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authorBaoquan He <bhe@redhat.com>2017-08-16 16:46:51 +0300
committerIngo Molnar <mingo@kernel.org>2017-08-17 11:50:57 +0300
commit02e43c2dcd3b3cf7244f6dda65a07e8dacadaf8d (patch)
treea33b802734e0ee58aa4dd3bd1539bf09b6e22901 /include/linux/efi.h
parent2257e268b1154966c5b0141b23695db1043ff39d (diff)
downloadlinux-02e43c2dcd3b3cf7244f6dda65a07e8dacadaf8d.tar.xz
efi: Introduce efi_early_memdesc_ptr to get pointer to memmap descriptor
The existing map iteration helper for_each_efi_memory_desc_in_map can only be used after the kernel initializes the EFI subsystem to set up struct efi_memory_map. Before that we also need iterate map descriptors which are stored in several intermediate structures, like struct efi_boot_memmap for arch independent usage and struct efi_info for x86 arch only. Introduce efi_early_memdesc_ptr() to get pointer to a map descriptor, and replace several places where that primitive is open coded. Signed-off-by: Baoquan He <bhe@redhat.com> [ Various improvements to the text. ] Acked-by: Matt Fleming <matt@codeblueprint.co.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: ard.biesheuvel@linaro.org Cc: fanc.fnst@cn.fujitsu.com Cc: izumi.taku@jp.fujitsu.com Cc: keescook@chromium.org Cc: linux-efi@vger.kernel.org Cc: n-horiguchi@ah.jp.nec.com Cc: thgarnie@google.com Link: http://lkml.kernel.org/r/20170816134651.GF21273@x1 Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/efi.h')
-rw-r--r--include/linux/efi.h22
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8269bcb8ccf7..a686ca9a7e5c 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1020,6 +1020,28 @@ extern int efi_memattr_init(void);
extern int efi_memattr_apply_permissions(struct mm_struct *mm,
efi_memattr_perm_setter fn);
+/*
+ * efi_early_memdesc_ptr - get the n-th EFI memmap descriptor
+ * @map: the start of efi memmap
+ * @desc_size: the size of space for each EFI memmap descriptor
+ * @n: the index of efi memmap descriptor
+ *
+ * EFI boot service provides the GetMemoryMap() function to get a copy of the
+ * current memory map which is an array of memory descriptors, each of
+ * which describes a contiguous block of memory. It also gets the size of the
+ * map, and the size of each descriptor, etc.
+ *
+ * Note that per section 6.2 of UEFI Spec 2.6 Errata A, the returned size of
+ * each descriptor might not be equal to sizeof(efi_memory_memdesc_t),
+ * since efi_memory_memdesc_t may be extended in the future. Thus the OS
+ * MUST use the returned size of the descriptor to find the start of each
+ * efi_memory_memdesc_t in the memory map array. This should only be used
+ * during bootup since for_each_efi_memory_desc_xxx() is available after the
+ * kernel initializes the EFI subsystem to set up struct efi_memory_map.
+ */
+#define efi_early_memdesc_ptr(map, desc_size, n) \
+ (efi_memory_desc_t *)((void *)(map) + ((n) * (desc_size)))
+
/* Iterate through an efi_memory_map */
#define for_each_efi_memory_desc_in_map(m, md) \
for ((md) = (m)->map; \