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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/x86/lib/usercopy_64.c
Initial import
Diffstat (limited to 'arch/x86/lib/usercopy_64.c')
-rw-r--r--arch/x86/lib/usercopy_64.c88
1 files changed, 88 insertions, 0 deletions
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
new file mode 100644
index 000000000..0a42327a5
--- /dev/null
+++ b/arch/x86/lib/usercopy_64.c
@@ -0,0 +1,88 @@
+/*
+ * User address space access functions.
+ *
+ * Copyright 1997 Andi Kleen <ak@muc.de>
+ * Copyright 1997 Linus Torvalds
+ * Copyright 2002 Andi Kleen <ak@suse.de>
+ */
+#include <linux/module.h>
+#include <asm/uaccess.h>
+
+/*
+ * Zero Userspace
+ */
+
+unsigned long __clear_user(void __user *addr, unsigned long size)
+{
+ long __d0;
+ might_fault();
+ /* no memory constraint because it doesn't change any memory gcc knows
+ about */
+ stac();
+ asm volatile(
+ " testq %[size8],%[size8]\n"
+ " jz 4f\n"
+ "0: movq %[zero],(%[dst])\n"
+ " addq %[eight],%[dst]\n"
+ " decl %%ecx ; jnz 0b\n"
+ "4: movq %[size1],%%rcx\n"
+ " testl %%ecx,%%ecx\n"
+ " jz 2f\n"
+ "1: movb %b[zero],(%[dst])\n"
+ " incq %[dst]\n"
+ " decl %%ecx ; jnz 1b\n"
+ "2:\n"
+ ".section .fixup,\"ax\"\n"
+ "3: lea 0(%[size1],%[size8],8),%[size8]\n"
+ " jmp 2b\n"
+ ".previous\n"
+ _ASM_EXTABLE(0b,3b)
+ _ASM_EXTABLE(1b,2b)
+ : [size8] "=&c"(size), [dst] "=&D" (__d0)
+ : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
+ [zero] "r" (0UL), [eight] "r" (8UL));
+ clac();
+ return size;
+}
+EXPORT_SYMBOL(__clear_user);
+
+unsigned long clear_user(void __user *to, unsigned long n)
+{
+ if (access_ok(VERIFY_WRITE, to, n))
+ return __clear_user(to, n);
+ return n;
+}
+EXPORT_SYMBOL(clear_user);
+
+unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
+{
+ if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) {
+ return copy_user_generic((__force void *)to, (__force void *)from, len);
+ }
+ return len;
+}
+EXPORT_SYMBOL(copy_in_user);
+
+/*
+ * Try to copy last bytes and clear the rest if needed.
+ * Since protection fault in copy_from/to_user is not a normal situation,
+ * it is not necessary to optimize tail handling.
+ */
+__visible unsigned long
+copy_user_handle_tail(char *to, char *from, unsigned len)
+{
+ for (; len; --len, to++) {
+ char c;
+
+ if (__get_user_nocheck(c, from++, sizeof(char)))
+ break;
+ if (__put_user_nocheck(c, to, sizeof(char)))
+ break;
+ }
+ clac();
+
+ /* If the destination is a kernel buffer, we always clear the end */
+ if (!__addr_ok(to))
+ memset(to, 0, len);
+ return len;
+}