Commit 2e766a1f authored Nov 03, 2024 by Masahiro Yamada

modpost: fix acpi MODULE_DEVICE_TABLE built with mismatched endianness



When CONFIG_SATA_AHCI_PLATFORM=m, modpost outputs incorect acpi
MODULE_ALIAS() if the endianness of the target and the build machine
do not match.

When the endianness of the target kernel and the build machine match,
the output is correct:

  $ grep 'MODULE_ALIAS("acpi' drivers/ata/ahci_platform.mod.c
  MODULE_ALIAS("acpi*:APMC0D33:*");
  MODULE_ALIAS("acpi*:010601:*");

However, when building a little-endian kernel on a big-endian machine
(or vice versa), the output is incorrect:

  $ grep 'MODULE_ALIAS("acpi' drivers/ata/ahci_platform.mod.c
  MODULE_ALIAS("acpi*:APMC0D33:*");
  MODULE_ALIAS("acpi*:0601??:*");

The 'cls' and 'cls_msk' fields are 32-bit.

DEF_FIELD() must be used instead of DEF_FIELD_ADDR() to correctly handle
endianness of these 32-bit fields.

The check 'if (cls)' was unnecessary; it never became NULL, as it was
the pointer to 'symval' plus the offset to the 'cls' field.

Fixes: 26095a01 ("ACPI / scan: Add support for ACPI _CLS device matching")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

parent d01661e1

scripts/mod/file2alias.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -567,12 +567,12 @@ static int do_acpi_entry(const char *filename,
		void symval, char alias)
		{
		DEF_FIELD_ADDR(symval, acpi_device_id, id);
		DEF_FIELD_ADDR(symval, acpi_device_id, cls);
		DEF_FIELD_ADDR(symval, acpi_device_id, cls_msk);
		DEF_FIELD(symval, acpi_device_id, cls);
		DEF_FIELD(symval, acpi_device_id, cls_msk);

		if (id && strlen((const char )id))
		sprintf(alias, "acpi:%s:", *id);
		else if (cls) {
		else {
		int i, byte_shift, cnt = 0;
		unsigned int msk;

		@@ -580,10 +580,10 @@ static int do_acpi_entry(const char *filename,
		cnt = 6;
		for (i = 1; i <= 3; i++) {
		byte_shift = 8 * (3-i);
		msk = (*cls_msk >> byte_shift) & 0xFF;
		msk = (cls_msk >> byte_shift) & 0xFF;
		if (msk)
		sprintf(&alias[cnt], "%02x",
		(*cls >> byte_shift) & 0xFF);
		(cls >> byte_shift) & 0xFF);
		else
		sprintf(&alias[cnt], "??");
		cnt += 2;