--- /dev/null
+/* Copyright 2002 Andi Kleen, SuSE Labs.
+ * Subject to the GNU Public License v2.
+ *
+ * Functions to copy from and to user space.
+ */
+
+#include <lwk/linkage.h>
+#include <arch/dwarf2.h>
+
+#include <arch/current.h>
+#include <arch/asm-offsets.h>
+
+/* Standard copy_to_user with segment limit checking */
+ENTRY(copy_to_user)
+ CFI_STARTPROC
+ GET_CURRENT(%rax)
+ movq %rdi,%rcx
+ addq %rdx,%rcx
+ jc bad_to_user
+ cmpq tsk_arch_addr_limit(%rax),%rcx
+ jae bad_to_user
+ xorl %eax,%eax /* clear zero flag */
+ jmp copy_user_generic_string
+ CFI_ENDPROC
+
+ENTRY(copy_user_generic)
+ CFI_STARTPROC
+ movl $1,%ecx /* set zero flag */
+ jmp copy_user_generic_string
+ CFI_ENDPROC
+
+ENTRY(__copy_from_user_inatomic)
+ CFI_STARTPROC
+ xorl %ecx,%ecx /* clear zero flag */
+ jmp copy_user_generic_string
+ CFI_ENDPROC
+
+/* Standard copy_from_user with segment limit checking */
+ENTRY(copy_from_user)
+ CFI_STARTPROC
+ GET_CURRENT(%rax)
+ movq %rsi,%rcx
+ addq %rdx,%rcx
+ jc bad_from_user
+ cmpq tsk_arch_addr_limit(%rax),%rcx
+ jae bad_from_user
+ movl $1,%ecx /* set zero flag */
+ jmp copy_user_generic_string
+ CFI_ENDPROC
+ENDPROC(copy_from_user)
+
+ .section .fixup,"ax"
+ /* must zero dest */
+bad_from_user:
+ CFI_STARTPROC
+ movl %edx,%ecx
+ xorl %eax,%eax
+ rep
+ stosb
+bad_to_user:
+ movl %edx,%eax
+ ret
+ CFI_ENDPROC
+END(bad_from_user)
+ .previous
+
+
+ /* rdi destination
+ * rsi source
+ * rdx count
+ * ecx zero flag
+ *
+ * Output:
+ * eax uncopied bytes or 0 if successfull.
+ *
+ * Only 4GB of copy is supported. This shouldn't be a problem
+ * because the kernel normally only writes from/to page sized chunks
+ * even if user space passed a longer buffer.
+ * And more would be dangerous because both Intel and AMD have
+ * errata with rep movsq > 4GB. If someone feels the need to fix
+ * this please consider this.
+ */
+ENTRY(copy_user_generic_string)
+ CFI_STARTPROC
+ movl %ecx,%r8d /* save zero flag */
+ movl %edx,%ecx
+ shrl $3,%ecx
+ andl $7,%edx
+ jz 10f
+1: rep
+ movsq
+ movl %edx,%ecx
+2: rep
+ movsb
+9: movl %ecx,%eax
+ ret
+
+ /* multiple of 8 byte */
+10: rep
+ movsq
+ xor %eax,%eax
+ ret
+
+ /* exception handling */
+3: lea (%rdx,%rcx,8),%rax /* exception on quad loop */
+ jmp 6f
+5: movl %ecx,%eax /* exception on byte loop */
+ /* eax: left over bytes */
+6: testl %r8d,%r8d /* zero flag set? */
+ jz 7f
+ movl %eax,%ecx /* initialize x86 loop counter */
+ push %rax
+ xorl %eax,%eax
+8: rep
+ stosb /* zero the rest */
+11: pop %rax
+7: ret
+ CFI_ENDPROC
+END(copy_user_generic_c)
+
+ .section __ex_table,"a"
+ .quad 1b,3b
+ .quad 2b,5b
+ .quad 8b,11b
+ .quad 10b,3b
+ .previous
