This approach helps to ensure that side-channel attacks leveraging
the paging structures do not function when PTI is enabled. It can be
-enabled by setting CONFIG_PAGE_TABLE_ISOLATION=y at compile time.
-Once enabled at compile-time, it can be disabled at boot with the
-'nopti' or 'pti=' kernel parameters (see kernel-parameters.txt).
+enabled by setting CONFIG_MITIGATION_PAGE_TABLE_ISOLATION=y at compile
+time. Once enabled at compile-time, it can be disabled at boot with
+the 'nopti' or 'pti=' kernel parameters (see kernel-parameters.txt).
Page Table Management
=====================
if SPECULATION_MITIGATIONS
-config PAGE_TABLE_ISOLATION
+config MITIGATION_PAGE_TABLE_ISOLATION
bool "Remove the kernel mapping in user mode"
default y
depends on (X86_64 || X86_PAE)
* Copyright (C) 2016 Kees Cook
*/
-/* No PAGE_TABLE_ISOLATION support needed either: */
-#undef CONFIG_PAGE_TABLE_ISOLATION
+/* No MITIGATION_PAGE_TABLE_ISOLATION support needed either: */
+#undef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
#include "error.h"
#include "misc.h"
.endif
.endm
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
/*
- * PAGE_TABLE_ISOLATION PGDs are 8k. Flip bit 12 to switch between the two
+ * MITIGATION_PAGE_TABLE_ISOLATION PGDs are 8k. Flip bit 12 to switch between the two
* halves:
*/
#define PTI_USER_PGTABLE_BIT PAGE_SHIFT
.macro ADJUST_KERNEL_CR3 reg:req
ALTERNATIVE "", "SET_NOFLUSH_BIT \reg", X86_FEATURE_PCID
- /* Clear PCID and "PAGE_TABLE_ISOLATION bit", point CR3 at kernel pagetables: */
+ /* Clear PCID and "MITIGATION_PAGE_TABLE_ISOLATION bit", point CR3 at kernel pagetables: */
andq $(~PTI_USER_PGTABLE_AND_PCID_MASK), \reg
.endm
.Lend_\@:
.endm
-#else /* CONFIG_PAGE_TABLE_ISOLATION=n: */
+#else /* CONFIG_MITIGATION_PAGE_TABLE_ISOLATION=n: */
.macro SWITCH_TO_KERNEL_CR3 scratch_reg:req
.endm
#ifdef CONFIG_XEN_PV
ALTERNATIVE "", "jmp xenpv_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV
#endif
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
ALTERNATIVE "", "jmp .Lpti_restore_regs_and_return_to_usermode", X86_FEATURE_PTI
#endif
jnz .Lnative_iret
ud2
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
.Lpti_restore_regs_and_return_to_usermode:
POP_REGS pop_rdi=0
*
* Registers:
* %r14: Used to save/restore the CR3 of the interrupted context
- * when PAGE_TABLE_ISOLATION is in use. Do not clobber.
+ * when MITIGATION_PAGE_TABLE_ISOLATION is in use. Do not clobber.
*/
SYM_CODE_START(asm_exc_nmi)
UNWIND_HINT_IRET_ENTRY
# define DISABLE_LA57 (1<<(X86_FEATURE_LA57 & 31))
#endif
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
# define DISABLE_PTI 0
#else
# define DISABLE_PTI (1 << (X86_FEATURE_PTI & 31))
*/
extern gfp_t __userpte_alloc_gfp;
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
/*
* Instead of one PGD, we acquire two PGDs. Being order-1, it is
* both 8k in size and 8k-aligned. That lets us just flip bit 12
static inline void native_set_pud(pud_t *pudp, pud_t pud)
{
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
pud.p4d.pgd = pti_set_user_pgtbl(&pudp->p4d.pgd, pud.p4d.pgd);
#endif
pxx_xchg64(pud, pudp, native_pud_val(pud));
pmd_t *populate_extra_pmd(unsigned long vaddr);
pte_t *populate_extra_pte(unsigned long vaddr);
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
pgd_t __pti_set_user_pgtbl(pgd_t *pgdp, pgd_t pgd);
/*
return pgd;
return __pti_set_user_pgtbl(pgdp, pgd);
}
-#else /* CONFIG_PAGE_TABLE_ISOLATION */
+#else /* CONFIG_MITIGATION_PAGE_TABLE_ISOLATION */
static inline pgd_t pti_set_user_pgtbl(pgd_t *pgdp, pgd_t pgd)
{
return pgd;
}
-#endif /* CONFIG_PAGE_TABLE_ISOLATION */
+#endif /* CONFIG_MITIGATION_PAGE_TABLE_ISOLATION */
#endif /* __ASSEMBLY__ */
{
unsigned long ignore_flags = _KERNPG_TABLE | _PAGE_USER;
- if (IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION))
+ if (IS_ENABLED(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION))
ignore_flags |= _PAGE_NX;
return (p4d_flags(p4d) & ~ignore_flags) != 0;
if (!pgtable_l5_enabled())
return 0;
- if (IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION))
+ if (IS_ENABLED(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION))
ignore_flags |= _PAGE_NX;
return (pgd_flags(pgd) & ~ignore_flags) != _KERNPG_TABLE;
#define pgd_leaf pgd_large
static inline int pgd_large(pgd_t pgd) { return 0; }
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
/*
- * All top-level PAGE_TABLE_ISOLATION page tables are order-1 pages
+ * All top-level MITIGATION_PAGE_TABLE_ISOLATION page tables are order-1 pages
* (8k-aligned and 8k in size). The kernel one is at the beginning 4k and
* the user one is in the last 4k. To switch between them, you
* just need to flip the 12th bit in their addresses.
{
return ptr_clear_bit(p4dp, PTI_PGTABLE_SWITCH_BIT);
}
-#endif /* CONFIG_PAGE_TABLE_ISOLATION */
+#endif /* CONFIG_MITIGATION_PAGE_TABLE_ISOLATION */
/*
* clone_pgd_range(pgd_t *dst, pgd_t *src, int count);
static inline void clone_pgd_range(pgd_t *dst, pgd_t *src, int count)
{
memcpy(dst, src, count * sizeof(pgd_t));
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
if (!static_cpu_has(X86_FEATURE_PTI))
return;
/* Clone the user space pgd as well */
{
pgd_t pgd;
- if (pgtable_l5_enabled() || !IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION)) {
+ if (pgtable_l5_enabled() ||
+ !IS_ENABLED(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION)) {
WRITE_ONCE(*p4dp, p4d);
return;
}
#define CR3_NOFLUSH 0
#endif
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
# define X86_CR3_PTI_PCID_USER_BIT 11
#endif
#define _ASM_X86_PTI_H
#ifndef __ASSEMBLY__
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
extern void pti_init(void);
extern void pti_check_boottime_disable(void);
extern void pti_finalize(void);
IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
- IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
+ IS_ENABLED(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION) ?
(boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
}
NOKPROBE_SYMBOL(__die_header);
.align 4
SYM_DATA(initial_code, .long i386_start_kernel)
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
#define PGD_ALIGN (2 * PAGE_SIZE)
#define PTI_USER_PGD_FILL 1024
#else
# endif
.align PAGE_SIZE /* needs to be page-sized too */
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
/*
* PTI needs another page so sync_initial_pagetable() works correctly
* and does not scribble over the data which is placed behind the
#define SYM_DATA_START_PAGE_ALIGNED(name) \
SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
/*
* Each PGD needs to be 8k long and 8k aligned. We do not
* ever go out to userspace with these, so we do not
return new_ldt;
}
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
static void do_sanity_check(struct mm_struct *mm,
bool had_kernel_mapping,
flush_tlb_mm_range(mm, va, va + nr_pages * PAGE_SIZE, PAGE_SHIFT, false);
}
-#else /* !CONFIG_PAGE_TABLE_ISOLATION */
+#else /* !CONFIG_MITIGATION_PAGE_TABLE_ISOLATION */
static int
map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
static void unmap_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt)
{
}
-#endif /* CONFIG_PAGE_TABLE_ISOLATION */
+#endif /* CONFIG_MITIGATION_PAGE_TABLE_ISOLATION */
static void free_ldt_pgtables(struct mm_struct *mm)
{
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
struct mmu_gather tlb;
unsigned long start = LDT_BASE_ADDR;
unsigned long end = LDT_END_ADDR;
obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o
obj-$(CONFIG_RANDOMIZE_MEMORY) += kaslr.o
-obj-$(CONFIG_PAGE_TABLE_ISOLATION) += pti.o
+obj-$(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION) += pti.o
obj-$(CONFIG_X86_MEM_ENCRYPT) += mem_encrypt.o
obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt_amd.o
DEFINE_SHOW_ATTRIBUTE(ptdump_curknl);
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
static int ptdump_curusr_show(struct seq_file *m, void *v)
{
if (current->mm->pgd)
debugfs_create_file("current_kernel", 0400, dir, NULL,
&ptdump_curknl_fops);
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
debugfs_create_file("current_user", 0400, dir, NULL,
&ptdump_curusr_fops);
#endif
bool user)
{
pgd_t *pgd = mm->pgd;
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
if (user && boot_cpu_has(X86_FEATURE_PTI))
pgd = kernel_to_user_pgdp(pgd);
#endif
void ptdump_walk_user_pgd_level_checkwx(void)
{
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
pgd_t *pgd = INIT_PGD;
if (!(__supported_pte_mask & _PAGE_NX) ||
for (i = 0; i < PREALLOCATED_PMDS; i++)
mop_up_one_pmd(mm, &pgdp[i]);
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
if (!boot_cpu_has(X86_FEATURE_PTI))
return;
}
}
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
pgd_t *k_pgd, pmd_t *pmds[])
{
#define CR3_HW_ASID_BITS 12
/*
- * When enabled, PAGE_TABLE_ISOLATION consumes a single bit for
+ * When enabled, MITIGATION_PAGE_TABLE_ISOLATION consumes a single bit for
* user/kernel switches
*/
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
# define PTI_CONSUMED_PCID_BITS 1
#else
# define PTI_CONSUMED_PCID_BITS 0
{
VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
/*
* Make sure that the dynamic ASID space does not conflict with the
* bit we are using to switch between user and kernel ASIDs.
static inline u16 user_pcid(u16 asid)
{
u16 ret = kern_pcid(asid);
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
ret |= 1 << X86_CR3_PTI_PCID_USER_BIT;
#endif
return ret;
static inline void invalidate_user_asid(u16 asid)
{
/* There is no user ASID if address space separation is off */
- if (!IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION))
+ if (!IS_ENABLED(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION))
return;
/*
#ifndef _INCLUDE_PTI_H
#define _INCLUDE_PTI_H
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
#include <asm/pti.h>
#else
static inline void pti_init(void) { }
# define DISABLE_LA57 (1<<(X86_FEATURE_LA57 & 31))
#endif
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
+#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
# define DISABLE_PTI 0
#else
# define DISABLE_PTI (1 << (X86_FEATURE_PTI & 31))