@@ -11,6 +11,7 @@
#ifndef QEMU_QEMU_PLUGIN_H
#define QEMU_QEMU_PLUGIN_H
+#include <glib.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stddef.h>
@@ -227,8 +228,8 @@ struct qemu_plugin_insn;
* @QEMU_PLUGIN_CB_R_REGS: callback reads the CPU's regs
* @QEMU_PLUGIN_CB_RW_REGS: callback reads and writes the CPU's regs
*
- * Note: currently unused, plugins cannot read or change system
- * register state.
+ * Note: currently QEMU_PLUGIN_CB_RW_REGS is unused, plugins cannot change
+ * system register state.
*/
enum qemu_plugin_cb_flags {
QEMU_PLUGIN_CB_NO_REGS,
@@ -708,4 +709,50 @@ uint64_t qemu_plugin_end_code(void);
QEMU_PLUGIN_API
uint64_t qemu_plugin_entry_code(void);
+/** struct qemu_plugin_register - Opaque handle for register access */
+struct qemu_plugin_register;
+
+/**
+ * typedef qemu_plugin_reg_descriptor - register descriptions
+ *
+ * @handle: opaque handle for retrieving value with qemu_plugin_read_register
+ * @name: register name
+ * @feature: optional feature descriptor, can be NULL
+ */
+typedef struct {
+ struct qemu_plugin_register *handle;
+ const char *name;
+ const char *feature;
+} qemu_plugin_reg_descriptor;
+
+/**
+ * qemu_plugin_get_registers() - return register list for vCPU
+ * @vcpu_index: vcpu to query
+ *
+ * Returns a GArray of qemu_plugin_reg_descriptor or NULL. Caller
+ * frees the array (but not the const strings).
+ *
+ * Should be used from a qemu_plugin_register_vcpu_init_cb() callback
+ * after the vCPU is initialised.
+ */
+GArray *qemu_plugin_get_registers(unsigned int vcpu_index);
+
+/**
+ * qemu_plugin_read_register() - read register
+ *
+ * @vcpu: vcpu index
+ * @handle: a @qemu_plugin_reg_handle handle
+ * @buf: A GByteArray for the data owned by the plugin
+ *
+ * This function is only available in a context that register read access is
+ * explicitly requested.
+ *
+ * Returns the size of the read register. The content of @buf is in target byte
+ * order. On failure returns -1
+ */
+int qemu_plugin_read_register(unsigned int vcpu,
+ struct qemu_plugin_register *handle,
+ GByteArray *buf);
+
+
#endif /* QEMU_QEMU_PLUGIN_H */
@@ -8,6 +8,7 @@
*
* qemu_plugin_tb
* qemu_plugin_insn
+ * qemu_plugin_register
*
* Which can then be passed back into the API to do additional things.
* As such all the public functions in here are exported in
@@ -35,10 +36,12 @@
*/
#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
#include "qemu/plugin.h"
#include "qemu/log.h"
#include "tcg/tcg.h"
#include "exec/exec-all.h"
+#include "exec/gdbstub.h"
#include "exec/ram_addr.h"
#include "disas/disas.h"
#include "plugin.h"
@@ -435,3 +438,111 @@ uint64_t qemu_plugin_entry_code(void)
#endif
return entry;
}
+
+/*
+ * Register handles
+ *
+ * The plugin infrastructure keeps hold of these internal data
+ * structures which are presented to plugins as opaque handles. They
+ * are global to the system and therefor additions to the hash table
+ * must be protected by the @reg_handle_lock.
+ *
+ * In order to future proof for up-coming heterogeneous work we want
+ * different entries for each CPU type while sharing them in the
+ * common case of multiple cores of the same type.
+ */
+
+static QemuMutex reg_handle_lock;
+
+struct qemu_plugin_register {
+ const char *name;
+ int gdb_reg_num;
+};
+
+static GHashTable *reg_handles; /* hash table of PluginReg */
+
+/* Generate a stable key - would xxhash be overkill? */
+static gpointer cpu_plus_reg_to_key(CPUState *cs, int gdb_regnum)
+{
+ uintptr_t key = (uintptr_t) cs->cc;
+ key ^= gdb_regnum;
+ return GUINT_TO_POINTER(key);
+}
+
+/*
+ * Create register handles.
+ *
+ * We need to create a handle for each register so the plugin
+ * infrastructure can call gdbstub to read a register. We also
+ * construct a result array with those handles and some ancillary data
+ * the plugin might find useful.
+ */
+
+static GArray *create_register_handles(CPUState *cs, GArray *gdbstub_regs)
+{
+ GArray *find_data = g_array_new(true, true,
+ sizeof(qemu_plugin_reg_descriptor));
+
+ WITH_QEMU_LOCK_GUARD(®_handle_lock) {
+
+ if (!reg_handles) {
+ reg_handles = g_hash_table_new(g_direct_hash, g_direct_equal);
+ }
+
+ for (int i = 0; i < gdbstub_regs->len; i++) {
+ GDBRegDesc *grd = &g_array_index(gdbstub_regs, GDBRegDesc, i);
+ gpointer key = cpu_plus_reg_to_key(cs, grd->gdb_reg);
+ struct qemu_plugin_register *val = g_hash_table_lookup(reg_handles,
+ key);
+
+ /* skip "un-named" regs */
+ if (!grd->name) {
+ continue;
+ }
+
+ /* Doesn't exist, create one */
+ if (!val) {
+ val = g_new0(struct qemu_plugin_register, 1);
+ val->gdb_reg_num = grd->gdb_reg;
+ val->name = g_intern_string(grd->name);
+
+ g_hash_table_insert(reg_handles, key, val);
+ }
+
+ /* Create a record for the plugin */
+ qemu_plugin_reg_descriptor desc = {
+ .handle = val,
+ .name = val->name,
+ .feature = g_intern_string(grd->feature_name)
+ };
+ g_array_append_val(find_data, desc);
+ }
+ }
+
+ return find_data;
+}
+
+GArray *qemu_plugin_get_registers(unsigned int vcpu)
+{
+ CPUState *cs = qemu_get_cpu(vcpu);
+ if (cs) {
+ g_autoptr(GArray) regs = gdb_get_register_list(cs);
+ return regs->len ? create_register_handles(cs, regs) : NULL;
+ } else {
+ return NULL;
+ }
+}
+
+int qemu_plugin_read_register(unsigned int vcpu,
+ struct qemu_plugin_register *reg, GByteArray *buf)
+{
+ CPUState *cs = qemu_get_cpu(vcpu);
+ /* assert with debugging on? */
+ return gdb_read_register(cs, buf, reg->gdb_reg_num);
+}
+
+static void __attribute__((__constructor__)) qemu_api_init(void)
+{
+ qemu_mutex_init(®_handle_lock);
+
+}
@@ -3,6 +3,7 @@
qemu_plugin_end_code;
qemu_plugin_entry_code;
qemu_plugin_get_hwaddr;
+ qemu_plugin_get_registers;
qemu_plugin_hwaddr_device_name;
qemu_plugin_hwaddr_is_io;
qemu_plugin_hwaddr_phys_addr;
@@ -20,6 +21,7 @@
qemu_plugin_n_vcpus;
qemu_plugin_outs;
qemu_plugin_path_to_binary;
+ qemu_plugin_read_register;
qemu_plugin_register_atexit_cb;
qemu_plugin_register_flush_cb;
qemu_plugin_register_vcpu_exit_cb;