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mpfs_opensbi_utils.S
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mpfs_opensbi_utils.S
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/****************************************************************************
* arch/risc-v/src/mpfs/mpfs_opensbi_utils.S
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sbi/riscv_asm.h>
#include <sbi/sbi_platform.h>
#include <sbi/sbi_scratch.h>
#include <sbi/sbi_trap.h>
#include <sbi/riscv_encoding.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Symbols
****************************************************************************/
.global mpfs_opensbi_prepare_hart
/****************************************************************************
* Private Data
****************************************************************************/
mpfs_global_pointer:
.dword __global_pointer$
/****************************************************************************
* Name: mpfs_opensbi_prepare_hart
*
* Description:
* Prepares the hart for OpenSBI execution. This installs the proper
* mtvec, global pointer and the stack (per hart) for the OpenSBI.
* mpfs_global_pointer is used to store the real __global_pointer$ as
* seen in the .map file. Loading gp, _global_pointer$ would default to
* mv gp, gp -instruction which isn't what we want. External libraries seem
* to link relative to gp. When trapping from the kernel, the gp has been
* utilized for other purposes, so we need to save and restore gp at all
* times.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
****************************************************************************/
.align 3
mpfs_opensbi_prepare_hart:
/* Setup OpenSBI exception handler */
la t0, mpfs_exception_opensbi
csrw CSR_MTVEC, t0
/* la gp, __global_pointer$ will not work. We want to have the gp as seen
* in the .map file exactly. We need to restore gp in the trap handler.
*/
la t0, mpfs_global_pointer
ld gp, 0(t0)
/* Setup stacks per hart, the stack top is the end of the hart's scratch */
csrr a0, CSR_MHARTID
li t1, SBI_SCRATCH_SIZE
mul t0, a0, t1
la sp, g_scratches
add sp, sp, t0
tail mpfs_opensbi_setup