We can only request a list of registers once the vCPU has been
initialised so the user needs to use either call the get function on
vCPU initialisation or during the translation phase.
We don't expose the reg number to the plugin instead hiding it behind
an opaque handle. This allows for a bit of future proofing should the
internals need to be changed while also being hashed against the
CPUClass so we can handle different register sets per-vCPU in
hetrogenous situations.
Having an internal state within the plugins also allows us to expand
the interface in future (for example providing callbacks on register
change if the translator can track changes).
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1706
Cc: Akihiko Odaki <akihiko.odaki@daynix.com>
Based-on: <20231025093128.33116-18-akihiko.odaki@daynix.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
v3
- also g_intern_string the register name
- make get_registers documentation a bit less verbose
v2
- use new get whole list api, and expose upwards
vAJB:
The main difference to Akikio's version is hiding the gdb register
detail from the plugin for the reasons described above.
---
include/qemu/qemu-plugin.h | 51 +++++++++++++++++-
plugins/api.c | 102 +++++++++++++++++++++++++++++++++++
plugins/qemu-plugins.symbols | 2 +
3 files changed, 153 insertions(+), 2 deletions(-)
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index 4daab6efd29..95380895f81 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -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;