From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout01.his.huawei.com (canpmsgout01.his.huawei.com [113.46.200.216]) (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 E5C13231832; Sat, 20 Dec 2025 02:59:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.216 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766199554; cv=none; b=PH0HzX+pUJC4pgwsvbYkZi6mDLOuOFxYFhDYtp/VTVFCofW0cBAB9ELHXMx+tzdkTFqoHQkKEIFHXFgz1vSEnUclLUkQfjLt9FDRbcs+lTpON/ug70YmXK+pnh2r3A6cZpFvRhSiIptBUhC9we8Hr6NgTX3oGVHtzZZGxQ3h0Jw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766199554; c=relaxed/simple; bh=J28oNl2NCk1XOkNnQCLnHSufhgUKpqlnU8Zixuti/VQ=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=T70elAr5TWo+r4C7niapww8ex8PPq76dwnSjzMJfL0Cr+9HNMAI3rGP2hA/JoVL00aS3XKBJ41fnY4QuTTvmwZqSgmm+ylpPDM3pT4UzGRqbGkkqW2uATmCr2r5SCuRQhQoLvraJjLxIKuNLaR7fjUmuS8vgGibtmzDFjeaGU1c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=j21JweUC; arc=none smtp.client-ip=113.46.200.216 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="j21JweUC" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=EpoQBSY67OhCanzVgZjorTnzYdt3NJZkBJh3zM1mpp8=; b=j21JweUC5ESmLGgsK0TPWA/tth8ojUddCNMdrk1uSnsDcKHygAwVt005gstkJX3WwaI3v+8lK oD9rFsnImjAnrmaHoq7QJ/g15R4bEFlDZSWOz25sQCXTFXP+6Kmo0BgTX9/T9pZZDjETOKV9aAo sLHqTtuXSAwJv0sVuwxZdP8= Received: from mail.maildlp.com (unknown [172.19.162.197]) by canpmsgout01.his.huawei.com (SkyGuard) with ESMTPS id 4dY8FG1xtpz1T4GK; Sat, 20 Dec 2025 10:56:50 +0800 (CST) Received: from kwepemf100007.china.huawei.com (unknown [7.202.181.221]) by mail.maildlp.com (Postfix) with ESMTPS id 3FC2840569; Sat, 20 Dec 2025 10:59:06 +0800 (CST) Received: from [10.67.108.204] (10.67.108.204) by kwepemf100007.china.huawei.com (7.202.181.221) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.36; Sat, 20 Dec 2025 10:59:05 +0800 Message-ID: <33977244-1266-4590-af38-e3be3e46d7f4@huawei.com> Date: Sat, 20 Dec 2025 10:59:04 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf v2] riscv, bpf: fix incorrect usage of BPF_TRAMP_F_ORIG_STACK Content-Language: en-US To: Menglong Dong , , CC: , , , , , , , , , , , , , , , , , , , References: <20251219142948.204312-1-dongml2@chinatelecom.cn> From: Pu Lehui In-Reply-To: <20251219142948.204312-1-dongml2@chinatelecom.cn> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To kwepemf100007.china.huawei.com (7.202.181.221) On 2025/12/19 22:29, Menglong Dong wrote: > The usage of BPF_TRAMP_F_ORIG_STACK in __arch_prepare_bpf_trampoline() is > wrong, and it should be BPF_TRAMP_F_CALL_ORIG, which caused crash as > Andreas reported: > > Insufficient stack space to handle exception! > Task stack: [0xff20000000010000..0xff20000000014000] > Overflow stack: [0xff600000ffdad070..0xff600000ffdae070] > CPU: 1 UID: 0 PID: 1 Comm: systemd Not tainted 6.18.0-rc5+ #15 PREEMPT(voluntary) > Hardware name: riscv-virtio qemu/qemu, BIOS 2025.10 10/01/2025 > epc : copy_from_kernel_nofault+0xa/0x198 > ra : bpf_probe_read_kernel+0x20/0x60 > epc : ffffffff802b732a ra : ffffffff801e6070 sp : ff2000000000ffe0 > gp : ffffffff82262ed0 tp : 0000000000000000 t0 : ffffffff80022320 > t1 : ffffffff801e6056 t2 : 0000000000000000 s0 : ff20000000010040 > s1 : 0000000000000008 a0 : ff20000000010050 a1 : ff60000083b3d320 > a2 : 0000000000000008 a3 : 0000000000000097 a4 : 0000000000000000 > a5 : 0000000000000000 a6 : 0000000000000021 a7 : 0000000000000003 > s2 : ff20000000010050 s3 : ff6000008459fc18 s4 : ff60000083b3d340 > s5 : ff20000000010060 s6 : 0000000000000000 s7 : ff20000000013aa8 > s8 : 0000000000000000 s9 : 0000000000008000 s10: 000000000058dcb0 > s11: 000000000058dca7 t3 : 000000006925116d t4 : ff6000008090f026 > t5 : 00007fff9b0cbaa8 t6 : 0000000000000016 > status: 0000000200000120 badaddr: 0000000000000000 cause: 8000000000000005 > Kernel panic - not syncing: Kernel stack overflow > CPU: 1 UID: 0 PID: 1 Comm: systemd Not tainted 6.18.0-rc5+ #15 PREEMPT(voluntary) > Hardware name: riscv-virtio qemu/qemu, BIOS 2025.10 10/01/2025 > Call Trace: > [] dump_backtrace+0x28/0x38 > [] show_stack+0x3a/0x50 > [] dump_stack_lvl+0x56/0x80 > [] dump_stack+0x18/0x22 > [] vpanic+0xf6/0x328 > [] panic+0x3e/0x40 > [] handle_bad_stack+0x98/0xa0 > [] bpf_probe_read_kernel+0x20/0x60 > > Just fix it. > > Fixes: 47c9214dcbea ("bpf: fix the usage of BPF_TRAMP_F_SKIP_FRAME") > Reported-by: Andreas Schwab > Closes: https://lore.kernel.org/bpf/874ipnkfvt.fsf@igel.home/ > Signed-off-by: Menglong Dong > --- > v2: > - merge the code > --- > arch/riscv/net/bpf_jit_comp64.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c > index 5f9457e910e8..37888abee70c 100644 > --- a/arch/riscv/net/bpf_jit_comp64.c > +++ b/arch/riscv/net/bpf_jit_comp64.c > @@ -1133,10 +1133,6 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, > > store_args(nr_arg_slots, args_off, ctx); > > - /* skip to actual body of traced function */ > - if (flags & BPF_TRAMP_F_ORIG_STACK) Oh, how did this weird flags get in here... > - orig_call += RV_FENTRY_NINSNS * 4; > - > if (flags & BPF_TRAMP_F_CALL_ORIG) { > emit_imm(RV_REG_A0, ctx->insns ? (const s64)im : RV_MAX_COUNT_IMM, ctx); > ret = emit_call((const u64)__bpf_tramp_enter, true, ctx); > @@ -1171,6 +1167,8 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, > } > > if (flags & BPF_TRAMP_F_CALL_ORIG) { > + /* skip to actual body of traced function */ > + orig_call += RV_FENTRY_NINSNS * 4; LGTM, let's revert it. Reviewed-by: Pu Lehui > restore_args(min_t(int, nr_arg_slots, RV_MAX_REG_ARGS), args_off, ctx); > restore_stack_args(nr_arg_slots - RV_MAX_REG_ARGS, args_off, stk_arg_off, ctx); > ret = emit_call((const u64)orig_call, true, ctx);