diff mbox series

[bpf-next,v4,03/15] libbpf: honor autocreate flag for struct_ops maps

Message ID 20240306104529.6453-4-eddyz87@gmail.com (mailing list archive)
State Accepted
Commit 08c5dde48dd02775008b880a2da5012bbb5e8731
Delegated to: BPF
Headers show
Series libbpf: type suffixes and autocreate flag for struct_ops maps | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 8 this patch: 8
netdev/build_tools success Errors and warnings before: 1 this patch: 1
netdev/cc_maintainers warning 6 maintainers not CCed: song@kernel.org john.fastabend@gmail.com haoluo@google.com sdf@google.com jolsa@kernel.org kpsingh@kernel.org
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 32 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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bpf/vmtest-bpf-next-VM_Test-8 success Logs for aarch64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on aarch64 with gcc
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bpf/vmtest-bpf-next-VM_Test-24 success Logs for x86_64-gcc / test (test_progs_no_alu32_parallel, true, 30) / test_progs_no_alu32_parallel on x86_64 with gcc
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bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-14 success Logs for s390x-gcc / test (test_progs, false, 360) / test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-15 success Logs for s390x-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on s390x with gcc

Commit Message

Eduard Zingerman March 6, 2024, 10:45 a.m. UTC 
Skip load steps for struct_ops maps not marked for automatic creation.
This should allow to load bpf object in situations like below:

    SEC("struct_ops/foo") int BPF_PROG(foo) { ... }
    SEC("struct_ops/bar") int BPF_PROG(bar) { ... }

    struct test_ops___v1 {
    	int (*foo)(void);
    };

    struct test_ops___v2 {
    	int (*foo)(void);
    	int (*does_not_exist)(void);
    };

    SEC(".struct_ops.link")
    struct test_ops___v1 map_for_old = {
    	.test_1 = (void *)foo
    };

    SEC(".struct_ops.link")
    struct test_ops___v2 map_for_new = {
    	.test_1 = (void *)foo,
    	.does_not_exist = (void *)bar
    };

Suppose program is loaded on old kernel that does not have definition
for 'does_not_exist' struct_ops member. After this commit it would be
possible to load such object file after the following tweaks:

    bpf_program__set_autoload(skel->progs.bar, false);
    bpf_map__set_autocreate(skel->maps.map_for_new, false);

Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 tools/lib/bpf/libbpf.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 2c0cb72bc7a4..1fb9a4f237b4 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1212,6 +1212,9 @@  static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
 		if (!bpf_map__is_struct_ops(map))
 			continue;
 
+		if (!map->autocreate)
+			continue;
+
 		err = bpf_map__init_kern_struct_ops(map);
 		if (err)
 			return err;
@@ -8133,11 +8136,20 @@  static void bpf_map_prepare_vdata(const struct bpf_map *map)
 
 static int bpf_object_prepare_struct_ops(struct bpf_object *obj)
 {
+	struct bpf_map *map;
 	int i;
 
-	for (i = 0; i < obj->nr_maps; i++)
-		if (bpf_map__is_struct_ops(&obj->maps[i]))
-			bpf_map_prepare_vdata(&obj->maps[i]);
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+
+		if (!bpf_map__is_struct_ops(map))
+			continue;
+
+		if (!map->autocreate)
+			continue;
+
+		bpf_map_prepare_vdata(map);
+	}
 
 	return 0;
 }