linux-kernel - [tip:x86/pti] x86/ldt: Reserve address-space range on 32 bit for the LDT

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Date:   Thu, 19 Jul 2018 16:35:47 -0700
From:   tip-bot for Joerg Roedel <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     jpoimboe@...hat.com, will.deacon@....com, jgross@...e.com,
        boris.ostrovsky@...cle.com, tglx@...utronix.de, mingo@...nel.org,
        peterz@...radead.org, jroedel@...e.de, brgerst@...il.com,
        torvalds@...ux-foundation.org, bp@...en8.de, dave.hansen@...el.com,
        pavel@....cz, dvlasenk@...hat.com, llong@...hat.com,
        aarcange@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, dhgutteridge@...patico.ca,
        David.Laight@...lab.com, luto@...nel.org, jkosina@...e.cz,
        eduval@...zon.com
Subject: [tip:x86/pti] x86/ldt: Reserve address-space range on 32 bit for
 the LDT

Commit-ID:  f3e48e546c42e31c0c095a6f917a4ad64668608c
Gitweb:     https://git.kernel.org/tip/f3e48e546c42e31c0c095a6f917a4ad64668608c
Author:     Joerg Roedel <jroedel@...e.de>
AuthorDate: Wed, 18 Jul 2018 11:41:10 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 20 Jul 2018 01:11:47 +0200

x86/ldt: Reserve address-space range on 32 bit for the LDT

Reserve 2MB/4MB of address-space for mapping the LDT to user-space on 32
bit PTI kernels.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Pavel Machek <pavel@....cz>
Cc: "H . Peter Anvin" <hpa@...or.com>
Cc: linux-mm@...ck.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Brian Gerst <brgerst@...il.com>
Cc: David Laight <David.Laight@...lab.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Eduardo Valentin <eduval@...zon.com>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Will Deacon <will.deacon@....com>
Cc: aliguori@...zon.com
Cc: daniel.gruss@...k.tugraz.at
Cc: hughd@...gle.com
Cc: keescook@...gle.com
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Waiman Long <llong@...hat.com>
Cc: "David H . Gutteridge" <dhgutteridge@...patico.ca>
Cc: joro@...tes.org
Link: https://lkml.kernel.org/r/1531906876-13451-34-git-send-email-joro@8bytes.org

---
 arch/x86/include/asm/pgtable_32_types.h | 7 +++++--
 arch/x86/mm/dump_pagetables.c           | 9 +++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_32_types.h b/arch/x86/include/asm/pgtable_32_types.h
index d9a001a4a872..7297810747cf 100644
--- a/arch/x86/include/asm/pgtable_32_types.h
+++ b/arch/x86/include/asm/pgtable_32_types.h
@@ -50,13 +50,16 @@ extern bool __vmalloc_start_set; /* set once high_memory is set */
 	((FIXADDR_TOT_START - PAGE_SIZE * (CPU_ENTRY_AREA_PAGES + 1))   \
 	 & PMD_MASK)
 
-#define PKMAP_BASE		\
+#define LDT_BASE_ADDR		\
 	((CPU_ENTRY_AREA_BASE - PAGE_SIZE) & PMD_MASK)
 
+#define PKMAP_BASE		\
+	((LDT_BASE_ADDR - PAGE_SIZE) & PMD_MASK)
+
 #ifdef CONFIG_HIGHMEM
 # define VMALLOC_END	(PKMAP_BASE - 2 * PAGE_SIZE)
 #else
-# define VMALLOC_END	(CPU_ENTRY_AREA_BASE - 2 * PAGE_SIZE)
+# define VMALLOC_END	(LDT_BASE_ADDR - 2 * PAGE_SIZE)
 #endif
 
 #define MODULES_VADDR	VMALLOC_START
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index e6fd0cdef9ad..ccd92c4da57c 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -122,6 +122,9 @@ enum address_markers_idx {
 	VMALLOC_END_NR,
 #ifdef CONFIG_HIGHMEM
 	PKMAP_BASE_NR,
+#endif
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+	LDT_NR,
 #endif
 	CPU_ENTRY_AREA_NR,
 	FIXADDR_START_NR,
@@ -135,6 +138,9 @@ static struct addr_marker address_markers[] = {
 	[VMALLOC_END_NR]	= { 0UL,		"vmalloc() End" },
 #ifdef CONFIG_HIGHMEM
 	[PKMAP_BASE_NR]		= { 0UL,		"Persistent kmap() Area" },
+#endif
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+	[LDT_NR]		= { 0UL,		"LDT remap" },
 #endif
 	[CPU_ENTRY_AREA_NR]	= { 0UL,		"CPU entry area" },
 	[FIXADDR_START_NR]	= { 0UL,		"Fixmap area" },
@@ -609,6 +615,9 @@ static int __init pt_dump_init(void)
 # endif
 	address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
 	address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
+# ifdef CONFIG_MODIFY_LDT_SYSCALL
+	address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
+# endif
 #endif
 	return 0;
 }