source: mainline/kernel/arch/ia32/src/asm.S@ b8230b9

#
# 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
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

## 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 paging_on
.global enable_l_apic_in_msr
.global interrupt_handlers
.global memsetb
.global memsetw
.global memcpy
.global memcpy_from_uspace
.global memcpy_from_uspace_failover_address
.global memcpy_to_uspace
.global memcpy_to_uspace_failover_address


# Wrapper for generic memsetb
memsetb:
        jmp _memsetb

# Wrapper for generic memsetw
memsetw:
        jmp _memsetw


#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 whole words */

        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

## Turn paging on
#
# Enable paging and write-back caching in CR0.
#
paging_on:
        movl %cr0, %edx
        orl $(1 << 31), %edx            # paging on
        # clear Cache Disable and not Write Though
        andl $~((1 << 30) | (1 << 29)), %edx
        movl %edx,%cr0
        jmp 0f
0:
        ret


## Enable local APIC
#
# Enable local APIC in MSR.
#
enable_l_apic_in_msr:
        movl $0x1b, %ecx
        rdmsr
        orl $(1 << 11), %eax
        orl $(0xfee00000), %eax
        wrmsr
        ret

# Clear nested flag
# overwrites %ecx
.macro CLEAR_NT_FLAG
        pushfl
        pop %ecx
        and $0xffffbfff, %ecx
        push %ecx
        popfl
.endm   

/*
 * The SYSENTER syscall mechanism can be used for syscalls with
 * four or fewer arguments. To pass these four arguments, we
 * use four registers: EDX, ECX, EBX, ESI. The syscall number
 * is passed in EAX. We use EDI to remember the return address
 * and EBP to remember the stack. The INT-based syscall mechanism
 * can actually handle six arguments plus the syscall number
 * entirely in registers.
 */
.global sysenter_handler
sysenter_handler:
        sti
        pushl %ebp      # remember user stack
        pushl %edi      # remember return user address

        pushl %gs       # remember TLS

        pushl %eax      # syscall number
        subl $8, %esp   # unused sixth and fifth argument
        pushl %esi      # fourth argument
        pushl %ebx      # third argument
        pushl %ecx      # second argument
        pushl %edx      # first argument

        movw $16, %ax
        movw %ax, %ds
        movw %ax, %es

        cld
        call syscall_handler
        addl $28, %esp  # remove arguments from stack

        pop %gs         # restore TLS

        pop %edx        # prepare return EIP for SYSEXIT
        pop %ecx        # prepare userspace ESP for SYSEXIT

        sysexit         # return to userspace


## Declare interrupt handlers
#
# Declare interrupt handlers for n interrupt
# vectors starting at vector i.
#
# The handlers setup data segment registers
# and call exc_dispatch().
#
#define INTERRUPT_ALIGN 64
.macro handler i n
        
        .ifeq \i - 0x30     # Syscall handler
                pushl %ds
                pushl %es
                pushl %fs
                pushl %gs
                
                #
                # Push syscall arguments onto the stack
                #
                # NOTE: The idea behind the order of arguments passed in registers is to
                #       use all scratch registers first and preserved registers next.
                #       An optimized libc syscall wrapper can make use of this setup.
                #
                pushl %eax
                pushl %ebp
                pushl %edi
                pushl %esi
                pushl %ebx
                pushl %ecx
                pushl %edx
                
                # we must fill the data segment registers
                movw $16, %ax
                movw %ax, %ds
                movw %ax, %es
                
                cld
                sti
                # syscall_handler(edx, ecx, ebx, esi, edi, ebp, eax)
                call syscall_handler
                cli
                addl $28, %esp         # clean-up of parameters
                
                popl %gs
                popl %fs
                popl %es
                popl %ds
                
                CLEAR_NT_FLAG
                iret
        .else
                /*
                 * This macro distinguishes between two versions of ia32 exceptions.
                 * One version has error word and the other does not have it.
                 * The latter version fakes the error word on the stack so that the
                 * handlers and istate_t can be the same for both types.
                 */
                .iflt \i - 32
                        .if (1 << \i) & ERROR_WORD_INTERRUPT_LIST
                                /*
                                 * With error word, do nothing
                                 */
                        .else
                                /*
                                 * Version without error word
                                 */
                                subl $4, %esp
                        .endif
                .else
                        /*
                         * Version without error word
                         */
                        subl $4, %esp
                .endif
                
                pushl %ds
                pushl %es
                pushl %fs
                pushl %gs
                
                pushl %ebp
                pushl %edx
                pushl %ecx
                pushl %eax
                
                # we must fill the data segment registers
                
                movw $16, %ax
                movw %ax, %ds
                movw %ax, %es
                
                # stop stack traces here
                xorl %ebp, %ebp
                
                pushl %esp          # *istate
                pushl $(\i)         # intnum
                call exc_dispatch   # exc_dispatch(intnum, *istate)
                addl $8, %esp       # Clear arguments from stack
                
                CLEAR_NT_FLAG # Modifies %ecx
                
                popl %eax
                popl %ecx
                popl %edx
                popl %ebp
                
                popl %gs
                popl %fs
                popl %es
                popl %ds
                
                # skip error word, no matter whether real or fake
                addl $4, %esp
                iret
        .endif
        
        .align INTERRUPT_ALIGN
        .if (\n- \i) - 1
                handler "(\i + 1)", \n
        .endif
.endm

# keep in sync with pm.h !!!
IDT_ITEMS = 64
.align INTERRUPT_ALIGN
interrupt_handlers:
h_start:
        handler 0 IDT_ITEMS
h_end:

.data
.global interrupt_handler_size

interrupt_handler_size: .long (h_end - h_start) / IDT_ITEMS