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/*
* Early initialization code for riscv
*
* Copyright 2015 Google Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; version 2 of
* the License.
*
* This program is distributed in the hope that 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.
*/
#include <bits.h>
#include <mcall.h>
.macro restore_regs
# restore x registers
LOAD x1,1*REGBYTES(a0)
LOAD x2,2*REGBYTES(a0)
LOAD x3,3*REGBYTES(a0)
LOAD x4,4*REGBYTES(a0)
LOAD x5,5*REGBYTES(a0)
LOAD x6,6*REGBYTES(a0)
LOAD x7,7*REGBYTES(a0)
LOAD x8,8*REGBYTES(a0)
LOAD x9,9*REGBYTES(a0)
LOAD x11,11*REGBYTES(a0)
LOAD x12,12*REGBYTES(a0)
LOAD x13,13*REGBYTES(a0)
LOAD x14,14*REGBYTES(a0)
LOAD x15,15*REGBYTES(a0)
LOAD x16,16*REGBYTES(a0)
LOAD x17,17*REGBYTES(a0)
LOAD x18,18*REGBYTES(a0)
LOAD x19,19*REGBYTES(a0)
LOAD x20,20*REGBYTES(a0)
LOAD x21,21*REGBYTES(a0)
LOAD x22,22*REGBYTES(a0)
LOAD x23,23*REGBYTES(a0)
LOAD x24,24*REGBYTES(a0)
LOAD x25,25*REGBYTES(a0)
LOAD x26,26*REGBYTES(a0)
LOAD x27,27*REGBYTES(a0)
LOAD x28,28*REGBYTES(a0)
LOAD x29,29*REGBYTES(a0)
LOAD x30,30*REGBYTES(a0)
LOAD x31,31*REGBYTES(a0)
# restore a0 last
LOAD x10,10*REGBYTES(a0)
.endm
.macro save_tf
# save gprs
STORE x1,1*REGBYTES(x2)
STORE x3,3*REGBYTES(x2)
STORE x4,4*REGBYTES(x2)
STORE x5,5*REGBYTES(x2)
STORE x6,6*REGBYTES(x2)
STORE x7,7*REGBYTES(x2)
STORE x8,8*REGBYTES(x2)
STORE x9,9*REGBYTES(x2)
STORE x10,10*REGBYTES(x2)
STORE x11,11*REGBYTES(x2)
STORE x12,12*REGBYTES(x2)
STORE x13,13*REGBYTES(x2)
STORE x14,14*REGBYTES(x2)
STORE x15,15*REGBYTES(x2)
STORE x16,16*REGBYTES(x2)
STORE x17,17*REGBYTES(x2)
STORE x18,18*REGBYTES(x2)
STORE x19,19*REGBYTES(x2)
STORE x20,20*REGBYTES(x2)
STORE x21,21*REGBYTES(x2)
STORE x22,22*REGBYTES(x2)
STORE x23,23*REGBYTES(x2)
STORE x24,24*REGBYTES(x2)
STORE x25,25*REGBYTES(x2)
STORE x26,26*REGBYTES(x2)
STORE x27,27*REGBYTES(x2)
STORE x28,28*REGBYTES(x2)
STORE x29,29*REGBYTES(x2)
STORE x30,30*REGBYTES(x2)
STORE x31,31*REGBYTES(x2)
# get sr, epc, badvaddr, cause
csrrw t0,mscratch,x0
csrr s0,mstatus
csrr t1,mepc
csrr t2,mbadaddr
csrr t3,mcause
STORE t0,2*REGBYTES(x2)
STORE s0,32*REGBYTES(x2)
STORE t1,33*REGBYTES(x2)
STORE t2,34*REGBYTES(x2)
STORE t3,35*REGBYTES(x2)
# get faulting insn, if it wasn't a fetch-related trap
li x5,-1
STORE x5,36*REGBYTES(x2)
.endm
.globl estack
.text
.global trap_entry
trap_entry:
csrw mscratch, sp
# SMP isn't supported yet, to avoid overwriting the same stack with different
# harts that handle traps at the same time.
# someday this gets fixed.
//csrr sp, mhartid
csrr sp, 0xf14
.Lsmp_hang:
bnez sp, .Lsmp_hang
# Use a different stack than in the main context, to to avoid overwriting
# stack data.
# TODO: Maybe use the old stack pointer (plus an offset) instead. But only if
# the previous mode was M, because it would be a very bad idea to use a stack
# pointer provided by unprivileged code!
la sp, _estack
addi sp, sp, -2048 # 2 KiB is half of the stack space
addi sp, sp, -MENTRY_FRAME_SIZE
save_tf
move a0,sp
jal trap_handler
trap_return:
csrr a0, mscratch
restore_regs
# go back to the previous mode
mret