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