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replay: check icount in cpu exec loop 

This patch adds check to break cpu loop when icount expires without
setting the TB_EXIT_ICOUNT_EXPIRED flag. It happens when there is no
available translated blocks and all instructions were executed.
In icount replay mode unnecessary tb_find will be called (which may
cause an exception) and execution will be non-deterministic.
Because cpu_loop_exec_tb cannot longjmp anymore, we can remove
the anticipated call to align_clocks in cpu_loop_exec_tb, as
well as the SyncClocks *sc argument.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <002801d2810f$18809c20$4981d460$@ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <dovgaluk@ispras.ru>
This commit is contained in:
Pavel Dovgalyuk 2017-02-07 09:54:57 +03:00 committed by Paolo Bonzini
parent 1aab16c28a
commit cfb2d02be9
1 changed files with 7 additions and 8 deletions
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15
cpu-exec.c
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@ -517,7 +517,10 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
*last_tb = NULL;
}
}
if (unlikely(atomic_read(&cpu->exit_request) || replay_has_interrupt())) {
/* Finally, check if we need to exit to the main loop. */
if (unlikely(atomic_read(&cpu->exit_request)
|| (use_icount && cpu->icount_decr.u16.low + cpu->icount_extra == 0))) {
atomic_set(&cpu->exit_request, 0);
cpu->exception_index = EXCP_INTERRUPT;
return true;
@ -527,8 +530,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
}
static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
TranslationBlock **last_tb, int *tb_exit,
SyncClocks *sc)
TranslationBlock **last_tb, int *tb_exit)
{
uintptr_t ret;
int32_t insns_left;
@ -579,10 +581,7 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
*/
if (insns_left > 0) {
cpu_exec_nocache(cpu, insns_left, tb, false);
align_clocks(sc, cpu);
}
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit(cpu);
}
#endif
}
@ -593,7 +592,7 @@ int cpu_exec(CPUState *cpu)
{
CPUClass *cc = CPU_GET_CLASS(cpu);
int ret;
SyncClocks sc;
SyncClocks sc = { 0 };
/* replay_interrupt may need current_cpu */
current_cpu = cpu;
@ -643,7 +642,7 @@ int cpu_exec(CPUState *cpu)
while (!cpu_handle_interrupt(cpu, &last_tb)) {
TranslationBlock *tb = tb_find(cpu, last_tb, tb_exit);
cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit, &sc);
cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit);
/* Try to align the host and virtual clocks
if the guest is in advance */
align_clocks(&sc, cpu);