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objtool: print out the symbol type when complaining about it
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commit 7fab1c1 upstream.

The objtool warning that the kvm instruction emulation code triggered
wasn't very useful:

    arch/x86/kvm/emulate.o: warning: objtool: __ex_table+0x4: don't know how to handle reloc symbol type: kvm_fastop_exception

in that it helpfully tells you which symbol name it had trouble figuring
out the relocation for, but it doesn't actually say what the unknown
symbol type was that triggered it all.

In this case it was because of missing type information (type 0, aka
STT_NOTYPE), but on the whole it really should just have printed that
out as part of the message.

Because if this warning triggers, that's very much the first thing you
want to know - why did reloc2sec_off() return failure for that symbol?

So rather than just saying you can't handle some type of symbol without
saying what the type _was_, just print out the type number too.

Fixes: 24ff652 ("objtool: Teach get_alt_entry() about more relocation types")
Link: https://lore.kernel.org/lkml/CAHk-=wiZwq-0LknKhXN4M+T8jbxn_2i9mcKpO+OaBSSq_Eh7tg@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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torvalds authored and gregkh committed Oct 7, 2021
1 parent a7d4cb2 commit fe6f7b7
Showing 1 changed file with 8 additions and 4 deletions.
12 changes: 8 additions & 4 deletions tools/objtool/special.c
Expand Up @@ -110,8 +110,10 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
return -1;
}
if (!reloc2sec_off(orig_reloc, &alt->orig_sec, &alt->orig_off)) {
WARN_FUNC("don't know how to handle reloc symbol type: %s",
sec, offset + entry->orig, orig_reloc->sym->name);
WARN_FUNC("don't know how to handle reloc symbol type %d: %s",
sec, offset + entry->orig,
orig_reloc->sym->type,
orig_reloc->sym->name);
return -1;
}

Expand All @@ -132,8 +134,10 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
return 1;

if (!reloc2sec_off(new_reloc, &alt->new_sec, &alt->new_off)) {
WARN_FUNC("don't know how to handle reloc symbol type: %s",
sec, offset + entry->new, new_reloc->sym->name);
WARN_FUNC("don't know how to handle reloc symbol type %d: %s",
sec, offset + entry->new,
new_reloc->sym->type,
new_reloc->sym->name);
return -1;
}

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