests case using __jited annotation like in verifier_ldsx.c? > arch/x86/net/bpf_jit_comp.c | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) >=20 > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c > index b69dc7194e2c..7f38481816f0 100644 > --- a/arch/x86/net/bpf_jit_comp.c > +++ b/arch/x86/net/bpf_jit_comp.c > @@ -1300,6 +1300,19 @@ static void emit_st_r12(u8 **pprog, u32 size, u32 = dst_reg, int off, int imm) > emit_st_index(pprog, size, dst_reg, X86_REG_R12, off, imm); > } > =20 > +static void emit_ldx_percpu_r0(u8 **pprog, const void __percpu *ptr) > +{ > + u8 *prog =3D *pprog; > + > + /* mov rax, gs:[offset] */ > + EMIT2(0x65, 0x48); > + EMIT2(0x8B, 0x04); > + EMIT1(0x25); > + EMIT((u32)(unsigned long)ptr, 4); > + > + *pprog =3D prog; > +} > + > static int emit_atomic_rmw(u8 **pprog, u32 atomic_op, > u32 dst_reg, u32 src_reg, s16 off, u8 bpf_size) > { > @@ -2435,6 +2448,15 @@ st: if (is_imm8(insn->off)) > case BPF_JMP | BPF_CALL: { > u8 *ip =3D image + addrs[i - 1]; > =20 > + if (insn->src_reg =3D=3D 0 && (insn->imm =3D=3D BPF_FUNC_get_current_= task || > + insn->imm =3D=3D BPF_FUNC_get_current_task_btf)) { > + if (IS_ENABLED(CONFIG_USE_X86_SEG_SUPPORT)) > + emit_ldx_percpu_r0(&prog, &const_current_task); > + else > + emit_ldx_percpu_r0(&prog, ¤t_task); Nit: arch/x86/include/asm/current.h says that current_task and const_curren= t_task are aliases. In that case, why would we need two branches here? > + break; > + } > + > func =3D (u8 *) __bpf_call_base + imm32; > if (src_reg =3D=3D BPF_PSEUDO_CALL && tail_call_reachable) { > LOAD_TAIL_CALL_CNT_PTR(stack_depth); > @@ -4067,3 +4089,14 @@ bool bpf_jit_supports_timed_may_goto(void) > { > return true; > } > + > +bool bpf_jit_inlines_helper_call(s32 imm) > +{ > + switch (imm) { > + case BPF_FUNC_get_current_task: > + case BPF_FUNC_get_current_task_btf: > + return true; > + default: > + return false; > + } > +}