#define __GFP_NOTRACK 0
#endif
+/*
+ * Define the page-table levels we clone for user-space on 32
+ * and 64 bit.
+ */
+#ifdef CONFIG_X86_64
+#define PTI_LEVEL_KERNEL_IMAGE PTI_CLONE_PMD
+#else
+#define PTI_LEVEL_KERNEL_IMAGE PTI_CLONE_PTE
+#endif
+
static void __init pti_print_if_insecure(const char *reason)
{
if (boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
if (pgd_none(*pgd)) {
unsigned long new_p4d_page = __get_free_page(gfp);
- if (!new_p4d_page)
+ if (WARN_ON_ONCE(!new_p4d_page))
return NULL;
set_pgd(pgd, __pgd(_KERNPG_TABLE | __pa(new_p4d_page)));
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);
+ p4d_t *p4d;
pud_t *pud;
+ p4d = pti_user_pagetable_walk_p4d(address);
+ if (!p4d)
+ return NULL;
+
BUILD_BUG_ON(p4d_large(*p4d) != 0);
if (p4d_none(*p4d)) {
unsigned long new_pud_page = __get_free_page(gfp);
- if (!new_pud_page)
+ if (WARN_ON_ONCE(!new_pud_page))
return NULL;
set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page)));
}
if (pud_none(*pud)) {
unsigned long new_pmd_page = __get_free_page(gfp);
- if (!new_pmd_page)
+ if (WARN_ON_ONCE(!new_pmd_page))
return NULL;
set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page)));
return pmd_offset(pud, address);
}
-#ifdef CONFIG_X86_VSYSCALL_EMULATION
/*
* Walk the shadow copy of the page tables (optionally) trying to allocate
* page table pages on the way down. Does not support large pages.
static __init pte_t *pti_user_pagetable_walk_pte(unsigned long address)
{
gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO);
- pmd_t *pmd = pti_user_pagetable_walk_pmd(address);
+ pmd_t *pmd;
pte_t *pte;
+ pmd = pti_user_pagetable_walk_pmd(address);
+ if (!pmd)
+ return NULL;
+
/* We can't do anything sensible if we hit a large mapping. */
if (pmd_large(*pmd)) {
WARN_ON(1);
return pte;
}
+#ifdef CONFIG_X86_VSYSCALL_EMULATION
static void __init pti_setup_vsyscall(void)
{
pte_t *pte, *target_pte;
static void __init pti_setup_vsyscall(void) { }
#endif
+enum pti_clone_level {
+ PTI_CLONE_PMD,
+ PTI_CLONE_PTE,
+};
+
static void
-pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
+pti_clone_pgtable(unsigned long start, unsigned long end,
+ enum pti_clone_level level)
{
unsigned long addr;
* Clone the populated PMDs which cover start to end. These PMD areas
* can have holes.
*/
- for (addr = start; addr < end; addr += PMD_SIZE) {
+ for (addr = start; addr < end;) {
+ pte_t *pte, *target_pte;
pmd_t *pmd, *target_pmd;
pgd_t *pgd;
p4d_t *p4d;
p4d = p4d_offset(pgd, addr);
if (WARN_ON(p4d_none(*p4d)))
return;
+
pud = pud_offset(p4d, addr);
- if (pud_none(*pud))
+ if (pud_none(*pud)) {
+ addr += PUD_SIZE;
continue;
+ }
+
pmd = pmd_offset(pud, addr);
- if (pmd_none(*pmd))
+ if (pmd_none(*pmd)) {
+ addr += PMD_SIZE;
continue;
+ }
- target_pmd = pti_user_pagetable_walk_pmd(addr);
- 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
- * address range
- */
- *target_pmd = pmd_clear_flags(*pmd, clear);
+ if (pmd_large(*pmd) || level == PTI_CLONE_PMD) {
+ target_pmd = pti_user_pagetable_walk_pmd(addr);
+ 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
+ * address range
+ */
+ *target_pmd = *pmd;
+
+ addr += PMD_SIZE;
+
+ } else if (level == PTI_CLONE_PTE) {
+
+ /* Walk the page-table down to the pte level */
+ pte = pte_offset_kernel(pmd, addr);
+ if (pte_none(*pte)) {
+ addr += PAGE_SIZE;
+ continue;
+ }
+
+ /* Only clone present PTEs */
+ if (WARN_ON(!(pte_flags(*pte) & _PAGE_PRESENT)))
+ return;
+
+ /* Allocate PTE in the user page-table */
+ target_pte = pti_user_pagetable_walk_pte(addr);
+ if (WARN_ON(!target_pte))
+ return;
+
+ /* Set GLOBAL bit in both PTEs */
+ if (boot_cpu_has(X86_FEATURE_PGE))
+ *pte = pte_set_flags(*pte, _PAGE_GLOBAL);
+
+ /* Clone the PTE */
+ *target_pte = *pte;
+
+ addr += PAGE_SIZE;
+
+ } else {
+ BUG();
+ }
}
}
pgd_t *kernel_pgd;
user_p4d = pti_user_pagetable_walk_p4d(addr);
+ if (!user_p4d)
+ return;
+
kernel_pgd = pgd_offset_k(addr);
kernel_p4d = p4d_offset(kernel_pgd, addr);
*user_p4d = *kernel_p4d;
start = CPU_ENTRY_AREA_BASE;
end = start + (PAGE_SIZE * CPU_ENTRY_AREA_PAGES);
- pti_clone_pmds(start, end, 0);
+ pti_clone_pgtable(start, end, PTI_CLONE_PMD);
}
#endif /* CONFIG_X86_64 */
*/
static void pti_clone_entry_text(void)
{
- pti_clone_pmds((unsigned long) __entry_text_start,
- (unsigned long) __irqentry_text_end,
- _PAGE_RW);
+ pti_clone_pgtable((unsigned long) __entry_text_start,
+ (unsigned long) __irqentry_text_end,
+ PTI_CLONE_PMD);
}
/*
return true;
}
+/*
+ * This is the only user for these and it is not arch-generic
+ * like the other set_memory.h functions. Just extern them.
+ */
+extern int set_memory_nonglobal(unsigned long addr, int numpages);
+extern int set_memory_global(unsigned long addr, int numpages);
+
/*
* For some configurations, map all of kernel text into the user page
* tables. This reduces TLB misses, especially on non-PCID systems.
* clone the areas past rodata, they might contain secrets.
*/
unsigned long start = PFN_ALIGN(_text);
- unsigned long end = (unsigned long)__end_rodata_aligned;
+ unsigned long end_clone = (unsigned long)__end_rodata_aligned;
+ unsigned long end_global = PFN_ALIGN((unsigned long)__stop___ex_table);
if (!pti_kernel_image_global_ok())
return;
* pti_set_kernel_image_nonglobal() did to clear the
* global bit.
*/
- pti_clone_pmds(start, end, 0);
+ pti_clone_pgtable(start, end_clone, PTI_LEVEL_KERNEL_IMAGE);
+
+ /*
+ * pti_clone_pgtable() will set the global bit in any PMDs
+ * that it clones, but we also need to get any PTEs in
+ * the last level for areas that are not huge-page-aligned.
+ */
+
+ /* Set the global bit for normal non-__init kernel text: */
+ set_memory_global(start, (end_global - start) >> PAGE_SHIFT);
}
-/*
- * 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);
-static void pti_set_kernel_image_nonglobal(void)
+void pti_set_kernel_image_nonglobal(void)
{
/*
* The identity map is created with PMDs, regardless of the
unsigned long start = PFN_ALIGN(_text);
unsigned long end = ALIGN((unsigned long)_end, PMD_PAGE_SIZE);
- if (pti_kernel_image_global_ok())
- return;
-
+ /*
+ * This clears _PAGE_GLOBAL from the entire kernel image.
+ * pti_clone_kernel_text() map put _PAGE_GLOBAL back for
+ * areas that are mapped to userspace.
+ */
set_memory_nonglobal(start, (end - start) >> PAGE_SHIFT);
}
pr_info("enabled\n");
+#ifdef CONFIG_X86_32
+ /*
+ * We check for X86_FEATURE_PCID here. But the init-code will
+ * clear the feature flag on 32 bit because the feature is not
+ * supported on 32 bit anyway. To print the warning we need to
+ * check with cpuid directly again.
+ */
+ if (cpuid_ecx(0x1) & BIT(17)) {
+ /* Use printk to work around pr_fmt() */
+ printk(KERN_WARNING "\n");
+ printk(KERN_WARNING "************************************************************\n");
+ printk(KERN_WARNING "** WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! **\n");
+ printk(KERN_WARNING "** **\n");
+ printk(KERN_WARNING "** You are using 32-bit PTI on a 64-bit PCID-capable CPU. **\n");
+ printk(KERN_WARNING "** Your performance will increase dramatically if you **\n");
+ printk(KERN_WARNING "** switch to a 64-bit kernel! **\n");
+ printk(KERN_WARNING "** **\n");
+ printk(KERN_WARNING "** WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! **\n");
+ printk(KERN_WARNING "************************************************************\n");
+ }
+#endif
+
pti_clone_user_shared();
/* Undo all global bits from the init pagetables in head_64.S: */
*/
pti_clone_entry_text();
pti_clone_kernel_text();
+
+ debug_checkwx_user();
}
git.samba.org / sfrench / cifs-2.6.git / blobdiff