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

Pull x86 PTI updates from Thomas Gleixner:
 "The Speck brigade sadly provides yet another large set of patches
  destroying the perfomance which we carefully built and preserved

   - PTI support for 32bit PAE. The missing counter part to the 64bit
     PTI code implemented by Joerg.

   - A set of fixes for the Global Bit mechanics for non PCID CPUs which
     were setting the Global Bit too widely and therefore possibly
     exposing interesting memory needlessly.

   - Protection against userspace-userspace SpectreRSB

   - Support for the upcoming Enhanced IBRS mode, which is preferred
     over IBRS. Unfortunately we dont know the performance impact of
     this, but it's expected to be less horrible than the IBRS
     hammering.

   - Cleanups and simplifications"

* 'x86/pti' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
  x86/mm/pti: Move user W+X check into pti_finalize()
  x86/relocs: Add __end_rodata_aligned to S_REL
  x86/mm/pti: Clone kernel-image on PTE level for 32 bit
  x86/mm/pti: Don't clear permissions in pti_clone_pmd()
  x86/mm/pti: Fix 32 bit PCID check
  x86/mm/init: Remove freed kernel image areas from alias mapping
  x86/mm/init: Add helper for freeing kernel image pages
  x86/mm/init: Pass unconverted symbol addresses to free_init_pages()
  mm: Allow non-direct-map arguments to free_reserved_area()
  x86/mm/pti: Clear Global bit more aggressively
  x86/speculation: Support Enhanced IBRS on future CPUs
  x86/speculation: Protect against userspace-userspace spectreRSB
  x86/kexec: Allocate 8k PGDs for PTI
  Revert "perf/core: Make sure the ring-buffer is mapped in all page-tables"
  x86/mm: Remove in_nmi() warning from vmalloc_fault()
  x86/entry/32: Check for VM86 mode in slow-path check
  perf/core: Make sure the ring-buffer is mapped in all page-tables
  x86/pti: Check the return value of pti_user_pagetable_walk_pmd()
  x86/pti: Check the return value of pti_user_pagetable_walk_p4d()
  x86/entry/32: Add debug code to check entry/exit CR3
  ...

1 files changed, 84 insertions, 21 deletions

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 0f1683fcb196..3ef095c70ae3 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -182,6 +182,14 @@ static void pgd_dtor(pgd_t *pgd)
  */
 #define PREALLOCATED_PMDS	UNSHARED_PTRS_PER_PGD
 
+/*
+ * We allocate separate PMDs for the kernel part of the user page-table
+ * when PTI is enabled. We need them to map the per-process LDT into the
+ * user-space page-table.
+ */
+#define PREALLOCATED_USER_PMDS	 (static_cpu_has(X86_FEATURE_PTI) ? \
+					KERNEL_PGD_PTRS : 0)
+
 void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
 {
 	paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
@@ -202,14 +210,14 @@ void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
 
 /* No need to prepopulate any pagetable entries in non-PAE modes. */
 #define PREALLOCATED_PMDS	0
-
+#define PREALLOCATED_USER_PMDS	 0
 #endif	/* CONFIG_X86_PAE */
 
-static void free_pmds(struct mm_struct *mm, pmd_t *pmds[])
+static void free_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
 {
 	int i;
 
-	for(i = 0; i < PREALLOCATED_PMDS; i++)
+	for (i = 0; i < count; i++)
 		if (pmds[i]) {
 			pgtable_pmd_page_dtor(virt_to_page(pmds[i]));
 			free_page((unsigned long)pmds[i]);
@@ -217,7 +225,7 @@ static void free_pmds(struct mm_struct *mm, pmd_t *pmds[])
 		}
 }
 
-static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[])
+static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
 {
 	int i;
 	bool failed = false;
@@ -226,7 +234,7 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[])
 	if (mm == &init_mm)
 		gfp &= ~__GFP_ACCOUNT;
 
-	for(i = 0; i < PREALLOCATED_PMDS; i++) {
+	for (i = 0; i < count; i++) {
 		pmd_t *pmd = (pmd_t *)__get_free_page(gfp);
 		if (!pmd)
 			failed = true;
@@ -241,7 +249,7 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[])
 	}
 
 	if (failed) {
-		free_pmds(mm, pmds);
+		free_pmds(mm, pmds, count);
 		return -ENOMEM;
 	}
 
@@ -254,23 +262,38 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[])
  * preallocate which never got a corresponding vma will need to be
  * freed manually.
  */
+static void mop_up_one_pmd(struct mm_struct *mm, pgd_t *pgdp)
+{
+	pgd_t pgd = *pgdp;
+
+	if (pgd_val(pgd) != 0) {
+		pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
+
+		*pgdp = native_make_pgd(0);
+
+		paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT);
+		pmd_free(mm, pmd);
+		mm_dec_nr_pmds(mm);
+	}
+}
+
 static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
 {
 	int i;
 
-	for(i = 0; i < PREALLOCATED_PMDS; i++) {
-		pgd_t pgd = pgdp[i];
+	for (i = 0; i < PREALLOCATED_PMDS; i++)
+		mop_up_one_pmd(mm, &pgdp[i]);
 
-		if (pgd_val(pgd) != 0) {
-			pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
 
-			pgdp[i] = native_make_pgd(0);
+	if (!static_cpu_has(X86_FEATURE_PTI))
+		return;
 
-			paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT);
-			pmd_free(mm, pmd);
-			mm_dec_nr_pmds(mm);
-		}
-	}
+	pgdp = kernel_to_user_pgdp(pgdp);
+
+	for (i = 0; i < PREALLOCATED_USER_PMDS; i++)
+		mop_up_one_pmd(mm, &pgdp[i + KERNEL_PGD_BOUNDARY]);
+#endif
 }
 
 static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
@@ -296,6 +319,38 @@ static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
 	}
 }
 
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
+				     pgd_t *k_pgd, pmd_t *pmds[])
+{
+	pgd_t *s_pgd = kernel_to_user_pgdp(swapper_pg_dir);
+	pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd);
+	p4d_t *u_p4d;
+	pud_t *u_pud;
+	int i;
+
+	u_p4d = p4d_offset(u_pgd, 0);
+	u_pud = pud_offset(u_p4d, 0);
+
+	s_pgd += KERNEL_PGD_BOUNDARY;
+	u_pud += KERNEL_PGD_BOUNDARY;
+
+	for (i = 0; i < PREALLOCATED_USER_PMDS; i++, u_pud++, s_pgd++) {
+		pmd_t *pmd = pmds[i];
+
+		memcpy(pmd, (pmd_t *)pgd_page_vaddr(*s_pgd),
+		       sizeof(pmd_t) * PTRS_PER_PMD);
+
+		pud_populate(mm, u_pud, pmd);
+	}
+
+}
+#else
+static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
+				     pgd_t *k_pgd, pmd_t *pmds[])
+{
+}
+#endif
 /*
  * Xen paravirt assumes pgd table should be in one page. 64 bit kernel also
  * assumes that pgd should be in one page.
@@ -340,7 +395,8 @@ static inline pgd_t *_pgd_alloc(void)
 	 * We allocate one page for pgd.
 	 */
 	if (!SHARED_KERNEL_PMD)
-		return (pgd_t *)__get_free_page(PGALLOC_GFP);
+		return (pgd_t *)__get_free_pages(PGALLOC_GFP,
+						 PGD_ALLOCATION_ORDER);
 
 	/*
 	 * Now PAE kernel is not running as a Xen domain. We can allocate
@@ -352,7 +408,7 @@ static inline pgd_t *_pgd_alloc(void)
 static inline void _pgd_free(pgd_t *pgd)
 {
 	if (!SHARED_KERNEL_PMD)
-		free_page((unsigned long)pgd);
+		free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
 	else
 		kmem_cache_free(pgd_cache, pgd);
 }
@@ -372,6 +428,7 @@ static inline void _pgd_free(pgd_t *pgd)
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
 	pgd_t *pgd;
+	pmd_t *u_pmds[PREALLOCATED_USER_PMDS];
 	pmd_t *pmds[PREALLOCATED_PMDS];
 
 	pgd = _pgd_alloc();
@@ -381,12 +438,15 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
 
 	mm->pgd = pgd;
 
-	if (preallocate_pmds(mm, pmds) != 0)
+	if (preallocate_pmds(mm, pmds, PREALLOCATED_PMDS) != 0)
 		goto out_free_pgd;
 
-	if (paravirt_pgd_alloc(mm) != 0)
+	if (preallocate_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS) != 0)
 		goto out_free_pmds;
 
+	if (paravirt_pgd_alloc(mm) != 0)
+		goto out_free_user_pmds;
+
 	/*
 	 * Make sure that pre-populating the pmds is atomic with
 	 * respect to anything walking the pgd_list, so that they
@@ -396,13 +456,16 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
 
 	pgd_ctor(mm, pgd);
 	pgd_prepopulate_pmd(mm, pgd, pmds);
+	pgd_prepopulate_user_pmd(mm, pgd, u_pmds);
 
 	spin_unlock(&pgd_lock);
 
 	return pgd;
 
+out_free_user_pmds:
+	free_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS);
 out_free_pmds:
-	free_pmds(mm, pmds);
+	free_pmds(mm, pmds, PREALLOCATED_PMDS);
 out_free_pgd:
 	_pgd_free(pgd);
 out: