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/**
* @file
*
* @ingroup ScoreCPU
*
* @brief RISC-V exception support implementation.
*/
/*
* Copyright (c) 2015 University of York.
* Hesham Almatary <hesham@alumni.york.ac.uk>
*
* 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.
*
* 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/cpu.h>
#include <rtems/asm.h>
#include <rtems/score/percpu.h>
EXTERN(bsp_start_vector_table_begin)
EXTERN(_Thread_Dispatch)
PUBLIC(ISR_Handler)
.section .text, "ax"
.align 4
TYPE_FUNC(ISR_Handler)
SYM(ISR_Handler):
addi sp, sp, -1 * 36 * CPU_SIZEOF_POINTER
SREG x1, (1 * CPU_SIZEOF_POINTER)(sp)
/* Skip x2/sp */
SREG x3, (3 * CPU_SIZEOF_POINTER)(sp)
SREG x4, (4 * CPU_SIZEOF_POINTER)(sp)
SREG x5, (5 * CPU_SIZEOF_POINTER)(sp)
SREG x6, (6 * CPU_SIZEOF_POINTER)(sp)
SREG x7, (7 * CPU_SIZEOF_POINTER)(sp)
SREG x8, (8 * CPU_SIZEOF_POINTER)(sp)
SREG x9, (9 * CPU_SIZEOF_POINTER)(sp)
SREG x10, (10 * CPU_SIZEOF_POINTER)(sp)
SREG x11, (11 * CPU_SIZEOF_POINTER)(sp)
SREG x12, (12 * CPU_SIZEOF_POINTER)(sp)
SREG x13, (13 * CPU_SIZEOF_POINTER)(sp)
SREG x14, (14 * CPU_SIZEOF_POINTER)(sp)
SREG x15, (15 * CPU_SIZEOF_POINTER)(sp)
SREG x16, (16 * CPU_SIZEOF_POINTER)(sp)
SREG x17, (17 * CPU_SIZEOF_POINTER)(sp)
SREG x18, (18 * CPU_SIZEOF_POINTER)(sp)
SREG x19, (19 * CPU_SIZEOF_POINTER)(sp)
SREG x20, (20 * CPU_SIZEOF_POINTER)(sp)
SREG x21, (21 * CPU_SIZEOF_POINTER)(sp)
SREG x22, (22 * CPU_SIZEOF_POINTER)(sp)
SREG x23, (23 * CPU_SIZEOF_POINTER)(sp)
SREG x24, (24 * CPU_SIZEOF_POINTER)(sp)
SREG x25, (25 * CPU_SIZEOF_POINTER)(sp)
SREG x26, (26 * CPU_SIZEOF_POINTER)(sp)
SREG x27, (27 * CPU_SIZEOF_POINTER)(sp)
SREG x28, (28 * CPU_SIZEOF_POINTER)(sp)
SREG x29, (28 * CPU_SIZEOF_POINTER)(sp)
SREG x30, (30 * CPU_SIZEOF_POINTER)(sp)
SREG x31, (31 * CPU_SIZEOF_POINTER)(sp)
/* Exception level related registers */
csrr a0, mstatus
SREG a0, (32 * CPU_SIZEOF_POINTER)(sp)
csrr a0, mcause
SREG a0, (33 * CPU_SIZEOF_POINTER)(sp)
csrr a1, mepc
SREG a1, (34 * CPU_SIZEOF_POINTER)(sp)
/* FIXME Only handle interrupts for now (MSB = 1) */
andi a0, a0, 0xf
/* Increment nesting level */
la t0, ISR_NEST_LEVEL
/* Disable multitasking */
la t1, THREAD_DISPATCH_DISABLE_LEVEL
lw t2, (t0)
lw t3, (t1)
addi t2, t2, 1
addi t3, t3, 1
sw t2, (t0)
sw t3, (t1)
/* Save interrupted task stack pointer */
addi t4, sp, 36 * CPU_SIZEOF_POINTER
SREG t4, (2 * CPU_SIZEOF_POINTER)(sp)
/* Keep sp (Exception frame address) in s1 */
mv s1, sp
/* Call the exception handler from vector table */
/* First function arg for C handler is vector number,
* and the second is a pointer to exception frame.
* a0/mcause/vector number is already loaded above */
mv a1, sp
/* calculate the offset */
la t5, bsp_start_vector_table_begin
#if __riscv_xlen == 32
slli t6, a0, 2
#else /* xlen = 64 */
slli t6, a0, 3
#endif
add t5, t5, t6
LREG t5, (t5)
/* Do not switch stacks if we are in a nested interrupt. At
* this point t2 should be holding ISR_NEST_LEVEL value.
*/
li s0, 1
bgtu t2, s0, jump_to_c_handler
/* Switch to RTEMS dedicated interrupt stack */
la sp, INTERRUPT_STACK_HIGH
LREG sp, (sp)
jump_to_c_handler:
jalr t5
/* Switch back to the interrupted task stack */
mv sp, s1
/* Decrement nesting level */
la t0, ISR_NEST_LEVEL
/* Enable multitasking */
la t1, THREAD_DISPATCH_DISABLE_LEVEL
Lw t2, (t0)
lw t3, (t1)
addi t2, t2, -1
addi t3, t3, -1
sw t2, (t0)
sw t3, (t1)
/* Check if _ISR_Nest_level > 0 */
bgtz t2, exception_frame_restore
/* Check if _Thread_Dispatch_disable_level > 0 */
bgtz t3, exception_frame_restore
/* Check if dispatch needed */
la x31, DISPATCH_NEEDED
lw x31, (x31)
beqz x31, exception_frame_restore
la x31, _Thread_Dispatch
jalr x31
SYM(exception_frame_restore):
LREG x1, (1 * CPU_SIZEOF_POINTER)(sp)
/* Skip sp/x2 */
LREG x3, (3 * CPU_SIZEOF_POINTER)(sp)
LREG x4, (4 * CPU_SIZEOF_POINTER)(sp)
LREG x5, (5 * CPU_SIZEOF_POINTER)(sp)
LREG x6, (6 * CPU_SIZEOF_POINTER)(sp)
LREG x7, (7 * CPU_SIZEOF_POINTER)(sp)
LREG x8, (8 * CPU_SIZEOF_POINTER)(sp)
LREG x9, (9 * CPU_SIZEOF_POINTER)(sp)
LREG x10, (10 * CPU_SIZEOF_POINTER)(sp)
LREG x11, (11 * CPU_SIZEOF_POINTER)(sp)
LREG x12, (12 * CPU_SIZEOF_POINTER)(sp)
LREG x13, (13 * CPU_SIZEOF_POINTER)(sp)
LREG x14, (14 * CPU_SIZEOF_POINTER)(sp)
LREG x15, (15 * CPU_SIZEOF_POINTER)(sp)
LREG x16, (16 * CPU_SIZEOF_POINTER)(sp)
LREG x17, (17 * CPU_SIZEOF_POINTER)(sp)
LREG x18, (18 * CPU_SIZEOF_POINTER)(sp)
LREG x19, (19 * CPU_SIZEOF_POINTER)(sp)
LREG x20, (20 * CPU_SIZEOF_POINTER)(sp)
LREG x21, (21 * CPU_SIZEOF_POINTER)(sp)
LREG x22, (22 * CPU_SIZEOF_POINTER)(sp)
LREG x23, (23 * CPU_SIZEOF_POINTER)(sp)
LREG x24, (24 * CPU_SIZEOF_POINTER)(sp)
LREG x25, (25 * CPU_SIZEOF_POINTER)(sp)
LREG x26, (26 * CPU_SIZEOF_POINTER)(sp)
LREG x27, (27 * CPU_SIZEOF_POINTER)(sp)
LREG x28, (28 * CPU_SIZEOF_POINTER)(sp)
LREG x29, (29 * CPU_SIZEOF_POINTER)(sp)
LREG x30, (30 * CPU_SIZEOF_POINTER)(sp)
/* Load mstatus */
LREG x31, (32 * CPU_SIZEOF_POINTER)(sp)
csrw mstatus, x31
/* Load mepc */
LREG x31, (34 * CPU_SIZEOF_POINTER)(sp)
csrw mepc, x31
LREG x31, (31 * CPU_SIZEOF_POINTER)(sp)
/* Unwind exception frame */
addi sp, sp, 36 * CPU_SIZEOF_POINTER
mret
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