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From: Alejandro Colomar <alx.manpages@gmail.com>
To: mtk.manpages@gmail.com, linux-man@vger.kernel.org
Cc: Alejandro Colomar <alx.manpages@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	glibc <libc-alpha@sourceware.org>, GCC <gcc-patches@gcc.gnu.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	bpf <bpf@vger.kernel.org>, David Laight <David.Laight@ACULAB.COM>,
	Zack Weinberg <zackw@panix.com>,
	Joseph Myers <joseph@codesourcery.com>
Subject: [RFC v2] bpf.2: Use standard types and attributes
Date: Tue,  4 May 2021 13:05:20 +0200
Message-ID: <20210504110519.16097-1-alx.manpages@gmail.com> (raw)
In-Reply-To: <20210423230609.13519-1-alx.manpages@gmail.com>

Some manual pages are already using C99 syntax for integral
types 'uint32_t', but some aren't.  There are some using kernel
syntax '__u32'.  Fix those.

Some pages also document attributes, using GNU syntax
'__attribute__((xxx))'.  Update those to use the shorter and more
portable C11 keywords such as 'alignas()' when possible, and C2x
syntax '[[gnu::xxx]]' elsewhere, which hasn't been standardized
yet, but is already implemented in GCC, and available through
either --std=c2x or any of the --std=gnu... options.

The standard isn't very clear on how to use alignas() or
[[]]-style attributes, so the following link is useful in the case
of 'alignas()' and '[[gnu::aligned()]]':
<https://stackoverflow.com/q/67271825/6872717>

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: glibc <libc-alpha@sourceware.org>
Cc: GCC <gcc-patches@gcc.gnu.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: bpf <bpf@vger.kernel.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Zack Weinberg <zackw@panix.com>
Cc: Joseph Myers <joseph@codesourcery.com>
---
 man2/bpf.2 | 49 ++++++++++++++++++++++++-------------------------
 1 file changed, 24 insertions(+), 25 deletions(-)

diff --git a/man2/bpf.2 b/man2/bpf.2
index 6e1ffa198..04b8fbcef 100644
--- a/man2/bpf.2
+++ b/man2/bpf.2
@@ -186,41 +186,40 @@ commands:
 .PP
 .in +4n
 .EX
-union bpf_attr {
+union [[gnu::aligned(8)]] bpf_attr {
     struct {    /* Used by BPF_MAP_CREATE */
-        __u32         map_type;
-        __u32         key_size;    /* size of key in bytes */
-        __u32         value_size;  /* size of value in bytes */
-        __u32         max_entries; /* maximum number of entries
-                                      in a map */
+        uint32_t    map_type;
+        uint32_t    key_size;    /* size of key in bytes */
+        uint32_t    value_size;  /* size of value in bytes */
+        uint32_t    max_entries; /* maximum number of entries
+                                    in a map */
     };
 
-    struct {    /* Used by BPF_MAP_*_ELEM and BPF_MAP_GET_NEXT_KEY
-                   commands */
-        __u32         map_fd;
-        __aligned_u64 key;
+    struct {    /* Used by BPF_MAP_*_ELEM and BPF_MAP_GET_NEXT_KEY commands */
+        uint32_t            map_fd;
+        uint64_t alignas(8) key;
         union {
-            __aligned_u64 value;
-            __aligned_u64 next_key;
+            uint64_t alignas(8) value;
+            uint64_t alignas(8) next_key;
         };
-        __u64         flags;
+        uint64_t            flags;
     };
 
     struct {    /* Used by BPF_PROG_LOAD */
-        __u32         prog_type;
-        __u32         insn_cnt;
-        __aligned_u64 insns;      /* \(aqconst struct bpf_insn *\(aq */
-        __aligned_u64 license;    /* \(aqconst char *\(aq */
-        __u32         log_level;  /* verbosity level of verifier */
-        __u32         log_size;   /* size of user buffer */
-        __aligned_u64 log_buf;    /* user supplied \(aqchar *\(aq
-                                     buffer */
-        __u32         kern_version;
-                                  /* checked when prog_type=kprobe
-                                     (since Linux 4.1) */
+        uint32_t            prog_type;
+        uint32_t            insn_cnt;
+        uint64_t alignas(8) insns;     /* \(aqconst struct bpf_insn *\(aq */
+        uint64_t alignas(8) license;   /* \(aqconst char *\(aq */
+        uint32_t            log_level; /* verbosity level of verifier */
+        uint32_t            log_size;  /* size of user buffer */
+        uint64_t alignas(8) log_buf;   /* user supplied \(aqchar *\(aq
+                                          buffer */
+        uint32_t            kern_version;
+                                       /* checked when prog_type=kprobe
+                                          (since Linux 4.1) */
 .\"                 commit 2541517c32be2531e0da59dfd7efc1ce844644f5
     };
-} __attribute__((aligned(8)));
+};
 .EE
 .in
 .\"
-- 
2.31.1


  parent reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210423230609.13519-1-alx.manpages@gmail.com>
2021-04-23 23:20 ` [RFC] " Alexei Starovoitov
2021-04-24 17:56   ` Alejandro Colomar (man-pages)
2021-04-25 16:52     ` Alexei Starovoitov
2021-04-25 19:12       ` Zack Weinberg
2021-04-24 20:43   ` David Laight
2021-04-25 19:16     ` Zack Weinberg
2021-04-25 21:09       ` David Laight
2021-05-04 11:05 ` Alejandro Colomar [this message]
2021-05-04 14:12   ` [RFC v2] " Alexei Starovoitov
2021-05-04 14:24     ` Greg KH
2021-05-04 15:53       ` Alejandro Colomar (man-pages)
2021-05-04 16:06         ` Greg KH
2021-05-04 18:37           ` Zack Weinberg
2021-05-04 18:54             ` Alejandro Colomar (man-pages)
2021-05-04 19:45               ` Florian Weimer
2021-05-04 19:59                 ` Alejandro Colomar (man-pages)
2021-05-05  8:23                 ` David Laight
2021-05-05 22:22                   ` Joseph Myers
2021-05-04 20:06               ` Daniel Borkmann
2021-05-04 20:16                 ` Alejandro Colomar (man-pages)
2021-05-04 20:33                 ` Zack Weinberg
2021-05-04 21:23                   ` Alexei Starovoitov
2021-05-15 19:01               ` [PATCH v3] " Alejandro Colomar
2021-05-16  9:16                 ` Alejandro Colomar (man-pages)
2021-05-17 18:56                   ` Daniel Borkmann
2021-05-21 11:12                     ` Alejandro Colomar
2021-05-04 16:08         ` [RFC v2] " Daniel Borkmann

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