linux-kernel - [RFC PATCH 07/28] scripts/kallsyms: Avoid 0x0 as the relative base

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Message-ID: <20240925150059.3955569-37-ardb+git@google.com>
Date: Wed, 25 Sep 2024 17:01:07 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-kernel@...r.kernel.org
Cc: Ard Biesheuvel <ardb@...nel.org>, x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
	Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Uros Bizjak <ubizjak@...il.com>, 
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	llvm@...ts.linux.dev
Subject: [RFC PATCH 07/28] scripts/kallsyms: Avoid 0x0 as the relative base

From: Ard Biesheuvel <ardb@...nel.org>

In some cases, LLVM's lld linker may emit the following symbol into the
symbol table

0000000000000000 ? _GLOBAL_OFFSET_TABLE_

and its presence throws off the relative base logic in kallsyms. Since
0x0 is never a valid relative base, just ignore it.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 scripts/kallsyms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 03852da3d249..09757d300a05 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -747,7 +747,7 @@ static void record_relative_base(void)
 	unsigned int i;
 
 	for (i = 0; i < table_cnt; i++)
-		if (!symbol_absolute(table[i])) {
+		if (table[i]->addr && !symbol_absolute(table[i])) {
 			/*
 			 * The table is sorted by address.
 			 * Take the first non-absolute symbol value.
-- 
2.46.0.792.g87dc391469-goog