linux-kernel - Re: [PATCH v1 5/6] perf parse-events: Vary default_breakpoint

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Message-ID: <ZtccNpePJAM24nA7@x1>
Date: Tue, 3 Sep 2024 11:24:54 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	Yang Jihong <yangjihong@...edance.com>,
	Colin Ian King <colin.i.king@...il.com>,
	Chaitanya S Prakash <chaitanyas.prakash@....com>,
	"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
	James Clark <james.clark@...aro.org>,
	John Garry <john.g.garry@...cle.com>,
	Junhao He <hejunhao3@...wei.com>,
	David Ahern <dsa@...ulusnetworks.com>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 5/6] perf parse-events: Vary default_breakpoint_len on
 i386 and arm64

On Sat, Aug 31, 2024 at 12:04:14AM -0700, Ian Rogers wrote:
> On arm64 the breakpoint length should be 4-bytes but 8-bytes is
> tolerated as perf passes that as sizeof(long). Just pass the correct
> value.
> 
> On i386 the sizeof(long) check in the kernel needs to match the
> kernel's long size. Check using an environment (uname checks) whether
> 4 or 8 bytes needs to be passed. Cache the value in a static.

⬢[acme@...lbox perf-tools-next]$ gcc --version
gcc (GCC) 14.2.1 20240801 (Red Hat 14.2.1-1)
Copyright (C) 2024 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

⬢[acme@...lbox perf-tools-next]$ gcc --version
gcc (GCC) 14.2.1 20240801 (Red Hat 14.2.1-1)
Copyright (C) 2024 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

⬢[acme@...lbox perf-tools-next]$ uname -a
Linux toolbox 6.10.4-200.fc40.x86_64 #1 SMP PREEMPT_DYNAMIC Sun Aug 11 15:32:50 UTC 2024 x86_64 GNU/Linux
⬢[acme@...lbox perf-tools-next]$ head /etc/os-release 
NAME="Fedora Linux"
VERSION="40 (Toolbx Container Image)"
ID=fedora
VERSION_ID=40
VERSION_CODENAME=""
PLATFORM_ID="platform:f40"
PRETTY_NAME="Fedora Linux 40 (Toolbx Container Image)"
ANSI_COLOR="0;38;2;60;110;180"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:40"
⬢[acme@...lbox perf-tools-next]$

 CC      /tmp/build/perf-tools-next/tests/bp_signal_overflow.o
tests/bp_signal.c: In function ‘__event’:
tests/bp_signal.c:115:28: error: operand of ‘?:’ changes signedness from ‘int’ to ‘long unsigned int’ due to unsignedness of other operand [-Werror=sign-compare]
  115 |         pe.bp_len = is_x ? default_breakpoint_len() : sizeof(long);
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~
  LD      /tmp/build/perf-tools-next/pmu-events/pmu-events-in.o
cc1: all warnings being treated as errors
make[4]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:105: /tmp/build/perf-tools-next/tests/bp_signal.o] Error 1
  CC      /tmp/build/perf-tools-next/builtin-mem.o
make[4]: *** Waiting for unfinished jobs....
  CC      /tmp/build/perf-tools-next/util/symbol.o
  CC      /tmp/build/perf-tools-next/builtin-version.o
  AR      /tmp/build/perf-tools-next/libpmu-events.a
  CC      /tmp/build/perf-tools-next/util/metricgroup.o
  CC      /tmp/build/perf-tools-next/builtin-c2c.o
  CC      /tmp/build/perf-tools-next/util/header.o
make[3]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:158: tests] Error 2
make[2]: *** [Makefile.perf:777: /tmp/build/perf-tools-next/perf-test-in.o] Error 2
make[2]: *** Waiting for unfinished jobs....