Thread (17 messages) 17 messages, 5 authors, 2015-07-06

[PATCH v3 2/3] ACPI / ARM64: add BAD_MADT_GICC_ENTRY() macro

From: catalin.marinas@arm.com (Catalin Marinas)
Date: 2015-07-03 14:06:12
Also in: linux-acpi, lkml

On Thu, Jul 02, 2015 at 05:48:35PM -0600, Al Stone wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 39248d3..a3c26a4 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -19,6 +19,17 @@
 #include <asm/psci.h>
 #include <asm/smp_plat.h>
 
+/* Macros for consistency checks of the GICC subtable of MADT */
+#define ACPI_MADT_GICC_51_LENGTH       76
+#define ACPI_MADT_GICC_60_LENGTH       80
+
+#define BAD_MADT_GICC_ENTRY(entry, end) (                                   \
+		(!entry) || (unsigned long)entry + sizeof(*entry) > end ||  \
+		((ACPI_FADT_SPEC_VERSION == ACPI_FADT_SPEC_VERSION_51) &&   \
+		 (entry->header.length != ACPI_MADT_GICC_51_LENGTH))    ||  \
+		((ACPI_FADT_SPEC_VERSION == ACPI_FADT_SPEC_VERSION_60) &&   \
+		 (entry->header.length != ACPI_MADT_GICC_60_LENGTH)))
This looks ugly but, well, we could live with this.

However, I'd like to avoid having to extend this macro every time we get
a new spec released, like 6.1 defining another 80 or 84 etc. So, how
about we only update this when there is an actual change in the length?
Something like:

#define ACPI_MADT_GICC_LENGTH	({					\
	u8 length;							\
	if (ACPI_FADT_SPEC_VERSION < ACPI_FADT_SPEC_VERSION_6_0)	\
		length = 76;						\
	else								\
		length = 80;						\
	length;								\
})

or just:

#define ACPI_MADT_GICC_LENGTH	\
	(ACPI_FADT_SPEC_VERSION < ACPI_FADT_SPEC_VERSION_6_0 ? 76 : 80)

(the latter is simpler but may not look nice if we change it again in
6.1; though we could re-write this macro when needed, not a problem)

-- 
Catalin
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