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 /* Access to this structure is protected by the BQL */ 31 typedef struct SemihostingConsole { 32 CharBackend backend; 33 Chardev *chr; 34 GSList *sleeping_cpus; 35 bool got; 36 Fifo8 fifo; 37 } SemihostingConsole; 38 39 static SemihostingConsole console; 40 41 #define FIFO_SIZE 1024 42 43 static int console_can_read(void *opaque) 44 { 45 SemihostingConsole *c = opaque; 46 int ret; 47 g_assert(qemu_mutex_iothread_locked()); 48 ret = (int) fifo8_num_free(&c->fifo); 49 return ret; 50 } 51 52 static void console_wake_up(gpointer data, gpointer user_data) 53 { 54 CPUState *cs = (CPUState *) data; 55 /* cpu_handle_halt won't know we have work so just unbung here */ 56 cs->halted = 0; 57 qemu_cpu_kick(cs); 58 } 59 60 static void console_read(void *opaque, const uint8_t *buf, int size) 61 { 62 SemihostingConsole *c = opaque; 63 g_assert(qemu_mutex_iothread_locked()); 64 while (size-- && !fifo8_is_full(&c->fifo)) { 65 fifo8_push(&c->fifo, *buf++); 66 } 67 g_slist_foreach(c->sleeping_cpus, console_wake_up, NULL); 68 c->sleeping_cpus = NULL; 69 } 70 71 bool qemu_semihosting_console_ready(void) 72 { 73 SemihostingConsole *c = &console; 74 75 g_assert(qemu_mutex_iothread_locked()); 76 return !fifo8_is_empty(&c->fifo); 77 } 78 79 void qemu_semihosting_console_block_until_ready(CPUState *cs) 80 { 81 SemihostingConsole *c = &console; 82 83 g_assert(qemu_mutex_iothread_locked()); 84 85 /* Block if the fifo is completely empty. */ 86 if (fifo8_is_empty(&c->fifo)) { 87 c->sleeping_cpus = g_slist_prepend(c->sleeping_cpus, cs); 88 cs->halted = 1; 89 cs->exception_index = EXCP_HALTED; 90 cpu_loop_exit(cs); 91 /* never returns */ 92 } 93 } 94 95 int qemu_semihosting_console_read(CPUState *cs, void *buf, int len) 96 { 97 SemihostingConsole *c = &console; 98 int ret = 0; 99 100 qemu_semihosting_console_block_until_ready(cs); 101 102 /* Read until buffer full or fifo exhausted. */ 103 do { 104 *(char *)(buf + ret) = fifo8_pop(&c->fifo); 105 ret++; 106 } while (ret < len && !fifo8_is_empty(&c->fifo)); 107 108 return ret; 109 } 110 111 int qemu_semihosting_console_write(void *buf, int len) 112 { 113 if (console.chr) { 114 return qemu_chr_write_all(console.chr, (uint8_t *)buf, len); 115 } else { 116 return fwrite(buf, 1, len, stderr); 117 } 118 } 119 120 void qemu_semihosting_console_init(Chardev *chr) 121 { 122 console.chr = chr; 123 if (chr) { 124 fifo8_create(&console.fifo, FIFO_SIZE); 125 qemu_chr_fe_init(&console.backend, chr, &error_abort); 126 qemu_chr_fe_set_handlers(&console.backend, 127 console_can_read, 128 console_read, 129 NULL, NULL, &console, 130 NULL, true); 131 } 132 133 qemu_semihosting_guestfd_init(); 134 } 135