linux-kernel - [PATCH v2] modpost: Don't let "driver"s reference .exit.*

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Message-Id: <20230930165204.2478282-1-u.kleine-koenig@pengutronix.de>
Date:   Sat, 30 Sep 2023 18:52:04 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, linux-kbuild@...r.kernel.org,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        coresight@...ts.linaro.org,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org,
        Nathan Chancellor <nathan@...nel.org>,
        James Clark <james.clark@....com>, kernel@...gutronix.de,
        Leo Yan <leo.yan@...aro.org>,
        Nicolas Schier <nicolas@...sle.eu>,
        linux-arm-kernel@...ts.infradead.org,
        Mike Leach <mike.leach@...aro.org>
Subject: [PATCH v2] modpost: Don't let "driver"s reference .exit.*

Drivers must not reference functions marked with __exit as these likely
are not available when the code is built-in.

There are few creative offenders uncovered for example in ARCH=amd64
allmodconfig builds. So only trigger the section mismatch warning for
W=1 builds.

The dual rule that drivers must not reference .init.* is implemented
since commit 0db252452378 ("modpost: don't allow *driver to reference
.init.*") which however missed that .exit.* should be handled in the
same way.

Thanks to Masahiro Yamada and Arnd Bergmann who gave valuable hints to
find this improvement.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
Hello,

changes since (implicit) v1, sent with Message-Id:
20230930140601.2457711-1-u.kleine-koenig@...gutronix.de:

 - enable the warning about .data -> .exit.* only in W=1 builds to keep
   normal builds without warnings. *sigh*
 - improved commit log and mention the above item.
 - updated the code comment to match the code

Thanks
Uwe

 scripts/mod/modpost.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index de499dce5265..b3dee80497cb 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1015,9 +1015,20 @@ static int secref_whitelist(const char *fromsec, const char *fromsym,
 				    "*_console")))
 		return 0;
 
-	/* symbols in data sections that may refer to meminit/exit sections */
+	/* symbols in data sections that may refer to meminit sections */
 	if (match(fromsec, PATTERNS(DATA_SECTIONS)) &&
-	    match(tosec, PATTERNS(ALL_XXXINIT_SECTIONS, ALL_EXIT_SECTIONS)) &&
+	    match(tosec, PATTERNS(ALL_XXXINIT_SECTIONS, ALL_XXXEXIT_SECTIONS)) &&
+	    match(fromsym, PATTERNS("*driver")))
+		return 0;
+
+	/*
+	 * symbols in data sections must not refer to .exit.*, but there are
+	 * quite a few offenders, so hide these unless for W=1 builds until
+	 * these are fixed.
+	 */
+	if (!extra_warn &&
+	    match(fromsec, PATTERNS(DATA_SECTIONS)) &&
+	    match(tosec, PATTERNS(EXIT_SECTIONS)) &&
 	    match(fromsym, PATTERNS("*driver")))
 		return 0;
 

base-commit: 6465e260f48790807eef06b583b38ca9789b6072
-- 
2.40.1