1 files changed, 232 insertions, 0 deletions
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
new file mode 100644
index 000000000..3fd1c81eb
--- /dev/null
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/compat.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/sched/mm.h>
+#include <linux/syscalls.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/smp.h>
+#include <linux/sem.h>
+#include <linux/msg.h>
+#include <linux/shm.h>
+#include <linux/stat.h>
+#include <linux/mman.h>
+#include <linux/file.h>
+#include <linux/utsname.h>
+#include <linux/personality.h>
+#include <linux/random.h>
+#include <linux/uaccess.h>
+#include <linux/elf.h>
+
+#include <asm/elf.h>
+#include <asm/ia32.h>
+
+/*
+ * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
+ */
+static unsigned long get_align_mask(void)
+{
+	/* handle 32- and 64-bit case with a single conditional */
+	if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
+		return 0;
+
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
+
+	return va_align.mask;
+}
+
+/*
+ * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
+ * va_align.bits, [12:upper_bit), are set to a random value instead of
+ * zeroing them. This random value is computed once per boot. This form
+ * of ASLR is known as "per-boot ASLR".
+ *
+ * To achieve this, the random value is added to the info.align_offset
+ * value before calling vm_unmapped_area() or ORed directly to the
+ * address.
+ */
+static unsigned long get_align_bits(void)
+{
+	return va_align.bits & get_align_mask();
+}
+
+unsigned long align_vdso_addr(unsigned long addr)
+{
+	unsigned long align_mask = get_align_mask();
+	addr = (addr + align_mask) & ~align_mask;
+	return addr | get_align_bits();
+}
+
+static int __init control_va_addr_alignment(char *str)
+{
+	/* guard against enabling this on other CPU families */
+	if (va_align.flags < 0)
+		return 1;
+
+	if (*str == 0)
+		return 1;
+
+	if (!strcmp(str, "32"))
+		va_align.flags = ALIGN_VA_32;
+	else if (!strcmp(str, "64"))
+		va_align.flags = ALIGN_VA_64;
+	else if (!strcmp(str, "off"))
+		va_align.flags = 0;
+	else if (!strcmp(str, "on"))
+		va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
+	else
+		pr_warn("invalid option value: 'align_va_addr=%s'\n", str);
+
+	return 1;
+}
+__setup("align_va_addr=", control_va_addr_alignment);
+
+SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
+		unsigned long, prot, unsigned long, flags,
+		unsigned long, fd, unsigned long, off)
+{
+	long error;
+	error = -EINVAL;
+	if (off & ~PAGE_MASK)
+		goto out;
+
+	error = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
+out:
+	return error;
+}
+
+static void find_start_end(unsigned long addr, unsigned long flags,
+		unsigned long *begin, unsigned long *end)
+{
+	if (!in_32bit_syscall() && (flags & MAP_32BIT)) {
+		/* This is usually used needed to map code in small
+		   model, so it needs to be in the first 31bit. Limit
+		   it to that.  This means we need to move the
+		   unmapped base down for this case. This can give
+		   conflicts with the heap, but we assume that glibc
+		   malloc knows how to fall back to mmap. Give it 1GB
+		   of playground for now. -AK */
+		*begin = 0x40000000;
+		*end = 0x80000000;
+		if (current->flags & PF_RANDOMIZE) {
+			*begin = randomize_page(*begin, 0x02000000);
+		}
+		return;
+	}
+
+	*begin	= get_mmap_base(1);
+	if (in_32bit_syscall())
+		*end = task_size_32bit();
+	else
+		*end = task_size_64bit(addr > DEFAULT_MAP_WINDOW);
+}
+
+unsigned long
+arch_get_unmapped_area(struct file *filp, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	struct vm_unmapped_area_info info;
+	unsigned long begin, end;
+
+	if (flags & MAP_FIXED)
+		return addr;
+
+	find_start_end(addr, flags, &begin, &end);
+
+	if (len > end)
+		return -ENOMEM;
+
+	if (addr) {
+		addr = PAGE_ALIGN(addr);
+		vma = find_vma(mm, addr);
+		if (end - len >= addr &&
+		    (!vma || addr + len <= vm_start_gap(vma)))
+			return addr;
+	}
+
+	info.flags = 0;
+	info.length = len;
+	info.low_limit = begin;
+	info.high_limit = end;
+	info.align_mask = 0;
+	info.align_offset = pgoff << PAGE_SHIFT;
+	if (filp) {
+		info.align_mask = get_align_mask();
+		info.align_offset += get_align_bits();
+	}
+	return vm_unmapped_area(&info);
+}
+
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+			  const unsigned long len, const unsigned long pgoff,
+			  const unsigned long flags)
+{
+	struct vm_area_struct *vma;
+	struct mm_struct *mm = current->mm;
+	unsigned long addr = addr0;
+	struct vm_unmapped_area_info info;
+
+	/* requested length too big for entire address space */
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
+	/* No address checking. See comment at mmap_address_hint_valid() */
+	if (flags & MAP_FIXED)
+		return addr;
+
+	/* for MAP_32BIT mappings we force the legacy mmap base */
+	if (!in_32bit_syscall() && (flags & MAP_32BIT))
+		goto bottomup;
+
+	/* requesting a specific address */
+	if (addr) {
+		addr &= PAGE_MASK;
+		if (!mmap_address_hint_valid(addr, len))
+			goto get_unmapped_area;
+
+		vma = find_vma(mm, addr);
+		if (!vma || addr + len <= vm_start_gap(vma))
+			return addr;
+	}
+get_unmapped_area:
+
+	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+	info.length = len;
+	info.low_limit = PAGE_SIZE;
+	info.high_limit = get_mmap_base(0);
+
+	/*
+	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
+	 * in the full address space.
+	 *
+	 * !in_32bit_syscall() check to avoid high addresses for x32
+	 * (and make it no op on native i386).
+	 */
+	if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
+		info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
+
+	info.align_mask = 0;
+	info.align_offset = pgoff << PAGE_SHIFT;
+	if (filp) {
+		info.align_mask = get_align_mask();
+		info.align_offset += get_align_bits();
+	}
+	addr = vm_unmapped_area(&info);
+	if (!(addr & ~PAGE_MASK))
+		return addr;
+	VM_BUG_ON(addr != -ENOMEM);
+
+bottomup:
+	/*
+	 * A failed mmap() very likely causes application failure,
+	 * so fall back to the bottom-up function here. This scenario
+	 * can happen with large stack limits and large mmap()
+	 * allocations.
+	 */
+	return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
+}