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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/vdso/vdso32/syscall.S
10818 views
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/*

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 * Code for the vDSO.  This version uses the syscall instruction.

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 *

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 * First get the common code for the sigreturn entry points.

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 * This must come first.

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 */

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#define SYSCALL_ENTER_KERNEL	syscall

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#include "sigreturn.S"

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#include <asm/segment.h>

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	.text

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	.globl __kernel_vsyscall

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	.type __kernel_vsyscall,@function

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	ALIGN

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__kernel_vsyscall:

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.LSTART_vsyscall:

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	push	%ebp

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.Lpush_ebp:

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	movl	%ecx, %ebp

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	syscall

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	movl	$__USER32_DS, %ecx

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	movl	%ecx, %ss

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	movl	%ebp, %ecx

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	popl	%ebp

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.Lpop_ebp:

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	ret

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.LEND_vsyscall:

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	.size __kernel_vsyscall,.-.LSTART_vsyscall

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	.section .eh_frame,"a",@progbits

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.LSTARTFRAME:

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	.long .LENDCIE-.LSTARTCIE

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.LSTARTCIE:

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	.long 0			/* CIE ID */

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	.byte 1			/* Version number */

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	.string "zR"		/* NUL-terminated augmentation string */

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	.uleb128 1		/* Code alignment factor */

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	.sleb128 -4		/* Data alignment factor */

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	.byte 8			/* Return address register column */

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	.uleb128 1		/* Augmentation value length */

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	.byte 0x1b		/* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */

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	.byte 0x0c		/* DW_CFA_def_cfa */

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	.uleb128 4

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	.uleb128 4

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	.byte 0x88		/* DW_CFA_offset, column 0x8 */

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	.uleb128 1

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	.align 4

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.LENDCIE:

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	.long .LENDFDE1-.LSTARTFDE1	/* Length FDE */

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.LSTARTFDE1:

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	.long .LSTARTFDE1-.LSTARTFRAME	/* CIE pointer */

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	.long .LSTART_vsyscall-.	/* PC-relative start address */

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	.long .LEND_vsyscall-.LSTART_vsyscall

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	.uleb128 0			/* Augmentation length */

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	/* What follows are the instructions for the table generation.

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	   We have to record all changes of the stack pointer.  */

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	.byte 0x40 + .Lpush_ebp-.LSTART_vsyscall /* DW_CFA_advance_loc */

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	.byte 0x0e		/* DW_CFA_def_cfa_offset */

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	.uleb128 8

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	.byte 0x85, 0x02	/* DW_CFA_offset %ebp -8 */

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	.byte 0x40 + .Lpop_ebp-.Lpush_ebp /* DW_CFA_advance_loc */

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	.byte 0xc5		/* DW_CFA_restore %ebp */

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	.byte 0x0e		/* DW_CFA_def_cfa_offset */

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	.uleb128 4

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	.align 4

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.LENDFDE1:

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	.previous

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	/*

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	 * Pad out the segment to match the size of the sysenter.S version.

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	 */

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VDSO32_vsyscall_eh_frame_size = 0x40

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	.section .data,"aw",@progbits

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	.space VDSO32_vsyscall_eh_frame_size-(.LENDFDE1-.LSTARTFRAME), 0

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	.previous

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