plugins: conditional callbacks

Extend plugins API to support callback called with a given criteria
(evaluated inline).

Added functions:
- qemu_plugin_register_vcpu_tb_exec_cond_cb
- qemu_plugin_register_vcpu_insn_exec_cond_cb

They expect as parameter a condition, a qemu_plugin_u64_t (op1) and an
immediate (op2). Callback is called if op1 |cond| op2 is true.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20240502211522.346467-6-pierrick.bouvier@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
[AJB: fix re-base conflict with tb_is_mem_only()]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240514174253.694591-8-alex.bennee@linaro.org>

2 files changed, 84 insertions, 0 deletions

diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h
index aaa4b83..2b126e1 100644
--- a/include/qemu/plugin.h
+++ b/include/qemu/plugin.h
@@ -68,6 +68,7 @@ union qemu_plugin_cb_sig {
 
 enum plugin_dyn_cb_type {
     PLUGIN_CB_REGULAR,
+    PLUGIN_CB_COND,
     PLUGIN_CB_MEM_REGULAR,
     PLUGIN_CB_INLINE_ADD_U64,
     PLUGIN_CB_INLINE_STORE_U64,
@@ -90,6 +91,13 @@ struct qemu_plugin_dyn_cb {
             TCGHelperInfo *info;
         } regular;
         struct {
+            union qemu_plugin_cb_sig f;
+            TCGHelperInfo *info;
+            qemu_plugin_u64 entry;
+            enum qemu_plugin_cond cond;
+            uint64_t imm;
+        } cond;
+        struct {
             qemu_plugin_u64 entry;
             enum qemu_plugin_op op;
             uint64_t imm;
diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index 29242d4..95703d8 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -263,6 +263,29 @@ enum qemu_plugin_mem_rw {
 };
 
 /**
+ * enum qemu_plugin_cond - condition to enable callback
+ *
+ * @QEMU_PLUGIN_COND_NEVER: false
+ * @QEMU_PLUGIN_COND_ALWAYS: true
+ * @QEMU_PLUGIN_COND_EQ: is equal?
+ * @QEMU_PLUGIN_COND_NE: is not equal?
+ * @QEMU_PLUGIN_COND_LT: is less than?
+ * @QEMU_PLUGIN_COND_LE: is less than or equal?
+ * @QEMU_PLUGIN_COND_GT: is greater than?
+ * @QEMU_PLUGIN_COND_GE: is greater than or equal?
+ */
+enum qemu_plugin_cond {
+    QEMU_PLUGIN_COND_NEVER,
+    QEMU_PLUGIN_COND_ALWAYS,
+    QEMU_PLUGIN_COND_EQ,
+    QEMU_PLUGIN_COND_NE,
+    QEMU_PLUGIN_COND_LT,
+    QEMU_PLUGIN_COND_LE,
+    QEMU_PLUGIN_COND_GT,
+    QEMU_PLUGIN_COND_GE,
+};
+
+/**
  * typedef qemu_plugin_vcpu_tb_trans_cb_t - translation callback
  * @id: unique plugin id
  * @tb: opaque handle used for querying and instrumenting a block.
@@ -302,6 +325,32 @@ void qemu_plugin_register_vcpu_tb_exec_cb(struct qemu_plugin_tb *tb,
                                           void *userdata);
 
 /**
+ * qemu_plugin_register_vcpu_tb_exec_cond_cb() - register conditional callback
+ * @tb: the opaque qemu_plugin_tb handle for the translation
+ * @cb: callback function
+ * @cond: condition to enable callback
+ * @entry: first operand for condition
+ * @imm: second operand for condition
+ * @flags: does the plugin read or write the CPU's registers?
+ * @userdata: any plugin data to pass to the @cb?
+ *
+ * The @cb function is called when a translated unit executes if
+ * entry @cond imm is true.
+ * If condition is QEMU_PLUGIN_COND_ALWAYS, condition is never interpreted and
+ * this function is equivalent to qemu_plugin_register_vcpu_tb_exec_cb.
+ * If condition QEMU_PLUGIN_COND_NEVER, condition is never interpreted and
+ * callback is never installed.
+ */
+QEMU_PLUGIN_API
+void qemu_plugin_register_vcpu_tb_exec_cond_cb(struct qemu_plugin_tb *tb,
+                                               qemu_plugin_vcpu_udata_cb_t cb,
+                                               enum qemu_plugin_cb_flags flags,
+                                               enum qemu_plugin_cond cond,
+                                               qemu_plugin_u64 entry,
+                                               uint64_t imm,
+                                               void *userdata);
+
+/**
  * enum qemu_plugin_op - describes an inline op
  *
  * @QEMU_PLUGIN_INLINE_ADD_U64: add an immediate value uint64_t
@@ -345,6 +394,33 @@ void qemu_plugin_register_vcpu_insn_exec_cb(struct qemu_plugin_insn *insn,
                                             void *userdata);
 
 /**
+ * qemu_plugin_register_vcpu_insn_exec_cond_cb() - conditional insn execution cb
+ * @insn: the opaque qemu_plugin_insn handle for an instruction
+ * @cb: callback function
+ * @flags: does the plugin read or write the CPU's registers?
+ * @cond: condition to enable callback
+ * @entry: first operand for condition
+ * @imm: second operand for condition
+ * @userdata: any plugin data to pass to the @cb?
+ *
+ * The @cb function is called when an instruction executes if
+ * entry @cond imm is true.
+ * If condition is QEMU_PLUGIN_COND_ALWAYS, condition is never interpreted and
+ * this function is equivalent to qemu_plugin_register_vcpu_insn_exec_cb.
+ * If condition QEMU_PLUGIN_COND_NEVER, condition is never interpreted and
+ * callback is never installed.
+ */
+QEMU_PLUGIN_API
+void qemu_plugin_register_vcpu_insn_exec_cond_cb(
+    struct qemu_plugin_insn *insn,
+    qemu_plugin_vcpu_udata_cb_t cb,
+    enum qemu_plugin_cb_flags flags,
+    enum qemu_plugin_cond cond,
+    qemu_plugin_u64 entry,
+    uint64_t imm,
+    void *userdata);
+
+/**
  * qemu_plugin_register_vcpu_insn_exec_inline_per_vcpu() - insn exec inline op
  * @insn: the opaque qemu_plugin_insn handle for an instruction
  * @op: the type of qemu_plugin_op (e.g. ADD_U64)