[tip:x86/efi] Documentation/x86: Update EFI memory region description

[tip-bot for Matt Fleming]

Commit-ID:  ff3d0a12fb2dc123e2b46e9524ebf4e08de5c59c
Gitweb:     http://git.kernel.org/tip/ff3d0a12fb2dc123e2b46e9524ebf4e08de5c59c
Author:     Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
AuthorDate: Fri, 27 Nov 2015 21:09:35 +0000
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sun, 29 Nov 2015 09:15:43 +0100

Documentation/x86: Update EFI memory region description

Make it clear that the EFI page tables are only available during
EFI runtime calls since that subject has come up a fair numbers
of times in the past.

Additionally, add the EFI region start and end addresses to the
table so that it's possible to see at a glance where they fall
in relation to other regions.

Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Cc: Stephen Smalley <sds@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1448658575-17029-7-git-send-email-matt@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 Documentation/x86/x86_64/mm.txt | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index 05712ac..c518dce 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -16,6 +16,8 @@ ffffec0000000000 - fffffc0000000000 (=44 bits) kasan shadow memory (16TB)
 ... unused hole ...
 ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
 ... unused hole ...
+ffffffef00000000 - ffffffff00000000 (=64 GB) EFI region mapping space
+... unused hole ...
 ffffffff80000000 - ffffffffa0000000 (=512 MB)  kernel text mapping, from phys 0
 ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space
 ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
@@ -32,11 +34,9 @@ reference.
 Current X86-64 implementations only support 40 bits of address space,
 but we support up to 46 bits. This expands into MBZ space in the page tables.
 
-->trampoline_pgd:
-
-We map EFI runtime services in the aforementioned PGD in the virtual
-range of 64Gb (arbitrarily set, can be raised if needed)
-
-0xffffffef00000000 - 0xffffffff00000000
+We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual
+memory window (this size is arbitrary, it can be raised later if needed).
+The mappings are not part of any other kernel PGD and are only available
+during EFI runtime calls.
 
 -Andi Kleen, Jul 2004
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