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From:   Masahiro Yamada <masahiroy@kernel.org>
To:     linux-kbuild@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Masahiro Yamada <masahiroy@kernel.org>,
        Hans de Goede <hdegoede@redhat.com>,
        Jiri Kosina <jkosina@suse.cz>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= <linux@weissschuh.net>
Subject: [PATCH 2/5] modpost: fix ishtp MODULE_DEVICE_TABLE built on big endian host
Date:   Sun,  8 Oct 2023 02:04:45 +0900
Message-Id: <20231007170448.505487-2-masahiroy@kernel.org>
In-Reply-To: <20231007170448.505487-1-masahiroy@kernel.org>
References: <20231007170448.505487-1-masahiroy@kernel.org>
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When MODULE_DEVICE_TABLE(ishtp, ) is built on a host with a different
endianness from the target architecture, it results in an incorrect
MODULE_ALIAS().

For example, see a case where drivers/platform/x86/intel/ishtp_eclite.c
is built as a module.

If you build it on a little endian host, you will get the correct
MODULE_ALIAS:

    $ grep MODULE_ALIAS drivers/platform/x86/intel/ishtp_eclite.mod.c
    MODULE_ALIAS("ishtp:{6A19CC4B-D760-4DE3-B14D-F25EBD0FBCD9}");

However, if you build it on a big endian host, you will get a wrong
MODULE_ALIAS:

    $ grep MODULE_ALIAS drivers/platform/x86/intel/ishtp_eclite.mod.c
    MODULE_ALIAS("ishtp:{BD0FBCD9-F25E-B14D-4DE3-D7606A19CC4B}");

This issue has been unnoticed because the x86 kernel is most likely built
natively on an x86 host.

The guid field must not be reversed because guid_t is an array of __u8.

Fixes: fa443bc3c1e4 ("HID: intel-ish-hid: add support for MODULE_DEVICE_TABLE()")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/mod/file2alias.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 70bf6a2f585c..6583b36dbe69 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1401,10 +1401,10 @@ static int do_mhi_ep_entry(const char *filename, void *symval, char *alias)
 /* Looks like: ishtp:{guid} */
 static int do_ishtp_entry(const char *filename, void *symval, char *alias)
 {
-	DEF_FIELD(symval, ishtp_device_id, guid);
+	DEF_FIELD_ADDR(symval, ishtp_device_id, guid);
 
 	strcpy(alias, ISHTP_MODULE_PREFIX "{");
-	add_guid(alias, guid);
+	add_guid(alias, *guid);
 	strcat(alias, "}");
 
 	return 1;
-- 
2.39.2