linux-kernel - [tip: objtool/core] objtool: Make find_symbol

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Message-ID: <176060838453.709179.413070869789332949.tip-bot2@tip-bot2>
Date: Thu, 16 Oct 2025 09:53:04 -0000
From: "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Petr Mladek <pmladek@...e.com>, Joe Lawrence <joe.lawrence@...hat.com>,
 Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject:
 [tip: objtool/core] objtool: Make find_symbol_containing() less arbitrary

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     07e1c3fd86d7a2ddce3ebc6b7390590c8524a484
Gitweb:        https://git.kernel.org/tip/07e1c3fd86d7a2ddce3ebc6b7390590c8524a484
Author:        Josh Poimboeuf <jpoimboe@...nel.org>
AuthorDate:    Wed, 17 Sep 2025 09:03:21 -07:00
Committer:     Josh Poimboeuf <jpoimboe@...nel.org>
CommitterDate: Tue, 14 Oct 2025 14:45:23 -07:00

objtool: Make find_symbol_containing() less arbitrary

In the rare case of overlapping symbols, find_symbol_containing() just
returns the first one it finds.  Make it slightly less arbitrary by
returning the smallest symbol with size > 0.

Acked-by: Petr Mladek <pmladek@...e.com>
Tested-by: Joe Lawrence <joe.lawrence@...hat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/elf.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index ca5d77d..1c1bb2c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -193,14 +193,29 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
 {
 	struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
-	struct symbol *iter;
+	struct symbol *sym = NULL, *tmp;
 
-	__sym_for_each(iter, tree, offset, offset) {
-		if (iter->type != STT_SECTION)
-			return iter;
+	__sym_for_each(tmp, tree, offset, offset) {
+		if (tmp->len) {
+			if (!sym) {
+				sym = tmp;
+				continue;
+			}
+
+			if (sym->offset != tmp->offset || sym->len != tmp->len) {
+				/*
+				 * In the rare case of overlapping symbols,
+				 * pick the smaller one.
+				 *
+				 * TODO: outlaw overlapping symbols
+				 */
+				if (tmp->len < sym->len)
+					sym = tmp;
+			}
+		}
 	}
 
-	return NULL;
+	return sym;
 }
 
 /*