Re: [PATCH 1/2] perf: Move arch specific code into separate archdirectory

[Masami Hiramatsu]

Hi Ian,

Ian Munsie wrote:
> From: Ian Munsie <imunsie@xxxxxxxxxx>
> 
> The perf userspace tool included some architecture specific code to map
> registers from the DWARF register number into the names used by the regs
> and stack access API.
> 
> This patch moves the architecture specific code out into a seperate
> arch/x86 directory along with the infrastructure required to use it.

Nice! :)
I have just some comments on it.

> 
> Signed-off-by: Ian Munsie <imunsie@xxxxxxxxxx>
> ---
>  tools/perf/Makefile                           |   18 ++++++-
>  tools/perf/arch/x86/Makefile                  |    1 +
>  tools/perf/arch/x86/include/arch_dwarf-regs.h |    6 ++
>  tools/perf/arch/x86/util/dwarf-regs.c         |   75 +++++++++++++++++++++++++
>  tools/perf/util/include/dwarf-regs.h          |    8 +++
>  tools/perf/util/probe-finder.c                |   55 ++----------------
>  6 files changed, 113 insertions(+), 50 deletions(-)
>  create mode 100644 tools/perf/arch/x86/Makefile
>  create mode 100644 tools/perf/arch/x86/include/arch_dwarf-regs.h
>  create mode 100644 tools/perf/arch/x86/util/dwarf-regs.c
>  create mode 100644 tools/perf/util/include/dwarf-regs.h
> 
> diff --git a/tools/perf/Makefile b/tools/perf/Makefile
> index f578b05..07a6ee2 100644
> --- a/tools/perf/Makefile
> +++ b/tools/perf/Makefile
> @@ -172,6 +172,20 @@ uname_R := $(shell sh -c 'uname -r 2>/dev/null || echo not')
>  uname_P := $(shell sh -c 'uname -p 2>/dev/null || echo not')
>  uname_V := $(shell sh -c 'uname -v 2>/dev/null || echo not')
>  
> +ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
> +				  -e s/arm.*/arm/ -e s/sa110/arm/ \
> +				  -e s/s390x/s390/ -e s/parisc64/parisc/ \
> +				  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
> +				  -e s/sh[234].*/sh/ )
> +
> +# Additional ARCH settings for x86
> +ifeq ($(ARCH),i386)
> +        ARCH := x86
> +endif
> +ifeq ($(ARCH),x86_64)
> +        ARCH := x86
> +endif
> +
>  # CFLAGS and LDFLAGS are for the users to override from the command line.
>  
>  #
> @@ -284,7 +298,7 @@ endif
>  # Those must not be GNU-specific; they are shared with perl/ which may
>  # be built by a different compiler. (Note that this is an artifact now
>  # but it still might be nice to keep that distinction.)
> -BASIC_CFLAGS = -Iutil/include
> +BASIC_CFLAGS = -Iutil/include -Iarch/$(ARCH)/include
>  BASIC_LDFLAGS =
>  
>  # Guard against environment variables
> @@ -366,6 +380,7 @@ LIB_H += util/include/asm/byteorder.h
>  LIB_H += util/include/asm/swab.h
>  LIB_H += util/include/asm/system.h
>  LIB_H += util/include/asm/uaccess.h
> +LIB_H += util/include/dwarf-regs.h
>  LIB_H += perf.h
>  LIB_H += util/cache.h
>  LIB_H += util/callchain.h
> @@ -484,6 +499,7 @@ PERFLIBS = $(LIB_FILE)
>  
>  -include config.mak.autogen
>  -include config.mak
> +-include arch/$(ARCH)/Makefile
>  
>  ifeq ($(uname_S),Darwin)
>  	ifndef NO_FINK

Could you add a check whether the get_arch_regstr() is defined
(or dwarf-regs.h is exist) in Makefile?
If it is not defined, we'd better drop dwarf support(so set NO_DWARF),
because it means we haven't ported perf probe on that architecture yet. :)
 
> diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile
> new file mode 100644
> index 0000000..1191403
> --- /dev/null
> +++ b/tools/perf/arch/x86/Makefile
> @@ -0,0 +1 @@
> +LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
> diff --git a/tools/perf/arch/x86/include/arch_dwarf-regs.h b/tools/perf/arch/x86/include/arch_dwarf-regs.h
> new file mode 100644
> index 0000000..9e8da6a
> --- /dev/null
> +++ b/tools/perf/arch/x86/include/arch_dwarf-regs.h
> @@ -0,0 +1,6 @@
> +#ifndef _PREF_ARCH_PPC_DWARF_REGS_H
> +#define _PREF_ARCH_PPC_DWARF_REGS_H

_PREF_ARCH_X86_DWARF_REGS_H ?

> +
> +#define get_arch_regstr(n) get_arch_regstr(n)

If we checked above dwarf support, we don't need this odd macro.

> +
> +#endif
> diff --git a/tools/perf/arch/x86/util/dwarf-regs.c b/tools/perf/arch/x86/util/dwarf-regs.c
> new file mode 100644
> index 0000000..a794d30
> --- /dev/null
> +++ b/tools/perf/arch/x86/util/dwarf-regs.c
> @@ -0,0 +1,75 @@
> +/*
> + * dwarf-regs.c : Mapping of DWARF debug register numbers into register names.
> + * Extracted from probe-finder.c
> + *
> + * Written by Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
> + *
> + */
> +
> +#include <libio.h>
> +#include <dwarf-regs.h>
> +
> +/*
> + * Generic dwarf analysis helpers
> + */
> +
> +#define X86_32_MAX_REGS 8
> +const char *x86_32_regs_table[X86_32_MAX_REGS] = {
> +	"%ax",
> +	"%cx",
> +	"%dx",
> +	"%bx",
> +	"$stack",	/* Stack address instead of %sp */
> +	"%bp",
> +	"%si",
> +	"%di",
> +};
> +
> +#define X86_64_MAX_REGS 16
> +const char *x86_64_regs_table[X86_64_MAX_REGS] = {
> +	"%ax",
> +	"%dx",
> +	"%cx",
> +	"%bx",
> +	"%si",
> +	"%di",
> +	"%bp",
> +	"%sp",
> +	"%r8",
> +	"%r9",
> +	"%r10",
> +	"%r11",
> +	"%r12",
> +	"%r13",
> +	"%r14",
> +	"%r15",
> +};
> +
> +/* TODO: switching by dwarf address size */
> +#ifdef __x86_64__
> +#define ARCH_MAX_REGS X86_64_MAX_REGS
> +#define arch_regs_table x86_64_regs_table
> +#else
> +#define ARCH_MAX_REGS X86_32_MAX_REGS
> +#define arch_regs_table x86_32_regs_table
> +#endif
> +
> +/* Return architecture dependent register string (for kprobe-tracer) */
> +const char *get_arch_regstr(unsigned int n)
> +{
> +	return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
> +}
> diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
> new file mode 100644
> index 0000000..2a1cf6f
> --- /dev/null
> +++ b/tools/perf/util/include/dwarf-regs.h
> @@ -0,0 +1,8 @@
> +#ifndef _PERF_DWARF_REGS_H_
> +#define _PERF_DWARF_REGS_H_
> +
> +#include <arch_dwarf-regs.h>
> +
> +const char *get_arch_regstr(unsigned int n);
> +
> +#endif
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index a851377..27020fe 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -31,6 +31,7 @@
>  #include <string.h>
>  #include <stdarg.h>
>  #include <ctype.h>
> +#include <dwarf-regs.h>
>  
>  #include "string.h"
>  #include "event.h"
> @@ -38,57 +39,13 @@
>  #include "util.h"
>  #include "probe-finder.h"
>  
> -
> -/*
> - * Generic dwarf analysis helpers
> - */
> -
> -#define X86_32_MAX_REGS 8
> -const char *x86_32_regs_table[X86_32_MAX_REGS] = {
> -	"%ax",
> -	"%cx",
> -	"%dx",
> -	"%bx",
> -	"$stack",	/* Stack address instead of %sp */
> -	"%bp",
> -	"%si",
> -	"%di",
> -};
> -
> -#define X86_64_MAX_REGS 16
> -const char *x86_64_regs_table[X86_64_MAX_REGS] = {
> -	"%ax",
> -	"%dx",
> -	"%cx",
> -	"%bx",
> -	"%si",
> -	"%di",
> -	"%bp",
> -	"%sp",
> -	"%r8",
> -	"%r9",
> -	"%r10",
> -	"%r11",
> -	"%r12",
> -	"%r13",
> -	"%r14",
> -	"%r15",
> -};
> -
> -/* TODO: switching by dwarf address size */
> -#ifdef __x86_64__
> -#define ARCH_MAX_REGS X86_64_MAX_REGS
> -#define arch_regs_table x86_64_regs_table
> -#else
> -#define ARCH_MAX_REGS X86_32_MAX_REGS
> -#define arch_regs_table x86_32_regs_table
> -#endif
> -
>  /* Return architecture dependent register string (for kprobe-tracer) */
> -static const char *get_arch_regstr(unsigned int n)
> +#ifndef get_arch_regstr
> +const char *get_arch_regstr(unsigned int n __attribute__((unused)))
>  {
> -	return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
> +	return NULL;
>  }
> +#endif

Again, if we add a check in Makefile, we can remove this completely.

>  
>  /*
>   * Compare the tail of two strings.
> @@ -397,7 +354,7 @@ static void convert_location(Dwarf_Op *op, struct probe_finder *pf)
>  
>  	regs = get_arch_regstr(regn);
>  	if (!regs)
> -		die("%u exceeds max register number.", regn);
> +		die("Mapping for DWARF register number %u missing on this architecture.", regn);
>  
>  	tvar->value = xstrdup(regs);
>  	if (ref) {

Thank you,

-- 
Masami Hiramatsu
e-mail: mhiramat@xxxxxxxxxx
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