bpf: refactor skeleton generation

This should hopefully fix cross compilation for the bpf programs.

10 files changed, 154 insertions, 25 deletions

diff --git a/src/core/bpf-socket-bind.c b/src/core/bpf-socket-bind.c
index e9c0a2f9bd..c5176aa481 100644
--- a/src/core/bpf-socket-bind.c
+++ b/src/core/bpf-socket-bind.c
@@ -11,7 +11,7 @@
 /* libbpf, clang, llvm and bpftool compile time dependencies are satisfied */
 #include "bpf-dlopen.h"
 #include "bpf-link.h"
-#include "bpf/socket_bind/socket-bind.skel.h"
+#include "bpf/socket_bind/socket-bind-skel.h"
 #include "bpf/socket_bind/socket-bind-api.bpf.h"
 
 static struct socket_bind_bpf *socket_bind_bpf_free(struct socket_bind_bpf *obj) {
diff --git a/src/core/bpf/meson.build b/src/core/bpf/meson.build
new file mode 100644
index 0000000000..ab1a7167a6
--- /dev/null
+++ b/src/core/bpf/meson.build
@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: LGPL-2.1+
+
+if conf.get('BPF_FRAMEWORK') == 1
+        clang_flags = [
+                '-Wno-compare-distinct-pointer-types',
+                '-O2',
+                '-target',
+                'bpf',
+                '-g',
+                '-c',
+        ]
+
+        clang_arch_flag = '-D__@0@__'.format(host_machine.cpu_family())
+
+        if meson.version().version_compare('>= 0.58')
+                libbpf_include_dir = libbpf.get_variable('includedir')
+        else
+                libbpf_include_dir = libbpf.get_variable(pkgconfig : 'includedir')
+        endif
+
+        bpf_o_unstripped_cmd = [
+                clang,
+                clang_flags,
+                clang_arch_flag,
+                '-I.'
+        ]
+
+        if not meson.is_cross_build()
+                target_triplet_cmd = run_command('gcc', '-dumpmachine', check: false)
+                if target_triplet_cmd.returncode() == 0
+                        target_triplet = target_triplet_cmd.stdout().strip()
+                        bpf_o_unstripped_cmd += [
+                                '-isystem',
+                                '/usr/include/@0@'.format(target_triplet)
+                        ]
+                endif
+        endif
+
+        bpf_o_unstripped_cmd += [
+                '-idirafter',
+                libbpf_include_dir,
+                '@INPUT@',
+                '-o',
+                '@OUTPUT@'
+        ]
+
+        bpf_o_cmd = [
+                llvm_strip,
+                '-g',
+                '@INPUT@',
+                '-o',
+                '@OUTPUT@'
+        ]
+
+        skel_h_cmd = [
+                bpftool,
+                'g',
+                's',
+                '@INPUT@'
+        ]
+endif
diff --git a/src/core/bpf/restrict_fs/meson.build b/src/core/bpf/restrict_fs/meson.build
index c92cccae26..dfe3f12033 100644
--- a/src/core/bpf/restrict_fs/meson.build
+++ b/src/core/bpf/restrict_fs/meson.build
@@ -1,14 +1,22 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 if conf.get('BPF_FRAMEWORK') == 1
-        restrict_fs_skel_h = custom_target(
-                'restrict-fs-skel.h',
+        restrict_fs_bpf_o_unstripped = custom_target(
+                'restrict-fs.bpf.unstripped.o',
                 input : 'restrict-fs.bpf.c',
-                output : 'restrict-fs-skel.h',
-                command : [build_bpf_skel_py,
-                           '--clang_exec', clang.path(),
-                           '--llvm_strip_exec', llvm_strip.path(),
-                           '--bpftool_exec', bpftool.path(),
-                           '--arch', host_machine.cpu_family(),
-                           '@INPUT@', '@OUTPUT@'])
+                output : 'restrict-fs.bpf.unstripped.o',
+                command : bpf_o_unstripped_cmd)
+
+        restrict_fs_bpf_o = custom_target(
+                'restrict-fs.bpf.o',
+                input : restrict_fs_bpf_o_unstripped,
+                output : 'restrict-fs.bpf.o',
+                command : bpf_o_cmd)
+
+        restrict_fs_skel_h = custom_target(
+                'restrict-fs.skel.h',
+                input : restrict_fs_bpf_o,
+                output : 'restrict-fs.skel.h',
+                command : skel_h_cmd,
+                capture : true)
 endif
diff --git a/src/core/bpf/restrict_fs/restrict-fs-skel.h b/src/core/bpf/restrict_fs/restrict-fs-skel.h
new file mode 100644
index 0000000000..412cf62eda
--- /dev/null
+++ b/src/core/bpf/restrict_fs/restrict-fs-skel.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+/* The SPDX header above is actually correct in claiming this was
+ * LGPL-2.1-or-later, because it is. Since the kernel doesn't consider that
+ * compatible with GPL we will claim this to be GPL however, which should be
+ * fine given that LGPL-2.1-or-later downgrades to GPL if needed.
+ */
+
+/* libbpf is used via dlopen(), so rename symbols */
+#define bpf_object__open_skeleton sym_bpf_object__open_skeleton
+#define bpf_object__load_skeleton sym_bpf_object__load_skeleton
+#define bpf_object__destroy_skeleton sym_bpf_object__destroy_skeleton
+
+#include "bpf/restrict_fs/restrict-fs.skel.h"
diff --git a/src/core/bpf/restrict_ifaces/meson.build b/src/core/bpf/restrict_ifaces/meson.build
index 38f7dbbd51..b7e2bc1519 100644
--- a/src/core/bpf/restrict_ifaces/meson.build
+++ b/src/core/bpf/restrict_ifaces/meson.build
@@ -1,14 +1,22 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 if conf.get('BPF_FRAMEWORK') == 1
+        restrict_ifaces_bpf_o_unstripped = custom_target(
+                'restrict-ifaces.bpf.unstripped.o',
+                input : 'restrict-ifaces.bpf.c',
+                output : 'restrict-ifaces.bpf.unstripped.o',
+                command : bpf_o_unstripped_cmd)
+
+        restrict_ifaces_bpf_o = custom_target(
+                'restrict-ifaces.bpf.o',
+                input : restrict_ifaces_bpf_o_unstripped,
+                output : 'restrict-ifaces.bpf.o',
+                command : bpf_o_cmd)
+
         restrict_ifaces_skel_h = custom_target(
                 'restrict-ifaces.skel.h',
-                input : 'restrict-ifaces.bpf.c',
+                input : restrict_ifaces_bpf_o,
                 output : 'restrict-ifaces.skel.h',
-                command : [build_bpf_skel_py,
-                           '--clang_exec', clang.path(),
-                           '--llvm_strip_exec', llvm_strip.path(),
-                           '--bpftool_exec', bpftool.path(),
-                           '--arch', host_machine.cpu_family(),
-                           '@INPUT@', '@OUTPUT@'])
+                command : skel_h_cmd,
+                capture : true)
 endif
diff --git a/src/core/bpf/restrict_ifaces/restrict-ifaces-skel.h b/src/core/bpf/restrict_ifaces/restrict-ifaces-skel.h
new file mode 100644
index 0000000000..f937490954
--- /dev/null
+++ b/src/core/bpf/restrict_ifaces/restrict-ifaces-skel.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+/* The SPDX header above is actually correct in claiming this was
+ * LGPL-2.1-or-later, because it is. Since the kernel doesn't consider that
+ * compatible with GPL we will claim this to be GPL however, which should be
+ * fine given that LGPL-2.1-or-later downgrades to GPL if needed.
+ */
+
+/* libbpf is used via dlopen(), so rename symbols */
+#define bpf_object__open_skeleton sym_bpf_object__open_skeleton
+#define bpf_object__load_skeleton sym_bpf_object__load_skeleton
+#define bpf_object__destroy_skeleton sym_bpf_object__destroy_skeleton
+
+#include "bpf/restrict_ifaces/restrict-ifaces.skel.h"
diff --git a/src/core/bpf/socket_bind/meson.build b/src/core/bpf/socket_bind/meson.build
index f5cfc04b00..8211a7a5c9 100644
--- a/src/core/bpf/socket_bind/meson.build
+++ b/src/core/bpf/socket_bind/meson.build
@@ -1,14 +1,22 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 if conf.get('BPF_FRAMEWORK') == 1
+        socket_bind_bpf_o_unstripped = custom_target(
+                'socket-bind.bpf.unstripped.o',
+                input : 'socket-bind.bpf.c',
+                output : 'socket-bind.bpf.unstripped.o',
+                command : bpf_o_unstripped_cmd)
+
+        socket_bind_bpf_o = custom_target(
+                'socket-bind.bpf.o',
+                input : socket_bind_bpf_o_unstripped,
+                output : 'socket-bind.bpf.o',
+                command : bpf_o_cmd)
+
         socket_bind_skel_h = custom_target(
                 'socket-bind.skel.h',
-                input : 'socket-bind.bpf.c',
+                input : socket_bind_bpf_o,
                 output : 'socket-bind.skel.h',
-                command : [build_bpf_skel_py,
-                           '--clang_exec', clang.path(),
-                           '--llvm_strip_exec', llvm_strip.path(),
-                           '--bpftool_exec', bpftool.path(),
-                           '--arch', host_machine.cpu_family(),
-                           '@INPUT@', '@OUTPUT@'])
+                command : skel_h_cmd,
+                capture : true)
 endif
diff --git a/src/core/bpf/socket_bind/socket-bind-skel.h b/src/core/bpf/socket_bind/socket-bind-skel.h
new file mode 100644
index 0000000000..e0d16269cd
--- /dev/null
+++ b/src/core/bpf/socket_bind/socket-bind-skel.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+/* The SPDX header above is actually correct in claiming this was
+ * LGPL-2.1-or-later, because it is. Since the kernel doesn't consider that
+ * compatible with GPL we will claim this to be GPL however, which should be
+ * fine given that LGPL-2.1-or-later downgrades to GPL if needed.
+ */
+
+/* libbpf is used via dlopen(), so rename symbols */
+#define bpf_object__open_skeleton sym_bpf_object__open_skeleton
+#define bpf_object__load_skeleton sym_bpf_object__load_skeleton
+#define bpf_object__destroy_skeleton sym_bpf_object__destroy_skeleton
+
+#include "bpf/socket_bind/socket-bind.skel.h"
diff --git a/src/core/meson.build b/src/core/meson.build
index c02543bd06..92a811f2f0 100644
--- a/src/core/meson.build
+++ b/src/core/meson.build
@@ -133,6 +133,8 @@ libcore_sources = '''
         unit.h
 '''.split()
 
+subdir('bpf')
+
 subdir('bpf/socket_bind')
 if conf.get('BPF_FRAMEWORK') == 1
         libcore_sources += [socket_bind_skel_h]
diff --git a/src/core/restrict-ifaces.c b/src/core/restrict-ifaces.c
index a17c5d2bf7..7650031434 100644
--- a/src/core/restrict-ifaces.c
+++ b/src/core/restrict-ifaces.c
@@ -10,7 +10,7 @@
 #include "bpf-dlopen.h"
 #include "bpf-link.h"
 
-#include "bpf/restrict_ifaces/restrict-ifaces.skel.h"
+#include "bpf/restrict_ifaces/restrict-ifaces-skel.h"
 
 static struct restrict_ifaces_bpf *restrict_ifaces_bpf_free(struct restrict_ifaces_bpf *obj) {
         restrict_ifaces_bpf__destroy(obj);