Commit 9373e632 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

tcg: introduce tcg_current_cpu 



This is already useful on Windows in order to remove tls.h, because
accesses to current_cpu are done from a different thread on that
platform.  It will be used on POSIX platforms as soon TCG stops using
signals to interrupt the execution of translated code.

Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 5039d6e2

cpu-exec.c

+5 −9
Original line number Diff line number Diff line
@@ -342,6 +342,7 @@ static void cpu_handle_debug_exception(CPUState *cpu) 
/* main execution loop */



volatile sig_atomic_t exit_request;

CPUState *tcg_current_cpu;



int cpu_exec(CPUState *cpu)

{
@@ -368,15 +369,7 @@ int cpu_exec(CPUState *cpu) 
    }



    current_cpu = cpu;



    /* As long as current_cpu is null, up to the assignment just above,

     * requests by other threads to exit the execution loop are expected to

     * be issued using the exit_request global. We must make sure that our

     * evaluation of the global value is performed past the current_cpu

     * value transition point, which requires a memory barrier as well as

     * an instruction scheduling constraint on modern architectures.  */

    smp_mb();



    atomic_mb_set(&tcg_current_cpu, cpu);

    rcu_read_lock();



    if (unlikely(exit_request)) {
@@ -579,5 +572,8 @@ int cpu_exec(CPUState *cpu) 


    /* fail safe : never use current_cpu outside cpu_exec() */

    current_cpu = NULL;



    /* Does not need atomic_mb_set because a spurious wakeup is okay.  */

    atomic_set(&tcg_current_cpu, NULL);

    return ret;

}

cpus.c

+3 −2
Original line number Diff line number Diff line
@@ -663,8 +663,9 @@ static void cpu_handle_guest_debug(CPUState *cpu) 


static void cpu_signal(int sig)

{

    if (current_cpu) {

        cpu_exit(current_cpu);

    CPUState *cpu = atomic_mb_read(&tcg_current_cpu);

    if (cpu) {

        cpu_exit(cpu);

    }

    exit_request = 1;

}

include/exec/exec-all.h

+1 −0
Original line number Diff line number Diff line
@@ -387,6 +387,7 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env1, target_ulong addr); 
extern int singlestep;



/* cpu-exec.c */

extern CPUState *tcg_current_cpu;

extern volatile sig_atomic_t exit_request;



#if !defined(CONFIG_USER_ONLY)