Re: [PATCH 2/3 v2] perf trace: Introduce errno_to_name()

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Thu, Dec 07, 2017 at 04:00:10PM +0100, Hendrik Brueckner escreveu:
> Introduce an errno_to_name() function to return the name of a
> give errno number as string.

Humm, we cannot use asm-generic for all, as there are differences in the
errno numbers from arch to arch, for instance:

In arch/alpha/include/uapi/asm/errno.h we use errno-base.h but even in
that part one of its entries gets a different number on the Alpha arch,
EAGAIN:

-------------------
#include <asm-generic/errno-base.h>

#undef  EAGAIN                  /* 11 in errno-base.h */

#define EDEADLK         11      /* Resource deadlock would occur */

#define EAGAIN          35      /* Try again */
#define EWOULDBLOCK     EAGAIN  /* Operation would block */
-------------------

And then all these are different:

-------------------
#define EINPROGRESS     36      /* Operation now in progress */
#define EALREADY        37      /* Operation already in progress */
#define ENOTSOCK        38      /* Socket operation on non-socket */
#define EDESTADDRREQ    39      /* Destination address required */
#define EMSGSIZE        40      /* Message too long */
#define EPROTOTYPE      41      /* Protocol wrong type for socket */
#define ENOPROTOOPT     42      /* Protocol not available */
<SNIP>
-------------------

mips also has differences, shares errno-base.h completely but:

arch/mips/include/uapi/asm/errno.h
-------------------
/*
 * These error numbers are intended to be MIPS ABI compatible
 */

#include <asm-generic/errno-base.h>

#define ENOMSG		35	/* No message of desired type */
#define EIDRM		36	/* Identifier removed */
#define ECHRNG		37	/* Channel number out of range */
#define EL2NSYNC	38	/* Level 2 not synchronized */
#define EL3HLT		39	/* Level 3 halted */
#define EL3RST		40	/* Level 3 reset */
#define ELNRNG		41	/* Link number out of range */
<SNIP>
-------------------

PARISC looks like MIPS, at least in this little excerpt:

arch/parisc/include/uapi/asm/errno.h
-------------------

#include <asm-generic/errno-base.h>

#define	ENOMSG		35	/* No message of desired type */
#define	EIDRM		36	/* Identifier removed */
#define	ECHRNG		37	/* Channel number out of range */
#define	EL2NSYNC	38	/* Level 2 not synchronized */
#define	EL3HLT		39	/* Level 3 halted */
#define	EL3RST		40	/* Level 3 reset */
#define	ELNRNG		41	/* Link number out of range */
<SNIP>
-------------------

PowerPC is more modest, wants only to change one entry:

#include <asm-generic/errno.h>

#undef  EDEADLOCK
#define EDEADLOCK       58      /* File locking deadlock error */

:-)

So you can try to copy all arch/*/include/uapi/asm/errno.h files and
use the arch to key that, i.e. its almost what you did, but needs to
take the arch into consideration.

Later we'll generate a two dimensional table of sorts, having the first
dimension be the arch name, so that we can translate errnos in a
perf.data file collected on, say, mips (one of these routers) in a tool
running on x86_64 (or S/390 :)).

- Arnaldo

 
> With this change, the dependency to libaudit can be removed for
> architectures that support syscall tables.  Hence, remove the
> audit_errno_to_name() call in builtin-trace.c and just link
> util/syscalltbl.c against libaudit.  A follow-up commit could
> then clean-up this dependency with respect to the syscall table.
> 
> The errno name strings are generated by util/generate-errno-names.sh
> script and saved as util/errno-names.h.
> 
> Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
> ---
>  tools/perf/.gitignore                   |  1 +
>  tools/perf/Makefile.config              |  2 +-
>  tools/perf/Makefile.perf                | 12 ++++++++++--
>  tools/perf/builtin-trace.c              | 17 ++++++++++++++---
>  tools/perf/util/generate-errno-names.sh | 32 ++++++++++++++++++++++++++++++++
>  5 files changed, 58 insertions(+), 6 deletions(-)
>  create mode 100755 tools/perf/util/generate-errno-names.sh
> 
> diff --git a/tools/perf/.gitignore b/tools/perf/.gitignore
> index 643cc4ba..4e022f9 100644
> --- a/tools/perf/.gitignore
> +++ b/tools/perf/.gitignore
> @@ -14,6 +14,7 @@ perf*.1
>  perf*.xml
>  perf*.html
>  common-cmds.h
> +errno-names.h
>  perf.data
>  perf.data.old
>  output.svg
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index ab16aab..d8447b1 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -251,7 +251,7 @@ INC_FLAGS += -I$(srctree)/tools/arch/$(SRCARCH)/include/uapi
>  INC_FLAGS += -I$(srctree)/tools/arch/$(SRCARCH)/include/
>  INC_FLAGS += -I$(srctree)/tools/arch/$(SRCARCH)/
>  
> -# $(obj-perf)      for generated common-cmds.h
> +# $(obj-perf)      for generated common-cmds.h and errno-names.h
>  # $(obj-perf)/util for generated bison/flex headers
>  ifneq ($(OUTPUT),)
>  INC_FLAGS += -I$(obj-perf)/util
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index 68cf136..82aed33d 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -518,6 +518,12 @@ $(OUTPUT)common-cmds.h: util/generate-cmdlist.sh command-list.txt
>  $(OUTPUT)common-cmds.h: $(wildcard Documentation/perf-*.txt)
>  	$(QUIET_GEN). util/generate-cmdlist.sh > $@+ && mv $@+ $@
>  
> +$(OUTPUT)util/errno-names.h: util/generate-errno-names.sh
> +	$(QUIET_GEN). util/generate-errno-names.sh \
> +	$(srctree)/include/uapi/asm-generic/errno-base.h \
> +	$(srctree)/include/uapi/asm-generic/errno.h \
> +	> $@+ && mv $@+ $@
> +
>  $(SCRIPTS) : % : %.sh
>  	$(QUIET_GEN)$(INSTALL) '$@.sh' '$(OUTPUT)$@'
>  
> @@ -565,7 +571,8 @@ prepare: $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)common-cmds.h archheaders $(drm_ioc
>  	$(vhost_virtio_ioctl_array) \
>  	$(madvise_behavior_array) \
>  	$(perf_ioctl_array) \
> -	$(prctl_option_array)
> +	$(prctl_option_array) \
> +	$(OUTPUT)util/errno-names.h
>  
>  $(OUTPUT)%.o: %.c prepare FORCE
>  	$(Q)$(MAKE) -f $(srctree)/tools/build/Makefile.build dir=$(build-dir) $@
> @@ -847,7 +854,8 @@ clean:: $(LIBTRACEEVENT)-clean $(LIBAPI)-clean $(LIBBPF)-clean $(LIBSUBCMD)-clea
>  		$(OUTPUT)$(kcmp_type_array) \
>  		$(OUTPUT)$(vhost_virtio_ioctl_array) \
>  		$(OUTPUT)$(perf_ioctl_array) \
> -		$(OUTPUT)$(prctl_option_array)
> +		$(OUTPUT)$(prctl_option_array) \
> +		$(OUTPUT)util/errno-names.h
>  	$(QUIET_SUBDIR0)Documentation $(QUIET_SUBDIR1) clean
>  
>  #
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 84debdb..04af6a1 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -42,17 +42,16 @@
>  #include "string2.h"
>  #include "syscalltbl.h"
>  #include "rb_resort.h"
> +#include "util/errno-names.h"
>  
>  #include <errno.h>
>  #include <inttypes.h>
> -#include <libaudit.h> /* FIXME: Still needed for audit_errno_to_name */
>  #include <poll.h>
>  #include <signal.h>
>  #include <stdlib.h>
>  #include <string.h>
>  #include <linux/err.h>
>  #include <linux/filter.h>
> -#include <linux/audit.h>
>  #include <linux/kernel.h>
>  #include <linux/random.h>
>  #include <linux/stringify.h>
> @@ -1659,6 +1658,18 @@ static int trace__fprintf_callchain(struct trace *trace, struct perf_sample *sam
>  	return sample__fprintf_callchain(sample, 38, print_opts, &callchain_cursor, trace->output);
>  }
>  
> +static const char *errno_to_name(int err)
> +{
> +	switch (err) {
> +#define ERRNO_NAME_MAP(_err, _num) case _num: return #_err;
> +	ALL_ERRNO_NAME_MAPPINGS
> +#undef ERRNO_NAME_MAP
> +	default:
> +		return "(unknown)";
> +		break;
> +	};
> +}
> +
>  static int trace__sys_exit(struct trace *trace, struct perf_evsel *evsel,
>  			   union perf_event *event __maybe_unused,
>  			   struct perf_sample *sample)
> @@ -1729,7 +1740,7 @@ static int trace__sys_exit(struct trace *trace, struct perf_evsel *evsel,
>  errno_print: {
>  		char bf[STRERR_BUFSIZE];
>  		const char *emsg = str_error_r(-ret, bf, sizeof(bf)),
> -			   *e = audit_errno_to_name(-ret);
> +			   *e = errno_to_name(-ret);
>  
>  		fprintf(trace->output, ") = -1 %s %s", e, emsg);
>  	}
> diff --git a/tools/perf/util/generate-errno-names.sh b/tools/perf/util/generate-errno-names.sh
> new file mode 100755
> index 0000000..6c114a8
> --- /dev/null
> +++ b/tools/perf/util/generate-errno-names.sh
> @@ -0,0 +1,32 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Generate errno names header file
> +#
> +# Copyright IBM Corp. 2017
> +# Author(s):  Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
> +
> +infiles="$@"
> +tmpfile=$(mktemp -t generate-errno-names.XXXXXXXXX)
> +
> +trap 'rm -f $tmpfile' 0
> +
> +grep -hE '^#define[[:blank:]]+([^[:blank:]]+)[[:blank:]]+([[:digit:]]+).*' $infiles \
> +	|awk '{ print $2", "$3; }' \
> +	|sort -t, -k2 -nu \
> +	|sed -e 's/^/\tERRNO_NAME_MAP(/' -e 's/$/)/' \
> +	>  $tmpfile
> +
> +cat <<EoHeader
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _UTIL_ERRNO_NAMES_H
> +#define _UTIL_ERRNO_NAMES_H
> +
> +#define ALL_ERRNO_NAME_MAPPINGS \\
> +EoHeader
> +head -n -1 $tmpfile |sed -e 's/$/ \\/'
> +tail -1 $tmpfile
> +
> +cat <<EoFooter
> +#endif	/* _UTIL_ERRNO_NAMES_H */
> +EoFooter
> -- 
> 1.8.3.1
> 
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