/** * @file * * @ingroup ScoreCPU * * @brief RISC-V exception support implementation. */ /* * Copyright (c) 2015 University of York. * Hesham Almatary * * 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 #include #include 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