Re: [Qemu-devel] [PATCH v4 05/11] qemu-log: Improve the "exec" TB execution logging

[Aurelien Jarno]

On 2015-08-03 10:14, Alex Bennée wrote:
> From: Peter Maydell <address@hidden>
> 
> Improve the TB execution logging so that it is easier to identify
> what is happening from trace logs:
>  * move the "Trace" logging of executed TBs into cpu_tb_exec()
>    so that it is emitted if and only if we actually execute a TB,
>    and for consistency for the CPU state logging
>  * log when we link two TBs together via tb_add_jump()
>  * log when cpu_tb_exec() returns early from a chain of TBs
> 
> The new style logging looks like this:
> 
> Trace 0x7fb7cc822ca0 [ffffffc0000dce00]
> Linking TBs 0x7fb7cc822ca0 [ffffffc0000dce00] index 0 -> 0x7fb7cc823110 
> [ffffffc0000dce10]
> Trace 0x7fb7cc823110 [ffffffc0000dce10]
> Trace 0x7fb7cc823420 [ffffffc000302688]
> Trace 0x7fb7cc8234a0 [ffffffc000302698]
> Trace 0x7fb7cc823520 [ffffffc0003026a4]
> Trace 0x7fb7cc823560 [ffffffc0000dce44]
> Linking TBs 0x7fb7cc823560 [ffffffc0000dce44] index 1 -> 0x7fb7cc8235d0 
> [ffffffc0000dce70]
> Trace 0x7fb7cc8235d0 [ffffffc0000dce70]
> Abandoned execution of TB chain before 0x7fb7cc8235d0 [ffffffc0000dce70]
> Trace 0x7fb7cc8235d0 [ffffffc0000dce70]
> Trace 0x7fb7cc822fd0 [ffffffc0000dd52c]
> 
> Signed-off-by: Peter Maydell <address@hidden>
> Signed-off-by: Alex Bennée <address@hidden>
> [AJB: reword patch title]
> ---
>  cpu-exec.c              | 20 +++++++++++---------
>  include/exec/exec-all.h |  3 +++
>  2 files changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/cpu-exec.c b/cpu-exec.c
> index 75694f3..a039f1a 100644
> --- a/cpu-exec.c
> +++ b/cpu-exec.c
> @@ -175,10 +175,14 @@ void cpu_reload_memory_map(CPUState *cpu)
>  #endif
>  
>  /* Execute a TB, and fix up the CPU state afterwards if necessary */
> -static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr)
> +static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock 
> *itb)
>  {
>      CPUArchState *env = cpu->env_ptr;
>      uintptr_t next_tb;
> +    uint8_t *tb_ptr = itb->tc_ptr;
> +
> +    qemu_log_mask(CPU_LOG_EXEC, "Trace %p [" TARGET_FMT_lx "] %s\n",
> +                  itb->tc_ptr, itb->pc, lookup_symbol(itb->pc));
>  
>  #if defined(DEBUG_DISAS)
>      if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) {
> @@ -209,6 +213,10 @@ static inline tcg_target_ulong cpu_tb_exec(CPUState 
> *cpu, uint8_t *tb_ptr)
>           */
>          CPUClass *cc = CPU_GET_CLASS(cpu);
>          TranslationBlock *tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
> +        qemu_log_mask(CPU_LOG_EXEC,
> +                      "Abandoned execution of TB chain before %p ["
> +                      TARGET_FMT_lx "] %s\n",
> +                      itb->tc_ptr, itb->pc, lookup_symbol(itb->pc));
>          if (cc->synchronize_from_tb) {
>              cc->synchronize_from_tb(cpu, tb);
>          } else {
> @@ -247,7 +255,7 @@ static void cpu_exec_nocache(CPUState *cpu, int 
> max_cycles,
>      cpu->current_tb = tb;
>      /* execute the generated code */
>      trace_exec_tb_nocache(tb, tb->pc);
> -    cpu_tb_exec(cpu, tb->tc_ptr);
> +    cpu_tb_exec(cpu, tb);
>      cpu->current_tb = NULL;
>      tb_phys_invalidate(tb, -1);
>      tb_free(tb);
> @@ -356,7 +364,6 @@ int cpu_exec(CPUState *cpu)
>  #endif
>      int ret, interrupt_request;
>      TranslationBlock *tb;
> -    uint8_t *tc_ptr;
>      uintptr_t next_tb;
>      SyncClocks sc;
>  
> @@ -491,10 +498,6 @@ int cpu_exec(CPUState *cpu)
>                      next_tb = 0;
>                      tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
>                  }
> -                if (qemu_loglevel_mask(CPU_LOG_EXEC)) {
> -                    qemu_log("Trace %p [" TARGET_FMT_lx "] %s\n",
> -                             tb->tc_ptr, tb->pc, lookup_symbol(tb->pc));
> -                }
>                  /* see if we can patch the calling TB. When the TB
>                     spans two pages, we cannot safely do a direct
>                     jump. */
> @@ -513,9 +516,8 @@ int cpu_exec(CPUState *cpu)
>                  barrier();
>                  if (likely(!cpu->exit_request)) {
>                      trace_exec_tb(tb, tb->pc);
> -                    tc_ptr = tb->tc_ptr;
>                      /* execute the generated code */
> -                    next_tb = cpu_tb_exec(cpu, tc_ptr);
> +                    next_tb = cpu_tb_exec(cpu, tb);
>                      switch (next_tb & TB_EXIT_MASK) {
>                      case TB_EXIT_REQUESTED:
>                          /* Something asked us to stop executing
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 7ac8e7e..361d3d2 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -282,6 +282,9 @@ static inline void tb_add_jump(TranslationBlock *tb, int 
> n,
>  {
>      /* NOTE: this test is only needed for thread safety */
>      if (!tb->jmp_next[n]) {
> +        qemu_log_mask(CPU_LOG_EXEC, "Linking TBs %p [" TARGET_FMT_lx
> +                      "] index %d -> %p [" TARGET_FMT_lx "]\n",
> +                      tb->tc_ptr, tb->pc, n, tb_next->tc_ptr, tb_next->pc);
>          /* patch the native jump address */
>          tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc_ptr);
>  

Reviewed-by: Aurelien Jarno <address@hidden>

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
address@hidden                 http://www.aurel32.net