v4.19.13 snapshot.
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
new file mode 100644
index 0000000..1e95d57
--- /dev/null
+++ b/arch/x86/mm/mmap.c
@@ -0,0 +1,263 @@
+/*
+ * Flexible mmap layout support
+ *
+ * Based on code by Ingo Molnar and Andi Kleen, copyrighted
+ * as follows:
+ *
+ * Copyright 2003-2009 Red Hat Inc.
+ * All Rights Reserved.
+ * Copyright 2005 Andi Kleen, SUSE Labs.
+ * Copyright 2007 Jiri Kosina, SUSE Labs.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/personality.h>
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/limits.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/mm.h>
+#include <linux/compat.h>
+#include <asm/elf.h>
+
+#include "physaddr.h"
+
+struct va_alignment __read_mostly va_align = {
+ .flags = -1,
+};
+
+unsigned long task_size_32bit(void)
+{
+ return IA32_PAGE_OFFSET;
+}
+
+unsigned long task_size_64bit(int full_addr_space)
+{
+ return full_addr_space ? TASK_SIZE_MAX : DEFAULT_MAP_WINDOW;
+}
+
+static unsigned long stack_maxrandom_size(unsigned long task_size)
+{
+ unsigned long max = 0;
+ if (current->flags & PF_RANDOMIZE) {
+ max = (-1UL) & __STACK_RND_MASK(task_size == task_size_32bit());
+ max <<= PAGE_SHIFT;
+ }
+
+ return max;
+}
+
+#ifdef CONFIG_COMPAT
+# define mmap32_rnd_bits mmap_rnd_compat_bits
+# define mmap64_rnd_bits mmap_rnd_bits
+#else
+# define mmap32_rnd_bits mmap_rnd_bits
+# define mmap64_rnd_bits mmap_rnd_bits
+#endif
+
+#define SIZE_128M (128 * 1024 * 1024UL)
+
+static int mmap_is_legacy(void)
+{
+ if (current->personality & ADDR_COMPAT_LAYOUT)
+ return 1;
+
+ return sysctl_legacy_va_layout;
+}
+
+static unsigned long arch_rnd(unsigned int rndbits)
+{
+ if (!(current->flags & PF_RANDOMIZE))
+ return 0;
+ return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
+}
+
+unsigned long arch_mmap_rnd(void)
+{
+ return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
+}
+
+static unsigned long mmap_base(unsigned long rnd, unsigned long task_size,
+ struct rlimit *rlim_stack)
+{
+ unsigned long gap = rlim_stack->rlim_cur;
+ unsigned long pad = stack_maxrandom_size(task_size) + stack_guard_gap;
+ unsigned long gap_min, gap_max;
+
+ /* Values close to RLIM_INFINITY can overflow. */
+ if (gap + pad > gap)
+ gap += pad;
+
+ /*
+ * Top of mmap area (just below the process stack).
+ * Leave an at least ~128 MB hole with possible stack randomization.
+ */
+ gap_min = SIZE_128M;
+ gap_max = (task_size / 6) * 5;
+
+ if (gap < gap_min)
+ gap = gap_min;
+ else if (gap > gap_max)
+ gap = gap_max;
+
+ return PAGE_ALIGN(task_size - gap - rnd);
+}
+
+static unsigned long mmap_legacy_base(unsigned long rnd,
+ unsigned long task_size)
+{
+ return __TASK_UNMAPPED_BASE(task_size) + rnd;
+}
+
+/*
+ * This function, called very early during the creation of a new
+ * process VM image, sets up which VM layout function to use:
+ */
+static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
+ unsigned long random_factor, unsigned long task_size,
+ struct rlimit *rlim_stack)
+{
+ *legacy_base = mmap_legacy_base(random_factor, task_size);
+ if (mmap_is_legacy())
+ *base = *legacy_base;
+ else
+ *base = mmap_base(random_factor, task_size, rlim_stack);
+}
+
+void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+{
+ if (mmap_is_legacy())
+ mm->get_unmapped_area = arch_get_unmapped_area;
+ else
+ mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+
+ arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base,
+ arch_rnd(mmap64_rnd_bits), task_size_64bit(0),
+ rlim_stack);
+
+#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
+ /*
+ * The mmap syscall mapping base decision depends solely on the
+ * syscall type (64-bit or compat). This applies for 64bit
+ * applications and 32bit applications. The 64bit syscall uses
+ * mmap_base, the compat syscall uses mmap_compat_base.
+ */
+ arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base,
+ arch_rnd(mmap32_rnd_bits), task_size_32bit(),
+ rlim_stack);
+#endif
+}
+
+unsigned long get_mmap_base(int is_legacy)
+{
+ struct mm_struct *mm = current->mm;
+
+#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
+ if (in_compat_syscall()) {
+ return is_legacy ? mm->mmap_compat_legacy_base
+ : mm->mmap_compat_base;
+ }
+#endif
+ return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+ if (vma->vm_flags & VM_MPX)
+ return "[mpx]";
+ return NULL;
+}
+
+/**
+ * mmap_address_hint_valid - Validate the address hint of mmap
+ * @addr: Address hint
+ * @len: Mapping length
+ *
+ * Check whether @addr and @addr + @len result in a valid mapping.
+ *
+ * On 32bit this only checks whether @addr + @len is <= TASK_SIZE.
+ *
+ * On 64bit with 5-level page tables another sanity check is required
+ * because mappings requested by mmap(@addr, 0) which cross the 47-bit
+ * virtual address boundary can cause the following theoretical issue:
+ *
+ * An application calls mmap(addr, 0), i.e. without MAP_FIXED, where @addr
+ * is below the border of the 47-bit address space and @addr + @len is
+ * above the border.
+ *
+ * With 4-level paging this request succeeds, but the resulting mapping
+ * address will always be within the 47-bit virtual address space, because
+ * the hint address does not result in a valid mapping and is
+ * ignored. Hence applications which are not prepared to handle virtual
+ * addresses above 47-bit work correctly.
+ *
+ * With 5-level paging this request would be granted and result in a
+ * mapping which crosses the border of the 47-bit virtual address
+ * space. If the application cannot handle addresses above 47-bit this
+ * will lead to misbehaviour and hard to diagnose failures.
+ *
+ * Therefore ignore address hints which would result in a mapping crossing
+ * the 47-bit virtual address boundary.
+ *
+ * Note, that in the same scenario with MAP_FIXED the behaviour is
+ * different. The request with @addr < 47-bit and @addr + @len > 47-bit
+ * fails on a 4-level paging machine but succeeds on a 5-level paging
+ * machine. It is reasonable to expect that an application does not rely on
+ * the failure of such a fixed mapping request, so the restriction is not
+ * applied.
+ */
+bool mmap_address_hint_valid(unsigned long addr, unsigned long len)
+{
+ if (TASK_SIZE - len < addr)
+ return false;
+
+ return (addr > DEFAULT_MAP_WINDOW) == (addr + len > DEFAULT_MAP_WINDOW);
+}
+
+/* Can we access it for direct reading/writing? Must be RAM: */
+int valid_phys_addr_range(phys_addr_t addr, size_t count)
+{
+ return addr + count <= __pa(high_memory);
+}
+
+/* Can we access it through mmap? Must be a valid physical address: */
+int valid_mmap_phys_addr_range(unsigned long pfn, size_t count)
+{
+ phys_addr_t addr = (phys_addr_t)pfn << PAGE_SHIFT;
+
+ return phys_addr_valid(addr + count - 1);
+}
+
+/*
+ * Only allow root to set high MMIO mappings to PROT_NONE.
+ * This prevents an unpriv. user to set them to PROT_NONE and invert
+ * them, then pointing to valid memory for L1TF speculation.
+ *
+ * Note: for locked down kernels may want to disable the root override.
+ */
+bool pfn_modify_allowed(unsigned long pfn, pgprot_t prot)
+{
+ if (!boot_cpu_has_bug(X86_BUG_L1TF))
+ return true;
+ if (!__pte_needs_invert(pgprot_val(prot)))
+ return true;
+ /* If it's real memory always allow */
+ if (pfn_valid(pfn))
+ return true;
+ if (pfn >= l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN))
+ return false;
+ return true;
+}