linux-kernel - Re: [PATCH] perf symbols: Fix annotation of objects with debuginfo files

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Message-Id: <20160812164703.GB12782@naverao1-tp.localdomain>
Date:	Fri, 12 Aug 2016 22:17:03 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	Anton Blanchard <anton@....ibm.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>,
	Wang Nan <wangnan0@...wei.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf symbols: Fix annotation of objects with debuginfo
 files

On 2016/08/12 04:35PM, Anton Blanchard wrote:
> From: Anton Blanchard <anton@...ba.org>
> 
> Commit 73cdf0c6ea9c ("perf symbols: Record text offset in dso
> to calculate objdump address") started storing the offset of
> the text section for all DSOs: 
> 
>        if (elf_section_by_name(elf, &ehdr, &tshdr, ".text", NULL))
>                dso->text_offset = tshdr.sh_addr - tshdr.sh_offset;
> 
> Unfortunately this breaks debuginfo files, because we need to calculate
> the offset of the text section in the associated executable file. As a
> result perf annotate returns junk for all debuginfo files.

I am able to reproduce this.

> 
> Fix this by using runtime_ss->elf which should point at the executable
> when parsing a debuginfo file.
> 
> Cc: stable@...r.kernel.org # v4.6+
> Fixes: 73cdf0c6ea9c ("perf symbols: Record text offset in dso to calculate objdump address")
> Signed-off-by: Anton Blanchard <anton@...ba.org>
> ---
> 
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index a34321e..9e36073 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -837,7 +837,7 @@ int dso__load_sym(struct dso *dso, struct map *map,
>  	sec = syms_ss->symtab;
>  	shdr = syms_ss->symshdr;
> 
> -	if (elf_section_by_name(elf, &ehdr, &tshdr, ".text", NULL))
> +	if (elf_section_by_name(runtime_ss->elf, &ehdr, &tshdr, ".text", NULL))
                                                 ^^^^^
I suppose you missed updating ehdr to runtime_ss->ehdr?
With that change, perf annotate works for me.

- Naveen