On 5/10/22 3:40 PM, Yonghong Song wrote:
On 5/9/22 4:25 PM, Andrii Nakryiko wrote:
On Sun, May 1, 2022 at 12:00 PM Yonghong Song <yhs@xxxxxx> wrote:
Add BTF_KIND_ENUM64 support. Deprecated btf__add_enum() and
btf__add_enum_value() and introduced the following new APIs
btf__add_enum32()
btf__add_enum32_value()
btf__add_enum64()
btf__add_enum64_value()
due to new kind and introduction of kflag.
To support old kernel with enum64, the sanitization is
added to replace BTF_KIND_ENUM64 with a bunch of
pointer-to-void types.
The enum64 value relocation is also supported. The enum64
forward resolution, with enum type as forward declaration
and enum64 as the actual definition, is also supported.
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
tools/lib/bpf/btf.c | 226 +++++++++++++++++-
tools/lib/bpf/btf.h | 21 ++
tools/lib/bpf/btf_dump.c | 94 ++++++--
tools/lib/bpf/libbpf.c | 64 ++++-
tools/lib/bpf/libbpf.map | 4 +
tools/lib/bpf/libbpf_internal.h | 2 +
tools/lib/bpf/linker.c | 2 +
tools/lib/bpf/relo_core.c | 93 ++++---
.../selftests/bpf/prog_tests/btf_dump.c | 10 +-
.../selftests/bpf/prog_tests/btf_write.c | 6 +-
10 files changed, 450 insertions(+), 72 deletions(-)
[...]
+ t->size = tsize;
+
+ return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_ENUM type with:
+ * - *name* - name of the enum, can be NULL or empty for anonymous
enums;
+ * - *is_unsigned* - whether the enum values are unsigned or not;
+ *
+ * Enum initially has no enum values in it (and corresponds to enum
forward
+ * declaration). Enumerator values can be added by
btf__add_enum64_value()
+ * immediately after btf__add_enum() succeeds.
+ *
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_enum32(struct btf *btf, const char *name, bool
is_unsigned)
given it's still BTF_KIND_ENUM in UAPI, let's keep 32-bit ones as just
btf__add_enum()/btf__add_enum_value() and not deprecate anything.
ENUM64 can be thought about as more of a special case, so I think it's
ok.
The current btf__add_enum api:
LIBBPF_API int btf__add_enum(struct btf *btf, const char *name, __u32
bytes_sz);
The issue is it doesn't have signedness parameter. if the user input
is
enum { A = -1, B = 0, C = 1 };
the actual printout btf format will be
enum { A 4294967295, B = 0, C = 1}
does not match the original source.
I think I found a way to keep the current btf__add_enum() API.
Initially, the signedness will be unsigned. But during
btf__add_enum_value() api calls, if any negative value
is found, the signedness will change to signed. I think
this should work.
+{
+ return btf_add_enum_common(btf, name, is_unsigned,
BTF_KIND_ENUM, 4);
+}
+
[...]
[...]
