[Qemu-devel] [PATCH] Fix CPU chaining in linux-user emulation

[Gwenole Beauchesne]

Hi,

This patch fixes chaining of CPU instances. It was simply trashed with the
memcpy() thus causing problems in threaded programs (N > 2): an infinite
loop in next cpu_init().

--- qemu-0.9.0/linux-user/syscall.c.cpuchain    2007-02-13 14:41:12.000000000 
+0100
+++ qemu-0.9.0/linux-user/syscall.c     2007-02-20 01:36:10.000000000 +0100
@@ -1720,8 +1720,7 @@ int do_fork(CPUState *env, unsigned int 
         ts->next = first_task_state;
         first_task_state = ts;
         /* we create a new CPU instance. */
-        new_env = cpu_init();
-        memcpy(new_env, env, sizeof(CPUState));
+        new_env = cpu_copy(env);
 #if defined(TARGET_I386)
         if (!newsp)
             newsp = env->regs[R_ESP];
--- qemu-0.9.0/exec.c.cpuchain  2007-02-20 01:31:45.000000000 +0100
+++ qemu-0.9.0/exec.c   2007-02-20 01:36:32.000000000 +0100
@@ -1222,6 +1222,18 @@ void cpu_abort(CPUState *env, const char
     abort();
 }
 
+CPUState *cpu_copy(CPUState *env)
+{
+    CPUState *new_env = cpu_init();
+    /* preserve chaining and index */
+    CPUState *next_cpu = new_env->next_cpu;
+    int cpu_index = new_env->cpu_index;
+    memcpy(new_env, env, sizeof(CPUState));
+    new_env->next_cpu = next_cpu;
+    new_env->cpu_index = cpu_index;
+    return new_env;
+}
+
 #if !defined(CONFIG_USER_ONLY)
 
 /* NOTE: if flush_global is true, also flush global entries (not
--- qemu-0.9.0/cpu-all.h.cpuchain       2007-02-18 14:40:33.000000000 +0100
+++ qemu-0.9.0/cpu-all.h        2007-02-20 01:34:53.000000000 +0100
@@ -760,6 +760,8 @@ void page_unprotect_range(target_ulong d
 
 #endif /* SINGLE_CPU_DEFINES */
 
+CPUState *cpu_copy(CPUState *env);
+
 void cpu_dump_state(CPUState *env, FILE *f, 
                     int (*cpu_fprintf)(FILE *f, const char *fmt, ...),
                     int flags);