linux-kernel - [PATCH 5.10 042/148] objtool: print out the symbol type when complaining about it

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Date:   Sat, 23 Jul 2022 11:54:14 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 5.10 042/148] objtool: print out the symbol type when complaining about it

From: Linus Torvalds <torvalds@...ux-foundation.org>

commit 7fab1c12bde926c5a8c7d5984c551d0854d7e0b3 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: 24ff65257375 ("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@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 tools/objtool/special.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -106,8 +106,10 @@ static int get_alt_entry(struct elf *elf
 		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;
 	}
 
@@ -128,8 +130,10 @@ static int get_alt_entry(struct elf *elf
 			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;
 		}