From: Pranith Kumar <bobby.pr...@gmail.com>
The patch enables handling atomic code in the guest. This should be
preferably done in cpu_handle_exception(), but the current assumptions
regarding when we can execute atomic sections cause a deadlock.
The current mechanism discards the flags which were set in atomic
execution. We ensure they are properly saved by calling the
cc->cpu_exec_enter/leave() functions around the loop.
As we are running cpu_exec_step_atomic() from the outermost loop we
need to avoid an abort() when single stepping over atomic code since
debug exception longjmp will point to the the setlongjmp in
cpu_exec(). We do this by setting a new jmp_env so that it jumps back
here on an exception.
Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
[AJB: tweak title, merge with new patches]
Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
[PENDING, CHANGES] Reviewed-by: Richard Henderson <r...@twiddle.net>
CC: Richard Henderson <r...@twiddle.net>
CC: Paolo Bonzini <pbonz...@redhat.com>
---
cpu-exec.c | 14 +++++++++++---
cpus.c | 9 +++++++++
2 files changed, 20 insertions(+), 3 deletions(-)
diff --git a/cpu-exec.c b/cpu-exec.c
index b0ddada8c1..e61f5747c8 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -228,6 +228,7 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
static void cpu_exec_step(CPUState *cpu)
{
+ CPUClass *cc = CPU_GET_CLASS(cpu);
CPUArchState *env = (CPUArchState *)cpu->env_ptr;
TranslationBlock *tb;
target_ulong cs_base, pc;
@@ -239,9 +240,16 @@ static void cpu_exec_step(CPUState *cpu)
1 | CF_NOCACHE | CF_IGNORE_ICOUNT);
tb->orig_tb = NULL;
tb_unlock();
- /* execute the generated code */
- trace_exec_tb_nocache(tb, pc);
- cpu_tb_exec(cpu, tb);
+
+ cc->cpu_exec_enter(cpu);
+
+ if (sigsetjmp(cpu->jmp_env, 0) == 0) {
+ /* execute the generated code */
+ trace_exec_tb_nocache(tb, pc);
+ cpu_tb_exec(cpu, tb);
+ }
+
+ cc->cpu_exec_exit(cpu);
tb_lock();
tb_phys_invalidate(tb, -1);
tb_free(tb);
diff --git a/cpus.c b/cpus.c
index 25897edbd3..cb44544fcf 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1347,6 +1347,11 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg)
if (r == EXCP_DEBUG) {
cpu_handle_guest_debug(cpu);
break;
+ } else if (r == EXCP_ATOMIC) {
+ qemu_mutex_unlock_iothread();
+ cpu_exec_step_atomic(cpu);
+ qemu_mutex_lock_iothread();
+ break;
}
} else if (cpu->stop) {
if (cpu->unplug) {
@@ -1457,6 +1462,10 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
*/
g_assert(cpu->halted);
break;
+ case EXCP_ATOMIC:
+ qemu_mutex_unlock_iothread();
+ cpu_exec_step_atomic(cpu);
+ qemu_mutex_lock_iothread();
default:
/* Ignore everything else? */
break;
--
2.11.0
