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