On Wed, May 11, 2022 at 10:18 PM Yonghong Song <yhs@xxxxxx> wrote: > > With latest llvm15 built kernel (make -j LLVM=1), I hit the following > error when build selftests (make -C tools/testing/selftests/bpf -j LLVM=1): > In file included from skeleton/pid_iter.bpf.c:3: > .../selftests/bpf/tools/build/bpftool/vmlinux.h:84050:9: error: unknown type name > '__builtin_va_list___2'; did you mean '__builtin_va_list'? > typedef __builtin_va_list___2 va_list___2; > ^~~~~~~~~~~~~~~~~~~~~ > __builtin_va_list > note: '__builtin_va_list' declared here > In file included from skeleton/profiler.bpf.c:3: > .../selftests/bpf/tools/build/bpftool/vmlinux.h:84050:9: error: unknown type name > '__builtin_va_list__ _2'; did you mean '__builtin_va_list'? > typedef __builtin_va_list___2 va_list___2; > ^~~~~~~~~~~~~~~~~~~~~ > __builtin_va_list > note: '__builtin_va_list' declared here > > The error can be easily explained with after-dedup vmlinux btf: > [21] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED > [2300] STRUCT '__va_list_tag' size=24 vlen=4 > 'gp_offset' type_id=2 bits_offset=0 > 'fp_offset' type_id=2 bits_offset=32 > 'overflow_arg_area' type_id=32 bits_offset=64 > 'reg_save_area' type_id=32 bits_offset=128 > [2308] TYPEDEF 'va_list' type_id=2309 > [2309] TYPEDEF '__builtin_va_list' type_id=2310 > [2310] ARRAY '(anon)' type_id=2300 index_type_id=21 nr_elems=1 > > [5289] PTR '(anon)' type_id=2308 > [158520] STRUCT 'warn_args' size=32 vlen=2 > 'fmt' type_id=14 bits_offset=0 > 'args' type_id=2308 bits_offset=64 > [27299] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none) > [34590] TYPEDEF '__builtin_va_list' type_id=34591 > [34591] ARRAY '(anon)' type_id=2300 index_type_id=27299 nr_elems=1 > > Note that two array index_type_id's are different so the va_list and __builtin_va_list > will have two versions in the BTF. With this, vmlinux.h contains the following code, > typedef __builtin_va_list va_list; > typedef __builtin_va_list___2 va_list___2; > Since __builtin_va_list is a builtin type for the compiler, > libbpf does not generate > typedef <...> __builtin_va_list > and this caused __builtin_va_list___2 is not defined and hence compilation error. > This happened when pahole is running with more than one jobs when parsing dwarf > and generating btfs. > > Function btf_encoder__encode_cu() is used to do btf encoding for > each cu. The function will try to find an "int" type for the cu > if it is available, otherwise, it will create a special type > with name __ARRAY_SIZE_TYPE__. For example, > file1: yes 'int' type > file2: no 'int' type > > In serial mode, file1 is processed first, followed by file2. > both will have 'int' type as the array index type since file2 > will inherit the index type from file1. > > In parallel mode though, arrays in file1 will have index type 'int', > and arrays in file2 wil have index type '__ARRAY_SIZE_TYPE__'. > This will prevent some legitimate dedup and may have generated > vmlinux.h having compilation error. > > This patch fixed the issue by creating an 'int' type as the > array index type, so all array index type should be the same > for all cu's even in parallel mode. > > Signed-off-by: Yonghong Song <yhs@xxxxxx> > --- > btf_encoder.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > LGTM, it should work reliably. Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > Changelog: > v1 -> v2: > - change creation of array index type to be 'int' type, > the same as the type encoder tries to search in the current > types. > > diff --git a/btf_encoder.c b/btf_encoder.c > index 1a42094..9e708e4 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -1460,7 +1460,8 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu) > > bt.name = 0; > bt.bit_size = 32; > - btf_encoder__add_base_type(encoder, &bt, "__ARRAY_SIZE_TYPE__"); > + bt.is_signed = true; > + btf_encoder__add_base_type(encoder, &bt, "int"); > encoder->has_index_type = true; > } > > -- > 2.30.2 >
