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From:   Oscar Carter <oscar.carter@gmx.com>
To:     Kees Cook <keescook@chromium.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jason Cooper <jason@lakedaemon.net>,
        Marc Zyngier <maz@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>
Cc:     Oscar Carter <oscar.carter@gmx.com>,
        kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org
Subject: [PATCH v4 1/3] drivers/acpi: Add new macro ACPI_DECLARE_SUBTABLE_PROBE_ENTRY
Date:   Sat, 30 May 2020 16:12:16 +0200
Message-Id: <20200530141218.4690-2-oscar.carter@gmx.com>
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In an effort to enable -Wcast-function-type in the top-level Makefile to
support Control Flow Integrity builds, there are the need to remove all
the function callback casts.

To do this, create a new macro called ACPI_DECLARE_SUBTABLE_PROBE_ENTRY
to initialize the acpi_probe_entry struct using the probe_subtbl field
instead of the probe_table field. This is a previous work to be able to
modify the IRQCHIP_ACPI_DECLARE macro to use this new defined macro.

Even though these two commented fields are part of a union, this is
necessary to avoid function cast mismatches. That is, due to the
IRQCHIP_ACPI_DECLARE invocations use as last parameter a function with
the protoype "int (*func)(struct acpi_subtable_header *, const unsigned
long)" it's necessary that this macro initialize the probe_subtbl field
of the acpi_probe_entry struct and not the probe_table field.

Signed-off-by: Oscar Carter <oscar.carter@gmx.com>
=2D--
 include/linux/acpi.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index d661cd0ee64d..cf74e044a570 100644
=2D-- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1154,6 +1154,17 @@ struct acpi_probe_entry {
 			.driver_data =3D data, 				\
 		   }

+#define ACPI_DECLARE_SUBTABLE_PROBE_ENTRY(table, name, table_id,	\
+					  subtable, valid, data, fn)	\
+	static const struct acpi_probe_entry __acpi_probe_##name	\
+		__used __section(__##table##_acpi_probe_table) =3D {	\
+			.id =3D table_id,					\
+			.type =3D subtable,				\
+			.subtable_valid =3D valid,			\
+			.probe_subtbl =3D fn,				\
+			.driver_data =3D data,				\
+		}
+
 #define ACPI_PROBE_TABLE(name)		__##name##_acpi_probe_table
 #define ACPI_PROBE_TABLE_END(name)	__##name##_acpi_probe_table_end

=2D-
2.20.1