From: Frederic Weisbecker <frederic@kernel.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: LKML <linux-kernel@vger.kernel.org>, Jiri Olsa <jolsa@redhat.com>,
Namhyung Kim <namhyung@kernel.org>,
Joel Fernandes <joel.opensrc@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Chris Zankel <chris@zankel.net>,
Paul Mackerras <paulus@samba.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will.deacon@arm.com>, Rich Felker <dalias@libc.org>,
Ingo Molnar <mingo@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Max Filippov <jcmvbkbc@gmail.com>
Subject: Re: [PATCH 04/12] powerpc: Implement hw_breakpoint_arch_parse()
Date: Fri, 1 Jun 2018 16:46:08 +0200 [thread overview]
Message-ID: <20180601144607.GA31501@lerouge> (raw)
In-Reply-To: <87in783tl0.fsf@concordia.ellerman.id.au>
On Mon, May 28, 2018 at 09:31:07PM +1000, Michael Ellerman wrote:
> Frederic Weisbecker <frederic@kernel.org> writes:
>
> > On Thu, May 24, 2018 at 12:01:52PM +1000, Michael Ellerman wrote:
> >> Frederic Weisbecker <frederic@kernel.org> writes:
> >>
> >> > diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
> >> > index 348cac9..fba6527 100644
> >> > --- a/arch/powerpc/kernel/hw_breakpoint.c
> >> > +++ b/arch/powerpc/kernel/hw_breakpoint.c
> >> > @@ -139,30 +139,31 @@ int arch_bp_generic_fields(int type, int *gen_bp_type)
> >> > /*
> >> > * Validate the arch-specific HW Breakpoint register settings
> >> > */
> >> > -int arch_validate_hwbkpt_settings(struct perf_event *bp)
> >> > +int hw_breakpoint_arch_parse(struct perf_event *bp,
> >> > + struct perf_event_attr *attr,
> >> > + struct arch_hw_breakpoint *hw)
> >>
> >> I think the semantics here are that we are reading from bp/attr and
> >> writing to hw?
> >>
> >> If so would some sprinkling of const on the first two parameters help
> >> make that clearer?
> >
> > I seem to remember there was an issue with that due to the various functions
> > we call that need to be converted to take const as well. I thought I would
> > do it in a seperate series but actually it should be no big deal to do it
> > on this one.
>
> Yeah, that does sometimes snowball out of control.
>
> > Let me try that and respin.
>
> Cool. It would be nice to have, but obviously not crucial.
So I managed to constify the perf_event_attr parameter but not the struct perf_event *bp
because the task target is fetched from it on is_compat_bp() on ARM64. I could constify it
all the way up to test_ti_thread_flag() but the thread info can only be retrieved through
a call to task_thread_info() and that's where the qualifier control ends. The const can not
be passed there and we can't afford to constify the function either, I fear, as it is used
everywhere for any purpose, including thread_info modifications.
next prev parent reply other threads:[~2018-06-01 14:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-19 2:45 [PATCH 00/12] breakpoint: Rework arch validation v2 Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 01/12] perf/breakpoint: Split attribute parse and commit Frederic Weisbecker
2018-05-24 1:56 ` Michael Ellerman
2018-05-25 13:58 ` Frederic Weisbecker
2018-05-28 11:29 ` Michael Ellerman
2018-05-19 2:45 ` [PATCH 02/12] perf/breakpoint: Pass arch breakpoint struct to arch_check_bp_in_kernelspace() Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 03/12] x86: Implement hw_breakpoint_arch_parse() Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 04/12] powerpc: " Frederic Weisbecker
2018-05-24 2:01 ` Michael Ellerman
2018-05-25 14:05 ` Frederic Weisbecker
2018-05-28 11:31 ` Michael Ellerman
2018-06-01 14:46 ` Frederic Weisbecker [this message]
2018-06-05 11:06 ` Michael Ellerman
2018-05-19 2:45 ` [PATCH 05/12] arm: " Frederic Weisbecker
2018-05-25 12:18 ` Mark Rutland
2018-05-19 2:45 ` [PATCH 06/12] arm64: " Frederic Weisbecker
2018-05-23 15:23 ` Will Deacon
2018-05-25 12:18 ` Mark Rutland
2018-05-19 2:45 ` [PATCH 07/12] sh: Remove "struct arch_hw_breakpoint::name" unused field Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 08/12] sh: Implement hw_breakpoint_arch_parse() Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 09/12] xtensa: " Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 10/12] perf/breakpoint: Remove default hw_breakpoint_arch_parse() Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 11/12] perf/breakpoint: Pass new breakpoint type to modify_breakpoint_slot() Frederic Weisbecker
2018-05-19 2:45 ` [PATCH 12/12] perf/breakpoint: Clean up and consolidate modify_user_hw_breakpoint_check() Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2018-06-01 14:31 [GIT PULL] breakpoint: Rework arch validation v3 Frederic Weisbecker
2018-06-01 14:31 ` [PATCH 04/12] powerpc: Implement hw_breakpoint_arch_parse() Frederic Weisbecker
2018-06-26 2:58 [GIT PULL] breakpoint: Rework arch validation v4 Frederic Weisbecker
2018-06-26 2:58 ` [PATCH 04/12] powerpc: Implement hw_breakpoint_arch_parse() Frederic Weisbecker
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