Currently, the pahole dwarf->btf conversion only supports one
compilation unit. This is not ideal since we would like using pahole to
generate BTF for vmlinux which has a lot of compilation units.
This patch added support to process multiple compilation units per ELF
file. Multiple ELF files are also supported properly.
The following is a demonstration example:
-bash-4.4$ cat t1.c
struct t1 {
int a1;
} g1;
int main(void) { return 0; }
-bash-4.4$ cat t2.c
struct t2 {
char a2;
} g2;
int main() { return 0; }
-bash-4.4$ cat t3.c
struct t3 {
unsigned char a1:4;
} g1;
int main(void) { return 0; }
-bash-4.4$ cat t4.c
struct t4 {
volatile char a4;
} g2;
int main() { return 0; }
-bash-4.4$ gcc -O2 -o t1 -g t1.c t2.c
-bash-4.4$ gcc -O2 -o t3 -g t3.c t4.c
Note that both the binary "t1" and "t3" have two compilation units in
their respective dwarf debug_info sections. The following is the pahole
verbose output for BTF conversion for these two binaries.
-bash-4.4$ pahole -JV t1 t3
File t1:
[1] STRUCT t1 size=4 vlen=1
a1 type_id=2 bits_offset=0
[2] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
[3] STRUCT t2 size=1 vlen=1
a2 type_id=4 bits_offset=0
[4] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[5] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
File t3:
[1] STRUCT t3 size=1 vlen=1
a1 type_id=3 bits_offset=0
[2] INT unsigned char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[3] INT unsigned char size=1 bit_offset=0 nr_bits=4 encoding=(none)
[4] INT (anon) size=4 bit_offset=0 nr_bits=32 encoding=(none)
[5] STRUCT t4 size=1 vlen=1
a4 type_id=6 bits_offset=0
[6] VOLATILE (anon) type_id=7
[7] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[8] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
Signed-off-by: Andrii Nakryiko <andriin@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>
Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This patch introduces BPF Type Format (BTF).
BTF (BPF Type Format) is the meta data format which describes
the data types of BPF program/map. Hence, it basically focus
on the C programming language which the modern BPF is primary
using. The first use case is to provide a generic pretty print
capability for a BPF map.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Domenico Andreoli
Andrii Nakryiko
Martin KaFai Lau