linux-kernel - Re: [RFC PATCH v2 03/15] perf bpf: Save pt

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Date:	Sun, 24 May 2015 22:31:21 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	He Kuang <hekuang@...wei.com>, wangnan0@...wei.com,
	paulus@...ba.org, a.p.zijlstra@...llo.nl, mingo@...hat.com,
	acme@...nel.org, namhyung@...nel.org, jolsa@...nel.org,
	ast@...mgrid.com, dsahern@...il.com, brendan.d.gregg@...il.com,
	daniel@...earbox.net
CC:	lizefan@...wei.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 03/15] perf bpf: Save pt_regs info from debuginfo

On 2015/05/24 17:27, He Kuang wrote:
> Save reg number in function convert_variable_location() instead of the
> register string name, so we can fetch the target register from bpf
> context register later.

This is not needed because you can also get reg number from reg string
afterwards.

Thank you,

> 
> Signed-off-by: He Kuang <hekuang@...wei.com>
> ---
>  tools/perf/util/include/dwarf-regs.h | 13 +++++++++++++
>  tools/perf/util/probe-event.h        |  1 +
>  tools/perf/util/probe-finder.c       | 11 +++++++++++
>  3 files changed, 25 insertions(+)
> 
> diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
> index 8f14965..566ff6d 100644
> --- a/tools/perf/util/include/dwarf-regs.h
> +++ b/tools/perf/util/include/dwarf-regs.h
> @@ -2,7 +2,20 @@
>  #define _PERF_DWARF_REGS_H_
>  
>  #ifdef HAVE_DWARF_SUPPORT
> +struct arch_regs_info {
> +	const char      *name;  /* Architecture dependent register string */
> +	int             offset; /* Reg offset in struct pt_regs */
> +	int             size;   /* Reg size */
> +};
> +
> +#define ARCH_REGS_INFO(r, pt_reg_name)					\
> +	{.name	= r,							\
> +	.offset = offsetof(struct pt_regs, pt_reg_name),		\
> +	.size   = sizeof(((struct pt_regs *)0)->pt_reg_name)}		\
> +
>  const char *get_arch_regstr(unsigned int n);
> +int get_arch_reg_offset(unsigned int n);
> +int get_arch_reg_size(unsigned int n);
>  #endif
>  
>  #endif
> diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
> index d6b7834..6c19395 100644
> --- a/tools/perf/util/probe-event.h
> +++ b/tools/perf/util/probe-event.h
> @@ -29,6 +29,7 @@ struct probe_trace_arg {
>  	char				*value;	/* Base value */
>  	char				*type;	/* Type name */
>  	struct probe_trace_arg_ref	*ref;	/* Referencing offset */
> +	unsigned int                    regn;   /* Regn from dwarf */
>  };
>  
>  /* kprobe-tracer and uprobe-tracer tracing event (point + arg) */
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index ee27b74..681af00 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -159,6 +159,16 @@ static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
>  	return ref;
>  }
>  
> +int __attribute__ ((weak))
> +get_arch_reg_offset(unsigned int n __maybe_unused) {
> +	return -1;
> +}
> +
> +int __attribute__ ((weak))
> +get_arch_reg_size(unsigned int n __maybe_unused) {
> +	return -1;
> +}
> +
>  /*
>   * Convert a location into trace_arg.
>   * If tvar == NULL, this just checks variable can be converted.
> @@ -260,6 +270,7 @@ static_var:
>  		return -ERANGE;
>  	}
>  
> +	tvar->regn = regn;
>  	tvar->value = strdup(regs);
>  	if (tvar->value == NULL)
>  		return -ENOMEM;
> 


-- 
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu.pt@...achi.com
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