[PATCH v2 5/7] xen/arm: acpi: add BAD_MADT_GICC_ENTRY() macro

[Julien Grall <julien@xxxxxxx>]

From: Julien Grall <julien.grall@xxxxxxx>

Imported from Linux commit b6cfb277378ef831c0fa84bcff5049307294adc6:

    The BAD_MADT_ENTRY() macro is designed to work for all of the subtables
    of the MADT.  In the ACPI 5.1 version of the spec, the struct for the
    GICC subtable (struct acpi_madt_generic_interrupt) is 76 bytes long; in
    ACPI 6.0, the struct is 80 bytes long.  But, there is only one definition
    in ACPICA for this struct -- and that is the 6.0 version.  Hence, when
    BAD_MADT_ENTRY() compares the struct size to the length in the GICC
    subtable, it fails if 5.1 structs are in use, and there are systems in
    the wild that have them.

    This patch adds the BAD_MADT_GICC_ENTRY() that checks the GICC subtable
    only, accounting for the difference in specification versions that are
    possible.  The BAD_MADT_ENTRY() will continue to work as is for all other
    MADT subtables.

    This code is being added to an arm64 header file since that is currently
    the only architecture using the GICC subtable of the MADT.  As a GIC is
    specific to ARM, it is also unlikely the subtable will be used elsewhere.

    Fixes: aeb823bbacc2 ("ACPICA: ACPI 6.0: Add changes for FADT table.")
    Signed-off-by: Al Stone <al.stone@xxxxxxxxxx>
    Acked-by: Will Deacon <will.deacon@xxxxxxx>
    Acked-by: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
    [catalin.marinas@xxxxxxx: extra brackets around macro arguments]
    Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

---

Changes in v2:
    - Patch added

We may want to consider to also import:

commit 9eb1c92b47c73249465d388eaa394fe436a3b489
Author: Jeremy Linton <jeremy.linton@xxxxxxx>
Date:   Tue Nov 27 17:59:12 2018 +0000

    arm64: acpi: Prepare for longer MADTs

    The BAD_MADT_GICC_ENTRY check is a little too strict because
    it rejects MADT entries that don't match the currently known
    lengths. We should remove this restriction to avoid problems
    if the table length changes. Future code which might depend on
    additional fields should be written to validate those fields
    before using them, rather than trying to globally check
    known MADT version lengths.

    Link: 
https://lkml.kernel.org/r/20181012192937.3819951-1-jeremy.linton@xxxxxxx
    Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
    [lorenzo.pieralisi@xxxxxxx: added MADT macro comments]
    Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
    Acked-by: Sudeep Holla <sudeep.holla@xxxxxxx>
    Cc: Will Deacon <will.deacon@xxxxxxx>
    Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
    Cc: Al Stone <ahs3@xxxxxxxxxx>
    Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
    Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
---
 xen/include/asm-arm/acpi.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/include/asm-arm/acpi.h b/xen/include/asm-arm/acpi.h
index 50340281a917..b52ae2d6ef72 100644
--- a/xen/include/asm-arm/acpi.h
+++ b/xen/include/asm-arm/acpi.h
@@ -54,6 +54,14 @@ void acpi_smp_init_cpus(void);
  */
 paddr_t acpi_get_table_offset(struct membank tbl_add[], EFI_MEM_RES index);
 
+/* Macros for consistency checks of the GICC subtable of MADT */
+#define ACPI_MADT_GICC_LENGTH  \
+    (acpi_gbl_FADT.header.revision < 6 ? 76 : 80)
+
+#define BAD_MADT_GICC_ENTRY(entry, end)                                        
        \
+    (!(entry) || (unsigned long)(entry) + sizeof(*(entry)) > (end) ||  \
+     (entry)->header.length != ACPI_MADT_GICC_LENGTH)
+
 #ifdef CONFIG_ACPI
 extern bool acpi_disabled;
 /* Basic configuration for ACPI */
-- 
2.17.1