[PATCH v5 1/3] drivers/acpi: Add new macro ACPI_DECLARE_SUBTABLE_PROBE_ENTRY

From: Oscar Carter
Date: Sat May 30 2020 - 10:35:24 EST


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.

Co-developed-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Oscar Carter <oscar.carter@xxxxxxx>
---
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
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1154,6 +1154,17 @@ struct acpi_probe_entry {
.driver_data = 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) = { \
+ .id = table_id, \
+ .type = subtable, \
+ .subtable_valid = valid, \
+ .probe_subtbl = fn, \
+ .driver_data = data, \
+ }
+
#define ACPI_PROBE_TABLE(name) __##name##_acpi_probe_table
#define ACPI_PROBE_TABLE_END(name) __##name##_acpi_probe_table_end

--
2.20.1