linux-kernel - [PATCH] objtool: Remove reloc symbol type checks in get_alt

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Message-Id: <feadbc3dfb3440d973580fad8d3db873cbfe1694.1633367242.git.jpoimboe@redhat.com>
Date:   Mon,  4 Oct 2021 10:07:50 -0700
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH] objtool: Remove reloc symbol type checks in get_alt_entry()

Converting a special section's relocation reference to a symbol is
straightforward.  No need for objtool to complain that it doesn't know
how to handle it.  Just handle it.

This fixes the following warning:

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

Fixes: 24ff65257375 ("objtool: Teach get_alt_entry() about more relocation types")
Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 tools/objtool/special.c | 32 +++++++-------------------------
 1 file changed, 7 insertions(+), 25 deletions(-)

diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index f58ecc50fb10..83d5f969bcb0 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -58,22 +58,11 @@ void __weak arch_handle_alternative(unsigned short feature, struct special_alt *
 {
 }
 
-static bool reloc2sec_off(struct reloc *reloc, struct section **sec, unsigned long *off)
+static void reloc_to_sec_off(struct reloc *reloc, struct section **sec,
+			     unsigned long *off)
 {
-	switch (reloc->sym->type) {
-	case STT_FUNC:
-		*sec = reloc->sym->sec;
-		*off = reloc->sym->offset + reloc->addend;
-		return true;
-
-	case STT_SECTION:
-		*sec = reloc->sym->sec;
-		*off = reloc->addend;
-		return true;
-
-	default:
-		return false;
-	}
+	*sec = reloc->sym->sec;
+	*off = reloc->sym->offset + reloc->addend;
 }
 
 static int get_alt_entry(struct elf *elf, struct special_entry *entry,
@@ -109,11 +98,8 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
 		WARN_FUNC("can't find orig reloc", sec, offset + entry->orig);
 		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);
-		return -1;
-	}
+
+	reloc_to_sec_off(orig_reloc, &alt->orig_sec, &alt->orig_off);
 
 	if (!entry->group || alt->new_len) {
 		new_reloc = find_reloc_by_dest(elf, sec, offset + entry->new);
@@ -131,11 +117,7 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
 		if (arch_is_retpoline(new_reloc->sym))
 			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);
-			return -1;
-		}
+		reloc_to_sec_off(new_reloc, &alt->new_sec, &alt->new_off);
 
 		/* _ASM_EXTABLE_EX hack */
 		if (alt->new_off >= 0x7ffffff0)
-- 
2.31.1