target/arm: Add the XML dynamic generation

Generate an XML description for the cp-regs.
Register these regs with the gdb_register_coprocessor().
Add arm_gdb_get_sysreg() to use it as a callback to read those regs.
Add a dummy arm_gdb_set_sysreg().

Signed-off-by: Abdallah Bouassida <abdallah.bouassida@lauterbach.com>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1524153386-3550-4-git-send-email-abdallah.bouassida@lauterbach.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

gdbstub.c

@@ -675,6 +675,16 @@ static const char *get_feature_xml(const char *p, const char **newp,
         }
         return target_xml;
     }
+    if (cc->gdb_get_dynamic_xml) {
+        CPUState *cpu = first_cpu;
+        char *xmlname = g_strndup(p, len);
+        const char *xml = cc->gdb_get_dynamic_xml(cpu, xmlname);
+
+        g_free(xmlname);
+        if (xml) {
+            return xml;
+        }
+    }
     for (i = 0; ; i++) {
         name = xml_builtin[i][0];
         if (!name || (strncmp(name, p, len) == 0 && strlen(name) == len))

include/qom/cpu.h

@@ -132,6 +132,9 @@ struct TranslationBlock;
  *           before the insn which triggers a watchpoint rather than after it.
  * @gdb_arch_name: Optional callback that returns the architecture name known
  * to GDB. The caller must free the returned string with g_free.
+ * @gdb_get_dynamic_xml: Callback to return dynamically generated XML for the
+ *   gdb stub. Returns a pointer to the XML contents for the specified XML file
+ *   or NULL if the CPU doesn't have a dynamically generated content for it.
  * @cpu_exec_enter: Callback for cpu_exec preparation.
  * @cpu_exec_exit: Callback for cpu_exec cleanup.
  * @cpu_exec_interrupt: Callback for processing interrupts in cpu_exec.
@@ -198,7 +201,7 @@ typedef struct CPUClass {
     const struct VMStateDescription *vmsd;
     const char *gdb_core_xml_file;
     gchar * (*gdb_arch_name)(CPUState *cpu);
-
+    const char * (*gdb_get_dynamic_xml)(CPUState *cpu, const char *xmlname);
     void (*cpu_exec_enter)(CPUState *cpu);
     void (*cpu_exec_exit)(CPUState *cpu);
     bool (*cpu_exec_interrupt)(CPUState *cpu, int interrupt_request);

target/arm/cpu.c

@@ -1908,6 +1908,7 @@ static void arm_cpu_class_init(ObjectClass *oc, void *data)
     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;
     cc->debug_excp_handler = arm_debug_excp_handler;
     cc->debug_check_watchpoint = arm_debug_check_watchpoint;

target/arm/cpu.h

@@ -133,6 +133,19 @@ enum {
    s<2n+1> maps to the most significant half of d<n>
  */
 
+/**
+ * DynamicGDBXMLInfo:
+ * @desc: Contains the XML descriptions.
+ * @num_cpregs: Number of the Coprocessor registers seen by GDB.
+ * @cpregs_keys: Array that contains the corresponding Key of
+ * a given cpreg with the same order of the cpreg in the XML description.
+ */
+typedef struct DynamicGDBXMLInfo {
+    char *desc;
+    int num_cpregs;
+    uint32_t *cpregs_keys;
+} DynamicGDBXMLInfo;
+
 /* CPU state for each instance of a generic timer (in cp15 c14) */
 typedef struct ARMGenericTimer {
     uint64_t cval; /* Timer CompareValue register */
@@ -687,6 +700,8 @@ struct ARMCPU {
     uint64_t *cpreg_vmstate_values;
     int32_t cpreg_vmstate_array_len;
 
+    DynamicGDBXMLInfo dyn_xml;
+
     /* Timers used by the generic (architected) timer */
     QEMUTimer *gt_timer[NUM_GTIMERS];
     /* GPIO outputs for generic timer */
@@ -868,6 +883,17 @@ hwaddr arm_cpu_get_phys_page_attrs_debug(CPUState *cpu, vaddr addr,
 int arm_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
 int arm_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
+/* Dynamically generates for gdb stub an XML description of the sysregs from
+ * the cp_regs hashtable. Returns the registered sysregs number.
+ */
+int arm_gen_dynamic_xml(CPUState *cpu);
+
+/* Returns the dynamically generated XML for the gdb stub.
+ * Returns a pointer to the XML contents for the specified XML file or NULL
+ * if the XML name doesn't match the predefined one.
+ */
+const char *arm_gdb_get_dynamic_xml(CPUState *cpu, const char *xmlname);
+
 int arm_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
                              int cpuid, void *opaque);
 int arm_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,

target/arm/gdbstub.c

@@ -22,6 +22,11 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
+typedef struct RegisterSysregXmlParam {
+    CPUState *cs;
+    GString *s;
+} RegisterSysregXmlParam;
+
 /* Old gdb always expect FPA registers.  Newer (xml-aware) gdb only expect
    whatever the target description contains.  Due to a historical mishap
    the FPA registers appear in between core integer regs and the CPSR.
@@ -101,3 +106,74 @@ int arm_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
     /* Unknown register.  */
     return 0;
 }
+
+static void arm_gen_one_xml_reg_tag(GString *s, DynamicGDBXMLInfo *dyn_xml,
+                                    ARMCPRegInfo *ri, uint32_t ri_key,
+                                    int bitsize)
+{
+    g_string_append_printf(s, "<reg name=\"%s\"", ri->name);
+    g_string_append_printf(s, " bitsize=\"%d\"", bitsize);
+    g_string_append_printf(s, " group=\"cp_regs\"/>");
+    dyn_xml->num_cpregs++;
+    dyn_xml->cpregs_keys[dyn_xml->num_cpregs - 1] = ri_key;
+}
+
+static void arm_register_sysreg_for_xml(gpointer key, gpointer value,
+                                        gpointer p)
+{
+    uint32_t ri_key = *(uint32_t *)key;
+    ARMCPRegInfo *ri = value;
+    RegisterSysregXmlParam *param = (RegisterSysregXmlParam *)p;
+    GString *s = param->s;
+    ARMCPU *cpu = ARM_CPU(param->cs);
+    CPUARMState *env = &cpu->env;
+    DynamicGDBXMLInfo *dyn_xml = &cpu->dyn_xml;
+
+    if (!(ri->type & (ARM_CP_NO_RAW | ARM_CP_NO_GDB))) {
+        if (arm_feature(env, ARM_FEATURE_AARCH64)) {
+            if (ri->state == ARM_CP_STATE_AA64) {
+                arm_gen_one_xml_reg_tag(s , dyn_xml, ri, ri_key, 64);
+            }
+        } else {
+            if (ri->state == ARM_CP_STATE_AA32) {
+                if (!arm_feature(env, ARM_FEATURE_EL3) &&
+                    (ri->secure & ARM_CP_SECSTATE_S)) {
+                    return;
+                }
+                if (ri->type & ARM_CP_64BIT) {
+                    arm_gen_one_xml_reg_tag(s , dyn_xml, ri, ri_key, 64);
+                } else {
+                    arm_gen_one_xml_reg_tag(s , dyn_xml, ri, ri_key, 32);
+                }
+            }
+        }
+    }
+}
+
+int arm_gen_dynamic_xml(CPUState *cs)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    GString *s = g_string_new(NULL);
+    RegisterSysregXmlParam param = {cs, s};
+
+    cpu->dyn_xml.num_cpregs = 0;
+    cpu->dyn_xml.cpregs_keys = g_malloc(sizeof(uint32_t *) *
+                                        g_hash_table_size(cpu->cp_regs));
+    g_string_printf(s, "<?xml version=\"1.0\"?>");
+    g_string_append_printf(s, "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">");
+    g_string_append_printf(s, "<feature name=\"org.qemu.gdb.arm.sys.regs\">");
+    g_hash_table_foreach(cpu->cp_regs, arm_register_sysreg_for_xml, &param);
+    g_string_append_printf(s, "</feature>");
+    cpu->dyn_xml.desc = g_string_free(s, false);
+    return cpu->dyn_xml.num_cpregs;
+}
+
+const char *arm_gdb_get_dynamic_xml(CPUState *cs, const char *xmlname)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+
+    if (strcmp(xmlname, "system-registers.xml") == 0) {
+        return cpu->dyn_xml.desc;
+    }
+    return NULL;
+}

target/arm/helper.c

@@ -215,6 +215,29 @@ static void write_raw_cp_reg(CPUARMState *env, const ARMCPRegInfo *ri,
     }
 }
 
+static int arm_gdb_get_sysreg(CPUARMState *env, uint8_t *buf, int reg)
+{
+    ARMCPU *cpu = arm_env_get_cpu(env);
+    const ARMCPRegInfo *ri;
+    uint32_t key;
+
+    key = cpu->dyn_xml.cpregs_keys[reg];
+    ri = get_arm_cp_reginfo(cpu->cp_regs, key);
+    if (ri) {
+        if (cpreg_field_is_64bit(ri)) {
+            return gdb_get_reg64(buf, (uint64_t)read_raw_cp_reg(env, ri));
+        } else {
+            return gdb_get_reg32(buf, (uint32_t)read_raw_cp_reg(env, ri));
+        }
+    }
+    return 0;
+}
+
+static int arm_gdb_set_sysreg(CPUARMState *env, uint8_t *buf, int reg)
+{
+    return 0;
+}
+
 static bool raw_accessors_invalid(const ARMCPRegInfo *ri)
 {
    /* Return true if the regdef would cause an assertion if you called
@@ -5488,6 +5511,9 @@ void arm_cpu_register_gdb_regs_for_features(ARMCPU *cpu)
         gdb_register_coprocessor(cs, vfp_gdb_get_reg, vfp_gdb_set_reg,
                                  19, "arm-vfp.xml", 0);
     }
+    gdb_register_coprocessor(cs, arm_gdb_get_sysreg, arm_gdb_set_sysreg,
+                             arm_gen_dynamic_xml(cs),
+                             "system-registers.xml", 0);
 }
 
 /* Sort alphabetically by type name, except for "any". */