LXR qemu/semihosting/console.c

   1/*
   2 * Semihosting Console Support
   3 *
   4 * Copyright (c) 2015 Imagination Technologies
   5 * Copyright (c) 2019 Linaro Ltd
   6 *
   7 * This provides support for outputting to a semihosting console.
   8 *
   9 * While most semihosting implementations support reading and writing
  10 * to arbitrary file descriptors we treat the console as something
  11 * specifically for debugging interaction. This means messages can be
  12 * re-directed to gdb (if currently being used to debug) or even
  13 * re-directed elsewhere.
  14 *
  15 * SPDX-License-Identifier: GPL-2.0-or-later
  16 */
  17
  18#include "qemu/osdep.h"
  19#include "cpu.h"
  20#include "semihosting/semihost.h"
  21#include "semihosting/console.h"
  22#include "exec/gdbstub.h"
  23#include "exec/exec-all.h"
  24#include "qemu/log.h"
  25#include "chardev/char.h"
  26#include "chardev/char-fe.h"
  27#include "sysemu/sysemu.h"
  28#include "qemu/main-loop.h"
  29#include "qapi/error.h"
  30#include "qemu/fifo8.h"
  31
  32int qemu_semihosting_log_out(const char *s, int len)
  33{
  34    Chardev *chardev = semihosting_get_chardev();
  35    if (chardev) {
  36        return qemu_chr_write_all(chardev, (uint8_t *) s, len);
  37    } else {
  38        return write(STDERR_FILENO, s, len);
  39    }
  40}
  41
  42/*
  43 * A re-implementation of lock_user_string that we can use locally
  44 * instead of relying on softmmu-semi. Hopefully we can deprecate that
  45 * in time. Copy string until we find a 0 or address error.
  46 */
  47static GString *copy_user_string(CPUArchState *env, target_ulong addr)
  48{
  49    CPUState *cpu = env_cpu(env);
  50    GString *s = g_string_sized_new(128);
  51    uint8_t c;
  52
  53    do {
  54        if (cpu_memory_rw_debug(cpu, addr++, &c, 1, 0) == 0) {
  55            if (c) {
  56                s = g_string_append_c(s, c);
  57            }
  58        } else {
  59            qemu_log_mask(LOG_GUEST_ERROR,
  60                          "%s: passed inaccessible address " TARGET_FMT_lx,
  61                          __func__, addr);
  62            break;
  63        }
  64    } while (c!=0);
  65
  66    return s;
  67}
  68
  69static void semihosting_cb(CPUState *cs, target_ulong ret, target_ulong err)
  70{
  71    if (ret == (target_ulong) -1) {
  72        qemu_log("%s: gdb console output failed ("TARGET_FMT_ld")",
  73                 __func__, err);
  74    }
  75}
  76
  77int qemu_semihosting_console_outs(CPUArchState *env, target_ulong addr)
  78{
  79    GString *s = copy_user_string(env, addr);
  80    int out = s->len;
  81
  82    if (use_gdb_syscalls()) {
  83        gdb_do_syscall(semihosting_cb, "write,2,%x,%x", addr, s->len);
  84    } else {
  85        out = qemu_semihosting_log_out(s->str, s->len);
  86    }
  87
  88    g_string_free(s, true);
  89    return out;
  90}
  91
  92void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
  93{
  94    CPUState *cpu = env_cpu(env);
  95    uint8_t c;
  96
  97    if (cpu_memory_rw_debug(cpu, addr, &c, 1, 0) == 0) {
  98        if (use_gdb_syscalls()) {
  99            gdb_do_syscall(semihosting_cb, "write,2,%x,%x", addr, 1);
 100        } else {
 101            qemu_semihosting_log_out((const char *) &c, 1);
 102        }
 103    } else {
 104        qemu_log_mask(LOG_GUEST_ERROR,
 105                      "%s: passed inaccessible address " TARGET_FMT_lx,
 106                      __func__, addr);
 107    }
 108}
 109
 110#define FIFO_SIZE   1024
 111
 112/* Access to this structure is protected by the BQL */
 113typedef struct SemihostingConsole {
 114    CharBackend         backend;
 115    GSList              *sleeping_cpus;
 116    bool                got;
 117    Fifo8               fifo;
 118} SemihostingConsole;
 119
 120static SemihostingConsole console;
 121
 122static int console_can_read(void *opaque)
 123{
 124    SemihostingConsole *c = opaque;
 125    int ret;
 126    g_assert(qemu_mutex_iothread_locked());
 127    ret = (int) fifo8_num_free(&c->fifo);
 128    return ret;
 129}
 130
 131static void console_wake_up(gpointer data, gpointer user_data)
 132{
 133    CPUState *cs = (CPUState *) data;
 134    /* cpu_handle_halt won't know we have work so just unbung here */
 135    cs->halted = 0;
 136    qemu_cpu_kick(cs);
 137}
 138
 139static void console_read(void *opaque, const uint8_t *buf, int size)
 140{
 141    SemihostingConsole *c = opaque;
 142    g_assert(qemu_mutex_iothread_locked());
 143    while (size-- && !fifo8_is_full(&c->fifo)) {
 144        fifo8_push(&c->fifo, *buf++);
 145    }
 146    g_slist_foreach(c->sleeping_cpus, console_wake_up, NULL);
 147    c->sleeping_cpus = NULL;
 148}
 149
 150target_ulong qemu_semihosting_console_inc(CPUArchState *env)
 151{
 152    uint8_t ch;
 153    SemihostingConsole *c = &console;
 154    g_assert(qemu_mutex_iothread_locked());
 155    g_assert(current_cpu);
 156    if (fifo8_is_empty(&c->fifo)) {
 157        c->sleeping_cpus = g_slist_prepend(c->sleeping_cpus, current_cpu);
 158        current_cpu->halted = 1;
 159        current_cpu->exception_index = EXCP_HALTED;
 160        cpu_loop_exit(current_cpu);
 161        /* never returns */
 162    }
 163    ch = fifo8_pop(&c->fifo);
 164    return (target_ulong) ch;
 165}
 166
 167void qemu_semihosting_console_init(void)
 168{
 169    Chardev *chr = semihosting_get_chardev();
 170
 171    if  (chr) {
 172        fifo8_create(&console.fifo, FIFO_SIZE);
 173        qemu_chr_fe_init(&console.backend, chr, &error_abort);
 174        qemu_chr_fe_set_handlers(&console.backend,
 175                                 console_can_read,
 176                                 console_read,
 177                                 NULL, NULL, &console,
 178                                 NULL, true);
 179    }
 180}
 181