qemu/hw/semihosting/console.c
Alex Bennée a331c6d774 semihosting: implement a semihosting console
This provides two functions for handling console output that handle
the common backend behaviour for semihosting.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
2019-05-28 10:28:50 +01:00

78 lines
2.2 KiB
C

/*
* 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 "cpu.h"
#include "hw/semihosting/console.h"
#include "exec/gdbstub.h"
#include "qemu/log.h"
int qemu_semihosting_log_out(const char *s, int len)
{
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. We either copy len bytes if specified or until we find a NULL.
*/
static GString *copy_user_string(CPUArchState *env, target_ulong addr, int len)
{
CPUState *cpu = ENV_GET_CPU(env);
GString *s = g_string_sized_new(len ? len : 128);
uint8_t c;
bool done;
do {
if (cpu_memory_rw_debug(cpu, addr++, &c, 1, 0) == 0) {
s = g_string_append_c(s, c);
done = len ? s->len == len : c == 0;
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"%s: passed inaccessible address " TARGET_FMT_lx,
__func__, addr);
done = true;
}
} while (!done);
return s;
}
static void semihosting_cb(CPUState *cs, target_ulong ret, target_ulong err)
{
if (ret == (target_ulong) -1) {
qemu_log("%s: gdb console output failed ("TARGET_FMT_ld")",
__func__, err);
}
}
int qemu_semihosting_console_out(CPUArchState *env, target_ulong addr, int len)
{
GString *s = copy_user_string(env, addr, len);
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;
}