[PATCH 29/34] x86/ldt: Reserve address-space range on 32 bit for the LDT

[Joerg Roedel]

From: Joerg Roedel <jroe...@suse.de>

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

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 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 0777e18..eb2e97a 100644
--- a/arch/x86/include/asm/pgtable_32_types.h
+++ b/arch/x86/include/asm/pgtable_32_types.h
@@ -48,13 +48,16 @@ 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 2151ebb..fdefdf0 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -117,6 +117,9 @@ enum address_markers_idx {
 #ifdef CONFIG_HIGHMEM
        PKMAP_BASE_NR,
 #endif
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+       LDT_NR,
+#endif
        CPU_ENTRY_AREA_NR,
        FIXADDR_START_NR,
        END_OF_SPACE_NR,
@@ -130,6 +133,9 @@ static struct addr_marker address_markers[] = {
 #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" },
        [END_OF_SPACE_NR]       = { -1,                 NULL }
@@ -579,6 +585,9 @@ 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;
 }
-- 
2.7.4