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-rw-r--r--arch/i386/lib/getuser.S70
1 files changed, 70 insertions, 0 deletions
diff --git a/arch/i386/lib/getuser.S b/arch/i386/lib/getuser.S
new file mode 100644
index 00000000000..62d7f178a32
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+++ b/arch/i386/lib/getuser.S
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+/*
+ * __get_user functions.
+ *
+ * (C) Copyright 1998 Linus Torvalds
+ *
+ * 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.
+ */
+#include <asm/thread_info.h>
+
+
+/*
+ * __get_user_X
+ *
+ * Inputs: %eax contains the address
+ *
+ * Outputs: %eax is error code (0 or -EFAULT)
+ * %edx contains zero-extended value
+ *
+ * These functions should not modify any other registers,
+ * as they get called from within inline assembly.
+ */
+
+.text
+.align 4
+.globl __get_user_1
+__get_user_1:
+ GET_THREAD_INFO(%edx)
+ cmpl TI_addr_limit(%edx),%eax
+ jae bad_get_user
+1: movzbl (%eax),%edx
+ xorl %eax,%eax
+ ret
+
+.align 4
+.globl __get_user_2
+__get_user_2:
+ addl $1,%eax
+ jc bad_get_user
+ GET_THREAD_INFO(%edx)
+ cmpl TI_addr_limit(%edx),%eax
+ jae bad_get_user
+2: movzwl -1(%eax),%edx
+ xorl %eax,%eax
+ ret
+
+.align 4
+.globl __get_user_4
+__get_user_4:
+ addl $3,%eax
+ jc bad_get_user
+ GET_THREAD_INFO(%edx)
+ cmpl TI_addr_limit(%edx),%eax
+ jae bad_get_user
+3: movl -3(%eax),%edx
+ xorl %eax,%eax
+ ret
+
+bad_get_user:
+ xorl %edx,%edx
+ movl $-14,%eax
+ ret
+
+.section __ex_table,"a"
+ .long 1b,bad_get_user
+ .long 2b,bad_get_user
+ .long 3b,bad_get_user
+.previous