target/ppc: Use GDBFeature for dynamic XML

In preparation for a change to use GDBFeature as a parameter of
gdb_register_coprocessor(), convert the internal representation of
dynamic feature from plain XML to GDBFeature.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231213-gdb-v17-2-777047380591@daynix.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240227144335.1196131-7-alex.bennee@linaro.org>

target/ppc/cpu-qom.h

@@ -20,6 +20,7 @@
 #ifndef QEMU_PPC_CPU_QOM_H
 #define QEMU_PPC_CPU_QOM_H
 
+#include "exec/gdbstub.h"
 #include "hw/core/cpu.h"
 
 #ifdef TARGET_PPC64

target/ppc/cpu.h

@@ -1492,8 +1492,7 @@ struct PowerPCCPUClass {
     int bfd_mach;
     uint32_t l1_dcache_size, l1_icache_size;
 #ifndef CONFIG_USER_ONLY
-    unsigned int gdb_num_sprs;
+    GDBFeature gdb_spr;
-    const char *gdb_spr_xml;
 #endif
     const PPCHash64Options *hash64_opts;
     struct ppc_radix_page_info *radix_page_info;
@@ -1546,7 +1545,6 @@ int ppc_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 int ppc_cpu_gdb_write_register_apple(CPUState *cpu, uint8_t *buf, int reg);
 #ifndef CONFIG_USER_ONLY
 hwaddr ppc_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-void ppc_gdb_gen_spr_xml(PowerPCCPU *cpu);
 const char *ppc_gdb_get_dynamic_xml(CPUState *cs, const char *xml_name);
 #endif
 int ppc64_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,

target/ppc/cpu_init.c

@@ -6682,10 +6682,6 @@ static void init_ppc_proc(PowerPCCPU *cpu)
     /* PowerPC implementation specific initialisations (SPRs, timers, ...) */
     (*pcc->init_proc)(env);
 
-#if !defined(CONFIG_USER_ONLY)
-    ppc_gdb_gen_spr_xml(cpu);
-#endif
-
     /* MSR bits & flags consistency checks */
     if (env->msr_mask & (1 << 25)) {
         switch (env->flags & (POWERPC_FLAG_SPE | POWERPC_FLAG_VRE)) {

target/ppc/gdbstub.c

@@ -300,15 +300,23 @@ int ppc_cpu_gdb_write_register_apple(CPUState *cs, uint8_t *mem_buf, int n)
 }
 
 #ifndef CONFIG_USER_ONLY
-void ppc_gdb_gen_spr_xml(PowerPCCPU *cpu)
+static void gdb_gen_spr_feature(CPUState *cs)
 {
-    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
+    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cs);
+    PowerPCCPU *cpu = POWERPC_CPU(cs);
     CPUPPCState *env = &cpu->env;
-    GString *xml;
+    GDBFeatureBuilder builder;
-    char *spr_name;
     unsigned int num_regs = 0;
     int i;
 
+    if (pcc->gdb_spr.xml) {
+        return;
+    }
+
+    gdb_feature_builder_init(&builder, &pcc->gdb_spr,
+                             "org.qemu.power.spr", "power-spr.xml",
+                             cs->gdb_num_regs);
+
     for (i = 0; i < ARRAY_SIZE(env->spr_cb); i++) {
         ppc_spr_t *spr = &env->spr_cb[i];
 
@@ -326,35 +334,13 @@ void ppc_gdb_gen_spr_xml(PowerPCCPU *cpu)
          */
         spr->gdb_id = num_regs;
         num_regs++;
+
+        gdb_feature_builder_append_reg(&builder, g_ascii_strdown(spr->name, -1),
+                                       TARGET_LONG_BITS, num_regs,
+                                       "int", "spr");
     }
 
-    if (pcc->gdb_spr_xml) {
+    gdb_feature_builder_end(&builder);
-        return;
-    }
-
-    xml = g_string_new("<?xml version=\"1.0\"?>");
-    g_string_append(xml, "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">");
-    g_string_append(xml, "<feature name=\"org.qemu.power.spr\">");
-
-    for (i = 0; i < ARRAY_SIZE(env->spr_cb); i++) {
-        ppc_spr_t *spr = &env->spr_cb[i];
-
-        if (!spr->name) {
-            continue;
-        }
-
-        spr_name = g_ascii_strdown(spr->name, -1);
-        g_string_append_printf(xml, "<reg name=\"%s\"", spr_name);
-        g_free(spr_name);
-
-        g_string_append_printf(xml, " bitsize=\"%d\"", TARGET_LONG_BITS);
-        g_string_append(xml, " group=\"spr\"/>");
-    }
-
-    g_string_append(xml, "</feature>");
-
-    pcc->gdb_num_sprs = num_regs;
-    pcc->gdb_spr_xml = g_string_free(xml, false);
 }
 
 const char *ppc_gdb_get_dynamic_xml(CPUState *cs, const char *xml_name)
@@ -362,7 +348,7 @@ const char *ppc_gdb_get_dynamic_xml(CPUState *cs, const char *xml_name)
     PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cs);
 
     if (strcmp(xml_name, "power-spr.xml") == 0) {
-        return pcc->gdb_spr_xml;
+        return pcc->gdb_spr.xml;
     }
     return NULL;
 }
@@ -635,7 +621,8 @@ void ppc_gdb_init(CPUState *cs, PowerPCCPUClass *pcc)
                                  32, "power-vsx.xml", 0);
     }
 #ifndef CONFIG_USER_ONLY
+    gdb_gen_spr_feature(cs);
     gdb_register_coprocessor(cs, gdb_get_spr_reg, gdb_set_spr_reg,
-                             pcc->gdb_num_sprs, "power-spr.xml", 0);
+                             pcc->gdb_spr.num_regs, "power-spr.xml", 0);
 #endif
 }