[PATCH 0/8] gdbstub and TCG plugin improvements

[PATCH 0/8] gdbstub and TCG plugin improvements

[Akihiko Odaki]

This series extracts fixes and refactorings that can be applied
independently from "[PATCH RESEND v5 00/26] plugins: Allow to read
registers" as suggested by Nicholas Piggin.

Patch "target/ppc: Remove references to gdb_has_xml" is also updated to
remove some dead code I missed earlier and thus the Reviewed-by tag is
dropped.

Akihiko Odaki (8):
  contrib/plugins: Use GRWLock in execlog
  gdbstub: Introduce GDBFeature structure
  target/arm: Move the reference to arm-core.xml
  hw/core/cpu: Return static value with gdb_arch_name()
  gdbstub: Dynamically allocate target.xml buffer
  target/arm: Remove references to gdb_has_xml
  target/ppc: Remove references to gdb_has_xml
  gdbstub: Remove gdb_has_xml variable

 MAINTAINERS               |  2 +-
 meson.build               |  2 +-
 gdbstub/internals.h       |  2 +-
 include/exec/gdbstub.h    | 17 ++++------
 include/hw/core/cpu.h     |  2 +-
 target/ppc/internal.h     |  2 +-
 contrib/plugins/execlog.c | 16 +++++----
 gdbstub/gdbstub.c         | 63 +++++++++++++++--------------------
 gdbstub/softmmu.c         |  3 +-
 gdbstub/user.c            |  1 -
 stubs/gdbstub.c           |  6 ++--
 target/arm/cpu.c          |  9 ++---
 target/arm/cpu64.c        |  4 +--
 target/arm/gdbstub.c      | 32 ++----------------
 target/i386/cpu.c         |  6 ++--
 target/loongarch/cpu.c    |  4 +--
 target/ppc/gdbstub.c      | 24 ++------------
 target/riscv/cpu.c        |  6 ++--
 target/s390x/cpu.c        |  4 +--
 target/tricore/cpu.c      |  4 +--
 scripts/feature_to_c.py   | 48 +++++++++++++++++++++++++++
 scripts/feature_to_c.sh   | 69 ---------------------------------------
 22 files changed, 124 insertions(+), 202 deletions(-)
 create mode 100755 scripts/feature_to_c.py
 delete mode 100644 scripts/feature_to_c.sh

-- 
2.42.0

[PATCH 1/8] contrib/plugins: Use GRWLock in execlog

[Akihiko Odaki]

execlog had the following comment:
> As we could have multiple threads trying to do this we need to
> serialise the expansion under a lock. Threads accessing already
> created entries can continue without issue even if the ptr array
> gets reallocated during resize.

However, when the ptr array gets reallocated, the other threads may have
a stale reference to the old buffer. This results in use-after-free.

Use GRWLock to properly fix this issue.

Fixes: 3d7caf145e ("contrib/plugins: add execlog to log instruction execution and memory access")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
---
 contrib/plugins/execlog.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/contrib/plugins/execlog.c b/contrib/plugins/execlog.c
index 7129d526f8..82dc2f584e 100644
--- a/contrib/plugins/execlog.c
+++ b/contrib/plugins/execlog.c
@@ -19,7 +19,7 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
 
 /* Store last executed instruction on each vCPU as a GString */
 static GPtrArray *last_exec;
-static GMutex expand_array_lock;
+static GRWLock expand_array_lock;
 
 static GPtrArray *imatches;
 static GArray *amatches;
@@ -28,18 +28,16 @@ static GArray *amatches;
  * Expand last_exec array.
  *
  * As we could have multiple threads trying to do this we need to
- * serialise the expansion under a lock. Threads accessing already
- * created entries can continue without issue even if the ptr array
- * gets reallocated during resize.
+ * serialise the expansion under a lock.
  */
 static void expand_last_exec(int cpu_index)
 {
-    g_mutex_lock(&expand_array_lock);
+    g_rw_lock_writer_lock(&expand_array_lock);
     while (cpu_index >= last_exec->len) {
         GString *s = g_string_new(NULL);
         g_ptr_array_add(last_exec, s);
     }
-    g_mutex_unlock(&expand_array_lock);
+    g_rw_lock_writer_unlock(&expand_array_lock);
 }
 
 /**
@@ -51,8 +49,10 @@ static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info,
     GString *s;
 
     /* Find vCPU in array */
+    g_rw_lock_reader_lock(&expand_array_lock);
     g_assert(cpu_index < last_exec->len);
     s = g_ptr_array_index(last_exec, cpu_index);
+    g_rw_lock_reader_unlock(&expand_array_lock);
 
     /* Indicate type of memory access */
     if (qemu_plugin_mem_is_store(info)) {
@@ -80,10 +80,14 @@ static void vcpu_insn_exec(unsigned int cpu_index, void *udata)
     GString *s;
 
     /* Find or create vCPU in array */
+    g_rw_lock_reader_lock(&expand_array_lock);
     if (cpu_index >= last_exec->len) {
+        g_rw_lock_reader_unlock(&expand_array_lock);
         expand_last_exec(cpu_index);
+        g_rw_lock_reader_lock(&expand_array_lock);
     }
     s = g_ptr_array_index(last_exec, cpu_index);
+    g_rw_lock_reader_unlock(&expand_array_lock);
 
     /* Print previous instruction in cache */
     if (s->len) {
-- 
2.42.0

[PATCH 2/8] gdbstub: Introduce GDBFeature structure

[Akihiko Odaki]

Before this change, the information from a XML file was stored in an
array that is not descriptive. Introduce a dedicated structure type to
make it easier to understand and to extend with more fields.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 MAINTAINERS             |  2 +-
 meson.build             |  2 +-
 include/exec/gdbstub.h  |  9 ++++--
 gdbstub/gdbstub.c       |  4 +--
 stubs/gdbstub.c         |  6 ++--
 scripts/feature_to_c.py | 48 ++++++++++++++++++++++++++++
 scripts/feature_to_c.sh | 69 -----------------------------------------
 7 files changed, 62 insertions(+), 78 deletions(-)
 create mode 100755 scripts/feature_to_c.py
 delete mode 100644 scripts/feature_to_c.sh

diff --git a/MAINTAINERS b/MAINTAINERS
index 12e59b6b27..514ac74101 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2826,7 +2826,7 @@ F: include/exec/gdbstub.h
 F: include/gdbstub/*
 F: gdb-xml/
 F: tests/tcg/multiarch/gdbstub/
-F: scripts/feature_to_c.sh
+F: scripts/feature_to_c.py
 F: scripts/probe-gdb-support.py
 
 Memory API
diff --git a/meson.build b/meson.build
index 98e68ef0b1..5c633f7e01 100644
--- a/meson.build
+++ b/meson.build
@@ -3683,7 +3683,7 @@ common_all = static_library('common',
                             dependencies: common_all.dependencies(),
                             name_suffix: 'fa')
 
-feature_to_c = find_program('scripts/feature_to_c.sh')
+feature_to_c = find_program('scripts/feature_to_c.py')
 
 if targetos == 'darwin'
   entitlement = find_program('scripts/entitlement.sh')
diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 7d743fe1e9..3f08093321 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -10,6 +10,11 @@
 #define GDB_WATCHPOINT_READ      3
 #define GDB_WATCHPOINT_ACCESS    4
 
+typedef struct GDBFeature {
+    const char *xmlname;
+    const char *xml;
+} GDBFeature;
+
 
 /* Get or set a register.  Returns the size of the register.  */
 typedef int (*gdb_get_reg_cb)(CPUArchState *env, GByteArray *buf, int reg);
@@ -38,7 +43,7 @@ void gdb_set_stop_cpu(CPUState *cpu);
  */
 extern bool gdb_has_xml;
 
-/* in gdbstub-xml.c, generated by scripts/feature_to_c.sh */
-extern const char *const xml_builtin[][2];
+/* in gdbstub-xml.c, generated by scripts/feature_to_c.py */
+extern const GDBFeature gdb_static_features[];
 
 #endif
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 6911b73c07..2772f07bbe 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -407,11 +407,11 @@ static const char *get_feature_xml(const char *p, const char **newp,
         }
     }
     for (i = 0; ; i++) {
-        name = xml_builtin[i][0];
+        name = gdb_static_features[i].xmlname;
         if (!name || (strncmp(name, p, len) == 0 && strlen(name) == len))
             break;
     }
-    return name ? xml_builtin[i][1] : NULL;
+    return name ? gdb_static_features[i].xml : NULL;
 }
 
 static int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
diff --git a/stubs/gdbstub.c b/stubs/gdbstub.c
index 2b7aee50d3..580e20702b 100644
--- a/stubs/gdbstub.c
+++ b/stubs/gdbstub.c
@@ -1,6 +1,6 @@
 #include "qemu/osdep.h"
-#include "exec/gdbstub.h"       /* xml_builtin */
+#include "exec/gdbstub.h"       /* gdb_static_features */
 
-const char *const xml_builtin[][2] = {
-  { NULL, NULL }
+const GDBFeature gdb_static_features[] = {
+  { NULL }
 };
diff --git a/scripts/feature_to_c.py b/scripts/feature_to_c.py
new file mode 100755
index 0000000000..bcbcb83beb
--- /dev/null
+++ b/scripts/feature_to_c.py
@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import os, sys
+
+def writeliteral(indent, bytes):
+    sys.stdout.write(' ' * indent)
+    sys.stdout.write('"')
+    quoted = True
+
+    for c in bytes:
+        if not quoted:
+            sys.stdout.write('\n')
+            sys.stdout.write(' ' * indent)
+            sys.stdout.write('"')
+            quoted = True
+
+        if c == b'"'[0]:
+            sys.stdout.write('\\"')
+        elif c == b'\\'[0]:
+            sys.stdout.write('\\\\')
+        elif c == b'\n'[0]:
+            sys.stdout.write('\\n"')
+            quoted = False
+        elif c >= 32 and c < 127:
+            sys.stdout.write(c.to_bytes(1, 'big').decode())
+        else:
+            sys.stdout.write(f'\{c:03o}')
+
+    if quoted:
+        sys.stdout.write('"')
+
+sys.stdout.write('#include "qemu/osdep.h"\n' \
+                 '#include "exec/gdbstub.h"\n' \
+                 '\n'
+                 'const GDBFeature gdb_static_features[] = {\n')
+
+for input in sys.argv[1:]:
+    with open(input, 'rb') as file:
+        read = file.read()
+
+    sys.stdout.write('    {\n')
+    writeliteral(8, bytes(os.path.basename(input), 'utf-8'))
+    sys.stdout.write(',\n')
+    writeliteral(8, read)
+    sys.stdout.write('\n    },\n')
+
+sys.stdout.write('    { NULL }\n};\n')
diff --git a/scripts/feature_to_c.sh b/scripts/feature_to_c.sh
deleted file mode 100644
index c1f67c8f6a..0000000000
--- a/scripts/feature_to_c.sh
+++ /dev/null
@@ -1,69 +0,0 @@
-#!/bin/sh
-
-# Convert text files to compilable C arrays.
-#
-# Copyright (C) 2007 Free Software Foundation, Inc.
-#
-# This file is part of GDB.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, see <http://www.gnu.org/licenses/>.
-
-if test -z "$1"; then
-  echo "Usage: $0 INPUTFILE..."
-  exit 1
-fi
-
-for input; do
-  arrayname=xml_feature_$(echo $input | sed 's,.*/,,; s/[-.]/_/g')
-
-  ${AWK:-awk} 'BEGIN { n = 0
-      printf "#include \"qemu/osdep.h\"\n"
-      print "static const char '$arrayname'[] = {"
-      for (i = 0; i < 255; i++)
-        _ord_[sprintf("%c", i)] = i
-    } {
-      split($0, line, "");
-      printf "  "
-      for (i = 1; i <= length($0); i++) {
-        c = line[i]
-        if (c == "'\''") {
-          printf "'\''\\'\'''\'', "
-        } else if (c == "\\") {
-          printf "'\''\\\\'\'', "
-        } else if (_ord_[c] >= 32 && _ord_[c] < 127) {
-	  printf "'\''%s'\'', ", c
-        } else {
-          printf "'\''\\%03o'\'', ", _ord_[c]
-        }
-        if (i % 10 == 0)
-          printf "\n   "
-      }
-      printf "'\''\\n'\'', \n"
-    } END {
-      print "  0 };"
-    }' < $input
-done
-
-echo
-echo '#include "exec/gdbstub.h"'
-echo "const char *const xml_builtin[][2] = {"
-
-for input; do
-  basename=$(echo $input | sed 's,.*/,,')
-  arrayname=xml_feature_$(echo $input | sed 's,.*/,,; s/[-.]/_/g')
-  echo "  { \"$basename\", $arrayname },"
-done
-
-echo "  { (char *)0, (char *)0 }"
-echo "};"
-- 
2.42.0

[PATCH 3/8] target/arm: Move the reference to arm-core.xml

[Akihiko Odaki]

Some subclasses overwrite gdb_core_xml_file member but others don't.
Always initialize the member in the subclasses for consistency.

This especially helps for AArch64; in a following change, the file
specified by gdb_core_xml_file is always looked up even if it's going to
be overwritten later. Looking up arm-core.xml results in an error as
it will not be embedded in the AArch64 build.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 93c28d50e5..d71a162070 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -2354,7 +2354,6 @@ static void arm_cpu_class_init(ObjectClass *oc, void *data)
     cc->sysemu_ops = &arm_sysemu_ops;
 #endif
     cc->gdb_num_core_regs = 26;
-    cc->gdb_core_xml_file = "arm-core.xml";
     cc->gdb_arch_name = arm_gdb_arch_name;
     cc->gdb_get_dynamic_xml = arm_gdb_get_dynamic_xml;
     cc->gdb_stop_before_watchpoint = true;
@@ -2376,8 +2375,10 @@ static void arm_cpu_instance_init(Object *obj)
 static void cpu_register_class_init(ObjectClass *oc, void *data)
 {
     ARMCPUClass *acc = ARM_CPU_CLASS(oc);
+    CPUClass *cc = CPU_CLASS(acc);
 
     acc->info = data;
+    cc->gdb_core_xml_file = "arm-core.xml";
 }
 
 void arm_cpu_register(const ARMCPUInfo *info)
-- 
2.42.0

[PATCH 4/8] hw/core/cpu: Return static value with gdb_arch_name()

[Akihiko Odaki]

All implementations of gdb_arch_name() returns dynamic duplicates of
static strings. It's also unlikely that there will be an implementation
of gdb_arch_name() that returns a truly dynamic value due to the nature
of the function returning a well-known identifiers. Qualify the value
gdb_arch_name() with const and make all of its implementations return
static strings.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
---
 include/hw/core/cpu.h  | 2 +-
 target/ppc/internal.h  | 2 +-
 gdbstub/gdbstub.c      | 4 +---
 target/arm/cpu.c       | 6 +++---
 target/arm/cpu64.c     | 4 ++--
 target/i386/cpu.c      | 6 +++---
 target/loongarch/cpu.c | 4 ++--
 target/ppc/gdbstub.c   | 6 +++---
 target/riscv/cpu.c     | 6 +++---
 target/s390x/cpu.c     | 4 ++--
 target/tricore/cpu.c   | 4 ++--
 11 files changed, 23 insertions(+), 25 deletions(-)

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index fdcbe87352..4f5c7eb04e 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -164,7 +164,7 @@ struct CPUClass {
     vaddr (*gdb_adjust_breakpoint)(CPUState *cpu, vaddr addr);
 
     const char *gdb_core_xml_file;
-    gchar * (*gdb_arch_name)(CPUState *cpu);
+    const gchar * (*gdb_arch_name)(CPUState *cpu);
     const char * (*gdb_get_dynamic_xml)(CPUState *cpu, const char *xmlname);
 
     void (*disas_set_info)(CPUState *cpu, disassemble_info *info);
diff --git a/target/ppc/internal.h b/target/ppc/internal.h
index 57acb3212c..974b37aa60 100644
--- a/target/ppc/internal.h
+++ b/target/ppc/internal.h
@@ -221,7 +221,7 @@ void destroy_ppc_opcodes(PowerPCCPU *cpu);
 
 /* gdbstub.c */
 void ppc_gdb_init(CPUState *cs, PowerPCCPUClass *ppc);
-gchar *ppc_gdb_arch_name(CPUState *cs);
+const gchar *ppc_gdb_arch_name(CPUState *cs);
 
 /**
  * prot_for_access_type:
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 2772f07bbe..78711801db 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -379,11 +379,9 @@ static const char *get_feature_xml(const char *p, const char **newp,
                     "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">"
                     "<target>");
             if (cc->gdb_arch_name) {
-                gchar *arch = cc->gdb_arch_name(cpu);
                 pstrcat(buf, buf_sz, "<architecture>");
-                pstrcat(buf, buf_sz, arch);
+                pstrcat(buf, buf_sz, cc->gdb_arch_name(cpu));
                 pstrcat(buf, buf_sz, "</architecture>");
-                g_free(arch);
             }
             pstrcat(buf, buf_sz, "<xi:include href=\"");
             pstrcat(buf, buf_sz, cc->gdb_core_xml_file);
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index d71a162070..4147c19597 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -2281,15 +2281,15 @@ static Property arm_cpu_properties[] = {
     DEFINE_PROP_END_OF_LIST()
 };
 
-static gchar *arm_gdb_arch_name(CPUState *cs)
+static const gchar *arm_gdb_arch_name(CPUState *cs)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
 
     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
-        return g_strdup("iwmmxt");
+        return "iwmmxt";
     }
-    return g_strdup("arm");
+    return "arm";
 }
 
 #ifndef CONFIG_USER_ONLY
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 96158093cc..6b91aab6b7 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -743,9 +743,9 @@ static void aarch64_cpu_finalizefn(Object *obj)
 {
 }
 
-static gchar *aarch64_gdb_arch_name(CPUState *cs)
+static const gchar *aarch64_gdb_arch_name(CPUState *cs)
 {
-    return g_strdup("aarch64");
+    return "aarch64";
 }
 
 static void aarch64_cpu_class_init(ObjectClass *oc, void *data)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 97ad229d8b..68bea8d3f0 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5910,12 +5910,12 @@ static void x86_cpu_load_model(X86CPU *cpu, X86CPUModel *model)
     memset(&env->user_features, 0, sizeof(env->user_features));
 }
 
-static gchar *x86_gdb_arch_name(CPUState *cs)
+static const gchar *x86_gdb_arch_name(CPUState *cs)
 {
 #ifdef TARGET_X86_64
-    return g_strdup("i386:x86-64");
+    return "i386:x86-64";
 #else
-    return g_strdup("i386");
+    return "i386";
 #endif
 }
 
diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
index ad93ecac92..49565da3fa 100644
--- a/target/loongarch/cpu.c
+++ b/target/loongarch/cpu.c
@@ -692,9 +692,9 @@ static const struct SysemuCPUOps loongarch_sysemu_ops = {
 };
 #endif
 
-static gchar *loongarch_gdb_arch_name(CPUState *cs)
+static const gchar *loongarch_gdb_arch_name(CPUState *cs)
 {
-    return g_strdup("loongarch64");
+    return "loongarch64";
 }
 
 static void loongarch_cpu_class_init(ObjectClass *c, void *data)
diff --git a/target/ppc/gdbstub.c b/target/ppc/gdbstub.c
index ca39efdc35..72df36ca06 100644
--- a/target/ppc/gdbstub.c
+++ b/target/ppc/gdbstub.c
@@ -589,12 +589,12 @@ static int gdb_set_vsx_reg(CPUPPCState *env, uint8_t *mem_buf, int n)
     return 0;
 }
 
-gchar *ppc_gdb_arch_name(CPUState *cs)
+const gchar *ppc_gdb_arch_name(CPUState *cs)
 {
 #if defined(TARGET_PPC64)
-    return g_strdup("powerpc:common64");
+    return "powerpc:common64";
 #else
-    return g_strdup("powerpc:common");
+    return "powerpc:common";
 #endif
 }
 
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 6b93b04453..ef8faaaff5 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -1939,17 +1939,17 @@ static Property riscv_cpu_properties[] = {
     DEFINE_PROP_END_OF_LIST(),
 };
 
-static gchar *riscv_gdb_arch_name(CPUState *cs)
+static const gchar *riscv_gdb_arch_name(CPUState *cs)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
     CPURISCVState *env = &cpu->env;
 
     switch (riscv_cpu_mxl(env)) {
     case MXL_RV32:
-        return g_strdup("riscv:rv32");
+        return "riscv:rv32";
     case MXL_RV64:
     case MXL_RV128:
-        return g_strdup("riscv:rv64");
+        return "riscv:rv64";
     default:
         g_assert_not_reached();
     }
diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
index df167493c3..cf4b5e43f2 100644
--- a/target/s390x/cpu.c
+++ b/target/s390x/cpu.c
@@ -284,9 +284,9 @@ static void s390_cpu_initfn(Object *obj)
 #endif
 }
 
-static gchar *s390_gdb_arch_name(CPUState *cs)
+static const gchar *s390_gdb_arch_name(CPUState *cs)
 {
-    return g_strdup("s390:64-bit");
+    return "s390:64-bit";
 }
 
 static Property s390x_cpu_properties[] = {
diff --git a/target/tricore/cpu.c b/target/tricore/cpu.c
index 133a9ac70e..44e3ba6f0e 100644
--- a/target/tricore/cpu.c
+++ b/target/tricore/cpu.c
@@ -29,9 +29,9 @@ static inline void set_feature(CPUTriCoreState *env, int feature)
     env->features |= 1ULL << feature;
 }
 
-static gchar *tricore_gdb_arch_name(CPUState *cs)
+static const gchar *tricore_gdb_arch_name(CPUState *cs)
 {
-    return g_strdup("tricore");
+    return "tricore";
 }
 
 static void tricore_cpu_set_pc(CPUState *cs, vaddr value)
-- 
2.42.0

[PATCH 5/8] gdbstub: Dynamically allocate target.xml buffer

[Akihiko Odaki]

There is no guarantee that target.xml fits in 1024 bytes, and the fixed
buffer length requires tedious buffer overflow check. Dynamically
allocate the target.xml buffer to resolve these problems.

Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 gdbstub/internals.h |  2 +-
 gdbstub/gdbstub.c   | 44 ++++++++++++++++++++++++--------------------
 gdbstub/softmmu.c   |  2 +-
 3 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/gdbstub/internals.h b/gdbstub/internals.h
index f2b46cce41..4876ebd74f 100644
--- a/gdbstub/internals.h
+++ b/gdbstub/internals.h
@@ -33,7 +33,7 @@ typedef struct GDBProcess {
     uint32_t pid;
     bool attached;
 
-    char target_xml[1024];
+    char *target_xml;
 } GDBProcess;
 
 enum RSState {
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 78711801db..3f97dc66e5 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -367,33 +367,37 @@ 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 (!buf[0]) {
+        if (!process->target_xml) {
+            g_autoptr(GPtrArray) a = g_ptr_array_new_with_free_func(g_free);
             GDBRegisterState *r;
 
-            pstrcat(buf, buf_sz,
-                    "<?xml version=\"1.0\"?>"
-                    "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">"
-                    "<target>");
+            g_ptr_array_add(
+                a,
+                g_strdup("<?xml version=\"1.0\"?>"
+                         "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">"
+                         "<target>"));
             if (cc->gdb_arch_name) {
-                pstrcat(buf, buf_sz, "<architecture>");
-                pstrcat(buf, buf_sz, cc->gdb_arch_name(cpu));
-                pstrcat(buf, buf_sz, "</architecture>");
+                g_ptr_array_add(
+                    a,
+                    g_markup_printf_escaped("<architecture>%s</architecture>",
+                                            cc->gdb_arch_name(cpu)));
             }
-            pstrcat(buf, buf_sz, "<xi:include href=\"");
-            pstrcat(buf, buf_sz, cc->gdb_core_xml_file);
-            pstrcat(buf, buf_sz, "\"/>");
+            g_ptr_array_add(
+                a,
+                g_markup_printf_escaped("<xi:include href=\"%s\"/>",
+                                        cc->gdb_core_xml_file));
             for (r = cpu->gdb_regs; r; r = r->next) {
-                pstrcat(buf, buf_sz, "<xi:include href=\"");
-                pstrcat(buf, buf_sz, r->xml);
-                pstrcat(buf, buf_sz, "\"/>");
+                g_ptr_array_add(
+                    a,
+                    g_markup_printf_escaped("<xi:include href=\"%s\"/>",
+                                            r->xml));
             }
-            pstrcat(buf, buf_sz, "</target>");
+            g_ptr_array_add(a, g_strdup("</target>"));
+            g_ptr_array_add(a, NULL);
+            process->target_xml = g_strjoinv(NULL, (void *)a->pdata);
         }
-        return buf;
+        return process->target_xml;
     }
     if (cc->gdb_get_dynamic_xml) {
         char *xmlname = g_strndup(p, len);
@@ -2199,6 +2203,6 @@ void gdb_create_default_process(GDBState *s)
     process = &s->processes[s->process_num - 1];
     process->pid = pid;
     process->attached = false;
-    process->target_xml[0] = '\0';
+    process->target_xml = NULL;
 }
 
diff --git a/gdbstub/softmmu.c b/gdbstub/softmmu.c
index f509b7285d..5282324764 100644
--- a/gdbstub/softmmu.c
+++ b/gdbstub/softmmu.c
@@ -293,7 +293,7 @@ static int find_cpu_clusters(Object *child, void *opaque)
         assert(cluster->cluster_id != UINT32_MAX);
         process->pid = cluster->cluster_id + 1;
         process->attached = false;
-        process->target_xml[0] = '\0';
+        process->target_xml = NULL;
 
         return 0;
     }
-- 
2.42.0

[PATCH 6/8] target/arm: Remove references to gdb_has_xml

[Akihiko Odaki]

GDB has XML support since 6.7 which was released in 2007.
It's time to remove support for old GDB versions without XML support.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
---
 target/arm/gdbstub.c | 32 ++------------------------------
 1 file changed, 2 insertions(+), 30 deletions(-)

diff --git a/target/arm/gdbstub.c b/target/arm/gdbstub.c
index f421c5d041..b7ace24bfc 100644
--- a/target/arm/gdbstub.c
+++ b/target/arm/gdbstub.c
@@ -46,21 +46,7 @@ int arm_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
         /* Core integer register.  */
         return gdb_get_reg32(mem_buf, env->regs[n]);
     }
-    if (n < 24) {
-        /* FPA registers.  */
-        if (gdb_has_xml) {
-            return 0;
-        }
-        return gdb_get_zeroes(mem_buf, 12);
-    }
-    switch (n) {
-    case 24:
-        /* FPA status register.  */
-        if (gdb_has_xml) {
-            return 0;
-        }
-        return gdb_get_reg32(mem_buf, 0);
-    case 25:
+    if (n == 25) {
         /* CPSR, or XPSR for M-profile */
         if (arm_feature(env, ARM_FEATURE_M)) {
             return gdb_get_reg32(mem_buf, xpsr_read(env));
@@ -100,21 +86,7 @@ int arm_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
         env->regs[n] = tmp;
         return 4;
     }
-    if (n < 24) { /* 16-23 */
-        /* FPA registers (ignored).  */
-        if (gdb_has_xml) {
-            return 0;
-        }
-        return 12;
-    }
-    switch (n) {
-    case 24:
-        /* FPA status register (ignored).  */
-        if (gdb_has_xml) {
-            return 0;
-        }
-        return 4;
-    case 25:
+    if (n == 25) {
         /* CPSR, or XPSR for M-profile */
         if (arm_feature(env, ARM_FEATURE_M)) {
             /*
-- 
2.42.0

[PATCH 7/8] target/ppc: Remove references to gdb_has_xml

[Akihiko Odaki]

GDB has XML support since 6.7 which was released in 2007.
It's time to remove support for old GDB versions without XML support.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 target/ppc/gdbstub.c | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/target/ppc/gdbstub.c b/target/ppc/gdbstub.c
index 72df36ca06..ec5731e5d6 100644
--- a/target/ppc/gdbstub.c
+++ b/target/ppc/gdbstub.c
@@ -54,12 +54,6 @@ static int ppc_gdb_register_len(int n)
     case 0 ... 31:
         /* gprs */
         return sizeof(target_ulong);
-    case 32 ... 63:
-        /* fprs */
-        if (gdb_has_xml) {
-            return 0;
-        }
-        return 8;
     case 66:
         /* cr */
     case 69:
@@ -74,12 +68,6 @@ static int ppc_gdb_register_len(int n)
     case 68:
         /* ctr */
         return sizeof(target_ulong);
-    case 70:
-        /* fpscr */
-        if (gdb_has_xml) {
-            return 0;
-        }
-        return sizeof(target_ulong);
     default:
         return 0;
     }
@@ -132,9 +120,6 @@ int ppc_cpu_gdb_read_register(CPUState *cs, GByteArray *buf, int n)
     if (n < 32) {
         /* gprs */
         gdb_get_regl(buf, env->gpr[n]);
-    } else if (n < 64) {
-        /* fprs */
-        gdb_get_reg64(buf, *cpu_fpr_ptr(env, n - 32));
     } else {
         switch (n) {
         case 64:
@@ -158,9 +143,6 @@ int ppc_cpu_gdb_read_register(CPUState *cs, GByteArray *buf, int n)
         case 69:
             gdb_get_reg32(buf, cpu_read_xer(env));
             break;
-        case 70:
-            gdb_get_reg32(buf, env->fpscr);
-            break;
         }
     }
     mem_buf = buf->data + buf->len - r;
-- 
2.42.0

[PATCH 8/8] gdbstub: Remove gdb_has_xml variable

[Akihiko Odaki]

GDB has XML support since 6.7 which was released in 2007.
It's time to remove support for old GDB versions without XML support.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 include/exec/gdbstub.h |  8 --------
 gdbstub/gdbstub.c      | 13 -------------
 gdbstub/softmmu.c      |  1 -
 gdbstub/user.c         |  1 -
 4 files changed, 23 deletions(-)

diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 3f08093321..ecbc60a934 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -35,14 +35,6 @@ int gdbserver_start(const char *port_or_device);
 
 void gdb_set_stop_cpu(CPUState *cpu);
 
-/**
- * gdb_has_xml:
- * This is an ugly hack to cope with both new and old gdb.
- * If gdb sends qXfer:features:read then assume we're talking to a newish
- * gdb that understands target descriptions.
- */
-extern bool gdb_has_xml;
-
 /* in gdbstub-xml.c, generated by scripts/feature_to_c.py */
 extern const GDBFeature gdb_static_features[];
 
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 3f97dc66e5..61c811f42b 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -75,8 +75,6 @@ void gdb_init_gdbserver_state(void)
     gdbserver_state.sstep_flags &= gdbserver_state.supported_sstep_flags;
 }
 
-bool gdb_has_xml;
-
 /* writes 2*len+1 bytes in buf */
 void gdb_memtohex(GString *buf, const uint8_t *mem, int len)
 {
@@ -1054,11 +1052,6 @@ static void handle_set_reg(GArray *params, void *user_ctx)
 {
     int reg_size;
 
-    if (!gdb_has_xml) {
-        gdb_put_packet("");
-        return;
-    }
-
     if (params->len != 2) {
         gdb_put_packet("E22");
         return;
@@ -1075,11 +1068,6 @@ static void handle_get_reg(GArray *params, void *user_ctx)
 {
     int reg_size;
 
-    if (!gdb_has_xml) {
-        gdb_put_packet("");
-        return;
-    }
-
     if (!params->len) {
         gdb_put_packet("E14");
         return;
@@ -1542,7 +1530,6 @@ static void handle_query_xfer_features(GArray *params, void *user_ctx)
         return;
     }
 
-    gdb_has_xml = true;
     p = get_param(params, 0)->data;
     xml = get_feature_xml(p, &p, process);
     if (!xml) {
diff --git a/gdbstub/softmmu.c b/gdbstub/softmmu.c
index 5282324764..42645d2220 100644
--- a/gdbstub/softmmu.c
+++ b/gdbstub/softmmu.c
@@ -97,7 +97,6 @@ static void gdb_chr_event(void *opaque, QEMUChrEvent event)
 
         vm_stop(RUN_STATE_PAUSED);
         replay_gdb_attached();
-        gdb_has_xml = false;
         break;
     default:
         break;
diff --git a/gdbstub/user.c b/gdbstub/user.c
index 5b375be1d9..7ab6e5d975 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -198,7 +198,6 @@ static void gdb_accept_init(int fd)
     gdbserver_state.c_cpu = gdb_first_attached_cpu();
     gdbserver_state.g_cpu = gdbserver_state.c_cpu;
     gdbserver_user_state.fd = fd;
-    gdb_has_xml = false;
 }
 
 static bool gdb_accept_socket(int gdb_fd)
-- 
2.42.0

Re: [PATCH 4/8] hw/core/cpu: Return static value with gdb_arch_name()

[Philippe Mathieu-Daudé]

On 3/9/23 06:30, Akihiko Odaki wrote:
> All implementations of gdb_arch_name() returns dynamic duplicates of
> static strings. It's also unlikely that there will be an implementation
> of gdb_arch_name() that returns a truly dynamic value due to the nature
> of the function returning a well-known identifiers. Qualify the value
> gdb_arch_name() with const and make all of its implementations return
> static strings.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>   include/hw/core/cpu.h  | 2 +-
>   target/ppc/internal.h  | 2 +-
>   gdbstub/gdbstub.c      | 4 +---
>   target/arm/cpu.c       | 6 +++---
>   target/arm/cpu64.c     | 4 ++--
>   target/i386/cpu.c      | 6 +++---
>   target/loongarch/cpu.c | 4 ++--
>   target/ppc/gdbstub.c   | 6 +++---
>   target/riscv/cpu.c     | 6 +++---
>   target/s390x/cpu.c     | 4 ++--
>   target/tricore/cpu.c   | 4 ++--
>   11 files changed, 23 insertions(+), 25 deletions(-)

Nice.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH 4/8] hw/core/cpu: Return static value with gdb_arch_name()

[Michael Tokarev]

03.09.2023 07:30, Akihiko Odaki wrote:
> All implementations of gdb_arch_name() returns dynamic duplicates of
> static strings. It's also unlikely that there will be an implementation
> of gdb_arch_name() that returns a truly dynamic value due to the nature
> of the function returning a well-known identifiers. Qualify the value
> gdb_arch_name() with const and make all of its implementations return
> static strings.

Why it needs to be a function, can't it be a char pointer
initialized at the cpu init time?

Reviewed-By: Michael Tokarev <mjt@tls.msk.ru>

(What a huge list of recipients in the Cc..)

/mjt

Re: [PATCH 4/8] hw/core/cpu: Return static value with gdb_arch_name()

[Akihiko Odaki]

On 2023/09/04 14:54, Michael Tokarev wrote:
> 03.09.2023 07:30, Akihiko Odaki wrote:
>> All implementations of gdb_arch_name() returns dynamic duplicates of
>> static strings. It's also unlikely that there will be an implementation
>> of gdb_arch_name() that returns a truly dynamic value due to the nature
>> of the function returning a well-known identifiers. Qualify the value
>> gdb_arch_name() with const and make all of its implementations return
>> static strings.
> 
> Why it needs to be a function, can't it be a char pointer
> initialized at the cpu init time?

There is no real reason I guess. Either is fine in my opinion.

> 
> Reviewed-By: Michael Tokarev <mjt@tls.msk.ru>
> 
> (What a huge list of recipients in the Cc..)
> 
> /mjt

Re: [PATCH 4/8] hw/core/cpu: Return static value with gdb_arch_name()

[Philippe Mathieu-Daudé]

On 4/9/23 07:54, Michael Tokarev wrote:
> 03.09.2023 07:30, Akihiko Odaki wrote:
>> All implementations of gdb_arch_name() returns dynamic duplicates of
>> static strings. It's also unlikely that there will be an implementation
>> of gdb_arch_name() that returns a truly dynamic value due to the nature
>> of the function returning a well-known identifiers. Qualify the value
>> gdb_arch_name() with const and make all of its implementations return
>> static strings.
> 
> Why it needs to be a function, can't it be a char pointer
> initialized at the cpu init time?

For x86_gdb_arch_name() or ppc_gdb_arch_name() we could by
moving the #ifdef'ry, but for arm_gdb_arch_name() we'd need
to add a specific class for the iwMMXt CPU. Not sure worth
it...