Two new btf kinds, BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO,
have been added in kernel since
https://patchwork.ozlabs.org/cover/1000176/
to support better func introspection.
Currently, for a DW_TAG_subroutine_type dwarf type,
a simple "void *" is generated instead of real subroutine type.
This patch teaches pahole to generate BTF_KIND_FUNC_PROTO
properly. After this patch, pahole should have complete
type coverage for C frontend with types a bpf program cares.
For example,
$ cat t1.c
typedef int __int32;
struct t1 {
int a1;
int (*f1)(char p1, __int32 p2);
} g1;
$ cat t2.c
typedef int __int32;
struct t2 {
int a2;
int (*f2)(char q1, __int32 q2, ...);
int (*f3)();
} g2;
int main() { return 0; }
$ gcc -O2 -o t1 -g t1.c t2.c
$ pahole -JV t1
File t1:
[1] TYPEDEF __int32 type_id=2
[2] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
[3] STRUCT t1 kind_flag=0 size=16 vlen=2
a1 type_id=2 bits_offset=0
f1 type_id=6 bits_offset=64
[4] FUNC_PROTO (anon) return=2 args=(5 (anon), 1 (anon))
[5] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[6] PTR (anon) type_id=4
[7] TYPEDEF __int32 type_id=8
[8] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
[9] STRUCT t2 kind_flag=0 size=24 vlen=3
a2 type_id=8 bits_offset=0
f2 type_id=12 bits_offset=64
f3 type_id=14 bits_offset=128
[10] FUNC_PROTO (anon) return=8 args=(11 (anon), 7 (anon), vararg)
[11] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[12] PTR (anon) type_id=10
[13] FUNC_PROTO (anon) return=8 args=(vararg)
[14] PTR (anon) type_id=13
$
In the above example, type [4], [10] and [13] represent the
func_proto types.
BTF_KIND_FUNC, which represents a real subprogram, is not generated in
this patch and will be considered later.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Build instructions:
1. install cmake
2. mkdir build
3. cd build
4. cmake -D__LIB=lib ..
5. make install
Default is to be installed on /usr/local, see rpm spec file for
installing on other places.
Known to work scenarios:
Mandriva Cooker:
cmake 2.4.5-1mdv2007.1
libelfutils1-devel 0.123-1mdv2007.1
Debian Unstable:
cmake 2.4.5-1
libdw-dev 0.123-2
Fedora Core 6:
cmake 2.4.5-2.fc6
elfutils-devel 0.126-1.fc6
3aa3fd506e