[PATCH v2 13/15] cpus: Add const-qualified CPU environment accessors

["Philippe Mathieu-Daudé" <philmd@oss.qualcomm.com>]

From: Philippe Mathieu-Daudé <philmd@linaro.org>

Use _Generic() controlling-expression to add the const-qualified
variants of cpu_env(), env_cpu() and env_archcpu(). This allows to
safely access CPU architecture state when it should not be modified.

Alias env_cpu_const() which is still used.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 include/exec/cpu-common.h | 30 +++++++++++-------------------
 include/hw/core/cpu.h     | 17 ++++++++++++-----
 2 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 6594f7fa1be..bffef677607 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -85,21 +85,11 @@ static inline bool cpu_loop_exit_requested(const CPUState *cpu)
  *
  * Return the ArchCPU associated with the environment.
  */
-static inline ArchCPU *env_archcpu(CPUArchState *env)
-{
-    return (void *)env - sizeof(CPUState);
-}
-
-/**
- * env_cpu_const(env)
- * @env: The architecture environment
- *
- * Return the CPUState associated with the environment.
- */
-static inline const CPUState *env_cpu_const(const CPUArchState *env)
-{
-    return (void *)env - sizeof(CPUState);
-}
+#define env_archcpu(env) _Generic(*(env), \
+            CPUArchState: \
+                (ArchCPU *)((void *)env - sizeof(CPUState)), \
+            const CPUArchState: \
+                (const ArchCPU *)((const void *)env - sizeof(CPUState)))
 
 /**
  * env_cpu(env)
@@ -107,9 +97,11 @@ static inline const CPUState *env_cpu_const(const CPUArchState *env)
  *
  * Return the CPUState associated with the environment.
  */
-static inline CPUState *env_cpu(CPUArchState *env)
-{
-    return (CPUState *)env_cpu_const(env);
-}
+#define env_cpu(env) _Generic(*(env), \
+            CPUArchState: \
+                (CPUState *)((void *)env - sizeof(CPUState)), \
+            const CPUArchState: \
+                (const CPUState *)((const void *)env - sizeof(CPUState)))
+#define env_cpu_const(cpu) env_cpu(cpu)
 
 #endif /* CPU_COMMON_H */
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index a16acf14370..372485a2e54 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -594,11 +594,18 @@ struct CPUState {
 QEMU_BUILD_BUG_ON(offsetof(CPUState, neg) !=
                   sizeof(CPUState) - sizeof(CPUNegativeOffsetState));
 
-static inline CPUArchState *cpu_env(CPUState *cpu)
-{
-    /* We validate that CPUArchState follows CPUState in cpu-target.c */
-    return (CPUArchState *)(cpu + 1);
-}
+/**
+ * cpu_env(cpu)
+ * @cpu: The vCPU
+ *
+ * Return the CPUArchState associated with the CPU.
+ */
+#define cpu_env(cpu) _Generic(*(cpu), \
+        /* We validate that CPUArchState follows CPUState in cpu-target.c */ \
+        CPUState: \
+            (CPUArchState *)(cpu + 1), \
+        const CPUState: \
+            (const CPUArchState *)(cpu + 1))
 
 #ifdef CONFIG_TCG
 /*
-- 
2.53.0