gdbstub: move chunks of user code into own files

The process was pretty similar to the softmmu move except we take the
time to split stuff between user.c and user-target.c to avoid as much
target specific compilation as possible. We also start to make use of
our shiny new header scheme so the user-only helpers can be included
without the rest of the exec/gsbstub.h cruft.

As before we split some functions into user and softmmu versions

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Message-Id: <20230302190846.2593720-12-alex.bennee@linaro.org>
Message-Id: <20230303025805.625589-12-richard.henderson@linaro.org>

1 files changed, 344 insertions, 0 deletions

diff --git a/gdbstub/user.c b/gdbstub/user.c
index 09a18fb23b..23b2e726f6 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -10,10 +10,354 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "qemu/sockets.h"
+#include "exec/hwaddr.h"
+#include "exec/tb-flush.h"
 #include "exec/gdbstub.h"
+#include "gdbstub/user.h"
 #include "hw/core/cpu.h"
+#include "trace.h"
 #include "internals.h"
 
+/* User-mode specific state */
+typedef struct {
+    int fd;
+    char *socket_path;
+    int running_state;
+} GDBUserState;
+
+static GDBUserState gdbserver_user_state;
+
+int gdb_get_char(void)
+{
+    uint8_t ch;
+    int ret;
+
+    for (;;) {
+        ret = recv(gdbserver_user_state.fd, &ch, 1, 0);
+        if (ret < 0) {
+            if (errno == ECONNRESET) {
+                gdbserver_user_state.fd = -1;
+            }
+            if (errno != EINTR) {
+                return -1;
+            }
+        } else if (ret == 0) {
+            close(gdbserver_user_state.fd);
+            gdbserver_user_state.fd = -1;
+            return -1;
+        } else {
+            break;
+        }
+    }
+    return ch;
+}
+
+void gdb_put_buffer(const uint8_t *buf, int len)
+{
+    int ret;
+
+    while (len > 0) {
+        ret = send(gdbserver_user_state.fd, buf, len, 0);
+        if (ret < 0) {
+            if (errno != EINTR) {
+                return;
+            }
+        } else {
+            buf += ret;
+            len -= ret;
+        }
+    }
+}
+
+/* Tell the remote gdb that the process has exited.  */
+void gdb_exit(int code)
+{
+    char buf[4];
+
+    if (!gdbserver_state.init) {
+        return;
+    }
+    if (gdbserver_user_state.socket_path) {
+        unlink(gdbserver_user_state.socket_path);
+    }
+    if (gdbserver_user_state.fd < 0) {
+        return;
+    }
+
+    trace_gdbstub_op_exiting((uint8_t)code);
+
+    snprintf(buf, sizeof(buf), "W%02x", (uint8_t)code);
+    gdb_put_packet(buf);
+}
+
+int gdb_handlesig(CPUState *cpu, int sig)
+{
+    char buf[256];
+    int n;
+
+    if (!gdbserver_state.init || gdbserver_user_state.fd < 0) {
+        return sig;
+    }
+
+    /* disable single step if it was enabled */
+    cpu_single_step(cpu, 0);
+    tb_flush(cpu);
+
+    if (sig != 0) {
+        gdb_set_stop_cpu(cpu);
+        g_string_printf(gdbserver_state.str_buf,
+                        "T%02xthread:", gdb_target_signal_to_gdb(sig));
+        gdb_append_thread_id(cpu, gdbserver_state.str_buf);
+        g_string_append_c(gdbserver_state.str_buf, ';');
+        gdb_put_strbuf();
+    }
+    /*
+     * gdb_put_packet() might have detected that the peer terminated the
+     * connection.
+     */
+    if (gdbserver_user_state.fd < 0) {
+        return sig;
+    }
+
+    sig = 0;
+    gdbserver_state.state = RS_IDLE;
+    gdbserver_user_state.running_state = 0;
+    while (gdbserver_user_state.running_state == 0) {
+        n = read(gdbserver_user_state.fd, buf, 256);
+        if (n > 0) {
+            int i;
+
+            for (i = 0; i < n; i++) {
+                gdb_read_byte(buf[i]);
+            }
+        } else {
+            /*
+             * XXX: Connection closed.  Should probably wait for another
+             * connection before continuing.
+             */
+            if (n == 0) {
+                close(gdbserver_user_state.fd);
+            }
+            gdbserver_user_state.fd = -1;
+            return sig;
+        }
+    }
+    sig = gdbserver_state.signal;
+    gdbserver_state.signal = 0;
+    return sig;
+}
+
+/* Tell the remote gdb that the process has exited due to SIG.  */
+void gdb_signalled(CPUArchState *env, int sig)
+{
+    char buf[4];
+
+    if (!gdbserver_state.init || gdbserver_user_state.fd < 0) {
+        return;
+    }
+
+    snprintf(buf, sizeof(buf), "X%02x", gdb_target_signal_to_gdb(sig));
+    gdb_put_packet(buf);
+}
+
+static void gdb_accept_init(int fd)
+{
+    gdb_init_gdbserver_state();
+    gdb_create_default_process(&gdbserver_state);
+    gdbserver_state.processes[0].attached = true;
+    gdbserver_state.c_cpu = gdb_first_attached_cpu();
+    gdbserver_state.g_cpu = gdbserver_state.c_cpu;
+    gdbserver_user_state.fd = fd;
+    gdb_has_xml = false;
+}
+
+static bool gdb_accept_socket(int gdb_fd)
+{
+    int fd;
+
+    for (;;) {
+        fd = accept(gdb_fd, NULL, NULL);
+        if (fd < 0 && errno != EINTR) {
+            perror("accept socket");
+            return false;
+        } else if (fd >= 0) {
+            qemu_set_cloexec(fd);
+            break;
+        }
+    }
+
+    gdb_accept_init(fd);
+    return true;
+}
+
+static int gdbserver_open_socket(const char *path)
+{
+    struct sockaddr_un sockaddr = {};
+    int fd, ret;
+
+    fd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (fd < 0) {
+        perror("create socket");
+        return -1;
+    }
+
+    sockaddr.sun_family = AF_UNIX;
+    pstrcpy(sockaddr.sun_path, sizeof(sockaddr.sun_path) - 1, path);
+    ret = bind(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr));
+    if (ret < 0) {
+        perror("bind socket");
+        close(fd);
+        return -1;
+    }
+    ret = listen(fd, 1);
+    if (ret < 0) {
+        perror("listen socket");
+        close(fd);
+        return -1;
+    }
+
+    return fd;
+}
+
+static bool gdb_accept_tcp(int gdb_fd)
+{
+    struct sockaddr_in sockaddr = {};
+    socklen_t len;
+    int fd;
+
+    for (;;) {
+        len = sizeof(sockaddr);
+        fd = accept(gdb_fd, (struct sockaddr *)&sockaddr, &len);
+        if (fd < 0 && errno != EINTR) {
+            perror("accept");
+            return false;
+        } else if (fd >= 0) {
+            qemu_set_cloexec(fd);
+            break;
+        }
+    }
+
+    /* set short latency */
+    if (socket_set_nodelay(fd)) {
+        perror("setsockopt");
+        close(fd);
+        return false;
+    }
+
+    gdb_accept_init(fd);
+    return true;
+}
+
+static int gdbserver_open_port(int port)
+{
+    struct sockaddr_in sockaddr;
+    int fd, ret;
+
+    fd = socket(PF_INET, SOCK_STREAM, 0);
+    if (fd < 0) {
+        perror("socket");
+        return -1;
+    }
+    qemu_set_cloexec(fd);
+
+    socket_set_fast_reuse(fd);
+
+    sockaddr.sin_family = AF_INET;
+    sockaddr.sin_port = htons(port);
+    sockaddr.sin_addr.s_addr = 0;
+    ret = bind(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr));
+    if (ret < 0) {
+        perror("bind");
+        close(fd);
+        return -1;
+    }
+    ret = listen(fd, 1);
+    if (ret < 0) {
+        perror("listen");
+        close(fd);
+        return -1;
+    }
+
+    return fd;
+}
+
+int gdbserver_start(const char *port_or_path)
+{
+    int port = g_ascii_strtoull(port_or_path, NULL, 10);
+    int gdb_fd;
+
+    if (port > 0) {
+        gdb_fd = gdbserver_open_port(port);
+    } else {
+        gdb_fd = gdbserver_open_socket(port_or_path);
+    }
+
+    if (gdb_fd < 0) {
+        return -1;
+    }
+
+    if (port > 0 && gdb_accept_tcp(gdb_fd)) {
+        return 0;
+    } else if (gdb_accept_socket(gdb_fd)) {
+        gdbserver_user_state.socket_path = g_strdup(port_or_path);
+        return 0;
+    }
+
+    /* gone wrong */
+    close(gdb_fd);
+    return -1;
+}
+
+/* Disable gdb stub for child processes.  */
+void gdbserver_fork(CPUState *cpu)
+{
+    if (!gdbserver_state.init || gdbserver_user_state.fd < 0) {
+        return;
+    }
+    close(gdbserver_user_state.fd);
+    gdbserver_user_state.fd = -1;
+    cpu_breakpoint_remove_all(cpu, BP_GDB);
+    /* no cpu_watchpoint_remove_all for user-mode */
+}
+
+/*
+ * Execution state helpers
+ */
+
+void gdb_continue(void)
+{
+    gdbserver_user_state.running_state = 1;
+    trace_gdbstub_op_continue();
+}
+
+/*
+ * Resume execution, for user-mode emulation it's equivalent to
+ * gdb_continue.
+ */
+int gdb_continue_partial(char *newstates)
+{
+    CPUState *cpu;
+    int res = 0;
+    /*
+     * This is not exactly accurate, but it's an improvement compared to the
+     * previous situation, where only one CPU would be single-stepped.
+     */
+    CPU_FOREACH(cpu) {
+        if (newstates[cpu->cpu_index] == 's') {
+            trace_gdbstub_op_stepping(cpu->cpu_index);
+            cpu_single_step(cpu, gdbserver_state.sstep_flags);
+        }
+    }
+    gdbserver_user_state.running_state = 1;
+    return res;
+}
+
+/*
+ * Break/Watch point helpers
+ */
+
 bool gdb_supports_guest_debug(void)
 {
     /* user-mode == TCG == supported */