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Subject[GIT pull] x86/pti updates for 4.17
Linus,

please pull the latest x86-pti-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-pti-for-linus

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.

Thanks,

tglx

------------------>
Andy Lutomirski (1):
x86/entry/64: Drop idtentry's manual stack switch for user entries

Dave Hansen (11):
x86/mm: Factor out pageattr _PAGE_GLOBAL setting
x86/mm: Undo double _PAGE_PSE clearing
x86/mm: Introduce "default" kernel PTE mask
x86/espfix: Document use of _PAGE_GLOBAL
x86/mm: Do not auto-massage page protections
x86/mm: Remove extra filtering in pageattr code
x86/mm: Comment _PAGE_GLOBAL mystery
x86/mm: Do not forbid _PAGE_RW before init for __ro_after_init
x86/pti: Enable global pages for shared areas
x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image
x86/pti: Leave kernel text global for !PCID

Dmitry V. Levin (1):
x86/uapi: Fix asm/bootparam.h userspace compilation errors

Joerg Roedel (1):
x86/pgtable: Don't set huge PUD/PMD on non-leaf entries


arch/x86/boot/compressed/kaslr.c | 3 +
arch/x86/entry/entry_64.S | 4 +-
arch/x86/include/asm/pgtable.h | 27 ++++++--
arch/x86/include/asm/pgtable_types.h | 29 ++++----
arch/x86/include/asm/pti.h | 2 +
arch/x86/include/uapi/asm/bootparam.h | 18 ++---
arch/x86/kernel/espfix_64.c | 4 ++
arch/x86/kernel/head64.c | 2 +
arch/x86/kernel/head_64.S | 11 ++-
arch/x86/kernel/ldt.c | 6 +-
arch/x86/mm/cpu_entry_area.c | 14 +++-
arch/x86/mm/ident_map.c | 3 +
arch/x86/mm/init.c | 14 ++--
arch/x86/mm/init_32.c | 8 ++-
arch/x86/mm/init_64.c | 11 +++
arch/x86/mm/iomap_32.c | 6 ++
arch/x86/mm/ioremap.c | 3 +
arch/x86/mm/kasan_init_64.c | 14 +++-
arch/x86/mm/pageattr.c | 97 ++++++++++++--------------
arch/x86/mm/pgtable.c | 12 ++++
arch/x86/mm/pti.c | 126 ++++++++++++++++++++++++++++++++--
arch/x86/power/hibernate_64.c | 20 ++++--
22 files changed, 329 insertions(+), 105 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 66e42a098d70..a0a50b91ecef 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -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;
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 936e19642eab..cb1d8a3b870b 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -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
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 89d5c8886c85..5f49b4ff0c24 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -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);
}
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index acfe755562a6..1e5a40673953 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -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;

diff --git a/arch/x86/include/asm/pti.h b/arch/x86/include/asm/pti.h
index 0b5ef05b2d2d..38a17f1d5c9d 100644
--- a/arch/x86/include/asm/pti.h
+++ b/arch/x86/include/asm/pti.h
@@ -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__ */
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index aebf60357758..a06cbf019744 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -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" */
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
index e5ec3cafa72e..aebd0d5bc086 100644
--- a/arch/x86/kernel/espfix_64.c
+++ b/arch/x86/kernel/espfix_64.c
@@ -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);
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 0c855deee165..0c408f8c4ed4 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -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;

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 48385c1074a5..8344dd2f310a 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -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)
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 26d713ecad34..d41d896481b8 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -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);
}
diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c
index 476d810639a8..b45f5aaefd74 100644
--- a/arch/x86/mm/cpu_entry_area.c
+++ b/arch/x86/mm/cpu_entry_area.c
@@ -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
diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index 9aa22be8331e..a2f0c7e20fb0 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -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;
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 82f5252c723a..fec82b577c18 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -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");
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 396e1f0151ac..07cdc2ed4965 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -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;
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 45241de66785..6d1ff39c2438 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -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;

@@ -1285,6 +1290,12 @@ 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)
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index ada98b39b8ad..b3294d36769d 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -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);
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index e2db83bebc3b..c63a545ec199 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -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
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index d8ff013ea9d0..980dbebd0ca7 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -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. */
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 85cf12219dea..0f3d50f4c48c 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -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;
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 34cda7e0551b..ffc8c13c50e4 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -1,6 +1,7 @@
// 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(
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 631507f0c198..f1fd52f449e0 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -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.
+ */
+ if (cpu_feature_enabled(X86_FEATURE_PCID))
+ return false;
+
+ /*
+ * Only do global kernel image for pti=auto. Do the most
+ * secure thing (not global) if pti=on specified.
+ */
+ if (pti_mode != PTI_AUTO)
+ return false;
+
+ /*
+ * K8 may not tolerate the cleared _PAGE_RW on the userspace
+ * global kernel image pages. Do the safe thing (disable
+ * global kernel image). This is unlikely to ever be
+ * noticed because PTI is disabled by default on AMD CPUs.
+ */
+ if (boot_cpu_has(X86_FEATURE_K8))
+ return false;
+
+ return true;
+}
+
+/*
+ * For some configurations, map all of kernel text into the user page
+ * tables. This reduces TLB misses, especially on non-PCID systems.
+ */
+void pti_clone_kernel_text(void)
+{
+ unsigned long start = PFN_ALIGN(_text);
+ unsigned long end = ALIGN((unsigned long)_end, PMD_PAGE_SIZE);
+
+ if (!pti_kernel_image_global_ok())
+ return;
+
+ pti_clone_pmds(start, end, _PAGE_RW);
+}
+
+/*
+ * This is the only user for it and it is not arch-generic like
+ * the other set_memory.h functions. Just extern it.
+ */
+extern int set_memory_nonglobal(unsigned long addr, int numpages);
+void pti_set_kernel_image_nonglobal(void)
+{
+ /*
+ * The identity map is created with PMDs, regardless of the
+ * actual length of the kernel. We need to clear
+ * _PAGE_GLOBAL up to a PMD boundary, not just to the end
+ * of the image.
+ */
+ unsigned long start = PFN_ALIGN(_text);
+ unsigned long end = ALIGN((unsigned long)_end, PMD_PAGE_SIZE);
+
+ if (pti_kernel_image_global_ok())
+ return;
+
+ pr_debug("set kernel image non-global\n");
+
+ set_memory_nonglobal(start, (end - start) >> PAGE_SHIFT);
}

/*
@@ -362,6 +474,10 @@ void __init pti_init(void)
pr_info("enabled\n");

pti_clone_user_shared();
+
+ /* Undo all global bits from the init pagetables in head_64.S: */
+ pti_set_kernel_image_nonglobal();
+ /* Replace some of the global bits just for shared entry text: */
pti_clone_entry_text();
pti_setup_espfix64();
pti_setup_vsyscall();
diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
index 74a532989308..48b14b534897 100644
--- a/arch/x86/power/hibernate_64.c
+++ b/arch/x86/power/hibernate_64.c
@@ -51,6 +51,12 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
pmd_t *pmd;
pud_t *pud;
p4d_t *p4d = NULL;
+ pgprot_t pgtable_prot = __pgprot(_KERNPG_TABLE);
+ pgprot_t pmd_text_prot = __pgprot(__PAGE_KERNEL_LARGE_EXEC);
+
+ /* Filter out unsupported __PAGE_KERNEL* bits: */
+ pgprot_val(pmd_text_prot) &= __default_kernel_pte_mask;
+ pgprot_val(pgtable_prot) &= __default_kernel_pte_mask;

/*
* The new mapping only has to cover the page containing the image
@@ -81,15 +87,19 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
return -ENOMEM;

set_pmd(pmd + pmd_index(restore_jump_address),
- __pmd((jump_address_phys & PMD_MASK) | __PAGE_KERNEL_LARGE_EXEC));
+ __pmd((jump_address_phys & PMD_MASK) | pgprot_val(pmd_text_prot)));
set_pud(pud + pud_index(restore_jump_address),
- __pud(__pa(pmd) | _KERNPG_TABLE));
+ __pud(__pa(pmd) | pgprot_val(pgtable_prot)));
if (p4d) {
- set_p4d(p4d + p4d_index(restore_jump_address), __p4d(__pa(pud) | _KERNPG_TABLE));
- set_pgd(pgd + pgd_index(restore_jump_address), __pgd(__pa(p4d) | _KERNPG_TABLE));
+ p4d_t new_p4d = __p4d(__pa(pud) | pgprot_val(pgtable_prot));
+ pgd_t new_pgd = __pgd(__pa(p4d) | pgprot_val(pgtable_prot));
+
+ set_p4d(p4d + p4d_index(restore_jump_address), new_p4d);
+ set_pgd(pgd + pgd_index(restore_jump_address), new_pgd);
} else {
/* No p4d for 4-level paging: point the pgd to the pud page table */
- set_pgd(pgd + pgd_index(restore_jump_address), __pgd(__pa(pud) | _KERNPG_TABLE));
+ pgd_t new_pgd = __pgd(__pa(p4d) | pgprot_val(pgtable_prot));
+ set_pgd(pgd + pgd_index(restore_jump_address), new_pgd);
}

return 0;
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