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-rw-r--r--arch/x86/lib/getuser_64.S109
1 files changed, 109 insertions, 0 deletions
diff --git a/arch/x86/lib/getuser_64.S b/arch/x86/lib/getuser_64.S
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+/*
+ * __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/dwarf2.h>
+#include <asm/page.h>
+#include <asm/errno.h>
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+
+ .text
+ENTRY(__get_user_1)
+ CFI_STARTPROC
+ GET_THREAD_INFO(%r8)
+ cmpq threadinfo_addr_limit(%r8),%rcx
+ jae bad_get_user
+1: movzb (%rcx),%edx
+ xorl %eax,%eax
+ ret
+ CFI_ENDPROC
+ENDPROC(__get_user_1)
+
+ENTRY(__get_user_2)
+ CFI_STARTPROC
+ 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
+ CFI_ENDPROC
+ENDPROC(__get_user_2)
+
+ENTRY(__get_user_4)
+ CFI_STARTPROC
+ 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
+ CFI_ENDPROC
+ENDPROC(__get_user_4)
+
+ENTRY(__get_user_8)
+ CFI_STARTPROC
+ GET_THREAD_INFO(%r8)
+ addq $7,%rcx
+ jc 40f
+ cmpq threadinfo_addr_limit(%r8),%rcx
+ jae 40f
+ subq $7,%rcx
+4: movq (%rcx),%rdx
+ xorl %eax,%eax
+ ret
+40: subq $7,%rcx
+ jmp bad_get_user
+ CFI_ENDPROC
+ENDPROC(__get_user_8)
+
+bad_get_user:
+ CFI_STARTPROC
+ xorl %edx,%edx
+ movq $(-EFAULT),%rax
+ ret
+ CFI_ENDPROC
+END(bad_get_user)
+
+.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