On Wed, Jan 13, 2021 at 09:20:17AM -0800, Yonghong Song wrote:
>
>
> On 1/13/21 2:25 AM, Jiri Olsa wrote:
> > When processing kernel image build by clang we can
> > find some functions without the name, which causes
> > pahole to segfault.
>
> Just curious. What kinds of functions gcc generates
> names and clang doesn't?
can't say.. I guess we could compare nm output
of both gcc and clang vmlinux for same .config
jirka
>
> >
> > Adding extra checks to make sure we always have
> > function's name defined before using it.
> >
> > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > ---
> > v2 changes:
> > - reorg the code based on Andrii's suggestion
> >
> > btf_encoder.c | 13 +++++++++++--
> > 1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/btf_encoder.c b/btf_encoder.c
> > index 333973054b61..5557c9efd365 100644
> > --- a/btf_encoder.c
> > +++ b/btf_encoder.c
> > @@ -68,10 +68,14 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym)
> > struct elf_function *new;
> > static GElf_Shdr sh;
> > static int last_idx;
> > + const char *name;
> > int idx;
> > if (elf_sym__type(sym) != STT_FUNC)
> > return 0;
> > + name = elf_sym__name(sym, btfe->symtab);
> > + if (!name)
> > + return 0;
> > if (functions_cnt == functions_alloc) {
> > functions_alloc = max(1000, functions_alloc * 3 / 2);
> > @@ -94,7 +98,7 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym)
> > last_idx = idx;
> > }
> > - functions[functions_cnt].name = elf_sym__name(sym, btfe->symtab);
> > + functions[functions_cnt].name = name;
> > functions[functions_cnt].addr = elf_sym__value(sym);
> > functions[functions_cnt].sh_addr = sh.sh_addr;
> > functions[functions_cnt].generated = false;
> > @@ -731,8 +735,13 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force,
> > continue;
> > if (functions_cnt) {
> > struct elf_function *func;
> > + const char *name;
> > +
> > + name = function__name(fn, cu);
> > + if (!name)
> > + continue;
> > - func = find_function(btfe, function__name(fn, cu));
> > + func = find_function(btfe, name);
> > if (!func || func->generated)
> > continue;
> > func->generated = true;
> >
>
