semihosting: Move hw/semihosting/ -> semihosting/

With the exception of hw/core/, the hw/ directory only contains
device models used in system emulation. Semihosting is also used
by user emulation. As a generic feature, move it out of hw/ directory.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210226131356.3964782-3-f4bug@amsat.org>
Message-Id: <20210305135451.15427-3-alex.bennee@linaro.org>

semihosting/console.c

@@ -0,0 +1,180 @@
+/*
+ * 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 "semihosting/semihost.h"
+#include "semihosting/console.h"
+#include "exec/gdbstub.h"
+#include "exec/exec-all.h"
+#include "qemu/log.h"
+#include "chardev/char.h"
+#include "chardev/char-fe.h"
+#include "sysemu/sysemu.h"
+#include "qemu/main-loop.h"
+#include "qapi/error.h"
+#include "qemu/fifo8.h"
+
+int qemu_semihosting_log_out(const char *s, int len)
+{
+    Chardev *chardev = semihosting_get_chardev();
+    if (chardev) {
+        return qemu_chr_write_all(chardev, (uint8_t *) s, len);
+    } else {
+        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. Copy string until we find a 0 or address error.
+ */
+static GString *copy_user_string(CPUArchState *env, target_ulong addr)
+{
+    CPUState *cpu = env_cpu(env);
+    GString *s = g_string_sized_new(128);
+    uint8_t c;
+
+    do {
+        if (cpu_memory_rw_debug(cpu, addr++, &c, 1, 0) == 0) {
+            if (c) {
+                s = g_string_append_c(s, c);
+            }
+        } else {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: passed inaccessible address " TARGET_FMT_lx,
+                          __func__, addr);
+            break;
+        }
+    } while (c!=0);
+
+    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_outs(CPUArchState *env, target_ulong addr)
+{
+    GString *s = copy_user_string(env, addr);
+    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;
+}
+
+void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
+{
+    CPUState *cpu = env_cpu(env);
+    uint8_t c;
+
+    if (cpu_memory_rw_debug(cpu, addr, &c, 1, 0) == 0) {
+        if (use_gdb_syscalls()) {
+            gdb_do_syscall(semihosting_cb, "write,2,%x,%x", addr, 1);
+        } else {
+            qemu_semihosting_log_out((const char *) &c, 1);
+        }
+    } else {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: passed inaccessible address " TARGET_FMT_lx,
+                      __func__, addr);
+    }
+}
+
+#define FIFO_SIZE   1024
+
+/* Access to this structure is protected by the BQL */
+typedef struct SemihostingConsole {
+    CharBackend         backend;
+    GSList              *sleeping_cpus;
+    bool                got;
+    Fifo8               fifo;
+} SemihostingConsole;
+
+static SemihostingConsole console;
+
+static int console_can_read(void *opaque)
+{
+    SemihostingConsole *c = opaque;
+    int ret;
+    g_assert(qemu_mutex_iothread_locked());
+    ret = (int) fifo8_num_free(&c->fifo);
+    return ret;
+}
+
+static void console_wake_up(gpointer data, gpointer user_data)
+{
+    CPUState *cs = (CPUState *) data;
+    /* cpu_handle_halt won't know we have work so just unbung here */
+    cs->halted = 0;
+    qemu_cpu_kick(cs);
+}
+
+static void console_read(void *opaque, const uint8_t *buf, int size)
+{
+    SemihostingConsole *c = opaque;
+    g_assert(qemu_mutex_iothread_locked());
+    while (size-- && !fifo8_is_full(&c->fifo)) {
+        fifo8_push(&c->fifo, *buf++);
+    }
+    g_slist_foreach(c->sleeping_cpus, console_wake_up, NULL);
+    c->sleeping_cpus = NULL;
+}
+
+target_ulong qemu_semihosting_console_inc(CPUArchState *env)
+{
+    uint8_t ch;
+    SemihostingConsole *c = &console;
+    g_assert(qemu_mutex_iothread_locked());
+    g_assert(current_cpu);
+    if (fifo8_is_empty(&c->fifo)) {
+        c->sleeping_cpus = g_slist_prepend(c->sleeping_cpus, current_cpu);
+        current_cpu->halted = 1;
+        current_cpu->exception_index = EXCP_HALTED;
+        cpu_loop_exit(current_cpu);
+        /* never returns */
+    }
+    ch = fifo8_pop(&c->fifo);
+    return (target_ulong) ch;
+}
+
+void qemu_semihosting_console_init(void)
+{
+    Chardev *chr = semihosting_get_chardev();
+
+    if  (chr) {
+        fifo8_create(&console.fifo, FIFO_SIZE);
+        qemu_chr_fe_init(&console.backend, chr, &error_abort);
+        qemu_chr_fe_set_handlers(&console.backend,
+                                 console_can_read,
+                                 console_read,
+                                 NULL, NULL, &console,
+                                 NULL, true);
+    }
+}