linux

iv/linux

History

Yonghong Song 63fe3fd393 libbpf: Do not use __builtin_offsetof for offsetof

Commit 5fbc220862fc ("tools/libpf: Add offsetof/container_of macro
in bpf_helpers.h") added a macro offsetof() to get the offset of a
structure member:

   #define offsetof(TYPE, MEMBER)  ((size_t)&((TYPE *)0)->MEMBER)

In certain use cases, size_t type may not be available so
Commit da7a35062bcc ("libbpf bpf_helpers: Use __builtin_offsetof
for offsetof") changed to use __builtin_offsetof which removed
the dependency on type size_t, which I suggested.

But using __builtin_offsetof will prevent CO-RE relocation
generation in case that, e.g., TYPE is annotated with "preserve_access_info"
where a relocation is desirable in case the member offset is changed
in a different kernel version. So this patch reverted back to
the original macro but using "unsigned long" instead of "site_t".

Fixes: da7a35062bcc ("libbpf bpf_helpers: Use __builtin_offsetof for offsetof")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/bpf/20200811030852.3396929-1-yhs@fb.com

2020-08-11 15:11:07 +02:00

api

libsymbols kallsyms: Parse using io api

2020-05-05 16:35:32 -03:00

bpf

libbpf: Do not use __builtin_offsetof for offsetof

2020-08-11 15:11:07 +02:00

lockdep

.gitignore: add SPDX License Identifier

2020-03-25 11:50:48 +01:00

perf

libperf evlist: Fix a refcount leak