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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/lib/putuser.S
10817 views
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/*

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 * __put_user functions.

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 *

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 * (C) Copyright 2005 Linus Torvalds

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 * (C) Copyright 2005 Andi Kleen

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 * (C) Copyright 2008 Glauber Costa

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 *

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 * These functions have a non-standard call interface

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 * to make them more efficient, especially as they

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 * return an error value in addition to the "real"

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 * return value.

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 */

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#include <linux/linkage.h>

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#include <asm/dwarf2.h>

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#include <asm/thread_info.h>

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#include <asm/errno.h>

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#include <asm/asm.h>

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/*

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 * __put_user_X

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 *

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 * Inputs:	%eax[:%edx] contains the data

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 *		%ecx contains the address

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 *

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 * Outputs:	%eax is error code (0 or -EFAULT)

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 *

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 * These functions should not modify any other registers,

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 * as they get called from within inline assembly.

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 */

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#define ENTER	CFI_STARTPROC ; \

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		GET_THREAD_INFO(%_ASM_BX)

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#define EXIT	ret ; \

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		CFI_ENDPROC

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.text

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ENTRY(__put_user_1)

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	ENTER

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	cmp TI_addr_limit(%_ASM_BX),%_ASM_CX

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	jae bad_put_user

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1:	movb %al,(%_ASM_CX)

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	xor %eax,%eax

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	EXIT

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ENDPROC(__put_user_1)

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ENTRY(__put_user_2)

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	ENTER

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	mov TI_addr_limit(%_ASM_BX),%_ASM_BX

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	sub $1,%_ASM_BX

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	cmp %_ASM_BX,%_ASM_CX

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	jae bad_put_user

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2:	movw %ax,(%_ASM_CX)

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	xor %eax,%eax

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	EXIT

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ENDPROC(__put_user_2)

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ENTRY(__put_user_4)

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	ENTER

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	mov TI_addr_limit(%_ASM_BX),%_ASM_BX

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	sub $3,%_ASM_BX

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	cmp %_ASM_BX,%_ASM_CX

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	jae bad_put_user

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3:	movl %eax,(%_ASM_CX)

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	xor %eax,%eax

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	EXIT

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ENDPROC(__put_user_4)

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ENTRY(__put_user_8)

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	ENTER

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	mov TI_addr_limit(%_ASM_BX),%_ASM_BX

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	sub $7,%_ASM_BX

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	cmp %_ASM_BX,%_ASM_CX

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	jae bad_put_user

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4:	mov %_ASM_AX,(%_ASM_CX)

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#ifdef CONFIG_X86_32

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5:	movl %edx,4(%_ASM_CX)

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#endif

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	xor %eax,%eax

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	EXIT

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ENDPROC(__put_user_8)

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bad_put_user:

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	CFI_STARTPROC

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	movl $-EFAULT,%eax

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	EXIT

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END(bad_put_user)

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.section __ex_table,"a"

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	_ASM_PTR 1b,bad_put_user

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	_ASM_PTR 2b,bad_put_user

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	_ASM_PTR 3b,bad_put_user

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	_ASM_PTR 4b,bad_put_user

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#ifdef CONFIG_X86_32

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	_ASM_PTR 5b,bad_put_user

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#endif

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.previous

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