Re: [Qemu-devel] [PATCH 01/23] target-arm: Log AArch64 exception returns

[Andrew Jones]

On Tue, Dec 13, 2016 at 10:36:02AM +0000, Peter Maydell wrote:
> We already log exception entry; add logging of the AArch64 exception
> return path as well.
> 
> Signed-off-by: Peter Maydell <address@hidden>
> Reviewed-by: Edgar E. Iglesias <address@hidden>
> ---
>  target-arm/op_helper.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> index cd94216..ba796d8 100644
> --- a/target-arm/op_helper.c
> +++ b/target-arm/op_helper.c
> @@ -17,6 +17,7 @@
>   * License along with this library; if not, see 
> <http://www.gnu.org/licenses/>.
>   */
>  #include "qemu/osdep.h"
> +#include "qemu/log.h"
>  #include "cpu.h"
>  #include "exec/helper-proto.h"
>  #include "internals.h"
> @@ -972,6 +973,9 @@ void HELPER(exception_return)(CPUARMState *env)
>          } else {
>              env->regs[15] = env->elr_el[cur_el] & ~0x3;
>          }
> +        qemu_log_mask(CPU_LOG_INT, "Exception return from AArch64 EL%d to "
> +                      "AArch32 EL%d PC 0x%" PRIx32 "\n",
> +                      cur_el, new_el, env->regs[15]);
>      } else {
>          env->aarch64 = 1;
>          pstate_write(env, spsr);
> @@ -980,6 +984,9 @@ void HELPER(exception_return)(CPUARMState *env)
>          }
>          aarch64_restore_sp(env, new_el);
>          env->pc = env->elr_el[cur_el];
> +        qemu_log_mask(CPU_LOG_INT, "Exception return from AArch64 EL%d to "
> +                      "AArch64 EL%d PC 0x%" PRIx64 "\n",
> +                      cur_el, new_el, env->pc);
>      }
>  
>      arm_call_el_change_hook(arm_env_get_cpu(env));
> @@ -1002,6 +1009,8 @@ illegal_return:
>      if (!arm_singlestep_active(env)) {
>          env->pstate &= ~PSTATE_SS;
>      }
> +    qemu_log_mask(LOG_GUEST_ERROR, "Illegal exception return at EL%d: "
> +                  "resuming execution at 0x%" PRIx64 "\n", cur_el, env->pc);
>  }
>  
>  /* Return true if the linked breakpoint entry lbn passes its checks */
> -- 
> 2.7.4
> 
>

Should we output both the destination PC (ELR) and the source PC (where
the eret was)? Otherwise if there are many erets to the same entry point,
then the logs won't fully enlighten us.

Thanks,
drew