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Fri, 10 Apr 2020 06:12:25 +0000 Subject: Re: [RFC PATCH bpf-next 09/16] bpf: add bpf_seq_printf and bpf_seq_write helpers To: Alexei Starovoitov CC: Andrii Nakryiko , , Martin KaFai Lau , , Alexei Starovoitov , Daniel Borkmann , References: <20200408232520.2675265-1-yhs@fb.com> <20200408232531.2676134-1-yhs@fb.com> <20200410032608.x5hloyizpfyxnudz@ast-mbp.dhcp.thefacebook.com> From: Yonghong Song Message-ID: <6dbe9918-0f6c-6b48-aa0c-f057deb18b0f@fb.com> Date: Thu, 9 Apr 2020 23:12:22 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 In-Reply-To: <20200410032608.x5hloyizpfyxnudz@ast-mbp.dhcp.thefacebook.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: CO2PR06CA0064.namprd06.prod.outlook.com (2603:10b6:104:3::22) To MW3PR15MB3883.namprd15.prod.outlook.com (2603:10b6:303:51::22) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from rutu-mbp.dhcp.thefacebook.com (2620:10d:c090:400::5:75b7) by CO2PR06CA0064.namprd06.prod.outlook.com (2603:10b6:104:3::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2900.17 via Frontend Transport; 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X-Microsoft-Antispam-Message-Info: KTrzrY41UlmYqyQXbZcJGKn1K087xA6l1G1BAzg8MEo3R3f/mRvTvHjqAa6G0k01gFdRiW5EdbP6ockFnh3nYAMhmHcp5MK79APFUSHrj90lMKb/boru9cJWvTH6ogJ1cRn7KWVv91J1jDp6VYMARmcPzxHsVDMhaiUugm7UbafBOpzBqt7BDS1VITSvbb9wM66IqJkgTZaDI5wMXyR4lfWDuEb56GiWI6TZ4E/41SUWO6HGUQn4XrV+yL3pKA+rWP0srU8E2exvjYenwElvUxk/aTWlMpmeIg1fNGEl8tzyv+IwU6jCv8a8KHbjXl3Ypcj00xcNJ5/GiAF7l0cf/kXKWEhYd9W1XNavQ4OjLZzhlglcJCEUHgPa/KbAA82Mh+Awm9K4lIJ8qmc6Z3BKmKiFZnetvMQXHytMKvRPto392y+UY6fZ74Jm2IrqBXVS X-MS-Exchange-AntiSpam-MessageData: KEcCHeGcbDNAsJNFnJixSYJHdSwOiYbjWG/bywhJBCaeJHMCHhy1lrVAWw0pqaMuJ8TgW5BWlieMAtHENoOGxUUCxak18PNz65AXqyw84GRcvz+PedEcTI1nqd/7VDqnqSdRfnoiD+jJl63uqiQ07s0XpmS49xfEou6CFg/RVhz/gdM6QvmXbtV9wz+MxXgp X-MS-Exchange-CrossTenant-Network-Message-Id: ebf74855-0267-4bbf-bd21-08d7dd16234a X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Apr 2020 06:12:24.9813 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: +qadJlbtu81Wvp2+ld8Ygsv+oTX6ra9NUjD9qqXTzquQbwviTN222L1+ZVTeytOi X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW3PR15MB3977 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-10_01:2020-04-07,2020-04-10 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 phishscore=0 mlxscore=0 priorityscore=1501 malwarescore=0 suspectscore=0 adultscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 clxscore=1015 mlxlogscore=999 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004100052 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 4/9/20 8:26 PM, Alexei Starovoitov wrote: > On Wed, Apr 08, 2020 at 04:25:31PM -0700, Yonghong Song wrote: >> >> +BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, u64, arg1, >> + u64, arg2) >> +{ >> + bool buf_used = false; >> + int i, copy_size; >> + int mod[2] = {}; >> + int fmt_cnt = 0; >> + u64 unsafe_addr; >> + char buf[64]; >> + >> + /* >> + * bpf_check()->check_func_arg()->check_stack_boundary() >> + * guarantees that fmt points to bpf program stack, >> + * fmt_size bytes of it were initialized and fmt_size > 0 >> + */ >> + if (fmt[--fmt_size] != 0) >> + return -EINVAL; > ... >> +/* Horrid workaround for getting va_list handling working with different >> + * argument type combinations generically for 32 and 64 bit archs. >> + */ >> +#define __BPF_SP_EMIT() __BPF_ARG2_SP() >> +#define __BPF_SP(...) \ >> + seq_printf(m, fmt, ##__VA_ARGS__) >> + >> +#define __BPF_ARG1_SP(...) \ >> + ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \ >> + ? __BPF_SP(arg1, ##__VA_ARGS__) \ >> + : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \ >> + ? __BPF_SP((long)arg1, ##__VA_ARGS__) \ >> + : __BPF_SP((u32)arg1, ##__VA_ARGS__))) >> + >> +#define __BPF_ARG2_SP(...) \ >> + ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \ >> + ? __BPF_ARG1_SP(arg2, ##__VA_ARGS__) \ >> + : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \ >> + ? __BPF_ARG1_SP((long)arg2, ##__VA_ARGS__) \ >> + : __BPF_ARG1_SP((u32)arg2, ##__VA_ARGS__))) >> + >> + __BPF_SP_EMIT(); >> + return seq_has_overflowed(m); >> +} > > This function is mostly a copy-paste of bpf_trace_printk() with difference > of printing via seq_printf vs __trace_printk. > Please find a way to share the code. Will do.