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riscv_syscall.S
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riscv_syscall.S
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/****************************************************************************
* arch/risc-v/src/common/supervisor/riscv_syscall.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.
*
****************************************************************************/
.file "riscv_syscall.S"
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <arch/mode.h>
#include "chip.h"
#include "riscv_macros.S"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Symbols
****************************************************************************/
.globl sys_call0
.globl sys_call1
.globl sys_call2
.globl sys_call3
.globl sys_call4
.globl sys_call5
.globl sys_call6
/****************************************************************************
* Name: sys_callx
*
* Description:
* Dispatch syscall from kernel
*
* C Function Prototype:
* uintptr_t sys_callx(unsigned int nbr, ...);
*
* Input Parameters:
* Assumes the context to return is already set up
*
* Returned Value:
* Return value of system call is returned into contex
*
* Assumptions:
* Task is running in privileged mode
*
****************************************************************************/
.type sys_call0, function
.type sys_call1, function
.type sys_call2, function
.type sys_call3, function
.type sys_call4, function
.type sys_call5, function
.type sys_call6, function
sys_call0:
sys_call1:
sys_call2:
sys_call3:
sys_call4:
sys_call5:
sys_call6:
addi sp, sp, -XCPTCONTEXT_SIZE /* make room */
save_ctx sp /* save current context */
/* Mask interrupts and store the status register to context */
li s1, STATUS_IE /* move IE -> PIE */
csrrc s0, CSR_STATUS, s1
and s1, s0, s1 /* if (STATUS & IE) */
beqz s1, 1f
li s1, ~STATUS_IE /* clear IE */
and s0, s0, s1
li s1, STATUS_PIE /* set PIE */
or s0, s0, s1
1:
/* Set previous privilege, we are in privileged mode now */
li s1, STATUS_PPP /* set previous privilege */
or s0, s0, s1
REGSTORE s0, REG_INT_CTX(sp) /* store status to context */
REGSTORE x1, REG_EPC(sp) /* save ra to epc */
addi s0, sp, XCPTCONTEXT_SIZE
REGSTORE s0, REG_SP(sp) /* original SP */
mv a0, sp /* a0 = context */
#if CONFIG_ARCH_INTERRUPTSTACK > 15
/* Switch to interrupt stack */
setintstack t0, t1
#endif
/* Run the handler */
jal x1, riscv_perform_syscall
/* Restore (potentially new) context */
mv sp, a0 /* use sp, as a0 gets wiped */
REGLOAD s0, REG_EPC(sp) /* restore epc */
csrw CSR_EPC, s0
/* Restore status register, but don't enable interrupts yet */
REGLOAD s0, REG_INT_CTX(sp) /* restore status */
li s1, STATUS_IE /* move IE -> PIE */
and s1, s0, s1 /* if (STATUS & IE) */
beqz s1, 1f
li s1, ~STATUS_IE /* clear IE */
and s0, s0, s1
li s1, STATUS_PIE /* set PIE */
or s0, s0, s1
1:
csrw CSR_STATUS, s0
#ifdef CONFIG_ARCH_KERNEL_STACK
/* Returning to userspace ? */
li s1, STATUS_PPP
and s0, s0, s1
bnez s0, 1f
/* Set the next task's kernel stack to the scratch area */
jal x1, riscv_current_ksp
csrr s0, CSR_SCRATCH
REGSTORE a0, RISCV_PERCPU_KSP(s0)
1:
#endif
load_ctx sp
REGLOAD sp, REG_SP(sp) /* restore original sp */
/* return from exception, which updates the status register */
ERET
.size sys_call0, .-sys_call0
.size sys_call1, .-sys_call1
.size sys_call2, .-sys_call2
.size sys_call3, .-sys_call3
.size sys_call4, .-sys_call4
.size sys_call5, .-sys_call5
.size sys_call6, .-sys_call6
.end