[RFC] bpf.2: Use standard types and attributes

[Alejandro Colomar]

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 C2x syntax, 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.

Signed-off-by: Alejandro Colomar <alx.manpages@xxxxxxxxx>
---
 man2/bpf.2 | 47 +++++++++++++++++++++++------------------------
 1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/man2/bpf.2 b/man2/bpf.2
index 6e1ffa198..204f01bfc 100644
--- a/man2/bpf.2
+++ b/man2/bpf.2
@@ -188,39 +188,38 @@ commands:
 .EX
 union 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 [[gnu::aligned(8)]] key;
         union {
-            __aligned_u64 value;
-            __aligned_u64 next_key;
+            uint64_t [[gnu::aligned(8)]] value;
+            uint64_t [[gnu::aligned(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 [[gnu::aligned(8)]] insns;     /* \(aqconst struct bpf_insn *\(aq */
+        uint64_t [[gnu::aligned(8)]] license;   /* \(aqconst char *\(aq */
+        uint32_t                     log_level; /* verbosity level of verifier */
+        uint32_t                     log_size;  /* size of user buffer */
+        uint64_t [[gnu::aligned(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)));
+} [[gnu::aligned(8)]];
 .EE
 .in
 .\"
-- 
2.31.0