X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=gdbstub.c;h=d54abd17cc29ea9f6d7a7a9952aa12217e33463c;hb=b396733df3554688c58678f454c34d5c07dd5ca2;hp=f936ddd32dab77cafe2edb38ccfdfddbed14b490;hpb=ca4e667dbf431d4a2a5a619cde79d30dd2ac3eb2;p=mirror_qemu.git

diff --git a/gdbstub.c b/gdbstub.c
index f936ddd32d..d54abd17cc 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -20,7 +20,7 @@
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "qemu/cutils.h"
-#include "cpu.h"
+#include "trace-root.h"
 #ifdef CONFIG_USER_ONLY
 #include "qemu.h"
 #else
@@ -29,6 +29,7 @@
 #include "chardev/char-fe.h"
 #include "sysemu/sysemu.h"
 #include "exec/gdbstub.h"
+#include "hw/cpu/cluster.h"
 #endif
 
 #define MAX_PACKET_LENGTH 4096
@@ -287,21 +288,6 @@ static int gdb_signal_to_target (int sig)
         return -1;
 }
 
-/* #define DEBUG_GDB */
-
-#ifdef DEBUG_GDB
-# define DEBUG_GDB_GATE 1
-#else
-# define DEBUG_GDB_GATE 0
-#endif
-
-#define gdb_debug(fmt, ...) do { \
-    if (DEBUG_GDB_GATE) { \
-        fprintf(stderr, "%s: " fmt, __func__, ## __VA_ARGS__); \
-    } \
-} while (0)
-
-
 typedef struct GDBRegisterState {
     int base_reg;
     int num_regs;
@@ -311,6 +297,13 @@ typedef struct GDBRegisterState {
     struct GDBRegisterState *next;
 } GDBRegisterState;
 
+typedef struct GDBProcess {
+    uint32_t pid;
+    bool attached;
+
+    char target_xml[1024];
+} GDBProcess;
+
 enum RSState {
     RS_INACTIVE,
     RS_IDLE,
@@ -339,6 +332,9 @@ typedef struct GDBState {
     CharBackend chr;
     Chardev *mon_chr;
 #endif
+    bool multiprocess;
+    GDBProcess *processes;
+    int process_num;
     char syscall_buf[256];
     gdb_syscall_complete_cb current_syscall_cb;
 } GDBState;
@@ -410,10 +406,13 @@ int use_gdb_syscalls(void)
 /* Resume execution.  */
 static inline void gdb_continue(GDBState *s)
 {
+
 #ifdef CONFIG_USER_ONLY
     s->running_state = 1;
+    trace_gdbstub_op_continue();
 #else
     if (!runstate_needs_reset()) {
+        trace_gdbstub_op_continue();
         vm_start();
     }
 #endif
@@ -434,6 +433,7 @@ static int gdb_continue_partial(GDBState *s, char *newstates)
      */
     CPU_FOREACH(cpu) {
         if (newstates[cpu->cpu_index] == 's') {
+            trace_gdbstub_op_stepping(cpu->cpu_index);
             cpu_single_step(cpu, sstep_flags);
         }
     }
@@ -452,11 +452,13 @@ static int gdb_continue_partial(GDBState *s, char *newstates)
             case 1:
                 break; /* nothing to do here */
             case 's':
+                trace_gdbstub_op_stepping(cpu->cpu_index);
                 cpu_single_step(cpu, sstep_flags);
                 cpu_resume(cpu);
                 flag = 1;
                 break;
             case 'c':
+                trace_gdbstub_op_continue_cpu(cpu->cpu_index);
                 cpu_resume(cpu);
                 flag = 1;
                 break;
@@ -515,6 +517,7 @@ static inline int tohex(int v)
         return v - 10 + 'a';
 }
 
+/* writes 2*len+1 bytes in buf */
 static void memtohex(char *buf, const uint8_t *mem, int len)
 {
     int i, c;
@@ -538,12 +541,49 @@ static void hextomem(uint8_t *mem, const char *buf, int len)
     }
 }
 
+static void hexdump(const char *buf, int len,
+                    void (*trace_fn)(size_t ofs, char const *text))
+{
+    char line_buffer[3 * 16 + 4 + 16 + 1];
+
+    size_t i;
+    for (i = 0; i < len || (i & 0xF); ++i) {
+        size_t byte_ofs = i & 15;
+
+        if (byte_ofs == 0) {
+            memset(line_buffer, ' ', 3 * 16 + 4 + 16);
+            line_buffer[3 * 16 + 4 + 16] = 0;
+        }
+
+        size_t col_group = (i >> 2) & 3;
+        size_t hex_col = byte_ofs * 3 + col_group;
+        size_t txt_col = 3 * 16 + 4 + byte_ofs;
+
+        if (i < len) {
+            char value = buf[i];
+
+            line_buffer[hex_col + 0] = tohex((value >> 4) & 0xF);
+            line_buffer[hex_col + 1] = tohex((value >> 0) & 0xF);
+            line_buffer[txt_col + 0] = (value >= ' ' && value < 127)
+                    ? value
+                    : '.';
+        }
+
+        if (byte_ofs == 0xF)
+            trace_fn(i & -16, line_buffer);
+    }
+}
+
 /* return -1 if error, 0 if OK */
-static int put_packet_binary(GDBState *s, const char *buf, int len)
+static int put_packet_binary(GDBState *s, const char *buf, int len, bool dump)
 {
     int csum, i;
     uint8_t *p;
 
+    if (dump && trace_event_get_state_backends(TRACE_GDBSTUB_IO_BINARYREPLY)) {
+        hexdump(buf, len, trace_gdbstub_io_binaryreply);
+    }
+
     for(;;) {
         p = s->last_packet;
         *(p++) = '$';
@@ -576,9 +616,9 @@ static int put_packet_binary(GDBState *s, const char *buf, int len)
 /* return -1 if error, 0 if OK */
 static int put_packet(GDBState *s, const char *buf)
 {
-    gdb_debug("reply='%s'\n", buf);
+    trace_gdbstub_io_reply(buf);
 
-    return put_packet_binary(s, buf, strlen(buf));
+    return put_packet_binary(s, buf, strlen(buf), false);
 }
 
 /* Encode data using the encoding for 'x' packets.  */
@@ -602,13 +642,162 @@ static int memtox(char *buf, const char *mem, int len)
     return p - buf;
 }
 
-static const char *get_feature_xml(const char *p, const char **newp,
-                                   CPUClass *cc)
+static uint32_t gdb_get_cpu_pid(const GDBState *s, CPUState *cpu)
+{
+    /* TODO: In user mode, we should use the task state PID */
+    if (cpu->cluster_index == UNASSIGNED_CLUSTER_INDEX) {
+        /* Return the default process' PID */
+        return s->processes[s->process_num - 1].pid;
+    }
+    return cpu->cluster_index + 1;
+}
+
+static GDBProcess *gdb_get_process(const GDBState *s, uint32_t pid)
+{
+    int i;
+
+    if (!pid) {
+        /* 0 means any process, we take the first one */
+        return &s->processes[0];
+    }
+
+    for (i = 0; i < s->process_num; i++) {
+        if (s->processes[i].pid == pid) {
+            return &s->processes[i];
+        }
+    }
+
+    return NULL;
+}
+
+static GDBProcess *gdb_get_cpu_process(const GDBState *s, CPUState *cpu)
+{
+    return gdb_get_process(s, gdb_get_cpu_pid(s, cpu));
+}
+
+static CPUState *find_cpu(uint32_t thread_id)
+{
+    CPUState *cpu;
+
+    CPU_FOREACH(cpu) {
+        if (cpu_gdb_index(cpu) == thread_id) {
+            return cpu;
+        }
+    }
+
+    return NULL;
+}
+
+static CPUState *get_first_cpu_in_process(const GDBState *s,
+                                          GDBProcess *process)
+{
+    CPUState *cpu;
+
+    CPU_FOREACH(cpu) {
+        if (gdb_get_cpu_pid(s, cpu) == process->pid) {
+            return cpu;
+        }
+    }
+
+    return NULL;
+}
+
+static CPUState *gdb_next_cpu_in_process(const GDBState *s, CPUState *cpu)
+{
+    uint32_t pid = gdb_get_cpu_pid(s, cpu);
+    cpu = CPU_NEXT(cpu);
+
+    while (cpu) {
+        if (gdb_get_cpu_pid(s, cpu) == pid) {
+            break;
+        }
+
+        cpu = CPU_NEXT(cpu);
+    }
+
+    return cpu;
+}
+
+/* Return the cpu following @cpu, while ignoring unattached processes. */
+static CPUState *gdb_next_attached_cpu(const GDBState *s, CPUState *cpu)
+{
+    cpu = CPU_NEXT(cpu);
+
+    while (cpu) {
+        if (gdb_get_cpu_process(s, cpu)->attached) {
+            break;
+        }
+
+        cpu = CPU_NEXT(cpu);
+    }
+
+    return cpu;
+}
+
+/* Return the first attached cpu */
+static CPUState *gdb_first_attached_cpu(const GDBState *s)
+{
+    CPUState *cpu = first_cpu;
+    GDBProcess *process = gdb_get_cpu_process(s, cpu);
+
+    if (!process->attached) {
+        return gdb_next_attached_cpu(s, cpu);
+    }
+
+    return cpu;
+}
+
+static CPUState *gdb_get_cpu(const GDBState *s, uint32_t pid, uint32_t tid)
+{
+    GDBProcess *process;
+    CPUState *cpu;
+
+    if (!pid && !tid) {
+        /* 0 means any process/thread, we take the first attached one */
+        return gdb_first_attached_cpu(s);
+    } else if (pid && !tid) {
+        /* any thread in a specific process */
+        process = gdb_get_process(s, pid);
+
+        if (process == NULL) {
+            return NULL;
+        }
+
+        if (!process->attached) {
+            return NULL;
+        }
+
+        return get_first_cpu_in_process(s, process);
+    } else {
+        /* a specific thread */
+        cpu = find_cpu(tid);
+
+        if (cpu == NULL) {
+            return NULL;
+        }
+
+        process = gdb_get_cpu_process(s, cpu);
+
+        if (pid && process->pid != pid) {
+            return NULL;
+        }
+
+        if (!process->attached) {
+            return NULL;
+        }
+
+        return cpu;
+    }
+}
+
+static const char *get_feature_xml(const GDBState *s, const char *p,
+                                   const char **newp, GDBProcess *process)
 {
     size_t len;
     int i;
     const char *name;
-    static char target_xml[1024];
+    CPUState *cpu = get_first_cpu_in_process(s, process);
+    CPUClass *cc = CPU_GET_CLASS(cpu);
 
     len = 0;
     while (p[len] && p[len] != ':')
@@ -617,33 +806,44 @@ static const char *get_feature_xml(const char *p, const char **newp,
 
     name = NULL;
     if (strncmp(p, "target.xml", len) == 0) {
+        char *buf = process->target_xml;
+        const size_t buf_sz = sizeof(process->target_xml);
+
         /* Generate the XML description for this CPU.  */
-        if (!target_xml[0]) {
+        if (!buf[0]) {
             GDBRegisterState *r;
-            CPUState *cpu = first_cpu;
 
-            pstrcat(target_xml, sizeof(target_xml),
+            pstrcat(buf, buf_sz,
                     "<?xml version=\"1.0\"?>"
                     "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">"
                     "<target>");
             if (cc->gdb_arch_name) {
                 gchar *arch = cc->gdb_arch_name(cpu);
-                pstrcat(target_xml, sizeof(target_xml), "<architecture>");
-                pstrcat(target_xml, sizeof(target_xml), arch);
-                pstrcat(target_xml, sizeof(target_xml), "</architecture>");
+                pstrcat(buf, buf_sz, "<architecture>");
+                pstrcat(buf, buf_sz, arch);
+                pstrcat(buf, buf_sz, "</architecture>");
                 g_free(arch);
             }
-            pstrcat(target_xml, sizeof(target_xml), "<xi:include href=\"");
-            pstrcat(target_xml, sizeof(target_xml), cc->gdb_core_xml_file);
-            pstrcat(target_xml, sizeof(target_xml), "\"/>");
+            pstrcat(buf, buf_sz, "<xi:include href=\"");
+            pstrcat(buf, buf_sz, cc->gdb_core_xml_file);
+            pstrcat(buf, buf_sz, "\"/>");
             for (r = cpu->gdb_regs; r; r = r->next) {
-                pstrcat(target_xml, sizeof(target_xml), "<xi:include href=\"");
-                pstrcat(target_xml, sizeof(target_xml), r->xml);
-                pstrcat(target_xml, sizeof(target_xml), "\"/>");
+                pstrcat(buf, buf_sz, "<xi:include href=\"");
+                pstrcat(buf, buf_sz, r->xml);
+                pstrcat(buf, buf_sz, "\"/>");
             }
-            pstrcat(target_xml, sizeof(target_xml), "</target>");
+            pstrcat(buf, buf_sz, "</target>");
+        }
+        return buf;
+    }
+    if (cc->gdb_get_dynamic_xml) {
+        char *xmlname = g_strndup(p, len);
+        const char *xml = cc->gdb_get_dynamic_xml(cpu, xmlname);
+
+        g_free(xmlname);
+        if (xml) {
+            return xml;
         }
-        return target_xml;
     }
     for (i = 0; ; i++) {
         name = xml_builtin[i][0];
@@ -823,6 +1023,24 @@ static int gdb_breakpoint_remove(target_ulong addr, target_ulong len, int type)
     }
 }
 
+static inline void gdb_cpu_breakpoint_remove_all(CPUState *cpu)
+{
+    cpu_breakpoint_remove_all(cpu, BP_GDB);
+#ifndef CONFIG_USER_ONLY
+    cpu_watchpoint_remove_all(cpu, BP_GDB);
+#endif
+}
+
+static void gdb_process_breakpoint_remove_all(const GDBState *s, GDBProcess *p)
+{
+    CPUState *cpu = get_first_cpu_in_process(s, p);
+
+    while (cpu) {
+        gdb_cpu_breakpoint_remove_all(cpu);
+        cpu = gdb_next_cpu_in_process(s, cpu);
+    }
+}
+
 static void gdb_breakpoint_remove_all(void)
 {
     CPUState *cpu;
@@ -833,10 +1051,7 @@ static void gdb_breakpoint_remove_all(void)
     }
 
     CPU_FOREACH(cpu) {
-        cpu_breakpoint_remove_all(cpu, BP_GDB);
-#ifndef CONFIG_USER_ONLY
-        cpu_watchpoint_remove_all(cpu, BP_GDB);
-#endif
+        gdb_cpu_breakpoint_remove_all(cpu);
     }
 }
 
@@ -848,17 +1063,71 @@ static void gdb_set_cpu_pc(GDBState *s, target_ulong pc)
     cpu_set_pc(cpu, pc);
 }
 
-static CPUState *find_cpu(uint32_t thread_id)
+static char *gdb_fmt_thread_id(const GDBState *s, CPUState *cpu,
+                           char *buf, size_t buf_size)
 {
-    CPUState *cpu;
+    if (s->multiprocess) {
+        snprintf(buf, buf_size, "p%02x.%02x",
+                 gdb_get_cpu_pid(s, cpu), cpu_gdb_index(cpu));
+    } else {
+        snprintf(buf, buf_size, "%02x", cpu_gdb_index(cpu));
+    }
 
-    CPU_FOREACH(cpu) {
-        if (cpu_gdb_index(cpu) == thread_id) {
-            return cpu;
+    return buf;
+}
+
+typedef enum GDBThreadIdKind {
+    GDB_ONE_THREAD = 0,
+    GDB_ALL_THREADS,     /* One process, all threads */
+    GDB_ALL_PROCESSES,
+    GDB_READ_THREAD_ERR
+} GDBThreadIdKind;
+
+static GDBThreadIdKind read_thread_id(const char *buf, const char **end_buf,
+                                      uint32_t *pid, uint32_t *tid)
+{
+    unsigned long p, t;
+    int ret;
+
+    if (*buf == 'p') {
+        buf++;
+        ret = qemu_strtoul(buf, &buf, 16, &p);
+
+        if (ret) {
+            return GDB_READ_THREAD_ERR;
         }
+
+        /* Skip '.' */
+        buf++;
+    } else {
+        p = 1;
     }
 
-    return NULL;
+    ret = qemu_strtoul(buf, &buf, 16, &t);
+
+    if (ret) {
+        return GDB_READ_THREAD_ERR;
+    }
+
+    *end_buf = buf;
+
+    if (p == -1) {
+        return GDB_ALL_PROCESSES;
+    }
+
+    if (pid) {
+        *pid = p;
+    }
+
+    if (t == -1) {
+        return GDB_ALL_THREADS;
+    }
+
+    if (tid) {
+        *tid = t;
+    }
+
+    return GDB_ONE_THREAD;
 }
 
 static int is_query_packet(const char *p, const char *query, char separator)
@@ -876,11 +1145,14 @@ static int is_query_packet(const char *p, const char *query, char separator)
  */
 static int gdb_handle_vcont(GDBState *s, const char *p)
 {
-    int res, idx, signal = 0;
+    int res, signal = 0;
     char cur_action;
     char *newstates;
     unsigned long tmp;
+    uint32_t pid, tid;
+    GDBProcess *process;
     CPUState *cpu;
+    GDBThreadIdKind kind;
 #ifdef CONFIG_USER_ONLY
     int max_cpus = 1; /* global variable max_cpus exists only in system mode */
 
@@ -911,7 +1183,7 @@ static int gdb_handle_vcont(GDBState *s, const char *p)
 
         cur_action = *p++;
         if (cur_action == 'C' || cur_action == 'S') {
-            cur_action = tolower(cur_action);
+            cur_action = qemu_tolower(cur_action);
             res = qemu_strtoul(p + 1, &p, 16, &tmp);
             if (res) {
                 goto out;
@@ -922,25 +1194,57 @@ static int gdb_handle_vcont(GDBState *s, const char *p)
             res = -ENOTSUP;
             goto out;
         }
-        /* thread specification. special values: (none), -1 = all; 0 = any */
-        if ((p[0] == ':' && p[1] == '-' && p[2] == '1') || (p[0] != ':')) {
-            if (*p == ':') {
-                p += 3;
-            }
-            for (idx = 0; idx < max_cpus; idx++) {
-                if (newstates[idx] == 1) {
-                    newstates[idx] = cur_action;
+
+        if (*p == '\0' || *p == ';') {
+            /*
+             * No thread specifier, action is on "all threads". The
+             * specification is unclear regarding the process to act on. We
+             * choose all processes.
+             */
+            kind = GDB_ALL_PROCESSES;
+        } else if (*p++ == ':') {
+            kind = read_thread_id(p, &p, &pid, &tid);
+        } else {
+            res = -ENOTSUP;
+            goto out;
+        }
+
+        switch (kind) {
+        case GDB_READ_THREAD_ERR:
+            res = -EINVAL;
+            goto out;
+
+        case GDB_ALL_PROCESSES:
+            cpu = gdb_first_attached_cpu(s);
+            while (cpu) {
+                if (newstates[cpu->cpu_index] == 1) {
+                    newstates[cpu->cpu_index] = cur_action;
                 }
+
+                cpu = gdb_next_attached_cpu(s, cpu);
             }
-        } else if (*p == ':') {
-            p++;
-            res = qemu_strtoul(p, &p, 16, &tmp);
-            if (res) {
+            break;
+
+        case GDB_ALL_THREADS:
+            process = gdb_get_process(s, pid);
+
+            if (!process->attached) {
+                res = -EINVAL;
                 goto out;
             }
 
-            /* 0 means any thread, so we pick the first valid CPU */
-            cpu = tmp ? find_cpu(tmp) : first_cpu;
+            cpu = get_first_cpu_in_process(s, process);
+            while (cpu) {
+                if (newstates[cpu->cpu_index] == 1) {
+                    newstates[cpu->cpu_index] = cur_action;
+                }
+
+                cpu = gdb_next_cpu_in_process(s, cpu);
+            }
+            break;
+
+        case GDB_ONE_THREAD:
+            cpu = gdb_get_cpu(s, pid, tid);
 
             /* invalid CPU/thread specified */
             if (!cpu) {
@@ -952,6 +1256,7 @@ static int gdb_handle_vcont(GDBState *s, const char *p)
             if (newstates[cpu->cpu_index] == 1) {
                 newstates[cpu->cpu_index] = cur_action;
             }
+            break;
         }
     }
     s->signal = signal;
@@ -966,25 +1271,30 @@ out:
 static int gdb_handle_packet(GDBState *s, const char *line_buf)
 {
     CPUState *cpu;
+    GDBProcess *process;
     CPUClass *cc;
     const char *p;
-    uint32_t thread;
+    uint32_t pid, tid;
     int ch, reg_size, type, res;
-    char buf[MAX_PACKET_LENGTH];
     uint8_t mem_buf[MAX_PACKET_LENGTH];
+    char buf[sizeof(mem_buf) + 1 /* trailing NUL */];
+    char thread_id[16];
     uint8_t *registers;
     target_ulong addr, len;
+    GDBThreadIdKind thread_kind;
 
-
-    gdb_debug("command='%s'\n", line_buf);
+    trace_gdbstub_io_command(line_buf);
 
     p = line_buf;
     ch = *p++;
     switch(ch) {
+    case '!':
+        put_packet(s, "OK");
+        break;
     case '?':
         /* TODO: Make this return the correct value for user-mode.  */
-        snprintf(buf, sizeof(buf), "T%02xthread:%02x;", GDB_SIGNAL_TRAP,
-                 cpu_gdb_index(s->c_cpu));
+        snprintf(buf, sizeof(buf), "T%02xthread:%s;", GDB_SIGNAL_TRAP,
+                 gdb_fmt_thread_id(s, s->c_cpu, thread_id, sizeof(thread_id)));
         put_packet(s, buf);
         /* Remove all the breakpoints when this query is issued,
          * because gdb is doing and initial connect and the state
@@ -999,7 +1309,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         }
         s->signal = 0;
         gdb_continue(s);
-	return RS_IDLE;
+        return RS_IDLE;
     case 'C':
         s->signal = gdb_signal_to_target (strtoul(p, (char **)&p, 16));
         if (s->signal == -1)
@@ -1024,6 +1334,46 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
                 goto unknown_command;
             }
             break;
+        } else if (strncmp(p, "Attach;", 7) == 0) {
+            unsigned long pid;
+
+            p += 7;
+
+            if (qemu_strtoul(p, &p, 16, &pid)) {
+                put_packet(s, "E22");
+                break;
+            }
+
+            process = gdb_get_process(s, pid);
+
+            if (process == NULL) {
+                put_packet(s, "E22");
+                break;
+            }
+
+            cpu = get_first_cpu_in_process(s, process);
+
+            if (cpu == NULL) {
+                /* Refuse to attach an empty process */
+                put_packet(s, "E22");
+                break;
+            }
+
+            process->attached = true;
+
+            s->g_cpu = cpu;
+            s->c_cpu = cpu;
+
+            snprintf(buf, sizeof(buf), "T%02xthread:%s;", GDB_SIGNAL_TRAP,
+                     gdb_fmt_thread_id(s, cpu, thread_id, sizeof(thread_id)));
+
+            put_packet(s, buf);
+            break;
+        } else if (strncmp(p, "Kill;", 5) == 0) {
+            /* Kill the target */
+            put_packet(s, "OK");
+            error_report("QEMU: Terminated via GDBstub");
+            exit(0);
         } else {
             goto unknown_command;
         }
@@ -1033,9 +1383,40 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         exit(0);
     case 'D':
         /* Detach packet */
-        gdb_breakpoint_remove_all();
-        gdb_syscall_mode = GDB_SYS_DISABLED;
-        gdb_continue(s);
+        pid = 1;
+
+        if (s->multiprocess) {
+            unsigned long lpid;
+            if (*p != ';') {
+                put_packet(s, "E22");
+                break;
+            }
+
+            if (qemu_strtoul(p + 1, &p, 16, &lpid)) {
+                put_packet(s, "E22");
+                break;
+            }
+
+            pid = lpid;
+        }
+
+        process = gdb_get_process(s, pid);
+        gdb_process_breakpoint_remove_all(s, process);
+        process->attached = false;
+
+        if (pid == gdb_get_cpu_pid(s, s->c_cpu)) {
+            s->c_cpu = gdb_first_attached_cpu(s);
+        }
+
+        if (pid == gdb_get_cpu_pid(s, s->g_cpu)) {
+            s->g_cpu = gdb_first_attached_cpu(s);
+        }
+
+        if (s->c_cpu == NULL) {
+            /* No more process attached */
+            gdb_syscall_mode = GDB_SYS_DISABLED;
+            gdb_continue(s);
+        }
         put_packet(s, "OK");
         break;
     case 's':
@@ -1045,7 +1426,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         }
         cpu_single_step(s->c_cpu, sstep_flags);
         gdb_continue(s);
-	return RS_IDLE;
+        return RS_IDLE;
     case 'F':
         {
             target_ulong ret;
@@ -1182,12 +1563,18 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         break;
     case 'H':
         type = *p++;
-        thread = strtoull(p, (char **)&p, 16);
-        if (thread == -1 || thread == 0) {
+
+        thread_kind = read_thread_id(p, &p, &pid, &tid);
+        if (thread_kind == GDB_READ_THREAD_ERR) {
+            put_packet(s, "E22");
+            break;
+        }
+
+        if (thread_kind != GDB_ONE_THREAD) {
             put_packet(s, "OK");
             break;
         }
-        cpu = find_cpu(thread);
+        cpu = gdb_get_cpu(s, pid, tid);
         if (cpu == NULL) {
             put_packet(s, "E22");
             break;
@@ -1207,8 +1594,12 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         }
         break;
     case 'T':
-        thread = strtoull(p, (char **)&p, 16);
-        cpu = find_cpu(thread);
+        thread_kind = read_thread_id(p, &p, &pid, &tid);
+        if (thread_kind == GDB_READ_THREAD_ERR) {
+            put_packet(s, "E22");
+            break;
+        }
+        cpu = gdb_get_cpu(s, pid, tid);
 
         if (cpu != NULL) {
             put_packet(s, "OK");
@@ -1242,31 +1633,56 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             put_packet(s, "OK");
             break;
         } else if (strcmp(p,"C") == 0) {
-            /* "Current thread" remains vague in the spec, so always return
-             *  the first CPU (gdb returns the first thread). */
-            put_packet(s, "QC1");
+            /*
+             * "Current thread" remains vague in the spec, so always return
+             * the first thread of the current process (gdb returns the
+             * first thread).
+             */
+            cpu = get_first_cpu_in_process(s, gdb_get_cpu_process(s, s->g_cpu));
+            snprintf(buf, sizeof(buf), "QC%s",
+                     gdb_fmt_thread_id(s, cpu, thread_id, sizeof(thread_id)));
+            put_packet(s, buf);
             break;
         } else if (strcmp(p,"fThreadInfo") == 0) {
-            s->query_cpu = first_cpu;
+            s->query_cpu = gdb_first_attached_cpu(s);
             goto report_cpuinfo;
         } else if (strcmp(p,"sThreadInfo") == 0) {
         report_cpuinfo:
             if (s->query_cpu) {
-                snprintf(buf, sizeof(buf), "m%x", cpu_gdb_index(s->query_cpu));
+                snprintf(buf, sizeof(buf), "m%s",
+                         gdb_fmt_thread_id(s, s->query_cpu,
+                                       thread_id, sizeof(thread_id)));
                 put_packet(s, buf);
-                s->query_cpu = CPU_NEXT(s->query_cpu);
+                s->query_cpu = gdb_next_attached_cpu(s, s->query_cpu);
             } else
                 put_packet(s, "l");
             break;
         } else if (strncmp(p,"ThreadExtraInfo,", 16) == 0) {
-            thread = strtoull(p+16, (char **)&p, 16);
-            cpu = find_cpu(thread);
+            if (read_thread_id(p + 16, &p, &pid, &tid) == GDB_READ_THREAD_ERR) {
+                put_packet(s, "E22");
+                break;
+            }
+            cpu = gdb_get_cpu(s, pid, tid);
             if (cpu != NULL) {
                 cpu_synchronize_state(cpu);
-                /* memtohex() doubles the required space */
-                len = snprintf((char *)mem_buf, sizeof(buf) / 2,
-                               "CPU#%d [%s]", cpu->cpu_index,
-                               cpu->halted ? "halted " : "running");
+
+                if (s->multiprocess && (s->process_num > 1)) {
+                    /* Print the CPU model and name in multiprocess mode */
+                    ObjectClass *oc = object_get_class(OBJECT(cpu));
+                    const char *cpu_model = object_class_get_name(oc);
+                    char *cpu_name =
+                        object_get_canonical_path_component(OBJECT(cpu));
+                    len = snprintf((char *)mem_buf, sizeof(buf) / 2,
+                                   "%s %s [%s]", cpu_model, cpu_name,
+                                   cpu->halted ? "halted " : "running");
+                    g_free(cpu_name);
+                } else {
+                    /* memtohex() doubles the required space */
+                    len = snprintf((char *)mem_buf, sizeof(buf) / 2,
+                                   "CPU#%d [%s]", cpu->cpu_index,
+                                   cpu->halted ? "halted " : "running");
+                }
+                trace_gdbstub_op_extra_info((char *)mem_buf);
                 memtohex(buf, mem_buf, len);
                 put_packet(s, buf);
             }
@@ -1307,6 +1723,12 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             if (cc->gdb_core_xml_file != NULL) {
                 pstrcat(buf, sizeof(buf), ";qXfer:features:read+");
             }
+
+            if (strstr(p, "multiprocess+")) {
+                s->multiprocess = true;
+            }
+            pstrcat(buf, sizeof(buf), ";multiprocess+");
+
             put_packet(s, buf);
             break;
         }
@@ -1314,14 +1736,15 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             const char *xml;
             target_ulong total_len;
 
-            cc = CPU_GET_CLASS(first_cpu);
+            process = gdb_get_cpu_process(s, s->g_cpu);
+            cc = CPU_GET_CLASS(s->g_cpu);
             if (cc->gdb_core_xml_file == NULL) {
                 goto unknown_command;
             }
 
             gdb_has_xml = true;
             p += 19;
-            xml = get_feature_xml(p, &p, cc);
+            xml = get_feature_xml(s, p, &p, process);
             if (!xml) {
                 snprintf(buf, sizeof(buf), "E00");
                 put_packet(s, buf);
@@ -1350,7 +1773,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
                 buf[0] = 'l';
                 len = memtox(buf + 1, xml + addr, total_len - addr);
             }
-            put_packet_binary(s, buf, len + 1);
+            put_packet_binary(s, buf, len + 1, true);
             break;
         }
         if (is_query_packet(p, "Attached", ':')) {
@@ -1372,6 +1795,16 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
 
 void gdb_set_stop_cpu(CPUState *cpu)
 {
+    GDBProcess *p = gdb_get_cpu_process(gdbserver_state, cpu);
+
+    if (!p->attached) {
+        /*
+         * Having a stop CPU corresponding to a process that is not attached
+         * confuses GDB. So we ignore the request.
+         */
+        return;
+    }
+
     gdbserver_state->c_cpu = cpu;
     gdbserver_state->g_cpu = cpu;
 }
@@ -1382,6 +1815,7 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
     GDBState *s = gdbserver_state;
     CPUState *cpu = s->c_cpu;
     char buf[256];
+    char thread_id[16];
     const char *type;
     int ret;
 
@@ -1393,6 +1827,14 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
         put_packet(s, s->syscall_buf);
         return;
     }
+
+    if (cpu == NULL) {
+        /* No process attached */
+        return;
+    }
+
+    gdb_fmt_thread_id(s, cpu, thread_id, sizeof(thread_id));
+
     switch (state) {
     case RUN_STATE_DEBUG:
         if (cpu->watchpoint_hit) {
@@ -1407,29 +1849,38 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
                 type = "";
                 break;
             }
+            trace_gdbstub_hit_watchpoint(type, cpu_gdb_index(cpu),
+                    (target_ulong)cpu->watchpoint_hit->vaddr);
             snprintf(buf, sizeof(buf),
-                     "T%02xthread:%02x;%swatch:" TARGET_FMT_lx ";",
-                     GDB_SIGNAL_TRAP, cpu_gdb_index(cpu), type,
+                     "T%02xthread:%s;%swatch:" TARGET_FMT_lx ";",
+                     GDB_SIGNAL_TRAP, thread_id, type,
                      (target_ulong)cpu->watchpoint_hit->vaddr);
             cpu->watchpoint_hit = NULL;
             goto send_packet;
+        } else {
+            trace_gdbstub_hit_break();
         }
         tb_flush(cpu);
         ret = GDB_SIGNAL_TRAP;
         break;
     case RUN_STATE_PAUSED:
+        trace_gdbstub_hit_paused();
         ret = GDB_SIGNAL_INT;
         break;
     case RUN_STATE_SHUTDOWN:
+        trace_gdbstub_hit_shutdown();
         ret = GDB_SIGNAL_QUIT;
         break;
     case RUN_STATE_IO_ERROR:
+        trace_gdbstub_hit_io_error();
         ret = GDB_SIGNAL_IO;
         break;
     case RUN_STATE_WATCHDOG:
+        trace_gdbstub_hit_watchdog();
         ret = GDB_SIGNAL_ALRM;
         break;
     case RUN_STATE_INTERNAL_ERROR:
+        trace_gdbstub_hit_internal_error();
         ret = GDB_SIGNAL_ABRT;
         break;
     case RUN_STATE_SAVE_VM:
@@ -1439,11 +1890,12 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
         ret = GDB_SIGNAL_XCPU;
         break;
     default:
+        trace_gdbstub_hit_unknown(state);
         ret = GDB_SIGNAL_UNKNOWN;
         break;
     }
     gdb_set_stop_cpu(cpu);
-    snprintf(buf, sizeof(buf), "T%02xthread:%02x;", ret, cpu_gdb_index(cpu));
+    snprintf(buf, sizeof(buf), "T%02xthread:%s;", ret, thread_id);
 
 send_packet:
     put_packet(s, buf);
@@ -1508,6 +1960,12 @@ void gdb_do_syscallv(gdb_syscall_complete_cb cb, const char *fmt, va_list va)
     *p = 0;
 #ifdef CONFIG_USER_ONLY
     put_packet(s, s->syscall_buf);
+    /* Return control to gdb for it to process the syscall request.
+     * Since the protocol requires that gdb hands control back to us
+     * using a "here are the results" F packet, we don't need to check
+     * gdb_handlesig's return value (which is the signal to deliver if
+     * execution was resumed via a continue packet).
+     */
     gdb_handlesig(s->c_cpu, 0);
 #else
     /* In this case wait to send the syscall packet until notification that
@@ -1538,12 +1996,12 @@ static void gdb_read_byte(GDBState *s, int ch)
         /* Waiting for a response to the last packet.  If we see the start
            of a new command then abandon the previous response.  */
         if (ch == '-') {
-            gdb_debug("Got NACK, retransmitting\n");
+            trace_gdbstub_err_got_nack();
             put_buffer(s, (uint8_t *)s->last_packet, s->last_packet_len);
         } else if (ch == '+') {
-            gdb_debug("Got ACK\n");
+            trace_gdbstub_io_got_ack();
         } else {
-            gdb_debug("Got '%c' when expecting ACK/NACK\n", ch);
+            trace_gdbstub_io_got_unexpected((uint8_t)ch);
         }
 
         if (ch == '+' || ch == '$')
@@ -1566,7 +2024,7 @@ static void gdb_read_byte(GDBState *s, int ch)
                 s->line_sum = 0;
                 s->state = RS_GETLINE;
             } else {
-                gdb_debug("received garbage between packets: 0x%x\n", ch);
+                trace_gdbstub_err_garbage((uint8_t)ch);
             }
             break;
         case RS_GETLINE:
@@ -1582,7 +2040,7 @@ static void gdb_read_byte(GDBState *s, int ch)
                 /* end of command, start of checksum*/
                 s->state = RS_CHKSUM1;
             } else if (s->line_buf_index >= sizeof(s->line_buf) - 1) {
-                gdb_debug("command buffer overrun, dropping command\n");
+                trace_gdbstub_err_overrun();
                 s->state = RS_IDLE;
             } else {
                 /* unescaped command character */
@@ -1596,7 +2054,7 @@ static void gdb_read_byte(GDBState *s, int ch)
                 s->state = RS_CHKSUM1;
             } else if (s->line_buf_index >= sizeof(s->line_buf) - 1) {
                 /* command buffer overrun */
-                gdb_debug("command buffer overrun, dropping command\n");
+                trace_gdbstub_err_overrun();
                 s->state = RS_IDLE;
             } else {
                 /* parse escaped character and leave escape state */
@@ -1608,18 +2066,18 @@ static void gdb_read_byte(GDBState *s, int ch)
         case RS_GETLINE_RLE:
             if (ch < ' ') {
                 /* invalid RLE count encoding */
-                gdb_debug("got invalid RLE count: 0x%x\n", ch);
+                trace_gdbstub_err_invalid_repeat((uint8_t)ch);
                 s->state = RS_GETLINE;
             } else {
                 /* decode repeat length */
                 int repeat = (unsigned char)ch - ' ' + 3;
                 if (s->line_buf_index + repeat >= sizeof(s->line_buf) - 1) {
                     /* that many repeats would overrun the command buffer */
-                    gdb_debug("command buffer overrun, dropping command\n");
+                    trace_gdbstub_err_overrun();
                     s->state = RS_IDLE;
                 } else if (s->line_buf_index < 1) {
                     /* got a repeat but we have nothing to repeat */
-                    gdb_debug("got invalid RLE sequence\n");
+                    trace_gdbstub_err_invalid_rle();
                     s->state = RS_GETLINE;
                 } else {
                     /* repeat the last character */
@@ -1634,7 +2092,7 @@ static void gdb_read_byte(GDBState *s, int ch)
         case RS_CHKSUM1:
             /* get high hex digit of checksum */
             if (!isxdigit(ch)) {
-                gdb_debug("got invalid command checksum digit\n");
+                trace_gdbstub_err_checksum_invalid((uint8_t)ch);
                 s->state = RS_GETLINE;
                 break;
             }
@@ -1645,14 +2103,14 @@ static void gdb_read_byte(GDBState *s, int ch)
         case RS_CHKSUM2:
             /* get low hex digit of checksum */
             if (!isxdigit(ch)) {
-                gdb_debug("got invalid command checksum digit\n");
+                trace_gdbstub_err_checksum_invalid((uint8_t)ch);
                 s->state = RS_GETLINE;
                 break;
             }
             s->line_csum |= fromhex(ch);
 
             if (s->line_csum != (s->line_sum & 0xff)) {
-                gdb_debug("got command packet with incorrect checksum\n");
+                trace_gdbstub_err_checksum_incorrect(s->line_sum, s->line_csum);
                 /* send NAK reply */
                 reply = '-';
                 put_buffer(s, &reply, 1);
@@ -1686,6 +2144,8 @@ void gdb_exit(CPUArchState *env, int code)
   }
 #endif
 
+  trace_gdbstub_op_exiting((uint8_t)code);
+
   snprintf(buf, sizeof(buf), "W%02x", (uint8_t)code);
   put_packet(s, buf);
 
@@ -1694,6 +2154,31 @@ void gdb_exit(CPUArchState *env, int code)
 #endif
 }
 
+/*
+ * Create the process that will contain all the "orphan" CPUs (that are not
+ * part of a CPU cluster). Note that if this process contains no CPUs, it won't
+ * be attachable and thus will be invisible to the user.
+ */
+static void create_default_process(GDBState *s)
+{
+    GDBProcess *process;
+    int max_pid = 0;
+
+    if (s->process_num) {
+        max_pid = s->processes[s->process_num - 1].pid;
+    }
+
+    s->processes = g_renew(GDBProcess, s->processes, ++s->process_num);
+    process = &s->processes[s->process_num - 1];
+
+    /* We need an available PID slot for this process */
+    assert(max_pid < UINT32_MAX);
+
+    process->pid = max_pid + 1;
+    process->attached = false;
+    process->target_xml[0] = '\0';
+}
+
 #ifdef CONFIG_USER_ONLY
 int
 gdb_handlesig(CPUState *cpu, int sig)
@@ -1762,7 +2247,7 @@ void gdb_signalled(CPUArchState *env, int sig)
     put_packet(s, buf);
 }
 
-static void gdb_accept(void)
+static bool gdb_accept(void)
 {
     GDBState *s;
     struct sockaddr_in sockaddr;
@@ -1774,25 +2259,30 @@ static void gdb_accept(void)
         fd = accept(gdbserver_fd, (struct sockaddr *)&sockaddr, &len);
         if (fd < 0 && errno != EINTR) {
             perror("accept");
-            return;
+            return false;
         } else if (fd >= 0) {
-#ifndef _WIN32
-            fcntl(fd, F_SETFD, FD_CLOEXEC);
-#endif
+            qemu_set_cloexec(fd);
             break;
         }
     }
 
     /* set short latency */
-    socket_set_nodelay(fd);
+    if (socket_set_nodelay(fd)) {
+        perror("setsockopt");
+        close(fd);
+        return false;
+    }
 
     s = g_malloc0(sizeof(GDBState));
-    s->c_cpu = first_cpu;
-    s->g_cpu = first_cpu;
+    create_default_process(s);
+    s->processes[0].attached = true;
+    s->c_cpu = gdb_first_attached_cpu(s);
+    s->g_cpu = s->c_cpu;
     s->fd = fd;
     gdb_has_xml = false;
 
     gdbserver_state = s;
+    return true;
 }
 
 static int gdbserver_open(int port)
@@ -1805,9 +2295,7 @@ static int gdbserver_open(int port)
         perror("socket");
         return -1;
     }
-#ifndef _WIN32
-    fcntl(fd, F_SETFD, FD_CLOEXEC);
-#endif
+    qemu_set_cloexec(fd);
 
     socket_set_fast_reuse(fd);
 
@@ -1835,7 +2323,11 @@ int gdbserver_start(int port)
     if (gdbserver_fd < 0)
         return -1;
     /* accept connections */
-    gdb_accept();
+    if (!gdb_accept()) {
+        close(gdbserver_fd);
+        gdbserver_fd = -1;
+        return -1;
+    }
     return 0;
 }
 
@@ -1871,8 +2363,19 @@ static void gdb_chr_receive(void *opaque, const uint8_t *buf, int size)
 
 static void gdb_chr_event(void *opaque, int event)
 {
+    int i;
+    GDBState *s = (GDBState *) opaque;
+
     switch (event) {
     case CHR_EVENT_OPENED:
+        /* Start with first process attached, others detached */
+        for (i = 0; i < s->process_num; i++) {
+            s->processes[i].attached = !i;
+        }
+
+        s->c_cpu = gdb_first_attached_cpu(s);
+        s->g_cpu = s->c_cpu;
+
         vm_stop(RUN_STATE_PAUSED);
         gdb_has_xml = false;
         break;
@@ -1942,8 +2445,70 @@ static const TypeInfo char_gdb_type_info = {
     .class_init = char_gdb_class_init,
 };
 
+static int find_cpu_clusters(Object *child, void *opaque)
+{
+    if (object_dynamic_cast(child, TYPE_CPU_CLUSTER)) {
+        GDBState *s = (GDBState *) opaque;
+        CPUClusterState *cluster = CPU_CLUSTER(child);
+        GDBProcess *process;
+
+        s->processes = g_renew(GDBProcess, s->processes, ++s->process_num);
+
+        process = &s->processes[s->process_num - 1];
+
+        /*
+         * GDB process IDs -1 and 0 are reserved. To avoid subtle errors at
+         * runtime, we enforce here that the machine does not use a cluster ID
+         * that would lead to PID 0.
+         */
+        assert(cluster->cluster_id != UINT32_MAX);
+        process->pid = cluster->cluster_id + 1;
+        process->attached = false;
+        process->target_xml[0] = '\0';
+
+        return 0;
+    }
+
+    return object_child_foreach(child, find_cpu_clusters, opaque);
+}
+
+static int pid_order(const void *a, const void *b)
+{
+    GDBProcess *pa = (GDBProcess *) a;
+    GDBProcess *pb = (GDBProcess *) b;
+
+    if (pa->pid < pb->pid) {
+        return -1;
+    } else if (pa->pid > pb->pid) {
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
+static void create_processes(GDBState *s)
+{
+    object_child_foreach(object_get_root(), find_cpu_clusters, s);
+
+    if (s->processes) {
+        /* Sort by PID */
+        qsort(s->processes, s->process_num, sizeof(s->processes[0]), pid_order);
+    }
+
+    create_default_process(s);
+}
+
+static void cleanup_processes(GDBState *s)
+{
+    g_free(s->processes);
+    s->process_num = 0;
+    s->processes = NULL;
+}
+
 int gdbserver_start(const char *device)
 {
+    trace_gdbstub_op_start(device);
+
     GDBState *s;
     char gdbstub_device_name[128];
     Chardev *chr = NULL;
@@ -1973,7 +2538,11 @@ int gdbserver_start(const char *device)
             sigaction(SIGINT, &act, NULL);
         }
 #endif
-        chr = qemu_chr_new_noreplay("gdb", device);
+        /*
+         * FIXME: it's a bit weird to allow using a mux chardev here
+         * and implicitly setup a monitor. We may want to break this.
+         */
+        chr = qemu_chr_new_noreplay("gdb", device, true, NULL);
         if (!chr)
             return -1;
     }
@@ -1987,20 +2556,22 @@ int gdbserver_start(const char *device)
 
         /* Initialize a monitor terminal for gdb */
         mon_chr = qemu_chardev_new(NULL, TYPE_CHARDEV_GDB,
-                                   NULL, &error_abort);
+                                   NULL, NULL, &error_abort);
         monitor_init(mon_chr, 0);
     } else {
         qemu_chr_fe_deinit(&s->chr, true);
         mon_chr = s->mon_chr;
+        cleanup_processes(s);
         memset(s, 0, sizeof(GDBState));
         s->mon_chr = mon_chr;
     }
-    s->c_cpu = first_cpu;
-    s->g_cpu = first_cpu;
+
+    create_processes(s);
+
     if (chr) {
         qemu_chr_fe_init(&s->chr, chr, &error_abort);
         qemu_chr_fe_set_handlers(&s->chr, gdb_chr_can_receive, gdb_chr_receive,
-                                 gdb_chr_event, NULL, NULL, NULL, true);
+                                 gdb_chr_event, NULL, s, NULL, true);
     }
     s->state = chr ? RS_IDLE : RS_INACTIVE;
     s->mon_chr = mon_chr;
@@ -2009,6 +2580,13 @@ int gdbserver_start(const char *device)
     return 0;
 }
 
+void gdbserver_cleanup(void)
+{
+    if (gdbserver_state) {
+        put_packet(gdbserver_state, "W00");
+    }
+}
+
 static void register_types(void)
 {
     type_register_static(&char_gdb_type_info);