1 files changed, 101 insertions, 0 deletions

diff --git a/arch/x86_64/lib/getuser.S b/arch/x86_64/lib/getuser.S
new file mode 100644
index 000000000000..f94ea8a44051
--- /dev/null
+++ b/arch/x86_64/lib/getuser.S
@@ -0,0 +1,101 @@
+/*
+ * __get_user functions.
+ *
+ * (C) Copyright 1998 Linus Torvalds
+ * (C) Copyright 2005 Andi Kleen
+ *
+ * These functions have a non-standard call interface
+ * to make them more efficient, especially as they
+ * return an error value in addition to the "real"
+ * return value.
+ */
+
+/*
+ * __get_user_X
+ *
+ * Inputs:      %rcx contains the address.
+ *              The register is modified, but all changes are undone
+ *              before returning because the C code doesn't know about it.
+ *
+ * Outputs:     %rax is error code (0 or -EFAULT)
+ *              %rdx contains zero-extended value
+ * 
+ * %r8 is destroyed.
+ *
+ * These functions should not modify any other registers,
+ * as they get called from within inline assembly.
+ */
+
+#include <linux/linkage.h>
+#include <asm/page.h>
+#include <asm/errno.h>
+#include <asm/offset.h>
+#include <asm/thread_info.h>
+
+        .text
+        .p2align 4
+.globl __get_user_1
+__get_user_1:   
+        GET_THREAD_INFO(%r8)
+        cmpq threadinfo_addr_limit(%r8),%rcx
+        jae bad_get_user
+1:      movzb (%rcx),%edx
+        xorl %eax,%eax
+        ret
+
+        .p2align 4
+.globl __get_user_2
+__get_user_2:
+        GET_THREAD_INFO(%r8)
+        addq $1,%rcx
+        jc 20f
+        cmpq threadinfo_addr_limit(%r8),%rcx
+        jae 20f
+        decq   %rcx
+2:      movzwl (%rcx),%edx
+        xorl %eax,%eax
+        ret
+20:     decq    %rcx
+        jmp     bad_get_user
+
+        .p2align 4
+.globl __get_user_4
+__get_user_4:
+        GET_THREAD_INFO(%r8)
+        addq $3,%rcx
+        jc 30f
+        cmpq threadinfo_addr_limit(%r8),%rcx
+        jae 30f
+        subq $3,%rcx
+3:      movl (%rcx),%edx
+        xorl %eax,%eax
+        ret
+30:     subq $3,%rcx
+        jmp bad_get_user
+
+        .p2align 4
+.globl __get_user_8
+__get_user_8:
+        GET_THREAD_INFO(%r8)
+        addq $7,%rcx
+        jc bad_get_user
+        cmpq threadinfo_addr_limit(%r8),%rcx
+        jae     bad_get_user
+        subq    $7,%rcx
+4:      movq (%rcx),%rdx
+        xorl %eax,%eax
+        ret
+40:     subq $7,%rcx
+        jmp bad_get_user
+
+bad_get_user:
+        xorl %edx,%edx
+        movq $(-EFAULT),%rax
+        ret
+
+.section __ex_table,"a"
+        .quad 1b,bad_get_user
+        .quad 2b,bad_get_user
+        .quad 3b,bad_get_user
+        .quad 4b,bad_get_user
+.previous