Commit 6b0a02e8 authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 pti updates from Thomas Gleixner:
 "Another series of PTI related changes:

   - Remove the manual stack switch for user entries from the idtentry
     code. This debloats entry by 5k+ bytes of text.

   - Use the proper types for the asm/bootparam.h defines to prevent
     user space compile errors.

   - Use PAGE_GLOBAL for !PCID systems to gain back performance

   - Prevent setting of huge PUD/PMD entries when the entries are not
     leaf entries otherwise the entries to which the PUD/PMD points to
     and are populated get lost"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/pgtable: Don't set huge PUD/PMD on non-leaf entries
  x86/pti: Leave kernel text global for !PCID
  x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image
  x86/pti: Enable global pages for shared areas
  x86/mm: Do not forbid _PAGE_RW before init for __ro_after_init
  x86/mm: Comment _PAGE_GLOBAL mystery
  x86/mm: Remove extra filtering in pageattr code
  x86/mm: Do not auto-massage page protections
  x86/espfix: Document use of _PAGE_GLOBAL
  x86/mm: Introduce "default" kernel PTE mask
  x86/mm: Undo double _PAGE_PSE clearing
  x86/mm: Factor out pageattr _PAGE_GLOBAL setting
  x86/entry/64: Drop idtentry's manual stack switch for user entries
  x86/uapi: Fix asm/bootparam.h userspace compilation errors
parents 71b8ebbf e3e28812
......@@ -54,6 +54,9 @@ unsigned int ptrs_per_p4d __ro_after_init = 1;
extern unsigned long get_cmd_line_ptr(void);
/* Used by PAGE_KERN* macros: */
pteval_t __default_kernel_pte_mask __read_mostly = ~0;
/* Simplified build-specific string for starting entropy. */
static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
......
......@@ -913,7 +913,7 @@ ENTRY(\sym)
pushq $-1 /* ORIG_RAX: no syscall to restart */
.endif
.if \paranoid < 2
.if \paranoid == 1
testb $3, CS-ORIG_RAX(%rsp) /* If coming from userspace, switch stacks */
jnz .Lfrom_usermode_switch_stack_\@
.endif
......@@ -960,7 +960,7 @@ ENTRY(\sym)
jmp error_exit
.endif
.if \paranoid < 2
.if \paranoid == 1
/*
* Entry from userspace. Switch stacks and treat it
* as a normal entry. This means that paranoid handlers
......
......@@ -526,22 +526,39 @@ static inline pgprotval_t massage_pgprot(pgprot_t pgprot)
return protval;
}
static inline pgprotval_t check_pgprot(pgprot_t pgprot)
{
pgprotval_t massaged_val = massage_pgprot(pgprot);
/* mmdebug.h can not be included here because of dependencies */
#ifdef CONFIG_DEBUG_VM
WARN_ONCE(pgprot_val(pgprot) != massaged_val,
"attempted to set unsupported pgprot: %016llx "
"bits: %016llx supported: %016llx\n",
(u64)pgprot_val(pgprot),
(u64)pgprot_val(pgprot) ^ massaged_val,
(u64)__supported_pte_mask);
#endif
return massaged_val;
}
static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
{
return __pte(((phys_addr_t)page_nr << PAGE_SHIFT) |
massage_pgprot(pgprot));
check_pgprot(pgprot));
}
static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
{
return __pmd(((phys_addr_t)page_nr << PAGE_SHIFT) |
massage_pgprot(pgprot));
check_pgprot(pgprot));
}
static inline pud_t pfn_pud(unsigned long page_nr, pgprot_t pgprot)
{
return __pud(((phys_addr_t)page_nr << PAGE_SHIFT) |
massage_pgprot(pgprot));
check_pgprot(pgprot));
}
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
......@@ -553,7 +570,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
* the newprot (if present):
*/
val &= _PAGE_CHG_MASK;
val |= massage_pgprot(newprot) & ~_PAGE_CHG_MASK;
val |= check_pgprot(newprot) & ~_PAGE_CHG_MASK;
return __pte(val);
}
......@@ -563,7 +580,7 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
pmdval_t val = pmd_val(pmd);
val &= _HPAGE_CHG_MASK;
val |= massage_pgprot(newprot) & ~_HPAGE_CHG_MASK;
val |= check_pgprot(newprot) & ~_HPAGE_CHG_MASK;
return __pmd(val);
}
......
......@@ -196,19 +196,21 @@ enum page_cache_mode {
#define __PAGE_KERNEL_NOENC (__PAGE_KERNEL)
#define __PAGE_KERNEL_NOENC_WP (__PAGE_KERNEL_WP)
#define PAGE_KERNEL __pgprot(__PAGE_KERNEL | _PAGE_ENC)
#define PAGE_KERNEL_NOENC __pgprot(__PAGE_KERNEL)
#define PAGE_KERNEL_RO __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC)
#define PAGE_KERNEL_EXEC __pgprot(__PAGE_KERNEL_EXEC | _PAGE_ENC)
#define PAGE_KERNEL_EXEC_NOENC __pgprot(__PAGE_KERNEL_EXEC)
#define PAGE_KERNEL_RX __pgprot(__PAGE_KERNEL_RX | _PAGE_ENC)
#define PAGE_KERNEL_NOCACHE __pgprot(__PAGE_KERNEL_NOCACHE | _PAGE_ENC)
#define PAGE_KERNEL_LARGE __pgprot(__PAGE_KERNEL_LARGE | _PAGE_ENC)
#define PAGE_KERNEL_LARGE_EXEC __pgprot(__PAGE_KERNEL_LARGE_EXEC | _PAGE_ENC)
#define PAGE_KERNEL_VVAR __pgprot(__PAGE_KERNEL_VVAR | _PAGE_ENC)
#define PAGE_KERNEL_IO __pgprot(__PAGE_KERNEL_IO)
#define PAGE_KERNEL_IO_NOCACHE __pgprot(__PAGE_KERNEL_IO_NOCACHE)
#define default_pgprot(x) __pgprot((x) & __default_kernel_pte_mask)
#define PAGE_KERNEL default_pgprot(__PAGE_KERNEL | _PAGE_ENC)
#define PAGE_KERNEL_NOENC default_pgprot(__PAGE_KERNEL)
#define PAGE_KERNEL_RO default_pgprot(__PAGE_KERNEL_RO | _PAGE_ENC)
#define PAGE_KERNEL_EXEC default_pgprot(__PAGE_KERNEL_EXEC | _PAGE_ENC)
#define PAGE_KERNEL_EXEC_NOENC default_pgprot(__PAGE_KERNEL_EXEC)
#define PAGE_KERNEL_RX default_pgprot(__PAGE_KERNEL_RX | _PAGE_ENC)
#define PAGE_KERNEL_NOCACHE default_pgprot(__PAGE_KERNEL_NOCACHE | _PAGE_ENC)
#define PAGE_KERNEL_LARGE default_pgprot(__PAGE_KERNEL_LARGE | _PAGE_ENC)
#define PAGE_KERNEL_LARGE_EXEC default_pgprot(__PAGE_KERNEL_LARGE_EXEC | _PAGE_ENC)
#define PAGE_KERNEL_VVAR default_pgprot(__PAGE_KERNEL_VVAR | _PAGE_ENC)
#define PAGE_KERNEL_IO default_pgprot(__PAGE_KERNEL_IO)
#define PAGE_KERNEL_IO_NOCACHE default_pgprot(__PAGE_KERNEL_IO_NOCACHE)
#endif /* __ASSEMBLY__ */
......@@ -483,6 +485,7 @@ static inline pgprot_t pgprot_large_2_4k(pgprot_t pgprot)
typedef struct page *pgtable_t;
extern pteval_t __supported_pte_mask;
extern pteval_t __default_kernel_pte_mask;
extern void set_nx(void);
extern int nx_enabled;
......
......@@ -6,8 +6,10 @@
#ifdef CONFIG_PAGE_TABLE_ISOLATION
extern void pti_init(void);
extern void pti_check_boottime_disable(void);
extern void pti_clone_kernel_text(void);
#else
static inline void pti_check_boottime_disable(void) { }
static inline void pti_clone_kernel_text(void) { }
#endif
#endif /* __ASSEMBLY__ */
......
......@@ -137,15 +137,15 @@ struct boot_e820_entry {
* setup data structure.
*/
struct jailhouse_setup_data {
u16 version;
u16 compatible_version;
u16 pm_timer_address;
u16 num_cpus;
u64 pci_mmconfig_base;
u32 tsc_khz;
u32 apic_khz;
u8 standard_ioapic;
u8 cpu_ids[255];
__u16 version;
__u16 compatible_version;
__u16 pm_timer_address;
__u16 num_cpus;
__u64 pci_mmconfig_base;
__u32 tsc_khz;
__u32 apic_khz;
__u8 standard_ioapic;
__u8 cpu_ids[255];
} __attribute__((packed));
/* The so-called "zeropage" */
......
......@@ -195,6 +195,10 @@ void init_espfix_ap(int cpu)
pte_p = pte_offset_kernel(&pmd, addr);
stack_page = page_address(alloc_pages_node(node, GFP_KERNEL, 0));
/*
* __PAGE_KERNEL_* includes _PAGE_GLOBAL, which we want since
* this is mapped to userspace.
*/
pte = __pte(__pa(stack_page) | ((__PAGE_KERNEL_RO | _PAGE_ENC) & ptemask));
for (n = 0; n < ESPFIX_PTE_CLONES; n++)
set_pte(&pte_p[n*PTE_STRIDE], pte);
......
......@@ -195,6 +195,8 @@ unsigned long __head __startup_64(unsigned long physaddr,
pud[i + 1] = (pudval_t)pmd + pgtable_flags;
pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
/* Filter out unsupported __PAGE_KERNEL_* bits: */
pmd_entry &= __supported_pte_mask;
pmd_entry += sme_get_me_mask();
pmd_entry += physaddr;
......
......@@ -399,8 +399,13 @@ NEXT_PAGE(level3_ident_pgt)
.quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
.fill 511, 8, 0
NEXT_PAGE(level2_ident_pgt)
/* Since I easily can, map the first 1G.
/*
* Since I easily can, map the first 1G.
* Don't set NX because code runs from these pages.
*
* Note: This sets _PAGE_GLOBAL despite whether
* the CPU supports it or it is enabled. But,
* the CPU should ignore the bit.
*/
PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
#else
......@@ -431,6 +436,10 @@ NEXT_PAGE(level2_kernel_pgt)
* (NOTE: at +512MB starts the module area, see MODULES_VADDR.
* If you want to increase this then increase MODULES_VADDR
* too.)
*
* This table is eventually used by the kernel during normal
* runtime. Care must be taken to clear out undesired bits
* later, like _PAGE_RW or _PAGE_GLOBAL in some cases.
*/
PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
KERNEL_IMAGE_SIZE/PMD_SIZE)
......
......@@ -145,6 +145,7 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
unsigned long offset = i << PAGE_SHIFT;
const void *src = (char *)ldt->entries + offset;
unsigned long pfn;
pgprot_t pte_prot;
pte_t pte, *ptep;
va = (unsigned long)ldt_slot_va(slot) + offset;
......@@ -163,7 +164,10 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
* target via some kernel interface which misses a
* permission check.
*/
pte = pfn_pte(pfn, __pgprot(__PAGE_KERNEL_RO & ~_PAGE_GLOBAL));
pte_prot = __pgprot(__PAGE_KERNEL_RO & ~_PAGE_GLOBAL);
/* Filter out unsuppored __PAGE_KERNEL* bits: */
pgprot_val(pte_prot) |= __supported_pte_mask;
pte = pfn_pte(pfn, pte_prot);
set_pte_at(mm, va, ptep, pte);
pte_unmap_unlock(ptep, ptl);
}
......
......@@ -27,8 +27,20 @@ EXPORT_SYMBOL(get_cpu_entry_area);
void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags)
{
unsigned long va = (unsigned long) cea_vaddr;
pte_t pte = pfn_pte(pa >> PAGE_SHIFT, flags);
set_pte_vaddr(va, pfn_pte(pa >> PAGE_SHIFT, flags));
/*
* The cpu_entry_area is shared between the user and kernel
* page tables. All of its ptes can safely be global.
* _PAGE_GLOBAL gets reused to help indicate PROT_NONE for
* non-present PTEs, so be careful not to set it in that
* case to avoid confusion.
*/
if (boot_cpu_has(X86_FEATURE_PGE) &&
(pgprot_val(flags) & _PAGE_PRESENT))
pte = pte_set_flags(pte, _PAGE_GLOBAL);
set_pte_vaddr(va, pte);
}
static void __init
......
......@@ -98,6 +98,9 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
if (!info->kernpg_flag)
info->kernpg_flag = _KERNPG_TABLE;
/* Filter out unsupported __PAGE_KERNEL_* bits: */
info->kernpg_flag &= __default_kernel_pte_mask;
for (; addr < end; addr = next) {
pgd_t *pgd = pgd_page + pgd_index(addr);
p4d_t *p4d;
......
......@@ -161,12 +161,6 @@ struct map_range {
static int page_size_mask;
static void enable_global_pages(void)
{
if (!static_cpu_has(X86_FEATURE_PTI))
__supported_pte_mask |= _PAGE_GLOBAL;
}
static void __init probe_page_size_mask(void)
{
/*
......@@ -187,9 +181,15 @@ static void __init probe_page_size_mask(void)
__supported_pte_mask &= ~_PAGE_GLOBAL;
if (boot_cpu_has(X86_FEATURE_PGE)) {
cr4_set_bits_and_update_boot(X86_CR4_PGE);
enable_global_pages();
__supported_pte_mask |= _PAGE_GLOBAL;
}
/* By the default is everything supported: */
__default_kernel_pte_mask = __supported_pte_mask;
/* Except when with PTI where the kernel is mostly non-Global: */
if (cpu_feature_enabled(X86_FEATURE_PTI))
__default_kernel_pte_mask &= ~_PAGE_GLOBAL;
/* Enable 1 GB linear kernel mappings if available: */
if (direct_gbpages && boot_cpu_has(X86_FEATURE_GBPAGES)) {
printk(KERN_INFO "Using GB pages for direct mapping\n");
......
......@@ -558,8 +558,14 @@ static void __init pagetable_init(void)
permanent_kmaps_init(pgd_base);
}
pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL);
#define DEFAULT_PTE_MASK ~(_PAGE_NX | _PAGE_GLOBAL)
/* Bits supported by the hardware: */
pteval_t __supported_pte_mask __read_mostly = DEFAULT_PTE_MASK;
/* Bits allowed in normal kernel mappings: */
pteval_t __default_kernel_pte_mask __read_mostly = DEFAULT_PTE_MASK;
EXPORT_SYMBOL_GPL(__supported_pte_mask);
/* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */
EXPORT_SYMBOL(__default_kernel_pte_mask);
/* user-defined highmem size */
static unsigned int highmem_pages = -1;
......
......@@ -65,8 +65,13 @@
* around without checking the pgd every time.
*/
/* Bits supported by the hardware: */
pteval_t __supported_pte_mask __read_mostly = ~0;
/* Bits allowed in normal kernel mappings: */
pteval_t __default_kernel_pte_mask __read_mostly = ~0;
EXPORT_SYMBOL_GPL(__supported_pte_mask);
/* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */
EXPORT_SYMBOL(__default_kernel_pte_mask);
int force_personality32;
......@@ -1286,6 +1291,12 @@ void mark_rodata_ro(void)
(unsigned long) __va(__pa_symbol(_sdata)));
debug_checkwx();
/*
* Do this after all of the manipulation of the
* kernel text page tables are complete.
*/
pti_clone_kernel_text();
}
int kern_addr_valid(unsigned long addr)
......
......@@ -44,6 +44,9 @@ int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
return ret;
*prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
/* Filter out unsupported __PAGE_KERNEL* bits: */
pgprot_val(*prot) &= __default_kernel_pte_mask;
return 0;
}
EXPORT_SYMBOL_GPL(iomap_create_wc);
......@@ -88,6 +91,9 @@ iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
prot = __pgprot(__PAGE_KERNEL |
cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
/* Filter out unsupported __PAGE_KERNEL* bits: */
pgprot_val(prot) &= __default_kernel_pte_mask;
return (void __force __iomem *) kmap_atomic_prot_pfn(pfn, prot);
}
EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
......
......@@ -816,6 +816,9 @@ void __init __early_set_fixmap(enum fixed_addresses idx,
}
pte = early_ioremap_pte(addr);
/* Sanitize 'prot' against any unsupported bits: */
pgprot_val(flags) &= __default_kernel_pte_mask;
if (pgprot_val(flags))
set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags));
else
......
......@@ -269,6 +269,12 @@ void __init kasan_early_init(void)
pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
/* Mask out unsupported __PAGE_KERNEL bits: */
pte_val &= __default_kernel_pte_mask;
pmd_val &= __default_kernel_pte_mask;
pud_val &= __default_kernel_pte_mask;
p4d_val &= __default_kernel_pte_mask;
for (i = 0; i < PTRS_PER_PTE; i++)
kasan_zero_pte[i] = __pte(pte_val);
......@@ -371,7 +377,13 @@ void __init kasan_init(void)
*/
memset(kasan_zero_page, 0, PAGE_SIZE);
for (i = 0; i < PTRS_PER_PTE; i++) {
pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO | _PAGE_ENC);
pte_t pte;
pgprot_t prot;
prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
pgprot_val(prot) &= __default_kernel_pte_mask;
pte = __pte(__pa(kasan_zero_page) | pgprot_val(prot));
set_pte(&kasan_zero_pte[i], pte);
}
/* Flush TLBs again to be sure that write protection applied. */
......
......@@ -298,9 +298,11 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
/*
* The .rodata section needs to be read-only. Using the pfn
* catches all aliases.
* catches all aliases. This also includes __ro_after_init,
* so do not enforce until kernel_set_to_readonly is true.
*/
if (within(pfn, __pa_symbol(__start_rodata) >> PAGE_SHIFT,
if (kernel_set_to_readonly &&
within(pfn, __pa_symbol(__start_rodata) >> PAGE_SHIFT,
__pa_symbol(__end_rodata) >> PAGE_SHIFT))
pgprot_val(forbidden) |= _PAGE_RW;
......@@ -512,6 +514,23 @@ static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
#endif
}
static pgprot_t pgprot_clear_protnone_bits(pgprot_t prot)
{
/*
* _PAGE_GLOBAL means "global page" for present PTEs.
* But, it is also used to indicate _PAGE_PROTNONE
* for non-present PTEs.
*
* This ensures that a _PAGE_GLOBAL PTE going from
* present to non-present is not confused as
* _PAGE_PROTNONE.
*/
if (!(pgprot_val(prot) & _PAGE_PRESENT))
pgprot_val(prot) &= ~_PAGE_GLOBAL;
return prot;
}
static int
try_preserve_large_page(pte_t *kpte, unsigned long address,
struct cpa_data *cpa)
......@@ -566,6 +585,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
* up accordingly.
*/
old_pte = *kpte;
/* Clear PSE (aka _PAGE_PAT) and move PAT bit to correct position */
req_prot = pgprot_large_2_4k(old_prot);
pgprot_val(req_prot) &= ~pgprot_val(cpa->mask_clr);
......@@ -577,19 +597,9 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
* different bit positions in the two formats.
*/
req_prot = pgprot_4k_2_large(req_prot);
/*
* Set the PSE and GLOBAL flags only if the PRESENT flag is
* set otherwise pmd_present/pmd_huge will return true even on
* a non present pmd. The canon_pgprot will clear _PAGE_GLOBAL
* for the ancient hardware that doesn't support it.
*/
req_prot = pgprot_clear_protnone_bits(req_prot);
if (pgprot_val(req_prot) & _PAGE_PRESENT)
pgprot_val(req_prot) |= _PAGE_PSE | _PAGE_GLOBAL;
else
pgprot_val(req_prot) &= ~(_PAGE_PSE | _PAGE_GLOBAL);
req_prot = canon_pgprot(req_prot);
pgprot_val(req_prot) |= _PAGE_PSE;
/*
* old_pfn points to the large page base pfn. So we need
......@@ -674,8 +684,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
switch (level) {
case PG_LEVEL_2M:
ref_prot = pmd_pgprot(*(pmd_t *)kpte);
/* clear PSE and promote PAT bit to correct position */
/*
* Clear PSE (aka _PAGE_PAT) and move
* PAT bit to correct position.
*/
ref_prot = pgprot_large_2_4k(ref_prot);
ref_pfn = pmd_pfn(*(pmd_t *)kpte);
break;
......@@ -698,23 +712,14 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
return 1;
}
/*
* Set the GLOBAL flags only if the PRESENT flag is set
* otherwise pmd/pte_present will return true even on a non
* present pmd/pte. The canon_pgprot will clear _PAGE_GLOBAL
* for the ancient hardware that doesn't support it.
*/
if (pgprot_val(ref_prot) & _PAGE_PRESENT)
pgprot_val(ref_prot) |= _PAGE_GLOBAL;
else
pgprot_val(ref_prot) &= ~_PAGE_GLOBAL;
ref_prot = pgprot_clear_protnone_bits(ref_prot);
/*
* Get the target pfn from the original entry:
*/
pfn = ref_pfn;
for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot)));
set_pte(&pbase[i], pfn_pte(pfn, ref_prot));
if (virt_addr_valid(address)) {
unsigned long pfn = PFN_DOWN(__pa(address));
......@@ -930,19 +935,7 @@ static void populate_pte(struct cpa_data *cpa,
pte = pte_offset_kernel(pmd, start);
/*
* Set the GLOBAL flags only if the PRESENT flag is
* set otherwise pte_present will return true even on
* a non present pte. The canon_pgprot will clear
* _PAGE_GLOBAL for the ancient hardware that doesn't
* support it.
*/
if (pgprot_val(pgprot) & _PAGE_PRESENT)
pgprot_val(pgprot) |= _PAGE_GLOBAL;
else
pgprot_val(pgprot) &= ~_PAGE_GLOBAL;
pgprot = canon_pgprot(pgprot);
pgprot = pgprot_clear_protnone_bits(pgprot);
while (num_pages-- && start < end) {
set_pte(pte, pfn_pte(cpa->pfn, pgprot));
......@@ -1234,24 +1227,14 @@ static int __change_page_attr(struct cpa_data *cpa, int primary)
new_prot = static_protections(new_prot, address, pfn);
/*
* Set the GLOBAL flags only if the PRESENT flag is
* set otherwise pte_present will return true even on
* a non present pte. The canon_pgprot will clear
* _PAGE_GLOBAL for the ancient hardware that doesn't
* support it.
*/
if (pgprot_val(new_prot) & _PAGE_PRESENT)
pgprot_val(new_prot) |= _PAGE_GLOBAL;
else
pgprot_val(new_prot) &= ~_PAGE_GLOBAL;
new_prot = pgprot_clear_protnone_bits(new_prot);
/*
* We need to keep the pfn from the existing PTE,
* after all we're only going to change it's attributes
* not the memory it points to
*/
new_pte = pfn_pte(pfn, canon_pgprot(new_prot));
new_pte = pfn_pte(pfn, new_prot);
cpa->pfn = pfn;
/*
* Do we really change anything ?
......@@ -1428,11 +1411,11 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages,
memset(&cpa, 0, sizeof(cpa));
/*
* Check, if we are requested to change a not supported
* feature:
* Check, if we are requested to set a not supported
* feature. Clearing non-supported features is OK.
*/
mask_set = canon_pgprot(mask_set);
mask_clr = canon_pgprot(mask_clr);
if (!pgprot_val(mask_set) && !pgprot_val(mask_clr) && !force_split)
return 0;
......@@ -1775,6 +1758,12 @@ int set_memory_4k(unsigned long addr, int numpages)
__pgprot(0), 1, 0, NULL);
}
int set_memory_nonglobal(unsigned long addr, int numpages)
{
return change_page_attr_clear(&addr, numpages,
__pgprot(_PAGE_GLOBAL), 0);
}
static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
{
struct cpa_data cpa;
......
// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/hugetlb.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
......@@ -583,6 +584,9 @@ void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys,
pgprot_t flags)
{
/* Sanitize 'prot' against any unsupported bits: */
pgprot_val(flags) &= __default_kernel_pte_mask;
__native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
}
......@@ -636,6 +640,10 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
(mtrr != MTRR_TYPE_WRBACK))
return 0;
/* Bail out if we are we on a populated non-leaf entry: */
if (pud_present(*pud) && !pud_huge(*pud))
return 0;
prot = pgprot_4k_2_large(prot);
set_pte((pte_t *)pud, pfn_pte(
......@@ -664,6 +672,10 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
return 0;
}
/* Bail out if we are we on a populated non-leaf entry: */
if (pmd_present(*pmd) && !pmd_huge(*pmd))
return 0;
prot = pgprot_4k_2_large(prot);
set_pte((pte_t *)pmd, pfn_pte(
......
......@@ -66,12 +66,22 @@ static void __init pti_print_if_secure(const char *reason)
pr_info("%s\n", reason);
}
enum pti_mode {
PTI_AUTO = 0,
PTI_FORCE_OFF,
PTI_FORCE_ON
} pti_mode;
void __init pti_check_boottime_disable(void)
{
char arg[5];
int ret;
/* Assume mode is auto unless overridden. */
pti_mode = PTI_AUTO;
if (hypervisor_is_type(X86_HYPER_XEN_PV)) {
pti_mode = PTI_FORCE_OFF;
pti_print_if_insecure("disabled on XEN PV.");
return;
}
......@@ -79,18 +89,23 @@ void __init pti_check_boottime_disable(void)
ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg));
if (ret > 0) {
if (ret == 3 && !strncmp(arg, "off", 3)) {
pti_mode = PTI_FORCE_OFF;
pti_print_if_insecure("disabled on command line.");
return;
}
if (ret == 2 && !strncmp(arg, "on", 2)) {
pti_mode = PTI_FORCE_ON;
pti_print_if_secure("force enabled on command line.");
goto enable;
}
if (ret == 4 && !strncmp(arg, "auto", 4))
if (ret == 4 && !strncmp(arg, "auto", 4)) {
pti_mode = PTI_AUTO;
goto autosel;
}
}
if (cmdline_find_option_bool(boot_command_line, "nopti")) {
pti_mode = PTI_FORCE_OFF;
pti_print_if_insecure("disabled on command line.");
return;
}
......@@ -149,7 +164,7 @@ pgd_t __pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)
*
* Returns a pointer to a P4D on success, or NULL on failure.
*/
static __init p4d_t *pti_user_pagetable_walk_p4d(unsigned long address)
static p4d_t *pti_user_pagetable_walk_p4d(unsigned long address)
{
pgd_t *pgd = kernel_to_user_pgdp(pgd_offset_k(address));
gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO);
......@@ -177,7 +192,7 @@ static __init p4d_t *pti_user_pagetable_walk_p4d(unsigned long address)
*
* Returns a pointer to a PMD on success, or NULL on failure.
*/
static __init pmd_t *pti_user_pagetable_walk_pmd(unsigned long address)
static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address)
{
gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO);
p4d_t *p4d = pti_user_pagetable_walk_p4d(address);
......@@ -267,7 +282,7 @@ static void __init pti_setup_vsyscall(void)
static void __init pti_setup_vsyscall(void) { }
#endif
static void __init
static void
pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
{
unsigned long addr;
......@@ -299,6 +314,27 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
if (WARN_ON(!target_pmd))
return;
/*
* Only clone present PMDs. This ensures only setting
* _PAGE_GLOBAL on present PMDs. This should only be
* called on well-known addresses anyway, so a non-
* present PMD would be a surprise.
*/
if (WARN_ON(!(pmd_flags(*pmd) & _PAGE_PRESENT)))
return;
/*
* Setting 'target_pmd' below creates a mapping in both
* the user and kernel page tables. It is effectively
* global, so set it as global in both copies. Note:
* the X86_FEATURE_PGE check is not _required_ because
* the CPU ignores _PAGE_GLOBAL when PGE is not
* supported. The check keeps consistentency with
* code that only set this bit when supported.
*/
if (boot_cpu_has(X86_FEATURE_PGE))
*pmd = pmd_set_flags(*pmd, _PAGE_GLOBAL);
/*
* Copy the PMD. That is, the kernelmode and usermode
* tables will share the last-level page tables of this
......@@ -348,7 +384,83 @@ static void __init pti_clone_entry_text(void)
{
pti_clone_pmds((unsigned long) __entry_text_start,
(unsigned long) __irqentry_text_end,
_PAGE_RW | _PAGE_GLOBAL);
_PAGE_RW);
}
/*
* Global pages and PCIDs are both ways to make kernel TLB entries
* live longer, reduce TLB misses and improve kernel performance.
* But, leaving all kernel text Global makes it potentially accessible
* to Meltdown-style attacks which make it trivial to find gadgets or
* defeat KASLR.
*
* Only use global pages when it is really worth it.
*/
static inline bool pti_kernel_image_global_ok(void)
{
/*
* Systems with PCIDs get litlle benefit from global
* kernel text and are not worth the downsides.