linux-kernel - Re: [PATCH] perf dwarf-aux: Fix build with HAVE_DWARF_CFI

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Date: Wed, 8 May 2024 14:04:58 -0700
From: Ian Rogers <irogers@...gle.com>
To: James Clark <james.clark@....com>
Cc: linux-perf-users@...r.kernel.org, leo.yan@...ux.dev, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, "Liang, Kan" <kan.liang@...ux.intel.com>, 
	Masami Hiramatsu <mhiramat@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf dwarf-aux: Fix build with HAVE_DWARF_CFI_SUPPORT

On Wed, May 8, 2024 at 7:15 AM James Clark <james.clark@....com> wrote:
>
> check_allowed_ops() is used from both HAVE_DWARF_GETLOCATIONS_SUPPORT
> and HAVE_DWARF_CFI_SUPPORT sections, so move it into the right place so
> that it's available when either are defined. This shows up when doing
> a static cross compile for arm64:
>
>   $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- LDFLAGS="-static" \
>     EXTRA_PERFLIBS="-lexpat"
>
>   util/dwarf-aux.c:1723:6: error: implicit declaration of function 'check_allowed_ops'
>
> Fixes: 55442cc2f22d ("perf dwarf-aux: Check allowed DWARF Ops")
> Signed-off-by: James Clark <james.clark@....com>

Reviewed-by: Ian Rogers <irogers@...gle.com>
(eye-balled to see the #if problem exists and this is the correct fix)

Thanks,
Ian

> ---
>  tools/perf/util/dwarf-aux.c | 56 ++++++++++++++++++-------------------
>  1 file changed, 28 insertions(+), 28 deletions(-)
>
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index c0a492e65388..c9584563cd56 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -1215,6 +1215,34 @@ static int offset_from_dwarf_op(Dwarf_Op *op)
>         }
>         return -1;
>  }
> +
> +static bool check_allowed_ops(Dwarf_Op *ops, size_t nops)
> +{
> +       /* The first op is checked separately */
> +       ops++;
> +       nops--;
> +
> +       /*
> +        * It needs to make sure if the location expression matches to the given
> +        * register and offset exactly.  Thus it rejects any complex expressions
> +        * and only allows a few of selected operators that doesn't change the
> +        * location.
> +        */
> +       while (nops) {
> +               switch (ops->atom) {
> +               case DW_OP_stack_value:
> +               case DW_OP_deref_size:
> +               case DW_OP_deref:
> +               case DW_OP_piece:
> +                       break;
> +               default:
> +                       return false;
> +               }
> +               ops++;
> +               nops--;
> +       }
> +       return true;
> +}
>  #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT || HAVE_DWARF_CFI_SUPPORT */
>
>  #ifdef HAVE_DWARF_GETLOCATIONS_SUPPORT
> @@ -1395,34 +1423,6 @@ static bool match_var_offset(Dwarf_Die *die_mem, struct find_var_data *data,
>         return true;
>  }
>
> -static bool check_allowed_ops(Dwarf_Op *ops, size_t nops)
> -{
> -       /* The first op is checked separately */
> -       ops++;
> -       nops--;
> -
> -       /*
> -        * It needs to make sure if the location expression matches to the given
> -        * register and offset exactly.  Thus it rejects any complex expressions
> -        * and only allows a few of selected operators that doesn't change the
> -        * location.
> -        */
> -       while (nops) {
> -               switch (ops->atom) {
> -               case DW_OP_stack_value:
> -               case DW_OP_deref_size:
> -               case DW_OP_deref:
> -               case DW_OP_piece:
> -                       break;
> -               default:
> -                       return false;
> -               }
> -               ops++;
> -               nops--;
> -       }
> -       return true;
> -}
> -
>  /* Only checks direct child DIEs in the given scope. */
>  static int __die_find_var_reg_cb(Dwarf_Die *die_mem, void *arg)
>  {
> --
> 2.34.1
>