From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85304C433E1 for ; Thu, 14 May 2020 23:43:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5FE242065C for ; Thu, 14 May 2020 23:43:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728510AbgENXnb (ORCPT ); Thu, 14 May 2020 19:43:31 -0400 Received: from smtprelay0252.hostedemail.com ([216.40.44.252]:36744 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728415AbgENXna (ORCPT ); Thu, 14 May 2020 19:43:30 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay05.hostedemail.com (Postfix) with ESMTP id 5EDA418029D8F; Thu, 14 May 2020 23:43:28 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: face85_754dbffefb147 X-Filterd-Recvd-Size: 8593 Received: from XPS-9350.home (unknown [47.151.136.130]) (Authenticated sender: joe@perches.com) by omf14.hostedemail.com (Postfix) with ESMTPA; Thu, 14 May 2020 23:43:25 +0000 (UTC) Message-ID: <28145b05ee792b89ab9cb560f4f9989fd3d5d93b.camel@perches.com> Subject: Re: [PATCH v2 bpf-next 4/7] printk: add type-printing %pT format specifier which uses BTF From: Joe Perches To: Alexei Starovoitov Cc: Alan Maguire , Alexei Starovoitov , Daniel Borkmann , bpf , Rasmus Villemoes , Arnaldo Carvalho de Melo , Yonghong Song , Martin KaFai Lau , Song Liu , Andrii Nakryiko , John Fastabend , KP Singh , LKML , Network Development Date: Thu, 14 May 2020 16:43:24 -0700 In-Reply-To: <397fb29abb20d11003a18919ee0c44918fc1a165.camel@perches.com> References: <1589263005-7887-1-git-send-email-alan.maguire@oracle.com> <1589263005-7887-5-git-send-email-alan.maguire@oracle.com> <1b63a6b193073674b6e0f9f95c62ce2af1b977cc.camel@perches.com> <397fb29abb20d11003a18919ee0c44918fc1a165.camel@perches.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.36.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2020-05-13 at 16:22 -0700, Joe Perches wrote: > On Wed, 2020-05-13 at 16:07 -0700, Alexei Starovoitov wrote: > > On Wed, May 13, 2020 at 4:05 PM Joe Perches wrote: > > > On Tue, 2020-05-12 at 06:56 +0100, Alan Maguire wrote: > > > > printk supports multiple pointer object type specifiers (printing > > > > netdev features etc). Extend this support using BTF to cover > > > > arbitrary types. "%pT" specifies the typed format, and the pointer > > > > argument is a "struct btf_ptr *" where struct btf_ptr is as follows: > > > > > > > > struct btf_ptr { > > > > void *ptr; > > > > const char *type; > > > > u32 id; > > > > }; > > > > > > > > Either the "type" string ("struct sk_buff") or the BTF "id" can be > > > > used to identify the type to use in displaying the associated "ptr" > > > > value. A convenience function to create and point at the struct > > > > is provided: > > > > > > > > printk(KERN_INFO "%pT", BTF_PTR_TYPE(skb, struct sk_buff)); > > > > > > > > When invoked, BTF information is used to traverse the sk_buff * > > > > and display it. Support is present for structs, unions, enums, > > > > typedefs and core types (though in the latter case there's not > > > > much value in using this feature of course). > > > > > > > > Default output is indented, but compact output can be specified > > > > via the 'c' option. Type names/member values can be suppressed > > > > using the 'N' option. Zero values are not displayed by default > > > > but can be using the '0' option. Pointer values are obfuscated > > > > unless the 'x' option is specified. As an example: > > > > > > > > struct sk_buff *skb = alloc_skb(64, GFP_KERNEL); > > > > pr_info("%pT", BTF_PTR_TYPE(skb, struct sk_buff)); > > > > > > > > ...gives us: > > > > > > > > (struct sk_buff){ > > > > .transport_header = (__u16)65535, > > > > .mac_header = (__u16)65535, > > > > .end = (sk_buff_data_t)192, > > > > .head = (unsigned char *)000000006b71155a, > > > > .data = (unsigned char *)000000006b71155a, > > > > .truesize = (unsigned int)768, > > > > .users = (refcount_t){ > > > > .refs = (atomic_t){ > > > > .counter = (int)1, > > > > > > Given > > > > > > #define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24) > > > > > > Maybe > > > > > > #define BTF_INT_SIGNED (1 << 0) > > > #define BTF_INT_CHAR (1 << 1) > > > #define BTF_INT_BOOL (1 << 2) > > > > > > could be extended to include > > > > > > #define BTF_INT_HEX (1 << 3) > > > > > > So hex values can be appropriately pretty-printed. > > > > Nack to that. > > why? > Tell me what's wrong with the idea. Here's a possible implementation: --- Documentation/bpf/btf.rst | 5 +++-- include/uapi/linux/btf.h | 1 + kernel/bpf/btf.c | 5 ++++- tools/bpf/bpftool/btf.c | 2 ++ tools/bpf/bpftool/btf_dumper.c | 13 +++++++++++++ tools/include/uapi/linux/btf.h | 1 + 6 files changed, 24 insertions(+), 3 deletions(-) diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst index 4d565d202ce3..56aaa189e7fb 100644 --- a/Documentation/bpf/btf.rst +++ b/Documentation/bpf/btf.rst @@ -139,10 +139,11 @@ The ``BTF_INT_ENCODING`` has the following attributes:: #define BTF_INT_SIGNED (1 << 0) #define BTF_INT_CHAR (1 << 1) #define BTF_INT_BOOL (1 << 2) + #define BTF_INT_HEX (1 << 3) The ``BTF_INT_ENCODING()`` provides extra information: signedness, char, or -bool, for the int type. The char and bool encoding are mostly useful for -pretty print. At most one encoding can be specified for the int type. +bool, for the int type. The char, bool and hex encodings are mostly useful +for pretty print. At most one encoding can be specified for the int type. The ``BTF_INT_BITS()`` specifies the number of actual bits held by this int type. For example, a 4-bit bitfield encodes ``BTF_INT_BITS()`` equals to 4. diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h index 5a667107ad2c..36f309209786 100644 --- a/include/uapi/linux/btf.h +++ b/include/uapi/linux/btf.h @@ -90,6 +90,7 @@ struct btf_type { #define BTF_INT_SIGNED (1 << 0) #define BTF_INT_CHAR (1 << 1) #define BTF_INT_BOOL (1 << 2) +#define BTF_INT_HEX (1 << 3) /* BTF_KIND_ENUM is followed by multiple "struct btf_enum". * The exact number of btf_enum is stored in the vlen (of the diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 58c9af1d4808..90bdc0635321 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -501,6 +501,8 @@ static const char *btf_int_encoding_str(u8 encoding) return "CHAR"; else if (encoding == BTF_INT_BOOL) return "BOOL"; + else if (encoding == BTF_INT_HEX) + return "HEX"; else return "UNKN"; } @@ -1404,7 +1406,8 @@ static s32 btf_int_check_meta(struct btf_verifier_env *env, if (encoding && encoding != BTF_INT_SIGNED && encoding != BTF_INT_CHAR && - encoding != BTF_INT_BOOL) { + encoding != BTF_INT_BOOL && + encoding != BTF_INT_HEX) { btf_verifier_log_type(env, t, "Unsupported encoding"); return -ENOTSUPP; } diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 41a1346934a1..44a129c40873 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -59,6 +59,8 @@ static const char *btf_int_enc_str(__u8 encoding) return "CHAR"; case BTF_INT_BOOL: return "BOOL"; + case BTF_INT_HEX: + return "HEX"; default: return "UNKN"; } diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c index ede162f83eea..96947ef92565 100644 --- a/tools/bpf/bpftool/btf_dumper.c +++ b/tools/bpf/bpftool/btf_dumper.c @@ -418,6 +418,19 @@ static int btf_dumper_int(const struct btf_type *t, __u8 bit_offset, case BTF_INT_BOOL: jsonw_bool(jw, *(int *)data); break; + case BTF_INT_HEX: + if (BTF_INT_BITS(*int_type) == 64) + jsonw_printf(jw, "%llx", *(long long *)data); + else if (BTF_INT_BITS(*int_type) == 32) + jsonw_printf(jw, "%x", *(int *)data); + else if (BTF_INT_BITS(*int_type) == 16) + jsonw_printf(jw, "%hx", *(short *)data); + else if (BTF_INT_BITS(*int_type) == 8) + jsonw_printf(jw, "%hhx", *(char *)data); + else + btf_dumper_int_bits(*int_type, bit_offset, data, jw, + is_plain_text); + break; default: /* shouldn't happen */ return -EINVAL; diff --git a/tools/include/uapi/linux/btf.h b/tools/include/uapi/linux/btf.h index 5a667107ad2c..36f309209786 100644 --- a/tools/include/uapi/linux/btf.h +++ b/tools/include/uapi/linux/btf.h @@ -90,6 +90,7 @@ struct btf_type { #define BTF_INT_SIGNED (1 << 0) #define BTF_INT_CHAR (1 << 1) #define BTF_INT_BOOL (1 << 2) +#define BTF_INT_HEX (1 << 3) /* BTF_KIND_ENUM is followed by multiple "struct btf_enum". * The exact number of btf_enum is stored in the vlen (of the