linux-kernel - [PATCH PTI v3 09/10] x86/mm/64: Make a full PGD-entry size hole in the memory map

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Message-Id: <711fab2fa394edf9b3a538caae4110ff24c54ec9.1513035461.git.luto@kernel.org>
Date:   Tue, 12 Dec 2017 07:56:44 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
        Brian Gerst <brgerst@...il.com>,
        David Laight <David.Laight@...lab.com>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Dave Hansen <dave.hansen@...el.com>
Subject: [PATCH PTI v3 09/10] x86/mm/64: Make a full PGD-entry size hole in the memory map

This patch shrinks vmalloc space from 16384TiB to 12800TiB to
enlarge the hole starting at 0xff90000000000000 to be a full PGD
entry.

A subsequent patch will use this hole for the pagetable isolation
LDT alias.

Cc: "Kirill A. Shutemov" <kirill@...temov.name>
Cc: Dave Hansen <dave.hansen@...el.com>
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 Documentation/x86/x86_64/mm.txt         | 4 ++--
 arch/x86/include/asm/pgtable_64_types.h | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index 63a41671d25b..6a28aeaccd53 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -28,8 +28,8 @@ Virtual memory map with 5 level page tables:
 hole caused by [56:63] sign extension
 ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor
 ff10000000000000 - ff8fffffffffffff (=55 bits) direct mapping of all phys. memory
-ff90000000000000 - ff91ffffffffffff (=49 bits) hole
-ff92000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space
+ff90000000000000 - ff9fffffffffffff (=52 bits) hole
+ffa0000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space
 ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole
 ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB)
 ... unused hole ...
diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index 6d5f45dcd4a1..6e2f50843c7d 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -78,8 +78,8 @@ typedef struct { pteval_t pte; } pte_t;
 /* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
 #define MAXMEM		_AC(__AC(1, UL) << MAX_PHYSMEM_BITS, UL)
 #ifdef CONFIG_X86_5LEVEL
-#define VMALLOC_SIZE_TB _AC(16384, UL)
-#define __VMALLOC_BASE	_AC(0xff92000000000000, UL)
+#define VMALLOC_SIZE_TB _AC(12800, UL)
+#define __VMALLOC_BASE	_AC(0xffa0000000000000, UL)
 #define __VMEMMAP_BASE	_AC(0xffd4000000000000, UL)
 #else
 #define VMALLOC_SIZE_TB	_AC(32, UL)
-- 
2.13.6