plugins: Use different helpers when reading registers

This avoids optimizations incompatible when reading registers.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20231213-gdb-v17-12-777047380591@daynix.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240227144335.1196131-21-alex.bennee@linaro.org>

4 files changed, 52 insertions, 7 deletions

diff --git a/accel/tcg/plugin-gen.c b/accel/tcg/plugin-gen.c
index 78b331b..b37ce76 100644
--- a/accel/tcg/plugin-gen.c
+++ b/accel/tcg/plugin-gen.c
@@ -79,6 +79,7 @@ enum plugin_gen_from {
 
 enum plugin_gen_cb {
     PLUGIN_GEN_CB_UDATA,
+    PLUGIN_GEN_CB_UDATA_R,
     PLUGIN_GEN_CB_INLINE,
     PLUGIN_GEN_CB_MEM,
     PLUGIN_GEN_ENABLE_MEM_HELPER,
@@ -90,7 +91,10 @@ enum plugin_gen_cb {
  * These helpers are stubs that get dynamically switched out for calls
  * direct to the plugin if they are subscribed to.
  */
-void HELPER(plugin_vcpu_udata_cb)(uint32_t cpu_index, void *udata)
+void HELPER(plugin_vcpu_udata_cb_no_wg)(uint32_t cpu_index, void *udata)
+{ }
+
+void HELPER(plugin_vcpu_udata_cb_no_rwg)(uint32_t cpu_index, void *udata)
 { }
 
 void HELPER(plugin_vcpu_mem_cb)(unsigned int vcpu_index,
@@ -98,7 +102,7 @@ void HELPER(plugin_vcpu_mem_cb)(unsigned int vcpu_index,
                                 void *userdata)
 { }
 
-static void gen_empty_udata_cb(void)
+static void gen_empty_udata_cb(void (*gen_helper)(TCGv_i32, TCGv_ptr))
 {
     TCGv_i32 cpu_index = tcg_temp_ebb_new_i32();
     TCGv_ptr udata = tcg_temp_ebb_new_ptr();
@@ -106,12 +110,22 @@ static void gen_empty_udata_cb(void)
     tcg_gen_movi_ptr(udata, 0);
     tcg_gen_ld_i32(cpu_index, tcg_env,
                    -offsetof(ArchCPU, env) + offsetof(CPUState, cpu_index));
-    gen_helper_plugin_vcpu_udata_cb(cpu_index, udata);
+    gen_helper(cpu_index, udata);
 
     tcg_temp_free_ptr(udata);
     tcg_temp_free_i32(cpu_index);
 }
 
+static void gen_empty_udata_cb_no_wg(void)
+{
+    gen_empty_udata_cb(gen_helper_plugin_vcpu_udata_cb_no_wg);
+}
+
+static void gen_empty_udata_cb_no_rwg(void)
+{
+    gen_empty_udata_cb(gen_helper_plugin_vcpu_udata_cb_no_rwg);
+}
+
 /*
  * For now we only support addi_i64.
  * When we support more ops, we can generate one empty inline cb for each.
@@ -192,7 +206,8 @@ static void plugin_gen_empty_callback(enum plugin_gen_from from)
                     gen_empty_mem_helper);
         /* fall through */
     case PLUGIN_GEN_FROM_TB:
-        gen_wrapped(from, PLUGIN_GEN_CB_UDATA, gen_empty_udata_cb);
+        gen_wrapped(from, PLUGIN_GEN_CB_UDATA, gen_empty_udata_cb_no_rwg);
+        gen_wrapped(from, PLUGIN_GEN_CB_UDATA_R, gen_empty_udata_cb_no_wg);
         gen_wrapped(from, PLUGIN_GEN_CB_INLINE, gen_empty_inline_cb);
         break;
     default:
@@ -588,6 +603,12 @@ static void plugin_gen_tb_udata(const struct qemu_plugin_tb *ptb,
     inject_udata_cb(ptb->cbs[PLUGIN_CB_REGULAR], begin_op);
 }
 
+static void plugin_gen_tb_udata_r(const struct qemu_plugin_tb *ptb,
+                                  TCGOp *begin_op)
+{
+    inject_udata_cb(ptb->cbs[PLUGIN_CB_REGULAR_R], begin_op);
+}
+
 static void plugin_gen_tb_inline(const struct qemu_plugin_tb *ptb,
                                  TCGOp *begin_op)
 {
@@ -602,6 +623,14 @@ static void plugin_gen_insn_udata(const struct qemu_plugin_tb *ptb,
     inject_udata_cb(insn->cbs[PLUGIN_CB_INSN][PLUGIN_CB_REGULAR], begin_op);
 }
 
+static void plugin_gen_insn_udata_r(const struct qemu_plugin_tb *ptb,
+                                    TCGOp *begin_op, int insn_idx)
+{
+    struct qemu_plugin_insn *insn = g_ptr_array_index(ptb->insns, insn_idx);
+
+    inject_udata_cb(insn->cbs[PLUGIN_CB_INSN][PLUGIN_CB_REGULAR_R], begin_op);
+}
+
 static void plugin_gen_insn_inline(const struct qemu_plugin_tb *ptb,
                                    TCGOp *begin_op, int insn_idx)
 {
@@ -721,6 +750,9 @@ static void plugin_gen_inject(struct qemu_plugin_tb *plugin_tb)
                 case PLUGIN_GEN_CB_UDATA:
                     plugin_gen_tb_udata(plugin_tb, op);
                     break;
+                case PLUGIN_GEN_CB_UDATA_R:
+                    plugin_gen_tb_udata_r(plugin_tb, op);
+                    break;
                 case PLUGIN_GEN_CB_INLINE:
                     plugin_gen_tb_inline(plugin_tb, op);
                     break;
@@ -737,6 +769,9 @@ static void plugin_gen_inject(struct qemu_plugin_tb *plugin_tb)
                 case PLUGIN_GEN_CB_UDATA:
                     plugin_gen_insn_udata(plugin_tb, op, insn_idx);
                     break;
+                case PLUGIN_GEN_CB_UDATA_R:
+                    plugin_gen_insn_udata_r(plugin_tb, op, insn_idx);
+                    break;
                 case PLUGIN_GEN_CB_INLINE:
                     plugin_gen_insn_inline(plugin_tb, op, insn_idx);
                     break;
diff --git a/accel/tcg/plugin-helpers.h b/accel/tcg/plugin-helpers.h
index 8e685e0..1179643 100644
--- a/accel/tcg/plugin-helpers.h
+++ b/accel/tcg/plugin-helpers.h
@@ -1,4 +1,5 @@
 #ifdef CONFIG_PLUGIN
-DEF_HELPER_FLAGS_2(plugin_vcpu_udata_cb, TCG_CALL_NO_RWG | TCG_CALL_PLUGIN, void, i32, ptr)
+DEF_HELPER_FLAGS_2(plugin_vcpu_udata_cb_no_wg, TCG_CALL_NO_WG | TCG_CALL_PLUGIN, void, i32, ptr)
+DEF_HELPER_FLAGS_2(plugin_vcpu_udata_cb_no_rwg, TCG_CALL_NO_RWG | TCG_CALL_PLUGIN, void, i32, ptr)
 DEF_HELPER_FLAGS_4(plugin_vcpu_mem_cb, TCG_CALL_NO_RWG | TCG_CALL_PLUGIN, void, i32, i32, i64, ptr)
 #endif
diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h
index 7fdc3a4..b0c5ac6 100644
--- a/include/qemu/plugin.h
+++ b/include/qemu/plugin.h
@@ -73,6 +73,7 @@ enum plugin_dyn_cb_type {
 
 enum plugin_dyn_cb_subtype {
     PLUGIN_CB_REGULAR,
+    PLUGIN_CB_REGULAR_R,
     PLUGIN_CB_INLINE,
     PLUGIN_N_CB_SUBTYPES,
 };
diff --git a/plugins/api.c b/plugins/api.c
index 116b8bd..54df72c 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -89,7 +89,11 @@ void qemu_plugin_register_vcpu_tb_exec_cb(struct qemu_plugin_tb *tb,
                                           void *udata)
 {
     if (!tb->mem_only) {
-        plugin_register_dyn_cb__udata(&tb->cbs[PLUGIN_CB_REGULAR],
+        int index = flags == QEMU_PLUGIN_CB_R_REGS ||
+                    flags == QEMU_PLUGIN_CB_RW_REGS ?
+                    PLUGIN_CB_REGULAR_R : PLUGIN_CB_REGULAR;
+
+        plugin_register_dyn_cb__udata(&tb->cbs[index],
                                       cb, flags, udata);
     }
 }
@@ -109,7 +113,11 @@ void qemu_plugin_register_vcpu_insn_exec_cb(struct qemu_plugin_insn *insn,
                                             void *udata)
 {
     if (!insn->mem_only) {
-        plugin_register_dyn_cb__udata(&insn->cbs[PLUGIN_CB_INSN][PLUGIN_CB_REGULAR],
+        int index = flags == QEMU_PLUGIN_CB_R_REGS ||
+                    flags == QEMU_PLUGIN_CB_RW_REGS ?
+                    PLUGIN_CB_REGULAR_R : PLUGIN_CB_REGULAR;
+
+        plugin_register_dyn_cb__udata(&insn->cbs[PLUGIN_CB_INSN][index],
                                       cb, flags, udata);
     }
 }