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

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Message-ID: <CAP-5=fVpT2ntV8YND4iuTWet1or8m2hPD-+Ohx_j1sdqgkwj6g@mail.gmail.com>
Date: Tue, 3 Sep 2024 22:03:09 -0700
From: Ian Rogers <irogers@...gle.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
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 Tue, Sep 3, 2024 at 7:24 AM Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
>
> 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

Teach me to build only with clang. Fixed in v2.

Thanks,
Ian

> 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....
>