On Fri, Jan 15, 2021 at 12:31:26PM +0100, Miroslav Benes wrote: > On Thu, 14 Jan 2021, Josh Poimboeuf wrote: > > > Thanks to a recent binutils change which doesn't generate unused > > symbols, it's now possible for thunk_64.o be completely empty with > > CONFIG_PREEMPTION: no text, no data, no symbols. > > "without CONFIG_PREEMPTION", or did I misunderstand?
Fixed. > > > We could edit the Makefile to only build that file when > > CONFIG_PREEMPTION is enabled, but that will likely create confusion > > if/when the thunks end up getting used by some other code again. > > > > Just ignore it and move on. > > > > Reported-by: Nathan Chancellor <[email protected]> > > Signed-off-by: Josh Poimboeuf <[email protected]> > > Reviewed-by: Miroslav Benes <[email protected]> Thanks! > > with the note below. > > > --- > > tools/objtool/elf.c | 7 +++++-- > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c > > index be89c741ba9a..2b0f4f52f7b5 100644 > > --- a/tools/objtool/elf.c > > +++ b/tools/objtool/elf.c > > @@ -380,8 +380,11 @@ static int read_symbols(struct elf *elf) > > > > symtab = find_section_by_name(elf, ".symtab"); > > if (!symtab) { > > - WARN("missing symbol table"); > > - return -1; > > + /* > > + * A missing symbol table is actually possible if it's an empty > > + * .o file. This can happen for thunk_64.o. > > + */ > > + return 0; > > } > > We rely on .symtab presence elsewhere in the code. See > elf_create_{rel,rela}_reloc_section(). However, there should never be a > problem. If there is a need to create a new reloc section (either for a > static call site, or ORC), there should always be a symbol to create it > for (or because of it). Right, let us hope so :-) -- Josh
