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/*
* Semihosting Console Support
*
* Copyright (c) 2015 Imagination Technologies
* Copyright (c) 2019 Linaro Ltd
*
* This provides support for outputting to a semihosting console.
*
* While most semihosting implementations support reading and writing
* to arbitrary file descriptors we treat the console as something
* specifically for debugging interaction. This means messages can be
* re-directed to gdb (if currently being used to debug) or even
* re-directed elsewhere.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "semihosting/semihost.h"
#include "semihosting/console.h"
#include "exec/gdbstub.h"
#include "exec/exec-all.h"
#include "qemu/log.h"
#include "chardev/char.h"
#include "chardev/char-fe.h"
#include "qemu/main-loop.h"
#include "qapi/error.h"
#include "qemu/fifo8.h"
int qemu_semihosting_log_out(const char *s, int len)
{
Chardev *chardev = semihosting_get_chardev();
if (chardev) {
return qemu_chr_write_all(chardev, (uint8_t *) s, len);
} else {
return write(STDERR_FILENO, s, len);
}
}
/*
* A re-implementation of lock_user_string that we can use locally
* instead of relying on softmmu-semi. Hopefully we can deprecate that
* in time. Copy string until we find a 0 or address error.
*/
static GString *copy_user_string(CPUArchState *env, target_ulong addr)
{
CPUState *cpu = env_cpu(env);
GString *s = g_string_sized_new(128);
uint8_t c;
do {
if (cpu_memory_rw_debug(cpu, addr++, &c, 1, 0) == 0) {
if (c) {
s = g_string_append_c(s, c);
}
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"%s: passed inaccessible address " TARGET_FMT_lx,
__func__, addr);
break;
}
} while (c!=0);
return s;
}
static void semihosting_cb(CPUState *cs, uint64_t ret, int err)
{
if (err) {
qemu_log("%s: gdb console output failed (%d)\n", __func__, err);
}
}
int qemu_semihosting_console_outs(CPUArchState *env, target_ulong addr)
{
GString *s = copy_user_string(env, addr);
int out = s->len;
if (use_gdb_syscalls()) {
gdb_do_syscall(semihosting_cb, "write,2,%x,%x", addr, s->len);
} else {
out = qemu_semihosting_log_out(s->str, s->len);
}
g_string_free(s, true);
return out;
}
void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
{
CPUState *cpu = env_cpu(env);
uint8_t c;
if (cpu_memory_rw_debug(cpu, addr, &c, 1, 0) == 0) {
if (use_gdb_syscalls()) {
gdb_do_syscall(semihosting_cb, "write,2,%x,%x", addr, 1);
} else {
qemu_semihosting_log_out((const char *) &c, 1);
}
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"%s: passed inaccessible address " TARGET_FMT_lx,
__func__, addr);
}
}
#define FIFO_SIZE 1024
/* Access to this structure is protected by the BQL */
typedef struct SemihostingConsole {
CharBackend backend;
GSList *sleeping_cpus;
bool got;
Fifo8 fifo;
} SemihostingConsole;
static SemihostingConsole console;
static int console_can_read(void *opaque)
{
SemihostingConsole *c = opaque;
int ret;
g_assert(qemu_mutex_iothread_locked());
ret = (int) fifo8_num_free(&c->fifo);
return ret;
}
static void console_wake_up(gpointer data, gpointer user_data)
{
CPUState *cs = (CPUState *) data;
/* cpu_handle_halt won't know we have work so just unbung here */
cs->halted = 0;
qemu_cpu_kick(cs);
}
static void console_read(void *opaque, const uint8_t *buf, int size)
{
SemihostingConsole *c = opaque;
g_assert(qemu_mutex_iothread_locked());
while (size-- && !fifo8_is_full(&c->fifo)) {
fifo8_push(&c->fifo, *buf++);
}
g_slist_foreach(c->sleeping_cpus, console_wake_up, NULL);
c->sleeping_cpus = NULL;
}
int qemu_semihosting_console_read(CPUState *cs, void *buf, int len)
{
SemihostingConsole *c = &console;
int ret = 0;
g_assert(qemu_mutex_iothread_locked());
/* Block if the fifo is completely empty. */
if (fifo8_is_empty(&c->fifo)) {
c->sleeping_cpus = g_slist_prepend(c->sleeping_cpus, cs);
cs->halted = 1;
cs->exception_index = EXCP_HALTED;
cpu_loop_exit(cs);
/* never returns */
}
/* Read until buffer full or fifo exhausted. */
do {
*(char *)(buf + ret) = fifo8_pop(&c->fifo);
ret++;
} while (ret < len && !fifo8_is_empty(&c->fifo));
return ret;
}
void qemu_semihosting_console_init(void)
{
Chardev *chr = semihosting_get_chardev();
if (chr) {
fifo8_create(&console.fifo, FIFO_SIZE);
qemu_chr_fe_init(&console.backend, chr, &error_abort);
qemu_chr_fe_set_handlers(&console.backend,
console_can_read,
console_read,
NULL, NULL, &console,
NULL, true);
}
}
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