efi: Implement generic support for the Memory Attributes table

This implements shared support for discovering the presence of the
Memory Attributes table, and for parsing and validating its contents.

The table is validated against the construction rules in the UEFI spec.
Since this is a new table, it makes sense to complain if we encounter
a table that does not follow those rules.

The parsing and validation routine takes a callback that can be specified
per architecture, that gets passed each unique validated region, with the
virtual address retrieved from the ordinary memory map.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[ Trim pr_*() strings to 80 cols and use EFI consistently. ]
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1461614832-17633-14-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 81af5feba1f7..e29a31d0fc35 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -969,6 +969,19 @@ extern void __init efi_fake_memmap(void);
 static inline void efi_fake_memmap(void) { }
 #endif
 
+/*
+ * efi_memattr_perm_setter - arch specific callback function passed into
+ *                           efi_memattr_apply_permissions() that updates the
+ *                           mapping permissions described by the second
+ *                           argument in the page tables referred to by the
+ *                           first argument.
+ */
+typedef int (*efi_memattr_perm_setter)(struct mm_struct *, efi_memory_desc_t *);
+
+extern int efi_memattr_init(void);
+extern int efi_memattr_apply_permissions(struct mm_struct *mm,
+					 efi_memattr_perm_setter fn);
+
 /* Iterate through an efi_memory_map */
 #define for_each_efi_memory_desc_in_map(m, md)				   \
 	for ((md) = (m)->map;						   \