objtool: Don't fail on missing symbol table

[ Upstream commit 1d489151e9f9d1647110277ff77282fe4d96d09b ]

Thanks to a recent binutils change which doesn't generate unused
symbols, it's now possible for thunk_64.o be completely empty without
CONFIG_PREEMPTION: no text, no data, no symbols.

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 <natechancellor@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1254
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Josh Poimboeuf 2021-01-14 16:14:01 -06:00 committed by Greg Kroah-Hartman
parent 88240f7ac2
commit 2d7ca4a84b

View File

@ -214,8 +214,11 @@ 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;
}
symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;