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/***************************************************************************
* Copyright (C) 2018 by Liviu Ionescu *
* ilg@livius.net *
* *
* Copyright (C) 2009 by Marvell Technology Group Ltd. *
* Written by Nicolas Pitre <nico@marvell.com> *
* *
* Copyright (C) 2010 by Spencer Oliver *
* spen@spen-soft.co.uk *
* *
* Copyright (C) 2016 by Square, Inc. *
* Steven Stallion <stallion@squareup.com> *
* *
* 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; either version 2 of the License, or *
* (at your option) any later version. *
* *
* 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. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/>. *
***************************************************************************/
/**
* @file
* Hold RISC-V semihosting support.
*
* The RISC-V code is inspired from ARM semihosting.
*
* Details can be found in chapter 8 of DUI0203I_rvct_developer_guide.pdf
* from ARM Ltd.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "log.h"
#include "target/target.h"
#include "target/semihosting_common.h"
#include "riscv.h"
static int riscv_semihosting_setup(struct target *target, int enable);
static int riscv_semihosting_post_result(struct target *target);
/**
* Initialize RISC-V semihosting. Use common ARM code.
*/
void riscv_semihosting_init(struct target *target)
{
semihosting_common_init(target, riscv_semihosting_setup,
riscv_semihosting_post_result);
}
/**
* Check for and process a semihosting request using the ARM protocol). This
* is meant to be called when the target is stopped due to a debug mode entry.
* If the value 0 is returned then there was nothing to process. A non-zero
* return value signifies that a request was processed and the target resumed,
* or an error was encountered, in which case the caller must return
* immediately.
*
* @param target Pointer to the target to process.
* @param retval Pointer to a location where the return code will be stored
* @return non-zero value if a request was processed or an error encountered
*/
int riscv_semihosting(struct target *target, int *retval)
{
struct semihosting *semihosting = target->semihosting;
if (!semihosting)
return 0;
if (!semihosting->is_active)
return 0;
riscv_reg_t dpc;
int result = riscv_get_register(target, &dpc, GDB_REGNO_DPC);
if (result != ERROR_OK)
return 0;
uint8_t tmp[12];
/* Read the current instruction, including the bracketing */
*retval = target_read_memory(target, dpc - 4, 2, 6, tmp);
if (*retval != ERROR_OK)
return 0;
/*
* The instructions that trigger a semihosting call,
* always uncompressed, should look like:
*
* 01f01013 slli zero,zero,0x1f
* 00100073 ebreak
* 40705013 srai zero,zero,0x7
*/
uint32_t pre = target_buffer_get_u32(target, tmp);
uint32_t ebreak = target_buffer_get_u32(target, tmp + 4);
uint32_t post = target_buffer_get_u32(target, tmp + 8);
LOG_DEBUG("check %08x %08x %08x from 0x%" PRIx64 "-4", pre, ebreak, post, dpc);
if (pre != 0x01f01013 || ebreak != 0x00100073 || post != 0x40705013) {
/* Not the magic sequence defining semihosting. */
return 0;
}
/*
* Perform semihosting call if we are not waiting on a fileio
* operation to complete.
*/
if (!semihosting->hit_fileio) {
/* RISC-V uses A0 and A1 to pass function arguments */
riscv_reg_t r0;
riscv_reg_t r1;
result = riscv_get_register(target, &r0, GDB_REGNO_A0);
if (result != ERROR_OK)
return 0;
result = riscv_get_register(target, &r1, GDB_REGNO_A1);
if (result != ERROR_OK)
return 0;
semihosting->op = r0;
semihosting->param = r1;
semihosting->word_size_bytes = riscv_xlen(target) / 8;
/* Check for ARM operation numbers. */
if (0 <= semihosting->op && semihosting->op <= 0x31) {
*retval = semihosting_common(target);
if (*retval != ERROR_OK) {
LOG_ERROR("Failed semihosting operation");
return 0;
}
} else {
/* Unknown operation number, not a semihosting call. */
return 0;
}
}
/*
* Resume target if we are not waiting on a fileio
* operation to complete.
*/
if (semihosting->is_resumable && !semihosting->hit_fileio) {
/* Resume right after the EBREAK 4 bytes instruction. */
*retval = target_resume(target, 0, dpc+4, 0, 0);
if (*retval != ERROR_OK) {
LOG_ERROR("Failed to resume target");
return 0;
}
return 1;
}
return 0;
}
/* -------------------------------------------------------------------------
* Local functions. */
/**
* Called via semihosting->setup() later, after the target is known,
* usually on the first semihosting command.
*/
static int riscv_semihosting_setup(struct target *target, int enable)
{
LOG_DEBUG("enable=%d", enable);
struct semihosting *semihosting = target->semihosting;
if (semihosting)
semihosting->setup_time = clock();
return ERROR_OK;
}
static int riscv_semihosting_post_result(struct target *target)
{
struct semihosting *semihosting = target->semihosting;
if (!semihosting) {
/* If not enabled, silently ignored. */
return 0;
}
LOG_DEBUG("0x%" PRIx64, semihosting->result);
riscv_set_register(target, GDB_REGNO_A0, semihosting->result);
return 0;
}
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