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Atmosphere/fusee/fusee-primary/src/exception_handlers_asm.s

125 lines
3.5 KiB
ArmAsm

/*
* Copyright (c) 2018 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
.macro GEN_USUAL_HANDLER name, index, lr_arm_displ, lr_thumb_displ
_exception_handler_\name:
ldr sp, =_regs
stmia sp!, {r0-r7}
/* Adjust lr to make it point to the location where the exception occured. */
mrs r1, spsr
tst r1, #0x20
subeq lr, lr, #\lr_arm_displ
subne lr, lr, #\lr_thumb_displ
mov r0, sp
mov r1, #\index
b _exception_handler_common
.endm
.section .text.exception_handlers_asm, "ax", %progbits
.arm
.align 5
_exception_handler_common:
mrs r2, spsr
mrs r3, cpsr
/* Mask interrupts. */
orr r3, #0xC0
msr cpsr_cx, r3
/* Switch to the mode that triggered the interrupt, get the remaining regs, switch back. */
ands r4, r2, #0xF
moveq r4, #0xF /* usr => sys */
bic r5, r3, #0xF
orr r5, r4
msr cpsr_c, r5
stmia r0!, {r8-lr}
msr cpsr_c, r3
str lr, [r0], #4
str r2, [r0]
/* Finally, switch to system mode, setting interrupts and clearing the flags; set sp as well. */
msr cpsr_cxsf, #0xDF
ldr sp, =(_exception_handler_stack + 0x1000)
ldr r0, =_regs
bl exception_handler_main
b .
GEN_USUAL_HANDLER undefined_instruction, 1, 4, 2
GEN_USUAL_HANDLER swi, 2, 4, 2
GEN_USUAL_HANDLER prefetch_abort, 3, 4, 4
GEN_USUAL_HANDLER data_abort_normal, 4, 8, 8
GEN_USUAL_HANDLER fiq, 7, 4, 4
_exception_handler_data_abort:
/* Mask interrupts (abort mode). */
msr cpsr_cx, #0xD7
adr sp, safecpy+8
cmp lr, sp
blo _exception_handler_data_abort_normal
adr sp, _safecpy_end+8
cmp lr, sp
bhs _exception_handler_data_abort_normal
/* Set the flags, set r12 to 0 for safecpy, return from exception. */
msr spsr_f, #(1 << 30)
mov r12, #0
subs pc, lr, #4
.global safecpy
.type safecpy, %function
safecpy:
push {r4, lr}
mov r3, #0
movs r12, #1
_safecpy_loop:
ldrb r4, [r1, r3]
cmp r12, #0
beq _safecpy_loop_end
strb r4, [r0, r3]
add r3, #1
cmp r3, r2
blo _safecpy_loop
_safecpy_loop_end:
mov r0, r3
pop {r4, lr}
bx lr /* Need to do that separately on ARMv4. */
_safecpy_end:
.section .rodata.exception_handlers_asm, "a", %progbits
.align 2
.global exception_handler_table
exception_handler_table:
.word 0 /* Reset */
.word _exception_handler_undefined_instruction
.word _exception_handler_swi
.word _exception_handler_prefetch_abort
.word _exception_handler_data_abort
.word 0 /* Reserved */
.word 0 /* IRQ */
.word _exception_handler_fiq
.section .bss.exception_handlers_asm, "w", %nobits
.align 4
_exception_handler_stack: .skip 0x1000
_regs: .skip (4 * 17)