linux-kernel - Re: [PATCH] perf tools: Fix kernel maps for kcore and eBPF

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Message-ID: <20200602140703.GP31795@kernel.org>
Date:   Tue, 2 Jun 2020 11:07:03 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf tools: Fix kernel maps for kcore and eBPF

Em Tue, Jun 02, 2020 at 02:25:05PM +0300, Adrian Hunter escreveu:
> Adjust pgoff also when moving a map's start address.
> 
> Example with v5.4.34 based kernel:
> 
>   Before:
> 
>     $ sudo tools/perf/perf record -a --kcore -e intel_pt//k sleep 1
>     [ perf record: Woken up 1 times to write data ]
>     [ perf record: Captured and wrote 1.958 MB perf.data ]
>     $ sudo tools/perf/perf script --itrace=e >/dev/null
>     Warning:
>     961 instruction trace errors
> 
>   After:
> 
>     $ sudo tools/perf/perf script --itrace=e >/dev/null
>     $

Thanks, tested on a kaby lake system (i5-7500) and applied,

- Arnaldo
 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> Fixes: fb5a88d4131a ("perf tools: Preserve eBPF maps when loading kcore")
> Cc: stable@...r.kernel.org
> ---
>  tools/perf/util/symbol.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index 57cbe7a29868..5ddf84dcbae7 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -1224,6 +1224,7 @@ int maps__merge_in(struct maps *kmaps, struct map *new_map)
>  
>  				m->end = old_map->start;
>  				list_add_tail(&m->node, &merged);
> +				new_map->pgoff += old_map->end - new_map->start;
>  				new_map->start = old_map->end;
>  			}
>  		} else {
> @@ -1244,6 +1245,7 @@ int maps__merge_in(struct maps *kmaps, struct map *new_map)
>  				 *      |new......| ->         |new...|
>  				 * |old....|        -> |old....|
>  				 */
> +				new_map->pgoff += old_map->end - new_map->start;
>  				new_map->start = old_map->end;
>  			}
>  		}
> -- 
> 2.17.1
> 

-- 

- Arnaldo