Merge branch 'bpf-libbpf-btf-defined-maps'

Andrii Nakryiko says:

====================
This patch set implements initial version (as discussed at LSF/MM2019
conference) of a new way to specify BPF maps, relying on BTF type information,
which allows for easy extensibility, preserving forward and backward
compatibility. See details and examples in description for patch #6.

[0] contains an outline of follow up extensions to be added after this basic
set of features lands. They are useful by itself, but also allows to bring
libbpf to feature-parity with iproute2 BPF loader. That should open a path
forward for BPF loaders unification.

Patch #1 centralizes commonly used min/max macro in libbpf_internal.h.
Patch #2 extracts .BTF and .BTF.ext loading loging from elf_collect().
Patch #3 simplifies elf_collect() error-handling logic.
Patch #4 refactors map initialization logic into user-provided maps and global
data maps, in preparation to adding another way (BTF-defined maps).
Patch #5 adds support for map definitions in multiple ELF sections and
deprecates bpf_object__find_map_by_offset() API which doesn't appear to be
used anymore and makes assumption that all map definitions reside in single
ELF section.
Patch #6 splits BTF intialization from sanitization/loading into kernel to
preserve original BTF at the time of map initialization.
Patch #7 adds support for BTF-defined maps.
Patch #8 adds new test for BTF-defined map definition.
Patches #9-11 convert test BPF map definitions to use BTF way.

[0] https://lore.kernel.org/bpf/CAEf4BzbfdG2ub7gCi0OYqBrUoChVHWsmOntWAkJt47=FE+km+A@mail.gmail.com/

v1->v2:
- more BTF-sanity checks in parsing map definitions (Song);
- removed confusing usage of "attribute", switched to "field;
- split off elf_collect() refactor from btf loading refactor (Song);
- split selftests conversion into 3 patches (Stanislav):
  1. test already relying on BTF;
  2. tests w/ custom types as key/value (so benefiting from BTF);
  3. all the rest tests (integers as key/value, special maps w/o BTF support).
- smaller code improvements (Song);

rfc->v1:
- error out on unknown field by default (Stanislav, Jakub, Lorenz);
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/lib/bpf/bpf.c

@@ -26,10 +26,11 @@
 #include <memory.h>
 #include <unistd.h>
 #include <asm/unistd.h>
+#include <errno.h>
 #include <linux/bpf.h>
 #include "bpf.h"
 #include "libbpf.h"
-#include <errno.h>
+#include "libbpf_internal.h"
 
 /*
  * When building perf, unistd.h is overridden. __NR_bpf is
@@ -53,10 +54,6 @@
 # endif
 #endif
 
-#ifndef min
-#define min(x, y) ((x) < (y) ? (x) : (y))
-#endif
-
 static inline __u64 ptr_to_u64(const void *ptr)
 {
 	return (__u64) (unsigned long) ptr;

tools/lib/bpf/bpf_prog_linfo.c

@@ -6,10 +6,7 @@
 #include <linux/err.h>
 #include <linux/bpf.h>
 #include "libbpf.h"
-
-#ifndef min
-#define min(x, y) ((x) < (y) ? (x) : (y))
-#endif
+#include "libbpf_internal.h"
 
 struct bpf_prog_linfo {
 	void *raw_linfo;

tools/lib/bpf/btf.c

@@ -16,9 +16,6 @@
 #include "libbpf_internal.h"
 #include "hashmap.h"
 
-#define max(a, b) ((a) > (b) ? (a) : (b))
-#define min(a, b) ((a) < (b) ? (a) : (b))
-
 #define BTF_MAX_NR_TYPES 0x7fffffff
 #define BTF_MAX_STR_OFFSET 0x7fffffff
 

tools/lib/bpf/btf.h

@@ -17,6 +17,7 @@ extern "C" {
 
 #define BTF_ELF_SEC ".BTF"
 #define BTF_EXT_ELF_SEC ".BTF.ext"
+#define MAPS_ELF_SEC ".maps"
 
 struct btf;
 struct btf_ext;

tools/lib/bpf/btf_dump.c

@@ -18,9 +18,6 @@
 #include "libbpf.h"
 #include "libbpf_internal.h"
 
-#define min(x, y) ((x) < (y) ? (x) : (y))
-#define max(x, y) ((x) < (y) ? (y) : (x))
-
 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;