libbpf: Poison kernel-only integer types

It's been a recurring issue with types like u32 slipping into libbpf source
code accidentally. This is not detected during builds inside kernel source
tree, but becomes a compilation error in libbpf's Github repo. Libbpf is
supposed to use only __{s,u}{8,16,32,64} typedefs, so poison {s,u}{8,16,32,64}
explicitly in every .c file. Doing that in a bit more centralized way, e.g.,
inside libbpf_internal.h breaks selftests, which are both using kernel u32 and
libbpf_internal.h.

This patch also fixes a new u32 occurence in libbpf.c, added recently.

Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support")
Signed-off-by: Andrii Nakryiko <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Acked-by: Martin KaFai Lau <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/lib/bpf/bpf.c

···
 #include "libbpf.h"
 #include "libbpf_internal.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 /*
  * When building perf, unistd.h is overridden. __NR_bpf is
  * required to be defined explicitly.

tools/lib/bpf/bpf_prog_linfo.c

···
 #include "libbpf.h"
 #include "libbpf_internal.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 struct bpf_prog_linfo {
 	void *raw_linfo;
 	void *raw_jited_linfo;

tools/lib/bpf/btf.c

···
 #include "libbpf_internal.h"
 #include "hashmap.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 #define BTF_MAX_NR_TYPES 0x7fffffff
 #define BTF_MAX_STR_OFFSET 0x7fffffff
 

tools/lib/bpf/btf_dump.c

···
 #include "libbpf.h"
 #include "libbpf_internal.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 static const char PREFIXES[] = "\t\t\t\t\t\t\t\t\t\t\t\t\t";
 static const size_t PREFIX_CNT = sizeof(PREFIXES) - 1;
 

tools/lib/bpf/hashmap.c

···
 #include <linux/err.h>
 #include "hashmap.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 /* start with 4 buckets */
 #define HASHMAP_MIN_CAP_BITS 2
 

tools/lib/bpf/libbpf.c

···
 #include "libbpf_internal.h"
 #include "hashmap.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 #ifndef EM_BPF
 #define EM_BPF 247
 #endif
···
 	Elf_Data *symbols;
 	unsigned int moff;
 	const char *name;
-	u32 member_idx;
+	__u32 member_idx;
 	GElf_Sym sym;
 	GElf_Rel rel;
 	int i, nrels;

tools/lib/bpf/libbpf_errno.c

···
 
 #include "libbpf.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 #define ERRNO_OFFSET(e)		((e) - __LIBBPF_ERRNO__START)
 #define ERRCODE_OFFSET(c)	ERRNO_OFFSET(LIBBPF_ERRNO__##c)
 #define NR_ERRNO	(__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)

tools/lib/bpf/libbpf_probes.c

···
 #include "libbpf.h"
 #include "libbpf_internal.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 static bool grep(const char *buffer, const char *pattern)
 {
 	return !!strstr(buffer, pattern);

tools/lib/bpf/netlink.c

···
 #include "libbpf_internal.h"
 #include "nlattr.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 #ifndef SOL_NETLINK
 #define SOL_NETLINK 270
 #endif

tools/lib/bpf/nlattr.c

···
 #include <string.h>
 #include <stdio.h>
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 static uint16_t nla_attr_minlen[LIBBPF_NLA_TYPE_MAX+1] = {
 	[LIBBPF_NLA_U8]		= sizeof(uint8_t),
 	[LIBBPF_NLA_U16]	= sizeof(uint16_t),

tools/lib/bpf/str_error.c

···
 #include <stdio.h>
 #include "str_error.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 /*
  * Wrapper to allow for building in non-GNU systems such as Alpine Linux's musl
  * libc, while checking strerror_r() return to avoid having to check this in

tools/lib/bpf/xsk.c

···
 #include "libbpf_internal.h"
 #include "xsk.h"
 
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 #ifndef SOL_XDP
  #define SOL_XDP 283
 #endif