Commit fdbc2b57 authored by Richard Henderson's avatar Richard Henderson
Browse files

tcg: Add EXCP_ATOMIC 



When we cannot emulate an atomic operation within a parallel
context, this exception allows us to stop the world and try
again in a serial context.

Reviewed-by: default avatarEmilio G. Cota <cota@braap.org>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
parent 1edaeee0

cpu-exec-common.c

+6 −0
Original line number Diff line number Diff line
@@ -77,3 +77,9 @@ void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc) 
    }

    siglongjmp(cpu->jmp_env, 1);

}



void cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc)

{

    cpu->exception_index = EXCP_ATOMIC;

    cpu_loop_exit_restore(cpu, pc);

}

cpu-exec.c

+30 −0
Original line number Diff line number Diff line
@@ -222,6 +222,36 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles, 
}

#endif



static void cpu_exec_step(CPUState *cpu)

{

    CPUArchState *env = (CPUArchState *)cpu->env_ptr;

    TranslationBlock *tb;

    target_ulong cs_base, pc;

    uint32_t flags;



    cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);

    tb = tb_gen_code(cpu, pc, cs_base, flags,

                     1 | CF_NOCACHE | CF_IGNORE_ICOUNT);

    tb->orig_tb = NULL;

    /* execute the generated code */

    trace_exec_tb_nocache(tb, pc);

    cpu_tb_exec(cpu, tb);

    tb_phys_invalidate(tb, -1);

    tb_free(tb);

}



void cpu_exec_step_atomic(CPUState *cpu)

{

    start_exclusive();



    /* Since we got here, we know that parallel_cpus must be true.  */

    parallel_cpus = false;

    cpu_exec_step(cpu);

    parallel_cpus = true;



    end_exclusive();

}



struct tb_desc {

    target_ulong pc;

    target_ulong cs_base;

cpus.c

+2 −0
Original line number Diff line number Diff line
@@ -1497,6 +1497,8 @@ static void tcg_exec_all(void) 
            if (r == EXCP_DEBUG) {

                cpu_handle_guest_debug(cpu);

                break;

            } else if (r == EXCP_ATOMIC) {

                cpu_exec_step_atomic(cpu);

            }

        } else if (cpu->stop || cpu->stopped) {

            if (cpu->unplug) {

include/exec/cpu-all.h

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#define EXCP_DEBUG      0x10002 /* cpu stopped after a breakpoint or singlestep */

#define EXCP_HALTED     0x10003 /* cpu is halted (waiting for external event) */

#define EXCP_YIELD      0x10004 /* cpu wants to yield timeslice to another */

#define EXCP_ATOMIC     0x10005 /* stop-the-world and emulate atomic */



/* some important defines:

 *

include/exec/exec-all.h

+1 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu, 


void QEMU_NORETURN cpu_loop_exit(CPUState *cpu);

void QEMU_NORETURN cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc);

void QEMU_NORETURN cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc);



#if !defined(CONFIG_USER_ONLY)

void cpu_reloading_memory_map(void);