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

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Date: Thu, 9 May 2024 10:11:36 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
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>, Ian
 Rogers <irogers@...gle.com>, 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,  8 May 2024 15:14:57 +0100
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'
> 

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thanks!

> Fixes: 55442cc2f22d ("perf dwarf-aux: Check allowed DWARF Ops")
> Signed-off-by: James Clark <james.clark@....com>
> ---
>  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
> 
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>