Merge remote-tracking branch 'remotes/stsquad/tags/pull-testing-and-gdbstub-170320-1' into staging

Testing and gdbstub updates:

  - docker updates for VirGL
  - re-factor gdbstub for static GDBState
  - re-factor gdbstub for dynamic arrays
  - add SVE support to arm gdbstub
  - add some guest debug tests to check-tcg
  - add aarch64 userspace register tests
  - remove packet size limit to gdbstub
  - simplify gdbstub monitor code
  - report vContSupported in gdbstub to use proper single-step

# gpg: Signature made Tue 17 Mar 2020 17:47:46 GMT
# gpg:                using RSA key 6685AE99E75167BCAFC8DF35FBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>" [full]
# Primary key fingerprint: 6685 AE99 E751 67BC AFC8  DF35 FBD0 DB09 5A9E 2A44

* remotes/stsquad/tags/pull-testing-and-gdbstub-170320-1: (28 commits)
  gdbstub: Fix single-step issue by confirming 'vContSupported+' feature to gdb
  gdbstub: do not split gdb_monitor_write payload
  gdbstub: change GDBState.last_packet to GByteArray
  tests/tcg/aarch64: add test-sve-ioctl guest-debug test
  tests/tcg/aarch64: add SVE iotcl test
  tests/tcg/aarch64: add a gdbstub testcase for SVE registers
  tests/guest-debug: add a simple test runner
  configure: allow user to specify what gdb to use
  tests/tcg/aarch64: userspace system register test
  target/arm: don't bother with id_aa64pfr0_read for USER_ONLY
  target/arm: generate xml description of our SVE registers
  target/arm: default SVE length to 64 bytes for linux-user
  target/arm: explicitly encode regnum in our XML
  target/arm: prepare for multiple dynamic XMLs
  gdbstub: extend GByteArray to read register helpers
  target/i386: use gdb_get_reg helpers
  target/m68k: use gdb_get_reg helpers
  target/arm: use gdb_get_reg helpers
  gdbstub: add helper for 128 bit registers
  gdbstub: move mem_buf to GDBState and use GByteArray
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 455 insertions, 481 deletions

diff --git a/gdbstub.c b/gdbstub.c
index 22a2d630cd..013fb1ac0f 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -319,8 +319,8 @@ static int gdb_signal_to_target (int sig)
 typedef struct GDBRegisterState {
     int base_reg;
     int num_regs;
-    gdb_reg_cb get_reg;
-    gdb_reg_cb set_reg;
+    gdb_get_reg_cb get_reg;
+    gdb_set_reg_cb set_reg;
     const char *xml;
     struct GDBRegisterState *next;
 } GDBRegisterState;
@@ -342,6 +342,7 @@ enum RSState {
     RS_CHKSUM2,
 };
 typedef struct GDBState {
+    bool init;       /* have we been initialised? */
     CPUState *c_cpu; /* current CPU for step/continue ops */
     CPUState *g_cpu; /* current CPU for other ops */
     CPUState *query_cpu; /* for q{f|s}ThreadInfo */
@@ -350,8 +351,7 @@ typedef struct GDBState {
     int line_buf_index;
     int line_sum; /* running checksum */
     int line_csum; /* checksum at the end of the packet */
-    uint8_t last_packet[MAX_PACKET_LENGTH + 4];
-    int last_packet_len;
+    GByteArray *last_packet;
     int signal;
 #ifdef CONFIG_USER_ONLY
     int fd;
@@ -365,6 +365,8 @@ typedef struct GDBState {
     int process_num;
     char syscall_buf[256];
     gdb_syscall_complete_cb current_syscall_cb;
+    GString *str_buf;
+    GByteArray *mem_buf;
 } GDBState;
 
 /* By default use no IRQs and no timers while single stepping so as to
@@ -372,7 +374,26 @@ typedef struct GDBState {
  */
 static int sstep_flags = SSTEP_ENABLE|SSTEP_NOIRQ|SSTEP_NOTIMER;
 
-static GDBState *gdbserver_state;
+static GDBState gdbserver_state;
+
+static void init_gdbserver_state(void)
+{
+    g_assert(!gdbserver_state.init);
+    memset(&gdbserver_state, 0, sizeof(GDBState));
+    gdbserver_state.init = true;
+    gdbserver_state.str_buf = g_string_new(NULL);
+    gdbserver_state.mem_buf = g_byte_array_sized_new(MAX_PACKET_LENGTH);
+    gdbserver_state.last_packet = g_byte_array_sized_new(MAX_PACKET_LENGTH + 4);
+}
+
+#ifndef CONFIG_USER_ONLY
+static void reset_gdbserver_state(void)
+{
+    g_free(gdbserver_state.processes);
+    gdbserver_state.processes = NULL;
+    gdbserver_state.process_num = 0;
+}
+#endif
 
 bool gdb_has_xml;
 
@@ -380,21 +401,21 @@ bool gdb_has_xml;
 /* XXX: This is not thread safe.  Do we care?  */
 static int gdbserver_fd = -1;
 
-static int get_char(GDBState *s)
+static int get_char(void)
 {
     uint8_t ch;
     int ret;
 
     for(;;) {
-        ret = qemu_recv(s->fd, &ch, 1, 0);
+        ret = qemu_recv(gdbserver_state.fd, &ch, 1, 0);
         if (ret < 0) {
             if (errno == ECONNRESET)
-                s->fd = -1;
+                gdbserver_state.fd = -1;
             if (errno != EINTR)
                 return -1;
         } else if (ret == 0) {
-            close(s->fd);
-            s->fd = -1;
+            close(gdbserver_state.fd);
+            gdbserver_state.fd = -1;
             return -1;
         } else {
             break;
@@ -425,18 +446,18 @@ int use_gdb_syscalls(void)
     /* -semihosting-config target=auto */
     /* On the first call check if gdb is connected and remember. */
     if (gdb_syscall_mode == GDB_SYS_UNKNOWN) {
-        gdb_syscall_mode = (gdbserver_state ? GDB_SYS_ENABLED
-                                            : GDB_SYS_DISABLED);
+        gdb_syscall_mode = gdbserver_state.init ?
+            GDB_SYS_ENABLED : GDB_SYS_DISABLED;
     }
     return gdb_syscall_mode == GDB_SYS_ENABLED;
 }
 
 /* Resume execution.  */
-static inline void gdb_continue(GDBState *s)
+static inline void gdb_continue(void)
 {
 
 #ifdef CONFIG_USER_ONLY
-    s->running_state = 1;
+    gdbserver_state.running_state = 1;
     trace_gdbstub_op_continue();
 #else
     if (!runstate_needs_reset()) {
@@ -450,7 +471,7 @@ static inline void gdb_continue(GDBState *s)
  * Resume execution, per CPU actions. For user-mode emulation it's
  * equivalent to gdb_continue.
  */
-static int gdb_continue_partial(GDBState *s, char *newstates)
+static int gdb_continue_partial(char *newstates)
 {
     CPUState *cpu;
     int res = 0;
@@ -465,7 +486,7 @@ static int gdb_continue_partial(GDBState *s, char *newstates)
             cpu_single_step(cpu, sstep_flags);
         }
     }
-    s->running_state = 1;
+    gdbserver_state.running_state = 1;
 #else
     int flag = 0;
 
@@ -503,13 +524,13 @@ static int gdb_continue_partial(GDBState *s, char *newstates)
     return res;
 }
 
-static void put_buffer(GDBState *s, const uint8_t *buf, int len)
+static void put_buffer(const uint8_t *buf, int len)
 {
 #ifdef CONFIG_USER_ONLY
     int ret;
 
     while (len > 0) {
-        ret = send(s->fd, buf, len, 0);
+        ret = send(gdbserver_state.fd, buf, len, 0);
         if (ret < 0) {
             if (errno != EINTR)
                 return;
@@ -521,7 +542,7 @@ static void put_buffer(GDBState *s, const uint8_t *buf, int len)
 #else
     /* XXX this blocks entire thread. Rewrite to use
      * qemu_chr_fe_write and background I/O callbacks */
-    qemu_chr_fe_write_all(&s->chr, buf, len);
+    qemu_chr_fe_write_all(&gdbserver_state.chr, buf, len);
 #endif
 }
 
@@ -546,25 +567,24 @@ static inline int tohex(int v)
 }
 
 /* writes 2*len+1 bytes in buf */
-static void memtohex(char *buf, const uint8_t *mem, int len)
+static void memtohex(GString *buf, const uint8_t *mem, int len)
 {
     int i, c;
-    char *q;
-    q = buf;
     for(i = 0; i < len; i++) {
         c = mem[i];
-        *q++ = tohex(c >> 4);
-        *q++ = tohex(c & 0xf);
+        g_string_append_c(buf, tohex(c >> 4));
+        g_string_append_c(buf, tohex(c & 0xf));
     }
-    *q = '\0';
+    g_string_append_c(buf, '\0');
 }
 
-static void hextomem(uint8_t *mem, const char *buf, int len)
+static void hextomem(GByteArray *mem, const char *buf, int len)
 {
     int i;
 
     for(i = 0; i < len; i++) {
-        mem[i] = (fromhex(buf[0]) << 4) | fromhex(buf[1]);
+        guint8 byte = fromhex(buf[0]) << 4 | fromhex(buf[1]);
+        g_byte_array_append(mem, &byte, 1);
         buf += 2;
     }
 }
@@ -603,33 +623,35 @@ static void hexdump(const char *buf, int len,
 }
 
 /* return -1 if error, 0 if OK */
-static int put_packet_binary(GDBState *s, const char *buf, int len, bool dump)
+static int put_packet_binary(const char *buf, int len, bool dump)
 {
     int csum, i;
-    uint8_t *p;
+    uint8_t footer[3];
 
     if (dump && trace_event_get_state_backends(TRACE_GDBSTUB_IO_BINARYREPLY)) {
         hexdump(buf, len, trace_gdbstub_io_binaryreply);
     }
 
     for(;;) {
-        p = s->last_packet;
-        *(p++) = '$';
-        memcpy(p, buf, len);
-        p += len;
+        g_byte_array_set_size(gdbserver_state.last_packet, 0);
+        g_byte_array_append(gdbserver_state.last_packet,
+                            (const uint8_t *) "$", 1);
+        g_byte_array_append(gdbserver_state.last_packet,
+                            (const uint8_t *) buf, len);
         csum = 0;
         for(i = 0; i < len; i++) {
             csum += buf[i];
         }
-        *(p++) = '#';
-        *(p++) = tohex((csum >> 4) & 0xf);
-        *(p++) = tohex((csum) & 0xf);
+        footer[0] = '#';
+        footer[1] = tohex((csum >> 4) & 0xf);
+        footer[2] = tohex((csum) & 0xf);
+        g_byte_array_append(gdbserver_state.last_packet, footer, 3);
 
-        s->last_packet_len = p - s->last_packet;
-        put_buffer(s, (uint8_t *)s->last_packet, s->last_packet_len);
+        put_buffer(gdbserver_state.last_packet->data,
+                   gdbserver_state.last_packet->len);
 
 #ifdef CONFIG_USER_ONLY
-        i = get_char(s);
+        i = get_char();
         if (i < 0)
             return -1;
         if (i == '+')
@@ -642,65 +664,69 @@ static int put_packet_binary(GDBState *s, const char *buf, int len, bool dump)
 }
 
 /* return -1 if error, 0 if OK */
-static int put_packet(GDBState *s, const char *buf)
+static int put_packet(const char *buf)
 {
     trace_gdbstub_io_reply(buf);
 
-    return put_packet_binary(s, buf, strlen(buf), false);
+    return put_packet_binary(buf, strlen(buf), false);
+}
+
+static void put_strbuf(void)
+{
+    put_packet(gdbserver_state.str_buf->str);
 }
 
 /* Encode data using the encoding for 'x' packets.  */
-static int memtox(char *buf, const char *mem, int len)
+static void memtox(GString *buf, const char *mem, int len)
 {
-    char *p = buf;
     char c;
 
     while (len--) {
         c = *(mem++);
         switch (c) {
         case '#': case '$': case '*': case '}':
-            *(p++) = '}';
-            *(p++) = c ^ 0x20;
+            g_string_append_c(buf, '}');
+            g_string_append_c(buf, c ^ 0x20);
             break;
         default:
-            *(p++) = c;
+            g_string_append_c(buf, c);
             break;
         }
     }
-    return p - buf;
 }
 
-static uint32_t gdb_get_cpu_pid(const GDBState *s, CPUState *cpu)
+static uint32_t gdb_get_cpu_pid(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;
+        int index = gdbserver_state.process_num - 1;
+        return gdbserver_state.processes[index].pid;
     }
     return cpu->cluster_index + 1;
 }
 
-static GDBProcess *gdb_get_process(const GDBState *s, uint32_t pid)
+static GDBProcess *gdb_get_process(uint32_t pid)
 {
     int i;
 
     if (!pid) {
         /* 0 means any process, we take the first one */
-        return &s->processes[0];
+        return &gdbserver_state.processes[0];
     }
 
-    for (i = 0; i < s->process_num; i++) {
-        if (s->processes[i].pid == pid) {
-            return &s->processes[i];
+    for (i = 0; i < gdbserver_state.process_num; i++) {
+        if (gdbserver_state.processes[i].pid == pid) {
+            return &gdbserver_state.processes[i];
         }
     }
 
     return NULL;
 }
 
-static GDBProcess *gdb_get_cpu_process(const GDBState *s, CPUState *cpu)
+static GDBProcess *gdb_get_cpu_process(CPUState *cpu)
 {
-    return gdb_get_process(s, gdb_get_cpu_pid(s, cpu));
+    return gdb_get_process(gdb_get_cpu_pid(cpu));
 }
 
 static CPUState *find_cpu(uint32_t thread_id)
@@ -716,13 +742,12 @@ static CPUState *find_cpu(uint32_t thread_id)
     return NULL;
 }
 
-static CPUState *get_first_cpu_in_process(const GDBState *s,
-                                          GDBProcess *process)
+static CPUState *get_first_cpu_in_process(GDBProcess *process)
 {
     CPUState *cpu;
 
     CPU_FOREACH(cpu) {
-        if (gdb_get_cpu_pid(s, cpu) == process->pid) {
+        if (gdb_get_cpu_pid(cpu) == process->pid) {
             return cpu;
         }
     }
@@ -730,13 +755,13 @@ static CPUState *get_first_cpu_in_process(const GDBState *s,
     return NULL;
 }
 
-static CPUState *gdb_next_cpu_in_process(const GDBState *s, CPUState *cpu)
+static CPUState *gdb_next_cpu_in_process(CPUState *cpu)
 {
-    uint32_t pid = gdb_get_cpu_pid(s, cpu);
+    uint32_t pid = gdb_get_cpu_pid(cpu);
     cpu = CPU_NEXT(cpu);
 
     while (cpu) {
-        if (gdb_get_cpu_pid(s, cpu) == pid) {
+        if (gdb_get_cpu_pid(cpu) == pid) {
             break;
         }
 
@@ -747,12 +772,12 @@ static CPUState *gdb_next_cpu_in_process(const GDBState *s, CPUState *cpu)
 }
 
 /* Return the cpu following @cpu, while ignoring unattached processes. */
-static CPUState *gdb_next_attached_cpu(const GDBState *s, CPUState *cpu)
+static CPUState *gdb_next_attached_cpu(CPUState *cpu)
 {
     cpu = CPU_NEXT(cpu);
 
     while (cpu) {
-        if (gdb_get_cpu_process(s, cpu)->attached) {
+        if (gdb_get_cpu_process(cpu)->attached) {
             break;
         }
 
@@ -763,29 +788,29 @@ static CPUState *gdb_next_attached_cpu(const GDBState *s, CPUState *cpu)
 }
 
 /* Return the first attached cpu */
-static CPUState *gdb_first_attached_cpu(const GDBState *s)
+static CPUState *gdb_first_attached_cpu(void)
 {
     CPUState *cpu = first_cpu;
-    GDBProcess *process = gdb_get_cpu_process(s, cpu);
+    GDBProcess *process = gdb_get_cpu_process(cpu);
 
     if (!process->attached) {
-        return gdb_next_attached_cpu(s, cpu);
+        return gdb_next_attached_cpu(cpu);
     }
 
     return cpu;
 }
 
-static CPUState *gdb_get_cpu(const GDBState *s, uint32_t pid, uint32_t tid)
+static CPUState *gdb_get_cpu(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);
+        return gdb_first_attached_cpu();
     } else if (pid && !tid) {
         /* any thread in a specific process */
-        process = gdb_get_process(s, pid);
+        process = gdb_get_process(pid);
 
         if (process == NULL) {
             return NULL;
@@ -795,7 +820,7 @@ static CPUState *gdb_get_cpu(const GDBState *s, uint32_t pid, uint32_t tid)
             return NULL;
         }
 
-        return get_first_cpu_in_process(s, process);
+        return get_first_cpu_in_process(process);
     } else {
         /* a specific thread */
         cpu = find_cpu(tid);
@@ -804,7 +829,7 @@ static CPUState *gdb_get_cpu(const GDBState *s, uint32_t pid, uint32_t tid)
             return NULL;
         }
 
-        process = gdb_get_cpu_process(s, cpu);
+        process = gdb_get_cpu_process(cpu);
 
         if (pid && process->pid != pid) {
             return NULL;
@@ -818,13 +843,13 @@ static CPUState *gdb_get_cpu(const GDBState *s, uint32_t pid, uint32_t tid)
     }
 }
 
-static const char *get_feature_xml(const GDBState *s, const char *p,
-                                   const char **newp, GDBProcess *process)
+static const char *get_feature_xml(const char *p, const char **newp,
+                                   GDBProcess *process)
 {
     size_t len;
     int i;
     const char *name;
-    CPUState *cpu = get_first_cpu_in_process(s, process);
+    CPUState *cpu = get_first_cpu_in_process(process);
     CPUClass *cc = CPU_GET_CLASS(cpu);
 
     len = 0;
@@ -881,19 +906,19 @@ static const char *get_feature_xml(const GDBState *s, const char *p,
     return name ? xml_builtin[i][1] : NULL;
 }
 
-static int gdb_read_register(CPUState *cpu, uint8_t *mem_buf, int reg)
+static int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
     CPUArchState *env = cpu->env_ptr;
     GDBRegisterState *r;
 
     if (reg < cc->gdb_num_core_regs) {
-        return cc->gdb_read_register(cpu, mem_buf, reg);
+        return cc->gdb_read_register(cpu, buf, reg);
     }
 
     for (r = cpu->gdb_regs; r; r = r->next) {
         if (r->base_reg <= reg && reg < r->base_reg + r->num_regs) {
-            return r->get_reg(env, mem_buf, reg - r->base_reg);
+            return r->get_reg(env, buf, reg - r->base_reg);
         }
     }
     return 0;
@@ -924,7 +949,7 @@ static int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
  */
 
 void gdb_register_coprocessor(CPUState *cpu,
-                              gdb_reg_cb get_reg, gdb_reg_cb set_reg,
+                              gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
                               int num_regs, const char *xml, int g_pos)
 {
     GDBRegisterState *s;
@@ -984,7 +1009,7 @@ static int gdb_breakpoint_insert(int type, target_ulong addr, target_ulong len)
     int err = 0;
 
     if (kvm_enabled()) {
-        return kvm_insert_breakpoint(gdbserver_state->c_cpu, addr, len, type);
+        return kvm_insert_breakpoint(gdbserver_state.c_cpu, addr, len, type);
     }
 
     switch (type) {
@@ -1021,7 +1046,7 @@ static int gdb_breakpoint_remove(int type, target_ulong addr, target_ulong len)
     int err = 0;
 
     if (kvm_enabled()) {
-        return kvm_remove_breakpoint(gdbserver_state->c_cpu, addr, len, type);
+        return kvm_remove_breakpoint(gdbserver_state.c_cpu, addr, len, type);
     }
 
     switch (type) {
@@ -1059,13 +1084,13 @@ static inline void gdb_cpu_breakpoint_remove_all(CPUState *cpu)
 #endif
 }
 
-static void gdb_process_breakpoint_remove_all(const GDBState *s, GDBProcess *p)
+static void gdb_process_breakpoint_remove_all(GDBProcess *p)
 {
-    CPUState *cpu = get_first_cpu_in_process(s, p);
+    CPUState *cpu = get_first_cpu_in_process(p);
 
     while (cpu) {
         gdb_cpu_breakpoint_remove_all(cpu);
-        cpu = gdb_next_cpu_in_process(s, cpu);
+        cpu = gdb_next_cpu_in_process(cpu);
     }
 }
 
@@ -1074,7 +1099,7 @@ static void gdb_breakpoint_remove_all(void)
     CPUState *cpu;
 
     if (kvm_enabled()) {
-        kvm_remove_all_breakpoints(gdbserver_state->c_cpu);
+        kvm_remove_all_breakpoints(gdbserver_state.c_cpu);
         return;
     }
 
@@ -1083,25 +1108,22 @@ static void gdb_breakpoint_remove_all(void)
     }
 }
 
-static void gdb_set_cpu_pc(GDBState *s, target_ulong pc)
+static void gdb_set_cpu_pc(target_ulong pc)
 {
-    CPUState *cpu = s->c_cpu;
+    CPUState *cpu = gdbserver_state.c_cpu;
 
     cpu_synchronize_state(cpu);
     cpu_set_pc(cpu, pc);
 }
 
-static char *gdb_fmt_thread_id(const GDBState *s, CPUState *cpu,
-                           char *buf, size_t buf_size)
+static void gdb_append_thread_id(CPUState *cpu, GString *buf)
 {
-    if (s->multiprocess) {
-        snprintf(buf, buf_size, "p%02x.%02x",
-                 gdb_get_cpu_pid(s, cpu), cpu_gdb_index(cpu));
+    if (gdbserver_state.multiprocess) {
+        g_string_append_printf(buf, "p%02x.%02x",
+                               gdb_get_cpu_pid(cpu), cpu_gdb_index(cpu));
     } else {
-        snprintf(buf, buf_size, "%02x", cpu_gdb_index(cpu));
+        g_string_append_printf(buf, "%02x", cpu_gdb_index(cpu));
     }
-
-    return buf;
 }
 
 typedef enum GDBThreadIdKind {
@@ -1163,7 +1185,7 @@ static GDBThreadIdKind read_thread_id(const char *buf, const char **end_buf,
  * returns -ENOTSUP if a command is unsupported, -EINVAL or -ERANGE if there is
  *         a format error, 0 on success.
  */
-static int gdb_handle_vcont(GDBState *s, const char *p)
+static int gdb_handle_vcont(const char *p)
 {
     int res, signal = 0;
     char cur_action;
@@ -1238,36 +1260,36 @@ static int gdb_handle_vcont(GDBState *s, const char *p)
             goto out;
 
         case GDB_ALL_PROCESSES:
-            cpu = gdb_first_attached_cpu(s);
+            cpu = gdb_first_attached_cpu();
             while (cpu) {
                 if (newstates[cpu->cpu_index] == 1) {
                     newstates[cpu->cpu_index] = cur_action;
                 }
 
-                cpu = gdb_next_attached_cpu(s, cpu);
+                cpu = gdb_next_attached_cpu(cpu);
             }
             break;
 
         case GDB_ALL_THREADS:
-            process = gdb_get_process(s, pid);
+            process = gdb_get_process(pid);
 
             if (!process->attached) {
                 res = -EINVAL;
                 goto out;
             }
 
-            cpu = get_first_cpu_in_process(s, process);
+            cpu = get_first_cpu_in_process(process);
             while (cpu) {
                 if (newstates[cpu->cpu_index] == 1) {
                     newstates[cpu->cpu_index] = cur_action;
                 }
 
-                cpu = gdb_next_cpu_in_process(s, cpu);
+                cpu = gdb_next_cpu_in_process(cpu);
             }
             break;
 
         case GDB_ONE_THREAD:
-            cpu = gdb_get_cpu(s, pid, tid);
+            cpu = gdb_get_cpu(pid, tid);
 
             /* invalid CPU/thread specified */
             if (!cpu) {
@@ -1282,8 +1304,8 @@ static int gdb_handle_vcont(GDBState *s, const char *p)
             break;
         }
     }
-    s->signal = signal;
-    gdb_continue_partial(s, newstates);
+    gdbserver_state.signal = signal;
+    gdb_continue_partial(newstates);
 
 out:
     g_free(newstates);
@@ -1392,11 +1414,8 @@ static int cmd_parse_params(const char *data, const char *schema,
 }
 
 typedef struct GdbCmdContext {
-    GDBState *s;
     GdbCmdVariant *params;
     int num_params;
-    uint8_t mem_buf[MAX_PACKET_LENGTH];
-    char str_buf[MAX_PACKET_LENGTH + 1];
 } GdbCmdContext;
 
 typedef void (*GdbCmdHandler)(GdbCmdContext *gdb_ctx, void *user_ctx);
@@ -1436,7 +1455,7 @@ static inline int startswith(const char *string, const char *pattern)
   return !strncmp(string, pattern, strlen(pattern));
 }
 
-static int process_string_cmd(GDBState *s, void *user_ctx, const char *data,
+static int process_string_cmd(void *user_ctx, const char *data,
                               const GdbCmdParseEntry *cmds, int num_cmds)
 {
     int i, schema_len, max_num_params = 0;
@@ -1473,7 +1492,6 @@ static int process_string_cmd(GDBState *s, void *user_ctx, const char *data,
             return -1;
         }
 
-        gdb_ctx.s = s;
         cmd->handler(&gdb_ctx, user_ctx);
         return 0;
     }
@@ -1481,53 +1499,54 @@ static int process_string_cmd(GDBState *s, void *user_ctx, const char *data,
     return -1;
 }
 
-static void run_cmd_parser(GDBState *s, const char *data,
-                           const GdbCmdParseEntry *cmd)
+static void run_cmd_parser(const char *data, const GdbCmdParseEntry *cmd)
 {
     if (!data) {
         return;
     }
 
+    g_string_set_size(gdbserver_state.str_buf, 0);
+    g_byte_array_set_size(gdbserver_state.mem_buf, 0);
+
     /* In case there was an error during the command parsing we must
     * send a NULL packet to indicate the command is not supported */
-    if (process_string_cmd(s, NULL, data, cmd, 1)) {
-        put_packet(s, "");
+    if (process_string_cmd(NULL, data, cmd, 1)) {
+        put_packet("");
     }
 }
 
 static void handle_detach(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     GDBProcess *process;
-    GDBState *s = gdb_ctx->s;
     uint32_t pid = 1;
 
-    if (s->multiprocess) {
+    if (gdbserver_state.multiprocess) {
         if (!gdb_ctx->num_params) {
-            put_packet(s, "E22");
+            put_packet("E22");
             return;
         }
 
         pid = gdb_ctx->params[0].val_ul;
     }
 
-    process = gdb_get_process(s, pid);
-    gdb_process_breakpoint_remove_all(s, process);
+    process = gdb_get_process(pid);
+    gdb_process_breakpoint_remove_all(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(gdbserver_state.c_cpu)) {
+        gdbserver_state.c_cpu = gdb_first_attached_cpu();
     }
 
-    if (pid == gdb_get_cpu_pid(s, s->g_cpu)) {
-        s->g_cpu = gdb_first_attached_cpu(s);
+    if (pid == gdb_get_cpu_pid(gdbserver_state.g_cpu)) {
+        gdbserver_state.g_cpu = gdb_first_attached_cpu();
     }
 
-    if (!s->c_cpu) {
+    if (!gdbserver_state.c_cpu) {
         /* No more process attached */
         gdb_syscall_mode = GDB_SYS_DISABLED;
-        gdb_continue(s);
+        gdb_continue();
     }
-    put_packet(s, "OK");
+    put_packet("OK");
 }
 
 static void handle_thread_alive(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1535,33 +1554,33 @@ static void handle_thread_alive(GdbCmdContext *gdb_ctx, void *user_ctx)
     CPUState *cpu;
 
     if (!gdb_ctx->num_params) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
     if (gdb_ctx->params[0].thread_id.kind == GDB_READ_THREAD_ERR) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
-    cpu = gdb_get_cpu(gdb_ctx->s, gdb_ctx->params[0].thread_id.pid,
+    cpu = gdb_get_cpu(gdb_ctx->params[0].thread_id.pid,
                       gdb_ctx->params[0].thread_id.tid);
     if (!cpu) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
-    put_packet(gdb_ctx->s, "OK");
+    put_packet("OK");
 }
 
 static void handle_continue(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     if (gdb_ctx->num_params) {
-        gdb_set_cpu_pc(gdb_ctx->s, gdb_ctx->params[0].val_ull);
+        gdb_set_cpu_pc(gdb_ctx->params[0].val_ull);
     }
 
-    gdb_ctx->s->signal = 0;
-    gdb_continue(gdb_ctx->s);
+    gdbserver_state.signal = 0;
+    gdb_continue();
 }
 
 static void handle_cont_with_sig(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1576,11 +1595,11 @@ static void handle_cont_with_sig(GdbCmdContext *gdb_ctx, void *user_ctx)
         signal = gdb_ctx->params[0].val_ul;
     }
 
-    gdb_ctx->s->signal = gdb_signal_to_target(signal);
-    if (gdb_ctx->s->signal == -1) {
-        gdb_ctx->s->signal = 0;
+    gdbserver_state.signal = gdb_signal_to_target(signal);
+    if (gdbserver_state.signal == -1) {
+        gdbserver_state.signal = 0;
     }
-    gdb_continue(gdb_ctx->s);
+    gdb_continue();
 }
 
 static void handle_set_thread(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1588,24 +1607,24 @@ static void handle_set_thread(GdbCmdContext *gdb_ctx, void *user_ctx)
     CPUState *cpu;
 
     if (gdb_ctx->num_params != 2) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
     if (gdb_ctx->params[1].thread_id.kind == GDB_READ_THREAD_ERR) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
     if (gdb_ctx->params[1].thread_id.kind != GDB_ONE_THREAD) {
-        put_packet(gdb_ctx->s, "OK");
+        put_packet("OK");
         return;
     }
 
-    cpu = gdb_get_cpu(gdb_ctx->s, gdb_ctx->params[1].thread_id.pid,
+    cpu = gdb_get_cpu(gdb_ctx->params[1].thread_id.pid,
                       gdb_ctx->params[1].thread_id.tid);
     if (!cpu) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
@@ -1615,15 +1634,15 @@ static void handle_set_thread(GdbCmdContext *gdb_ctx, void *user_ctx)
      */
     switch (gdb_ctx->params[0].opcode) {
     case 'c':
-        gdb_ctx->s->c_cpu = cpu;
-        put_packet(gdb_ctx->s, "OK");
+        gdbserver_state.c_cpu = cpu;
+        put_packet("OK");
         break;
     case 'g':
-        gdb_ctx->s->g_cpu = cpu;
-        put_packet(gdb_ctx->s, "OK");
+        gdbserver_state.g_cpu = cpu;
+        put_packet("OK");
         break;
     default:
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         break;
     }
 }
@@ -1633,7 +1652,7 @@ static void handle_insert_bp(GdbCmdContext *gdb_ctx, void *user_ctx)
     int res;
 
     if (gdb_ctx->num_params != 3) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
@@ -1641,14 +1660,14 @@ static void handle_insert_bp(GdbCmdContext *gdb_ctx, void *user_ctx)
                                 gdb_ctx->params[1].val_ull,
                                 gdb_ctx->params[2].val_ull);
     if (res >= 0) {
-        put_packet(gdb_ctx->s, "OK");
+        put_packet("OK");
         return;
     } else if (res == -ENOSYS) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
         return;
     }
 
-    put_packet(gdb_ctx->s, "E22");
+    put_packet("E22");
 }
 
 static void handle_remove_bp(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1656,7 +1675,7 @@ static void handle_remove_bp(GdbCmdContext *gdb_ctx, void *user_ctx)
     int res;
 
     if (gdb_ctx->num_params != 3) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
@@ -1664,14 +1683,14 @@ static void handle_remove_bp(GdbCmdContext *gdb_ctx, void *user_ctx)
                                 gdb_ctx->params[1].val_ull,
                                 gdb_ctx->params[2].val_ull);
     if (res >= 0) {
-        put_packet(gdb_ctx->s, "OK");
+        put_packet("OK");
         return;
     } else if (res == -ENOSYS) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
         return;
     }
 
-    put_packet(gdb_ctx->s, "E22");
+    put_packet("E22");
 }
 
 /*
@@ -1690,20 +1709,20 @@ static void handle_set_reg(GdbCmdContext *gdb_ctx, void *user_ctx)
     int reg_size;
 
     if (!gdb_has_xml) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
         return;
     }
 
     if (gdb_ctx->num_params != 2) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
     reg_size = strlen(gdb_ctx->params[1].data) / 2;
-    hextomem(gdb_ctx->mem_buf, gdb_ctx->params[1].data, reg_size);
-    gdb_write_register(gdb_ctx->s->g_cpu, gdb_ctx->mem_buf,
+    hextomem(gdbserver_state.mem_buf, gdb_ctx->params[1].data, reg_size);
+    gdb_write_register(gdbserver_state.g_cpu, gdbserver_state.mem_buf->data,
                        gdb_ctx->params[0].val_ull);
-    put_packet(gdb_ctx->s, "OK");
+    put_packet("OK");
 }
 
 static void handle_get_reg(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1711,73 +1730,79 @@ static void handle_get_reg(GdbCmdContext *gdb_ctx, void *user_ctx)
     int reg_size;
 
     if (!gdb_has_xml) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
         return;
     }
 
     if (!gdb_ctx->num_params) {
-        put_packet(gdb_ctx->s, "E14");
+        put_packet("E14");
         return;
     }
 
-    reg_size = gdb_read_register(gdb_ctx->s->g_cpu, gdb_ctx->mem_buf,
+    reg_size = gdb_read_register(gdbserver_state.g_cpu,
+                                 gdbserver_state.mem_buf,
                                  gdb_ctx->params[0].val_ull);
     if (!reg_size) {
-        put_packet(gdb_ctx->s, "E14");
+        put_packet("E14");
         return;
+    } else {
+        g_byte_array_set_size(gdbserver_state.mem_buf, reg_size);
     }
 
-    memtohex(gdb_ctx->str_buf, gdb_ctx->mem_buf, reg_size);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    memtohex(gdbserver_state.str_buf, gdbserver_state.mem_buf->data, reg_size);
+    put_strbuf();
 }
 
 static void handle_write_mem(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     if (gdb_ctx->num_params != 3) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
     /* hextomem() reads 2*len bytes */
     if (gdb_ctx->params[1].val_ull > strlen(gdb_ctx->params[2].data) / 2) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
-    hextomem(gdb_ctx->mem_buf, gdb_ctx->params[2].data,
+    hextomem(gdbserver_state.mem_buf, gdb_ctx->params[2].data,
              gdb_ctx->params[1].val_ull);
-    if (target_memory_rw_debug(gdb_ctx->s->g_cpu, gdb_ctx->params[0].val_ull,
-                               gdb_ctx->mem_buf,
-                               gdb_ctx->params[1].val_ull, true)) {
-        put_packet(gdb_ctx->s, "E14");
+    if (target_memory_rw_debug(gdbserver_state.g_cpu, gdb_ctx->params[0].val_ull,
+                               gdbserver_state.mem_buf->data,
+                               gdbserver_state.mem_buf->len, true)) {
+        put_packet("E14");
         return;
     }
 
-    put_packet(gdb_ctx->s, "OK");
+    put_packet("OK");
 }
 
 static void handle_read_mem(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     if (gdb_ctx->num_params != 2) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
     /* memtohex() doubles the required space */
     if (gdb_ctx->params[1].val_ull > MAX_PACKET_LENGTH / 2) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
-    if (target_memory_rw_debug(gdb_ctx->s->g_cpu, gdb_ctx->params[0].val_ull,
-                               gdb_ctx->mem_buf,
-                               gdb_ctx->params[1].val_ull, false)) {
-        put_packet(gdb_ctx->s, "E14");
+    g_byte_array_set_size(gdbserver_state.mem_buf, gdb_ctx->params[1].val_ull);
+
+    if (target_memory_rw_debug(gdbserver_state.g_cpu, gdb_ctx->params[0].val_ull,
+                               gdbserver_state.mem_buf->data,
+                               gdbserver_state.mem_buf->len, false)) {
+        put_packet("E14");
         return;
     }
 
-    memtohex(gdb_ctx->str_buf, gdb_ctx->mem_buf, gdb_ctx->params[1].val_ull);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    memtohex(gdbserver_state.str_buf, gdbserver_state.mem_buf->data,
+             gdbserver_state.mem_buf->len);
+    put_strbuf();
 }
 
 static void handle_write_all_regs(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1790,37 +1815,40 @@ static void handle_write_all_regs(GdbCmdContext *gdb_ctx, void *user_ctx)
         return;
     }
 
-    cpu_synchronize_state(gdb_ctx->s->g_cpu);
-    registers = gdb_ctx->mem_buf;
+    cpu_synchronize_state(gdbserver_state.g_cpu);
     len = strlen(gdb_ctx->params[0].data) / 2;
-    hextomem(registers, gdb_ctx->params[0].data, len);
-    for (addr = 0; addr < gdb_ctx->s->g_cpu->gdb_num_g_regs && len > 0;
+    hextomem(gdbserver_state.mem_buf, gdb_ctx->params[0].data, len);
+    registers = gdbserver_state.mem_buf->data;
+    for (addr = 0; addr < gdbserver_state.g_cpu->gdb_num_g_regs && len > 0;
          addr++) {
-        reg_size = gdb_write_register(gdb_ctx->s->g_cpu, registers, addr);
+        reg_size = gdb_write_register(gdbserver_state.g_cpu, registers, addr);
         len -= reg_size;
         registers += reg_size;
     }
-    put_packet(gdb_ctx->s, "OK");
+    put_packet("OK");
 }
 
 static void handle_read_all_regs(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     target_ulong addr, len;
 
-    cpu_synchronize_state(gdb_ctx->s->g_cpu);
+    cpu_synchronize_state(gdbserver_state.g_cpu);
+    g_byte_array_set_size(gdbserver_state.mem_buf, 0);
     len = 0;
-    for (addr = 0; addr < gdb_ctx->s->g_cpu->gdb_num_g_regs; addr++) {
-        len += gdb_read_register(gdb_ctx->s->g_cpu, gdb_ctx->mem_buf + len,
+    for (addr = 0; addr < gdbserver_state.g_cpu->gdb_num_g_regs; addr++) {
+        len += gdb_read_register(gdbserver_state.g_cpu,
+                                 gdbserver_state.mem_buf,
                                  addr);
     }
+    g_assert(len == gdbserver_state.mem_buf->len);
 
-    memtohex(gdb_ctx->str_buf, gdb_ctx->mem_buf, len);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    memtohex(gdbserver_state.str_buf, gdbserver_state.mem_buf->data, len);
+    put_strbuf();
 }
 
 static void handle_file_io(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    if (gdb_ctx->num_params >= 1 && gdb_ctx->s->current_syscall_cb) {
+    if (gdb_ctx->num_params >= 1 && gdbserver_state.current_syscall_cb) {
         target_ulong ret, err;
 
         ret = (target_ulong)gdb_ctx->params[0].val_ull;
@@ -1829,31 +1857,31 @@ static void handle_file_io(GdbCmdContext *gdb_ctx, void *user_ctx)
         } else {
             err = 0;
         }
-        gdb_ctx->s->current_syscall_cb(gdb_ctx->s->c_cpu, ret, err);
-        gdb_ctx->s->current_syscall_cb = NULL;
+        gdbserver_state.current_syscall_cb(gdbserver_state.c_cpu, ret, err);
+        gdbserver_state.current_syscall_cb = NULL;
     }
 
     if (gdb_ctx->num_params >= 3 && gdb_ctx->params[2].opcode == (uint8_t)'C') {
-        put_packet(gdb_ctx->s, "T02");
+        put_packet("T02");
         return;
     }
 
-    gdb_continue(gdb_ctx->s);
+    gdb_continue();
 }
 
 static void handle_step(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     if (gdb_ctx->num_params) {
-        gdb_set_cpu_pc(gdb_ctx->s, (target_ulong)gdb_ctx->params[0].val_ull);
+        gdb_set_cpu_pc((target_ulong)gdb_ctx->params[0].val_ull);
     }
 
-    cpu_single_step(gdb_ctx->s->c_cpu, sstep_flags);
-    gdb_continue(gdb_ctx->s);
+    cpu_single_step(gdbserver_state.c_cpu, sstep_flags);
+    gdb_continue();
 }
 
 static void handle_v_cont_query(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    put_packet(gdb_ctx->s, "vCont;c;C;s;S");
+    put_packet("vCont;c;C;s;S");
 }
 
 static void handle_v_cont(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1864,11 +1892,11 @@ static void handle_v_cont(GdbCmdContext *gdb_ctx, void *user_ctx)
         return;
     }
 
-    res = gdb_handle_vcont(gdb_ctx->s, gdb_ctx->params[0].data);
+    res = gdb_handle_vcont(gdb_ctx->params[0].data);
     if ((res == -EINVAL) || (res == -ERANGE)) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
     } else if (res) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
     }
 }
 
@@ -1876,38 +1904,37 @@ static void handle_v_attach(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     GDBProcess *process;
     CPUState *cpu;
-    char thread_id[16];
 
-    pstrcpy(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "E22");
+    g_string_assign(gdbserver_state.str_buf, "E22");
     if (!gdb_ctx->num_params) {
         goto cleanup;
     }
 
-    process = gdb_get_process(gdb_ctx->s, gdb_ctx->params[0].val_ul);
+    process = gdb_get_process(gdb_ctx->params[0].val_ul);
     if (!process) {
         goto cleanup;
     }
 
-    cpu = get_first_cpu_in_process(gdb_ctx->s, process);
+    cpu = get_first_cpu_in_process(process);
     if (!cpu) {
         goto cleanup;
     }
 
     process->attached = true;
-    gdb_ctx->s->g_cpu = cpu;
-    gdb_ctx->s->c_cpu = cpu;
+    gdbserver_state.g_cpu = cpu;
+    gdbserver_state.c_cpu = cpu;
 
-    gdb_fmt_thread_id(gdb_ctx->s, cpu, thread_id, sizeof(thread_id));
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "T%02xthread:%s;",
-             GDB_SIGNAL_TRAP, thread_id);
+    g_string_printf(gdbserver_state.str_buf, "T%02xthread:", GDB_SIGNAL_TRAP);
+    gdb_append_thread_id(cpu, gdbserver_state.str_buf);
+    g_string_append_c(gdbserver_state.str_buf, ';');
 cleanup:
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    put_strbuf();
 }
 
 static void handle_v_kill(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     /* Kill the target */
-    put_packet(gdb_ctx->s, "OK");
+    put_packet("OK");
     error_report("QEMU: Terminated via GDBstub");
     exit(0);
 }
@@ -1944,19 +1971,18 @@ static void handle_v_commands(GdbCmdContext *gdb_ctx, void *user_ctx)
         return;
     }
 
-    if (process_string_cmd(gdb_ctx->s, NULL, gdb_ctx->params[0].data,
+    if (process_string_cmd(NULL, gdb_ctx->params[0].data,
                            gdb_v_commands_table,
                            ARRAY_SIZE(gdb_v_commands_table))) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
     }
 }
 
 static void handle_query_qemu_sstepbits(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf),
-             "ENABLE=%x,NOIRQ=%x,NOTIMER=%x", SSTEP_ENABLE,
-             SSTEP_NOIRQ, SSTEP_NOTIMER);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    g_string_printf(gdbserver_state.str_buf, "ENABLE=%x,NOIRQ=%x,NOTIMER=%x",
+                    SSTEP_ENABLE, SSTEP_NOIRQ, SSTEP_NOTIMER);
+    put_strbuf();
 }
 
 static void handle_set_qemu_sstep(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -1966,68 +1992,63 @@ static void handle_set_qemu_sstep(GdbCmdContext *gdb_ctx, void *user_ctx)
     }
 
     sstep_flags = gdb_ctx->params[0].val_ul;
-    put_packet(gdb_ctx->s, "OK");
+    put_packet("OK");
 }
 
 static void handle_query_qemu_sstep(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "0x%x", sstep_flags);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    g_string_printf(gdbserver_state.str_buf, "0x%x", sstep_flags);
+    put_strbuf();
 }
 
 static void handle_query_curr_tid(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     CPUState *cpu;
     GDBProcess *process;
-    char thread_id[16];
 
     /*
      * "Current thread" remains vague in the spec, so always return
      * the first thread of the current process (gdb returns the
      * first thread).
      */
-    process = gdb_get_cpu_process(gdb_ctx->s, gdb_ctx->s->g_cpu);
-    cpu = get_first_cpu_in_process(gdb_ctx->s, process);
-    gdb_fmt_thread_id(gdb_ctx->s, cpu, thread_id, sizeof(thread_id));
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "QC%s", thread_id);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    process = gdb_get_cpu_process(gdbserver_state.g_cpu);
+    cpu = get_first_cpu_in_process(process);
+    g_string_assign(gdbserver_state.str_buf, "QC");
+    gdb_append_thread_id(cpu, gdbserver_state.str_buf);
+    put_strbuf();
 }
 
 static void handle_query_threads(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    char thread_id[16];
-
-    if (!gdb_ctx->s->query_cpu) {
-        put_packet(gdb_ctx->s, "l");
+    if (!gdbserver_state.query_cpu) {
+        put_packet("l");
         return;
     }
 
-    gdb_fmt_thread_id(gdb_ctx->s, gdb_ctx->s->query_cpu, thread_id,
-                      sizeof(thread_id));
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "m%s", thread_id);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
-    gdb_ctx->s->query_cpu =
-        gdb_next_attached_cpu(gdb_ctx->s, gdb_ctx->s->query_cpu);
+    g_string_assign(gdbserver_state.str_buf, "m");
+    gdb_append_thread_id(gdbserver_state.query_cpu, gdbserver_state.str_buf);
+    put_strbuf();
+    gdbserver_state.query_cpu = gdb_next_attached_cpu(gdbserver_state.query_cpu);
 }
 
 static void handle_query_first_threads(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    gdb_ctx->s->query_cpu = gdb_first_attached_cpu(gdb_ctx->s);
+    gdbserver_state.query_cpu = gdb_first_attached_cpu();
     handle_query_threads(gdb_ctx, user_ctx);
 }
 
 static void handle_query_thread_extra(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
+    g_autoptr(GString) rs = g_string_new(NULL);
     CPUState *cpu;
-    int len;
 
     if (!gdb_ctx->num_params ||
         gdb_ctx->params[0].thread_id.kind == GDB_READ_THREAD_ERR) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
-    cpu = gdb_get_cpu(gdb_ctx->s, gdb_ctx->params[0].thread_id.pid,
+    cpu = gdb_get_cpu(gdb_ctx->params[0].thread_id.pid,
                       gdb_ctx->params[0].thread_id.tid);
     if (!cpu) {
         return;
@@ -2035,24 +2056,21 @@ static void handle_query_thread_extra(GdbCmdContext *gdb_ctx, void *user_ctx)
 
     cpu_synchronize_state(cpu);
 
-    if (gdb_ctx->s->multiprocess && (gdb_ctx->s->process_num > 1)) {
+    if (gdbserver_state.multiprocess && (gdbserver_state.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 *)gdb_ctx->mem_buf, sizeof(gdb_ctx->str_buf) / 2,
-                       "%s %s [%s]", cpu_model, cpu_name,
-                       cpu->halted ? "halted " : "running");
-        g_free(cpu_name);
+        g_autofree char *cpu_name;
+        cpu_name  = object_get_canonical_path_component(OBJECT(cpu));
+        g_string_printf(rs, "%s %s [%s]", cpu_model, cpu_name,
+                        cpu->halted ? "halted " : "running");
     } else {
-        /* memtohex() doubles the required space */
-        len = snprintf((char *)gdb_ctx->mem_buf, sizeof(gdb_ctx->str_buf) / 2,
-                        "CPU#%d [%s]", cpu->cpu_index,
+        g_string_printf(rs, "CPU#%d [%s]", cpu->cpu_index,
                         cpu->halted ? "halted " : "running");
     }
-    trace_gdbstub_op_extra_info((char *)gdb_ctx->mem_buf);
-    memtohex(gdb_ctx->str_buf, gdb_ctx->mem_buf, len);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    trace_gdbstub_op_extra_info(rs->str);
+    memtohex(gdbserver_state.str_buf, (uint8_t *)rs->str, rs->len);
+    put_strbuf();
 }
 
 #ifdef CONFIG_USER_ONLY
@@ -2060,37 +2078,40 @@ static void handle_query_offsets(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     TaskState *ts;
 
-    ts = gdb_ctx->s->c_cpu->opaque;
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf),
-             "Text=" TARGET_ABI_FMT_lx ";Data=" TARGET_ABI_FMT_lx
-             ";Bss=" TARGET_ABI_FMT_lx,
-             ts->info->code_offset,
-             ts->info->data_offset,
-             ts->info->data_offset);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    ts = gdbserver_state.c_cpu->opaque;
+    g_string_printf(gdbserver_state.str_buf,
+                    "Text=" TARGET_ABI_FMT_lx
+                    ";Data=" TARGET_ABI_FMT_lx
+                    ";Bss=" TARGET_ABI_FMT_lx,
+                    ts->info->code_offset,
+                    ts->info->data_offset,
+                    ts->info->data_offset);
+    put_strbuf();
 }
 #else
 static void handle_query_rcmd(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
+    const guint8 zero = 0;
     int len;
 
     if (!gdb_ctx->num_params) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
     len = strlen(gdb_ctx->params[0].data);
     if (len % 2) {
-        put_packet(gdb_ctx->s, "E01");
+        put_packet("E01");
         return;
     }
 
+    g_assert(gdbserver_state.mem_buf->len == 0);
     len = len / 2;
-    hextomem(gdb_ctx->mem_buf, gdb_ctx->params[0].data, len);
-    gdb_ctx->mem_buf[len++] = 0;
-    qemu_chr_be_write(gdb_ctx->s->mon_chr, gdb_ctx->mem_buf, len);
-    put_packet(gdb_ctx->s, "OK");
-
+    hextomem(gdbserver_state.mem_buf, gdb_ctx->params[0].data, len);
+    g_byte_array_append(gdbserver_state.mem_buf, &zero, 1);
+    qemu_chr_be_write(gdbserver_state.mon_chr, gdbserver_state.mem_buf->data,
+                      gdbserver_state.mem_buf->len);
+    put_packet("OK");
 }
 #endif
 
@@ -2098,21 +2119,19 @@ static void handle_query_supported(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     CPUClass *cc;
 
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "PacketSize=%x",
-             MAX_PACKET_LENGTH);
+    g_string_printf(gdbserver_state.str_buf, "PacketSize=%x", MAX_PACKET_LENGTH);
     cc = CPU_GET_CLASS(first_cpu);
     if (cc->gdb_core_xml_file) {
-        pstrcat(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf),
-                ";qXfer:features:read+");
+        g_string_append(gdbserver_state.str_buf, ";qXfer:features:read+");
     }
 
     if (gdb_ctx->num_params &&
         strstr(gdb_ctx->params[0].data, "multiprocess+")) {
-        gdb_ctx->s->multiprocess = true;
+        gdbserver_state.multiprocess = true;
     }
 
-    pstrcat(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), ";multiprocess+");
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    g_string_append(gdbserver_state.str_buf, ";vContSupported+;multiprocess+");
+    put_strbuf();
 }
 
 static void handle_query_xfer_features(GdbCmdContext *gdb_ctx, void *user_ctx)
@@ -2124,22 +2143,22 @@ static void handle_query_xfer_features(GdbCmdContext *gdb_ctx, void *user_ctx)
     const char *p;
 
     if (gdb_ctx->num_params < 3) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
-    process = gdb_get_cpu_process(gdb_ctx->s, gdb_ctx->s->g_cpu);
-    cc = CPU_GET_CLASS(gdb_ctx->s->g_cpu);
+    process = gdb_get_cpu_process(gdbserver_state.g_cpu);
+    cc = CPU_GET_CLASS(gdbserver_state.g_cpu);
     if (!cc->gdb_core_xml_file) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
         return;
     }
 
     gdb_has_xml = true;
     p = gdb_ctx->params[0].data;
-    xml = get_feature_xml(gdb_ctx->s, p, &p, process);
+    xml = get_feature_xml(p, &p, process);
     if (!xml) {
-        put_packet(gdb_ctx->s, "E00");
+        put_packet("E00");
         return;
     }
 
@@ -2147,7 +2166,7 @@ static void handle_query_xfer_features(GdbCmdContext *gdb_ctx, void *user_ctx)
     len = gdb_ctx->params[2].val_ul;
     total_len = strlen(xml);
     if (addr > total_len) {
-        put_packet(gdb_ctx->s, "E00");
+        put_packet("E00");
         return;
     }
 
@@ -2156,42 +2175,43 @@ static void handle_query_xfer_features(GdbCmdContext *gdb_ctx, void *user_ctx)
     }
 
     if (len < total_len - addr) {
-        gdb_ctx->str_buf[0] = 'm';
-        len = memtox(gdb_ctx->str_buf + 1, xml + addr, len);
+        g_string_assign(gdbserver_state.str_buf, "m");
+        memtox(gdbserver_state.str_buf, xml + addr, len);
     } else {
-        gdb_ctx->str_buf[0] = 'l';
-        len = memtox(gdb_ctx->str_buf + 1, xml + addr, total_len - addr);
+        g_string_assign(gdbserver_state.str_buf, "l");
+        memtox(gdbserver_state.str_buf, xml + addr, total_len - addr);
     }
 
-    put_packet_binary(gdb_ctx->s, gdb_ctx->str_buf, len + 1, true);
+    put_packet_binary(gdbserver_state.str_buf->str,
+                      gdbserver_state.str_buf->len, true);
 }
 
 static void handle_query_attached(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    put_packet(gdb_ctx->s, GDB_ATTACHED);
+    put_packet(GDB_ATTACHED);
 }
 
 static void handle_query_qemu_supported(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "sstepbits;sstep");
+    g_string_printf(gdbserver_state.str_buf, "sstepbits;sstep");
 #ifndef CONFIG_USER_ONLY
-    pstrcat(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), ";PhyMemMode");
+    g_string_append(gdbserver_state.str_buf, ";PhyMemMode");
 #endif
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    put_strbuf();
 }
 
 #ifndef CONFIG_USER_ONLY
 static void handle_query_qemu_phy_mem_mode(GdbCmdContext *gdb_ctx,
                                            void *user_ctx)
 {
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "%d", phy_memory_mode);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    g_string_printf(gdbserver_state.str_buf, "%d", phy_memory_mode);
+    put_strbuf();
 }
 
 static void handle_set_qemu_phy_mem_mode(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
     if (!gdb_ctx->num_params) {
-        put_packet(gdb_ctx->s, "E22");
+        put_packet("E22");
         return;
     }
 
@@ -2200,7 +2220,7 @@ static void handle_set_qemu_phy_mem_mode(GdbCmdContext *gdb_ctx, void *user_ctx)
     } else {
         phy_memory_mode = 1;
     }
-    put_packet(gdb_ctx->s, "OK");
+    put_packet("OK");
 }
 #endif
 
@@ -2316,16 +2336,16 @@ static void handle_gen_query(GdbCmdContext *gdb_ctx, void *user_ctx)
         return;
     }
 
-    if (!process_string_cmd(gdb_ctx->s, NULL, gdb_ctx->params[0].data,
+    if (!process_string_cmd(NULL, gdb_ctx->params[0].data,
                             gdb_gen_query_set_common_table,
                             ARRAY_SIZE(gdb_gen_query_set_common_table))) {
         return;
     }
 
-    if (process_string_cmd(gdb_ctx->s, NULL, gdb_ctx->params[0].data,
+    if (process_string_cmd(NULL, gdb_ctx->params[0].data,
                            gdb_gen_query_table,
                            ARRAY_SIZE(gdb_gen_query_table))) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
     }
 }
 
@@ -2335,28 +2355,25 @@ static void handle_gen_set(GdbCmdContext *gdb_ctx, void *user_ctx)
         return;
     }
 
-    if (!process_string_cmd(gdb_ctx->s, NULL, gdb_ctx->params[0].data,
+    if (!process_string_cmd(NULL, gdb_ctx->params[0].data,
                             gdb_gen_query_set_common_table,
                             ARRAY_SIZE(gdb_gen_query_set_common_table))) {
         return;
     }
 
-    if (process_string_cmd(gdb_ctx->s, NULL, gdb_ctx->params[0].data,
+    if (process_string_cmd(NULL, gdb_ctx->params[0].data,
                            gdb_gen_set_table,
                            ARRAY_SIZE(gdb_gen_set_table))) {
-        put_packet(gdb_ctx->s, "");
+        put_packet("");
     }
 }
 
 static void handle_target_halt(GdbCmdContext *gdb_ctx, void *user_ctx)
 {
-    char thread_id[16];
-
-    gdb_fmt_thread_id(gdb_ctx->s, gdb_ctx->s->c_cpu, thread_id,
-                      sizeof(thread_id));
-    snprintf(gdb_ctx->str_buf, sizeof(gdb_ctx->str_buf), "T%02xthread:%s;",
-             GDB_SIGNAL_TRAP, thread_id);
-    put_packet(gdb_ctx->s, gdb_ctx->str_buf);
+    g_string_printf(gdbserver_state.str_buf, "T%02xthread:", GDB_SIGNAL_TRAP);
+    gdb_append_thread_id(gdbserver_state.c_cpu, gdbserver_state.str_buf);
+    g_string_append_c(gdbserver_state.str_buf, ';');
+    put_strbuf();
     /*
      * Remove all the breakpoints when this query is issued,
      * because gdb is doing an initial connect and the state
@@ -2365,7 +2382,7 @@ static void handle_target_halt(GdbCmdContext *gdb_ctx, void *user_ctx)
     gdb_breakpoint_remove_all();
 }
 
-static int gdb_handle_packet(GDBState *s, const char *line_buf)
+static int gdb_handle_packet(const char *line_buf)
 {
     const GdbCmdParseEntry *cmd_parser = NULL;
 
@@ -2373,7 +2390,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
 
     switch (line_buf[0]) {
     case '!':
-        put_packet(s, "OK");
+        put_packet("OK");
         break;
     case '?':
         {
@@ -2588,12 +2605,12 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         break;
     default:
         /* put empty packet */
-        put_packet(s, "");
+        put_packet("");
         break;
     }
 
     if (cmd_parser) {
-        run_cmd_parser(s, line_buf, cmd_parser);
+        run_cmd_parser(line_buf, cmd_parser);
     }
 
     return RS_IDLE;
@@ -2601,7 +2618,7 @@ 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);
+    GDBProcess *p = gdb_get_cpu_process(cpu);
 
     if (!p->attached) {
         /*
@@ -2611,26 +2628,25 @@ void gdb_set_stop_cpu(CPUState *cpu)
         return;
     }
 
-    gdbserver_state->c_cpu = cpu;
-    gdbserver_state->g_cpu = cpu;
+    gdbserver_state.c_cpu = cpu;
+    gdbserver_state.g_cpu = cpu;
 }
 
 #ifndef CONFIG_USER_ONLY
 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];
+    CPUState *cpu = gdbserver_state.c_cpu;
+    g_autoptr(GString) buf = g_string_new(NULL);
+    g_autoptr(GString) tid = g_string_new(NULL);
     const char *type;
     int ret;
 
-    if (running || s->state == RS_INACTIVE) {
+    if (running || gdbserver_state.state == RS_INACTIVE) {
         return;
     }
     /* Is there a GDB syscall waiting to be sent?  */
-    if (s->current_syscall_cb) {
-        put_packet(s, s->syscall_buf);
+    if (gdbserver_state.current_syscall_cb) {
+        put_packet(gdbserver_state.syscall_buf);
         return;
     }
 
@@ -2639,7 +2655,7 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
         return;
     }
 
-    gdb_fmt_thread_id(s, cpu, thread_id, sizeof(thread_id));
+    gdb_append_thread_id(cpu, tid);
 
     switch (state) {
     case RUN_STATE_DEBUG:
@@ -2657,10 +2673,9 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
             }
             trace_gdbstub_hit_watchpoint(type, cpu_gdb_index(cpu),
                     (target_ulong)cpu->watchpoint_hit->vaddr);
-            snprintf(buf, sizeof(buf),
-                     "T%02xthread:%s;%swatch:" TARGET_FMT_lx ";",
-                     GDB_SIGNAL_TRAP, thread_id, type,
-                     (target_ulong)cpu->watchpoint_hit->vaddr);
+            g_string_printf(buf, "T%02xthread:%s;%swatch:" TARGET_FMT_lx ";",
+                            GDB_SIGNAL_TRAP, tid->str, type,
+                            (target_ulong)cpu->watchpoint_hit->vaddr);
             cpu->watchpoint_hit = NULL;
             goto send_packet;
         } else {
@@ -2701,10 +2716,10 @@ static void gdb_vm_state_change(void *opaque, int running, RunState state)
         break;
     }
     gdb_set_stop_cpu(cpu);
-    snprintf(buf, sizeof(buf), "T%02xthread:%s;", ret, thread_id);
+    g_string_printf(buf, "T%02xthread:%s;", ret, tid->str);
 
 send_packet:
-    put_packet(s, buf);
+    put_packet(buf->str);
 
     /* disable single step if it was enabled */
     cpu_single_step(cpu, 0);
@@ -2722,17 +2737,17 @@ void gdb_do_syscallv(gdb_syscall_complete_cb cb, const char *fmt, va_list va)
     char *p_end;
     target_ulong addr;
     uint64_t i64;
-    GDBState *s;
 
-    s = gdbserver_state;
-    if (!s)
+    if (!gdbserver_state.init) {
         return;
-    s->current_syscall_cb = cb;
+    }
+
+    gdbserver_state.current_syscall_cb = cb;
 #ifndef CONFIG_USER_ONLY
     vm_stop(RUN_STATE_DEBUG);
 #endif
-    p = s->syscall_buf;
-    p_end = &s->syscall_buf[sizeof(s->syscall_buf)];
+    p = &gdbserver_state.syscall_buf[0];
+    p_end = &gdbserver_state.syscall_buf[sizeof(gdbserver_state.syscall_buf)];
     *(p++) = 'F';
     while (*fmt) {
         if (*fmt == '%') {
@@ -2765,14 +2780,14 @@ 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);
+    put_packet(gdbserver_state.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);
+    gdb_handlesig(gdbserver_state.c_cpu, 0);
 #else
     /* In this case wait to send the syscall packet until notification that
        the CPU has stopped.  This must be done because if the packet is sent
@@ -2780,7 +2795,7 @@ void gdb_do_syscallv(gdb_syscall_complete_cb cb, const char *fmt, va_list va)
        is still in the running state, which can cause packets to be dropped
        and state transition 'T' packets to be sent while the syscall is still
        being processed.  */
-    qemu_cpu_kick(s->c_cpu);
+    qemu_cpu_kick(gdbserver_state.c_cpu);
 #endif
 }
 
@@ -2793,25 +2808,27 @@ void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...)
     va_end(va);
 }
 
-static void gdb_read_byte(GDBState *s, uint8_t ch)
+static void gdb_read_byte(uint8_t ch)
 {
     uint8_t reply;
 
 #ifndef CONFIG_USER_ONLY
-    if (s->last_packet_len) {
+    if (gdbserver_state.last_packet->len) {
         /* Waiting for a response to the last packet.  If we see the start
            of a new command then abandon the previous response.  */
         if (ch == '-') {
             trace_gdbstub_err_got_nack();
-            put_buffer(s, (uint8_t *)s->last_packet, s->last_packet_len);
+            put_buffer(gdbserver_state.last_packet->data,
+                       gdbserver_state.last_packet->len);
         } else if (ch == '+') {
             trace_gdbstub_io_got_ack();
         } else {
             trace_gdbstub_io_got_unexpected(ch);
         }
 
-        if (ch == '+' || ch == '$')
-            s->last_packet_len = 0;
+        if (ch == '+' || ch == '$') {
+            g_byte_array_set_size(gdbserver_state.last_packet, 0);
+        }
         if (ch != '$')
             return;
     }
@@ -2822,13 +2839,13 @@ static void gdb_read_byte(GDBState *s, uint8_t ch)
     } else
 #endif
     {
-        switch(s->state) {
+        switch(gdbserver_state.state) {
         case RS_IDLE:
             if (ch == '$') {
                 /* start of command packet */
-                s->line_buf_index = 0;
-                s->line_sum = 0;
-                s->state = RS_GETLINE;
+                gdbserver_state.line_buf_index = 0;
+                gdbserver_state.line_sum = 0;
+                gdbserver_state.state = RS_GETLINE;
             } else {
                 trace_gdbstub_err_garbage(ch);
             }
@@ -2836,37 +2853,37 @@ static void gdb_read_byte(GDBState *s, uint8_t ch)
         case RS_GETLINE:
             if (ch == '}') {
                 /* start escape sequence */
-                s->state = RS_GETLINE_ESC;
-                s->line_sum += ch;
+                gdbserver_state.state = RS_GETLINE_ESC;
+                gdbserver_state.line_sum += ch;
             } else if (ch == '*') {
                 /* start run length encoding sequence */
-                s->state = RS_GETLINE_RLE;
-                s->line_sum += ch;
+                gdbserver_state.state = RS_GETLINE_RLE;
+                gdbserver_state.line_sum += ch;
             } else if (ch == '#') {
                 /* end of command, start of checksum*/
-                s->state = RS_CHKSUM1;
-            } else if (s->line_buf_index >= sizeof(s->line_buf) - 1) {
+                gdbserver_state.state = RS_CHKSUM1;
+            } else if (gdbserver_state.line_buf_index >= sizeof(gdbserver_state.line_buf) - 1) {
                 trace_gdbstub_err_overrun();
-                s->state = RS_IDLE;
+                gdbserver_state.state = RS_IDLE;
             } else {
                 /* unescaped command character */
-                s->line_buf[s->line_buf_index++] = ch;
-                s->line_sum += ch;
+                gdbserver_state.line_buf[gdbserver_state.line_buf_index++] = ch;
+                gdbserver_state.line_sum += ch;
             }
             break;
         case RS_GETLINE_ESC:
             if (ch == '#') {
                 /* unexpected end of command in escape sequence */
-                s->state = RS_CHKSUM1;
-            } else if (s->line_buf_index >= sizeof(s->line_buf) - 1) {
+                gdbserver_state.state = RS_CHKSUM1;
+            } else if (gdbserver_state.line_buf_index >= sizeof(gdbserver_state.line_buf) - 1) {
                 /* command buffer overrun */
                 trace_gdbstub_err_overrun();
-                s->state = RS_IDLE;
+                gdbserver_state.state = RS_IDLE;
             } else {
                 /* parse escaped character and leave escape state */
-                s->line_buf[s->line_buf_index++] = ch ^ 0x20;
-                s->line_sum += ch;
-                s->state = RS_GETLINE;
+                gdbserver_state.line_buf[gdbserver_state.line_buf_index++] = ch ^ 0x20;
+                gdbserver_state.line_sum += ch;
+                gdbserver_state.state = RS_GETLINE;
             }
             break;
         case RS_GETLINE_RLE:
@@ -2877,25 +2894,25 @@ static void gdb_read_byte(GDBState *s, uint8_t ch)
             if (ch < ' ' || ch == '#' || ch == '$' || ch > 126) {
                 /* invalid RLE count encoding */
                 trace_gdbstub_err_invalid_repeat(ch);
-                s->state = RS_GETLINE;
+                gdbserver_state.state = RS_GETLINE;
             } else {
                 /* decode repeat length */
                 int repeat = ch - ' ' + 3;
-                if (s->line_buf_index + repeat >= sizeof(s->line_buf) - 1) {
+                if (gdbserver_state.line_buf_index + repeat >= sizeof(gdbserver_state.line_buf) - 1) {
                     /* that many repeats would overrun the command buffer */
                     trace_gdbstub_err_overrun();
-                    s->state = RS_IDLE;
-                } else if (s->line_buf_index < 1) {
+                    gdbserver_state.state = RS_IDLE;
+                } else if (gdbserver_state.line_buf_index < 1) {
                     /* got a repeat but we have nothing to repeat */
                     trace_gdbstub_err_invalid_rle();
-                    s->state = RS_GETLINE;
+                    gdbserver_state.state = RS_GETLINE;
                 } else {
                     /* repeat the last character */
-                    memset(s->line_buf + s->line_buf_index,
-                           s->line_buf[s->line_buf_index - 1], repeat);
-                    s->line_buf_index += repeat;
-                    s->line_sum += ch;
-                    s->state = RS_GETLINE;
+                    memset(gdbserver_state.line_buf + gdbserver_state.line_buf_index,
+                           gdbserver_state.line_buf[gdbserver_state.line_buf_index - 1], repeat);
+                    gdbserver_state.line_buf_index += repeat;
+                    gdbserver_state.line_sum += ch;
+                    gdbserver_state.state = RS_GETLINE;
                 }
             }
             break;
@@ -2903,33 +2920,33 @@ static void gdb_read_byte(GDBState *s, uint8_t ch)
             /* get high hex digit of checksum */
             if (!isxdigit(ch)) {
                 trace_gdbstub_err_checksum_invalid(ch);
-                s->state = RS_GETLINE;
+                gdbserver_state.state = RS_GETLINE;
                 break;
             }
-            s->line_buf[s->line_buf_index] = '\0';
-            s->line_csum = fromhex(ch) << 4;
-            s->state = RS_CHKSUM2;
+            gdbserver_state.line_buf[gdbserver_state.line_buf_index] = '\0';
+            gdbserver_state.line_csum = fromhex(ch) << 4;
+            gdbserver_state.state = RS_CHKSUM2;
             break;
         case RS_CHKSUM2:
             /* get low hex digit of checksum */
             if (!isxdigit(ch)) {
                 trace_gdbstub_err_checksum_invalid(ch);
-                s->state = RS_GETLINE;
+                gdbserver_state.state = RS_GETLINE;
                 break;
             }
-            s->line_csum |= fromhex(ch);
+            gdbserver_state.line_csum |= fromhex(ch);
 
-            if (s->line_csum != (s->line_sum & 0xff)) {
-                trace_gdbstub_err_checksum_incorrect(s->line_sum, s->line_csum);
+            if (gdbserver_state.line_csum != (gdbserver_state.line_sum & 0xff)) {
+                trace_gdbstub_err_checksum_incorrect(gdbserver_state.line_sum, gdbserver_state.line_csum);
                 /* send NAK reply */
                 reply = '-';
-                put_buffer(s, &reply, 1);
-                s->state = RS_IDLE;
+                put_buffer(&reply, 1);
+                gdbserver_state.state = RS_IDLE;
             } else {
                 /* send ACK reply */
                 reply = '+';
-                put_buffer(s, &reply, 1);
-                s->state = gdb_handle_packet(s, s->line_buf);
+                put_buffer(&reply, 1);
+                gdbserver_state.state = gdb_handle_packet(gdbserver_state.line_buf);
             }
             break;
         default:
@@ -2941,15 +2958,13 @@ static void gdb_read_byte(GDBState *s, uint8_t ch)
 /* Tell the remote gdb that the process has exited.  */
 void gdb_exit(CPUArchState *env, int code)
 {
-  GDBState *s;
   char buf[4];
 
-  s = gdbserver_state;
-  if (!s) {
+  if (!gdbserver_state.init) {
       return;
   }
 #ifdef CONFIG_USER_ONLY
-  if (gdbserver_fd < 0 || s->fd < 0) {
+  if (gdbserver_fd < 0 || gdbserver_state.fd < 0) {
       return;
   }
 #endif
@@ -2957,10 +2972,10 @@ void gdb_exit(CPUArchState *env, int code)
   trace_gdbstub_op_exiting((uint8_t)code);
 
   snprintf(buf, sizeof(buf), "W%02x", (uint8_t)code);
-  put_packet(s, buf);
+  put_packet(buf);
 
 #ifndef CONFIG_USER_ONLY
-  qemu_chr_fe_deinit(&s->chr, true);
+  qemu_chr_fe_deinit(&gdbserver_state.chr, true);
 #endif
 }
 
@@ -2974,7 +2989,7 @@ static void create_default_process(GDBState *s)
     GDBProcess *process;
     int max_pid = 0;
 
-    if (s->process_num) {
+    if (gdbserver_state.process_num) {
         max_pid = s->processes[s->process_num - 1].pid;
     }
 
@@ -2993,12 +3008,10 @@ static void create_default_process(GDBState *s)
 int
 gdb_handlesig(CPUState *cpu, int sig)
 {
-    GDBState *s;
     char buf[256];
     int n;
 
-    s = gdbserver_state;
-    if (gdbserver_fd < 0 || s->fd < 0) {
+    if (gdbserver_fd < 0 || gdbserver_state.fd < 0) {
         return sig;
     }
 
@@ -3008,58 +3021,55 @@ gdb_handlesig(CPUState *cpu, int sig)
 
     if (sig != 0) {
         snprintf(buf, sizeof(buf), "S%02x", target_signal_to_gdb(sig));
-        put_packet(s, buf);
+        put_packet(buf);
     }
     /* put_packet() might have detected that the peer terminated the
        connection.  */
-    if (s->fd < 0) {
+    if (gdbserver_state.fd < 0) {
         return sig;
     }
 
     sig = 0;
-    s->state = RS_IDLE;
-    s->running_state = 0;
-    while (s->running_state == 0) {
-        n = read(s->fd, buf, 256);
+    gdbserver_state.state = RS_IDLE;
+    gdbserver_state.running_state = 0;
+    while (gdbserver_state.running_state == 0) {
+        n = read(gdbserver_state.fd, buf, 256);
         if (n > 0) {
             int i;
 
             for (i = 0; i < n; i++) {
-                gdb_read_byte(s, buf[i]);
+                gdb_read_byte(buf[i]);
             }
         } else {
             /* XXX: Connection closed.  Should probably wait for another
                connection before continuing.  */
             if (n == 0) {
-                close(s->fd);
+                close(gdbserver_state.fd);
             }
-            s->fd = -1;
+            gdbserver_state.fd = -1;
             return sig;
         }
     }
-    sig = s->signal;
-    s->signal = 0;
+    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)
 {
-    GDBState *s;
     char buf[4];
 
-    s = gdbserver_state;
-    if (gdbserver_fd < 0 || s->fd < 0) {
+    if (gdbserver_fd < 0 || gdbserver_state.fd < 0) {
         return;
     }
 
     snprintf(buf, sizeof(buf), "X%02x", target_signal_to_gdb(sig));
-    put_packet(s, buf);
+    put_packet(buf);
 }
 
 static bool gdb_accept(void)
 {
-    GDBState *s;
     struct sockaddr_in sockaddr;
     socklen_t len;
     int fd;
@@ -3083,15 +3093,13 @@ static bool gdb_accept(void)
         return false;
     }
 
-    s = g_malloc0(sizeof(GDBState));
-    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;
+    init_gdbserver_state();
+    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_state.fd = fd;
     gdb_has_xml = false;
-
-    gdbserver_state = s;
     return true;
 }
 
@@ -3144,13 +3152,11 @@ int gdbserver_start(int port)
 /* Disable gdb stub for child processes.  */
 void gdbserver_fork(CPUState *cpu)
 {
-    GDBState *s = gdbserver_state;
-
-    if (gdbserver_fd < 0 || s->fd < 0) {
+    if (gdbserver_fd < 0 || gdbserver_state.fd < 0) {
         return;
     }
-    close(s->fd);
-    s->fd = -1;
+    close(gdbserver_state.fd);
+    gdbserver_state.fd = -1;
     cpu_breakpoint_remove_all(cpu, BP_GDB);
     cpu_watchpoint_remove_all(cpu, BP_GDB);
 }
@@ -3167,7 +3173,7 @@ static void gdb_chr_receive(void *opaque, const uint8_t *buf, int size)
     int i;
 
     for (i = 0; i < size; i++) {
-        gdb_read_byte(gdbserver_state, buf[i]);
+        gdb_read_byte(buf[i]);
     }
 }
 
@@ -3183,7 +3189,7 @@ static void gdb_chr_event(void *opaque, QEMUChrEvent event)
             s->processes[i].attached = !i;
         }
 
-        s->c_cpu = gdb_first_attached_cpu(s);
+        s->c_cpu = gdb_first_attached_cpu();
         s->g_cpu = s->c_cpu;
 
         vm_stop(RUN_STATE_PAUSED);
@@ -3194,32 +3200,11 @@ static void gdb_chr_event(void *opaque, QEMUChrEvent event)
     }
 }
 
-static void gdb_monitor_output(GDBState *s, const char *msg, int len)
-{
-    char buf[MAX_PACKET_LENGTH];
-
-    buf[0] = 'O';
-    if (len > (MAX_PACKET_LENGTH/2) - 1)
-        len = (MAX_PACKET_LENGTH/2) - 1;
-    memtohex(buf + 1, (uint8_t *)msg, len);
-    put_packet(s, buf);
-}
-
 static int gdb_monitor_write(Chardev *chr, const uint8_t *buf, int len)
 {
-    const char *p = (const char *)buf;
-    int max_sz;
-
-    max_sz = (sizeof(gdbserver_state->last_packet) - 2) / 2;
-    for (;;) {
-        if (len <= max_sz) {
-            gdb_monitor_output(gdbserver_state, p, len);
-            break;
-        }
-        gdb_monitor_output(gdbserver_state, p, max_sz);
-        p += max_sz;
-        len -= max_sz;
-    }
+    g_autoptr(GString) hex_buf = g_string_new("O");
+    memtohex(hex_buf, buf, len);
+    put_packet(hex_buf->str);
     return len;
 }
 
@@ -3300,26 +3285,18 @@ static void create_processes(GDBState *s)
 {
     object_child_foreach(object_get_root(), find_cpu_clusters, s);
 
-    if (s->processes) {
+    if (gdbserver_state.processes) {
         /* Sort by PID */
-        qsort(s->processes, s->process_num, sizeof(s->processes[0]), pid_order);
+        qsort(gdbserver_state.processes, gdbserver_state.process_num, sizeof(gdbserver_state.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;
     Chardev *mon_chr;
@@ -3357,10 +3334,8 @@ int gdbserver_start(const char *device)
             return -1;
     }
 
-    s = gdbserver_state;
-    if (!s) {
-        s = g_malloc0(sizeof(GDBState));
-        gdbserver_state = s;
+    if (!gdbserver_state.init) {
+        init_gdbserver_state();
 
         qemu_add_vm_change_state_handler(gdb_vm_state_change, NULL);
 
@@ -3369,31 +3344,30 @@ int gdbserver_start(const char *device)
                                    NULL, NULL, &error_abort);
         monitor_init_hmp(mon_chr, false, &error_abort);
     } 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;
+        qemu_chr_fe_deinit(&gdbserver_state.chr, true);
+        mon_chr = gdbserver_state.mon_chr;
+        reset_gdbserver_state();
     }
 
-    create_processes(s);
+    create_processes(&gdbserver_state);
 
     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, s, NULL, true);
+        qemu_chr_fe_init(&gdbserver_state.chr, chr, &error_abort);
+        qemu_chr_fe_set_handlers(&gdbserver_state.chr, gdb_chr_can_receive,
+                                 gdb_chr_receive, gdb_chr_event,
+                                 NULL, &gdbserver_state, NULL, true);
     }
-    s->state = chr ? RS_IDLE : RS_INACTIVE;
-    s->mon_chr = mon_chr;
-    s->current_syscall_cb = NULL;
+    gdbserver_state.state = chr ? RS_IDLE : RS_INACTIVE;
+    gdbserver_state.mon_chr = mon_chr;
+    gdbserver_state.current_syscall_cb = NULL;
 
     return 0;
 }
 
 void gdbserver_cleanup(void)
 {
-    if (gdbserver_state) {
-        put_packet(gdbserver_state, "W00");
+    if (gdbserver_state.init) {
+        put_packet("W00");
     }
 }