source: mainline/kernel/arch/ia32xen/src/asm.S@ da349da0

#
# Copyright (c) 2001-2004 Jakub Jermar
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
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# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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## very low and hardware-level functions

# Mask for interrupts 0 - 31 (bits 0 - 31) where 0 means that int has no error word
# and 1 means interrupt with error word
#define ERROR_WORD_INTERRUPT_LIST 0x00027D00

.text

.global xen_callback
.global xen_failsafe_callback
.global enable_l_apic_in_msr
.global memcpy
.global memcpy_from_uspace
.global memcpy_from_uspace_failover_address
.global memcpy_to_uspace
.global memcpy_to_uspace_failover_address


xen_callback:
        iret

xen_failsafe_callback:
        iret


#define MEMCPY_DST      4
#define MEMCPY_SRC      8
#define MEMCPY_SIZE     12

/** Copy memory to/from userspace.
 *
 * This is almost conventional memcpy().
 * The difference is that there is a failover part
 * to where control is returned from a page fault
 * if the page fault occurs during copy_from_uspace()
 * or copy_to_uspace().
 *
 * @param MEMCPY_DST(%esp)      Destination address.
 * @param MEMCPY_SRC(%esp)      Source address.
 * @param MEMCPY_SIZE(%esp)     Size.
 *
 * @return MEMCPY_DST(%esp) on success and 0 on failure.
 */
memcpy:
memcpy_from_uspace:
memcpy_to_uspace:
        movl %edi, %edx                         /* save %edi */
        movl %esi, %eax                         /* save %esi */
        
        movl MEMCPY_SIZE(%esp), %ecx
        shrl $2, %ecx                           /* size / 4 */
        
        movl MEMCPY_DST(%esp), %edi
        movl MEMCPY_SRC(%esp), %esi
        
        rep movsl                               /* copy as much as possible word by word */

        movl MEMCPY_SIZE(%esp), %ecx
        andl $3, %ecx                           /* size % 4 */
        jz 0f
        
        rep movsb                               /* copy the rest byte by byte */

0:
        movl %edx, %edi
        movl %eax, %esi
        movl MEMCPY_DST(%esp), %eax             /* MEMCPY_DST(%esp), success */
        ret
        
/*
 * We got here from as_page_fault() after the memory operations
 * above had caused a page fault.
 */
memcpy_from_uspace_failover_address:
memcpy_to_uspace_failover_address:
        movl %edx, %edi
        movl %eax, %esi
        xorl %eax, %eax                         /* return 0, failure */
        ret


## Enable local APIC
#
# Enable local APIC in MSR.
#
enable_l_apic_in_msr:
        push %eax

        movl $0x1b, %ecx
        rdmsr
        orl $(1<<11),%eax
        orl $(0xfee00000),%eax
        wrmsr

        pop %eax
        ret