[xen staging] xen/arm: acpi: add BAD_MADT_GICC_ENTRY() macro

[patchbot@xxxxxxx]

commit 7056f2f89f03f2f804ac7e776c7b2b000cd716cd
Author:     Julien Grall <julien.grall@xxxxxxx>
AuthorDate: Wed Sep 30 12:25:04 2020 +0100
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Fri Oct 30 18:47:14 2020 +0000

    xen/arm: acpi: add BAD_MADT_GICC_ENTRY() macro
    
    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>
    Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    Tested-by: Elliott Mitchell <ehem+xen@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 50340281a9..b52ae2d6ef 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 */
--
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