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Mon, 2 Mar 2020 16:22:14 +0000 Subject: Re: [PATCH v2 bpf-next 1/3] bpf: switch BPF UAPI #define constants to enums To: Andrii Nakryiko , , , , CC: , References: <20200301062405.2850114-1-andriin@fb.com> <20200301062405.2850114-2-andriin@fb.com> From: Yonghong Song Message-ID: Date: Mon, 2 Mar 2020 08:22:11 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 In-Reply-To: <20200301062405.2850114-2-andriin@fb.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MWHPR11CA0003.namprd11.prod.outlook.com (2603:10b6:301:1::13) To DM6PR15MB3001.namprd15.prod.outlook.com (2603:10b6:5:13c::16) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from macbook-pro-52.dhcp.thefacebook.com (2620:10d:c090:500::6:87b3) by MWHPR11CA0003.namprd11.prod.outlook.com (2603:10b6:301:1::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2772.14 via Frontend Transport; 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X-Microsoft-Antispam-Message-Info: eKY51mVM5D8qf/NevavaTbaQi2xl2kSAcpfxk2wUvCUubQv8UD4E7UV1JuI6w5L5yy8sWM4Gr7juuZ6X/+1Cbi7cH3nnY9j6swTS7MrtXwtpZFFOwAwEQ+FLIBLuqpM7rFoWHsTUSFy8Emq+MBDaANeysFNh/zKVVfGnJv+JMejGhoNP8gv0ntYA1u84EWaBGQHXY1v/lSSCWyQFp3l8fA4SsnsrNWjbDzvC59E2W1n+iSqWzs1JQThD/DmKMA/3IzesaGSoabo+YiK+yBDnRy2L9O9txBxYCGOxH6JJCe/EaGrvlTjJAUEXl12m5hhfpfj78dVN/UG69Vhc1vptuDd+mezLvInsColKgppc35iRiUgHu8c3gjXcUKWsX7RdeYu4vFYn4b5tIgKYM18yAVb0WqWFEDITogkXWVEKjwndQRevvEJw8MS3nfy1MP6+ X-MS-Exchange-AntiSpam-MessageData: ii/JXAlIlUSM57MS8WggCjQW1iXxxxF+FU2aV3RkI4071RVtx6EgGzPaQsJau7euQAGrMw1+PAUhkC0FLSvraeKOblTw0uGkY/rSeu5eOIeIK9GnTiDKm7aFFxlYLZwMu+hPGsnBJzjOx8TFQKulumO7jlNdtSwMqgOgg4QDoWyyRSmHIMo9gszltYhcn28r X-MS-Exchange-CrossTenant-Network-Message-Id: d94c60d1-cc0b-4a7c-50a8-08d7bec5de24 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Mar 2020 16:22:14.3069 (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: 1B2oJ1lUBnugevDv7fWXnGHmgbemz9O1qv3hkKbBXAWe9Xv+K++FRt5QgoZA4YlG X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR15MB3338 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-03-02_06:2020-03-02,2020-03-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 clxscore=1015 lowpriorityscore=0 priorityscore=1501 suspectscore=0 spamscore=0 malwarescore=0 impostorscore=0 mlxlogscore=999 bulkscore=0 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003020113 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 2/29/20 10:24 PM, Andrii Nakryiko wrote: > Switch BPF UAPI constants, previously defined as #define macro, to anonymous > enum values. This preserves constants values and behavior in expressions, but > has added advantaged of being captured as part of DWARF and, subsequently, BTF > type info. Which, in turn, greatly improves usefulness of generated vmlinux.h > for BPF applications, as it will not require BPF users to copy/paste various > flags and constants, which are frequently used with BPF helpers. > > Signed-off-by: Andrii Nakryiko > --- > include/uapi/linux/bpf.h | 272 +++++++++++++++---------- > include/uapi/linux/bpf_common.h | 86 ++++---- > include/uapi/linux/btf.h | 60 +++--- > tools/include/uapi/linux/bpf.h | 274 ++++++++++++++++---------- > tools/include/uapi/linux/bpf_common.h | 86 ++++---- > tools/include/uapi/linux/btf.h | 60 +++--- > 6 files changed, 497 insertions(+), 341 deletions(-) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 8e98ced0963b..03e08f256bd1 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -14,34 +14,36 @@ > /* Extended instruction set based on top of classic BPF */ > > /* instruction classes */ > -#define BPF_JMP32 0x06 /* jmp mode in word width */ > -#define BPF_ALU64 0x07 /* alu mode in double word width */ > +enum { > + BPF_JMP32 = 0x06, /* jmp mode in word width */ > + BPF_ALU64 = 0x07, /* alu mode in double word width */ Not sure whether we have uapi backward compatibility or not. One possibility is to add #define BPF_ALU64 BPF_ALU64 this way, people uses macros will continue to work. If this is an acceptable solution, we have a lot of constants in net related headers and will benefit from this conversion for kprobe/tracepoint of networking related functions. > > /* ld/ldx fields */ > -#define BPF_DW 0x18 /* double word (64-bit) */ > -#define BPF_XADD 0xc0 /* exclusive add */ > + BPF_DW = 0x18, /* double word (64-bit) */ > + BPF_XADD = 0xc0, /* exclusive add */ > > /* alu/jmp fields */ > -#define BPF_MOV 0xb0 /* mov reg to reg */ > -#define BPF_ARSH 0xc0 /* sign extending arithmetic shift right */ > + BPF_MOV = 0xb0, /* mov reg to reg */ > + BPF_ARSH = 0xc0, /* sign extending arithmetic shift right */ > > /* change endianness of a register */ > -#define BPF_END 0xd0 /* flags for endianness conversion: */ > -#define BPF_TO_LE 0x00 /* convert to little-endian */ > -#define BPF_TO_BE 0x08 /* convert to big-endian */ > -#define BPF_FROM_LE BPF_TO_LE > -#define BPF_FROM_BE BPF_TO_BE > + BPF_END = 0xd0, /* flags for endianness conversion: */ > + BPF_TO_LE = 0x00, /* convert to little-endian */ > + BPF_TO_BE = 0x08, /* convert to big-endian */ > + BPF_FROM_LE = BPF_TO_LE, > + BPF_FROM_BE = BPF_TO_BE, > > /* jmp encodings */ > -#define BPF_JNE 0x50 /* jump != */ > -#define BPF_JLT 0xa0 /* LT is unsigned, '<' */ > -#define BPF_JLE 0xb0 /* LE is unsigned, '<=' */ > -#define BPF_JSGT 0x60 /* SGT is signed '>', GT in x86 */ > -#define BPF_JSGE 0x70 /* SGE is signed '>=', GE in x86 */ > -#define BPF_JSLT 0xc0 /* SLT is signed, '<' */ > -#define BPF_JSLE 0xd0 /* SLE is signed, '<=' */ > -#define BPF_CALL 0x80 /* function call */ > -#define BPF_EXIT 0x90 /* function return */ > + BPF_JNE = 0x50, /* jump != */ > + BPF_JLT = 0xa0, /* LT is unsigned, '<' */ > + BPF_JLE = 0xb0, /* LE is unsigned, '<=' */ > + BPF_JSGT = 0x60, /* SGT is signed '>', GT in x86 */ > + BPF_JSGE = 0x70, /* SGE is signed '>=', GE in x86 */ > + BPF_JSLT = 0xc0, /* SLT is signed, '<' */ > + BPF_JSLE = 0xd0, /* SLE is signed, '<=' */ > + BPF_CALL = 0x80, /* function call */ > + BPF_EXIT = 0x90, /* function return */ > +}; > [...]