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/*
*
* Copyright 2013 Google Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*/
.align 4
.global exception_stack_end
exception_stack_end:
.long 0
.global exception_state
exception_state:
.long 0
/* Some temporary variables which are used while saving exception state. */
vector:
.long 0
error_code:
.long 0
old_esp:
.long 0
old_eax:
.long 0
.align 8
/*
* Each exception vector has a small stub associated with it which sets aside
* the error code, if any, records which vector we entered from, and calls
* the common exception entry point. Some exceptions have error codes and some
* don't, so we have a macro for each type.
*/
.macro stub num
exception_stub_\num:
movl $0, error_code
movl $\num, vector
jmp exception_common
.endm
.macro stub_err num
exception_stub_\num:
popl error_code
movl $\num, vector
jmp exception_common
.endm
.altmacro
.macro user_defined_stubs from, to
stub \from
.if \to-\from
user_defined_stubs %(from+1),\to
.endif
.endm
stub 0
stub 1
stub 2
stub 3
stub 4
stub 5
stub 6
stub 7
stub_err 8
stub 9
stub_err 10
stub_err 11
stub_err 12
stub_err 13
stub_err 14
stub 15
stub 16
stub_err 17
stub 18
stub 19
stub 20
stub 21
stub 22
stub 23
stub 24
stub 25
stub 26
stub 27
stub 28
stub 29
stub_err 30
stub 31
/* Split the macro so we avoid a stack overflow. */
user_defined_stubs 32, 63
user_defined_stubs 64, 127
user_defined_stubs 128, 191
user_defined_stubs 192, 255
exception_common:
/*
* Save off the stack pointer and old eax value and install the
* exception stack. eax points to the old stack which has the
* exception ip, cs, and flags.
*/
mov %esp, old_esp
addl $12, old_esp
mov %eax, old_eax
mov %esp, %eax
mov exception_stack_end, %esp
/*
* Push values onto the top of the exception stack to form an
* exception state structure.
*/
pushl vector
pushl error_code
pushl %gs
pushl %fs
pushl %es
pushl %ds
pushl %ss
pushl 4(%eax)
pushl 8(%eax)
pushl (%eax)
pushl %edi
pushl %esi
pushl %ebp
pushl old_esp
pushl %ebx
pushl %edx
pushl %ecx
pushl old_eax
/*
* Call the C exception handler. It will find the exception state
* using the exception_state global pointer. Not
* passing parameters means we don't have to worry about what ABI
* is being used.
*/
mov %esp, exception_state
call exception_dispatch
/*
* Restore state from the exception state structure, including any
* changes that might have been made.
*/
popl old_eax
popl %ecx
popl %edx
popl %ebx
popl old_esp
mov old_esp, %eax
subl $12, %eax
popl %ebp
popl %esi
popl %edi
popl (%eax)
popl 8(%eax)
popl 4(%eax)
popl %ss
popl %ds
popl %es
popl %fs
popl %gs
mov %eax, %esp
mov old_eax, %eax
/* Return from the exception. */
iretl
/*
* We need segment selectors for the IDT, so we need to know where things are
* in the GDT. We set one up here which is pretty standard and largely copied
* from coreboot.
*/
.align 8
gdt:
/* selgdt 0, unused */
.word 0x0000, 0x0000
.byte 0x00, 0x00, 0x00, 0x00
/* selgdt 8, unused */
.word 0x0000, 0x0000
.byte 0x00, 0x00, 0x00, 0x00
/* selgdt 0x10, flat 4GB code segment */
.word 0xffff, 0x0000
.byte 0x00, 0x9b, 0xcf, 0x00
/* selgdt 0x18, flat 4GB data segment */
.word 0xffff, 0x0000
.byte 0x00, 0x93, 0xcf, 0x00
gdt_end:
/* GDT pointer for use with lgdt */
gdt_ptr:
.word gdt_end - gdt - 1
.long gdt
/*
* Record the target and construct the actual entry at init time. This
* is necessary because the linker doesn't want to construct the entry
* for us.
*/
.macro interrupt_gate target
.long \target
.long \target
.endm
.altmacro
.macro user_defined_gates from, to
interrupt_gate exception_stub_\from
.if \to-\from
user_defined_gates %(from+1),\to
.endif
.endm
.align 8
.global idt
idt:
interrupt_gate exception_stub_0
interrupt_gate exception_stub_1
interrupt_gate exception_stub_2
interrupt_gate exception_stub_3
interrupt_gate exception_stub_4
interrupt_gate exception_stub_5
interrupt_gate exception_stub_6
interrupt_gate exception_stub_7
interrupt_gate exception_stub_8
interrupt_gate exception_stub_9
interrupt_gate exception_stub_10
interrupt_gate exception_stub_11
interrupt_gate exception_stub_12
interrupt_gate exception_stub_13
interrupt_gate exception_stub_14
interrupt_gate exception_stub_15
interrupt_gate exception_stub_16
interrupt_gate exception_stub_17
interrupt_gate exception_stub_18
interrupt_gate exception_stub_19
interrupt_gate exception_stub_20
interrupt_gate exception_stub_21
interrupt_gate exception_stub_22
interrupt_gate exception_stub_23
interrupt_gate exception_stub_24
interrupt_gate exception_stub_25
interrupt_gate exception_stub_26
interrupt_gate exception_stub_27
interrupt_gate exception_stub_28
interrupt_gate exception_stub_29
interrupt_gate exception_stub_30
interrupt_gate exception_stub_31
user_defined_gates 32, 63
user_defined_gates 64, 127
user_defined_gates 128, 191
user_defined_gates 192, 255
idt_end:
/* IDT pointer for use with lidt */
idt_ptr:
.word idt_end - idt - 1
.long idt
.global exception_init_asm
exception_init_asm:
/* Save eax so we can use it as a temporary variable. */
pushl %eax
/* Install the GDT. */
lgdt gdt_ptr
/* Load the segment registers from it. */
ljmp $0x10, $1f
1: movl $0x18, %eax
movl %eax, %ds
movl %eax, %es
movl %eax, %ss
movl %eax, %fs
movl %eax, %gs
/*
* Loop over the entries which start out as two copies of the target
* address. We can turn them into real interrupt gates by selectively
* replacing certain bit fields.
*/
movl $idt, %eax
1:
andl $0x0000ffff, (%eax)
orl $0x00100000, (%eax)
andl $0xffff0000, 4(%eax)
orl $0x0000ee00, 4(%eax)
addl $8, %eax
cmp $idt_end, %eax
jne 1b
/* Install the IDT. */
lidt idt_ptr
/* Restore eax and return to the caller. */
popl %eax
ret
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