From: Masami Hiramatsu <mhiramat@kernel.org>
To: Will Deacon <will.deacon@arm.com>
Cc: He Kuang <hekuang@huawei.com>,
peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
alexander.shishkin@linux.intel.com, jolsa@redhat.com,
mhiramat@kernel.org, wangnan0@huawei.com,
bintian.wang@huawei.com, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2 v2] perf tools: Enable bpf prologue for arm64
Date: Thu, 26 Jan 2017 10:49:16 +0900 [thread overview]
Message-ID: <20170126104916.971478fa29083cf4ae14fac3@kernel.org> (raw)
In-Reply-To: <20170125133201.GC27026@arm.com>
On Wed, 25 Jan 2017 13:32:01 +0000
Will Deacon <will.deacon@arm.com> wrote:
> On Wed, Jan 25, 2017 at 07:23:11AM +0000, He Kuang wrote:
> > Since HAVE_KPROBES can be enabled in arm64, this patch introduces
> > regs_query_register_offset() to convert register name to offset for
> > arm64, so the BPF prologue feature is ready to use.
> >
> > This patch also changes the 'dwarfnum' to 'offset' in register table,
> > so the related functions are consistent with x86.
>
> Wouldn't it be an awful lot simpler just to leave the code as-is, and
> implement regs_query_register_offset in the same way that we implement
> get_arch_regstr but return the dwarfnum?
No, since the offset is not same as dwarfnum.
With this style, the index of array becomes the dwarfnum (the index of
each register defined by DWARF) and the "offset" member means the
byte-offset of the register in (user_)pt_regs. Those should be different.
> I don't really see the point of all the refactoring.
Also, from the maintenance point of view, this rewrite work makes
the code simply similar to x86 implementation, that will be easier to
maintain :)
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
WARNING: multiple messages have this Message-ID (diff)
From: mhiramat@kernel.org (Masami Hiramatsu)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2 v2] perf tools: Enable bpf prologue for arm64
Date: Thu, 26 Jan 2017 10:49:16 +0900 [thread overview]
Message-ID: <20170126104916.971478fa29083cf4ae14fac3@kernel.org> (raw)
In-Reply-To: <20170125133201.GC27026@arm.com>
On Wed, 25 Jan 2017 13:32:01 +0000
Will Deacon <will.deacon@arm.com> wrote:
> On Wed, Jan 25, 2017 at 07:23:11AM +0000, He Kuang wrote:
> > Since HAVE_KPROBES can be enabled in arm64, this patch introduces
> > regs_query_register_offset() to convert register name to offset for
> > arm64, so the BPF prologue feature is ready to use.
> >
> > This patch also changes the 'dwarfnum' to 'offset' in register table,
> > so the related functions are consistent with x86.
>
> Wouldn't it be an awful lot simpler just to leave the code as-is, and
> implement regs_query_register_offset in the same way that we implement
> get_arch_regstr but return the dwarfnum?
No, since the offset is not same as dwarfnum.
With this style, the index of array becomes the dwarfnum (the index of
each register defined by DWARF) and the "offset" member means the
byte-offset of the register in (user_)pt_regs. Those should be different.
> I don't really see the point of all the refactoring.
Also, from the maintenance point of view, this rewrite work makes
the code simply similar to x86 implementation, that will be easier to
maintain :)
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2017-01-26 1:49 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 10:30 [PATCH 0/2] Support bpf prologue for arm64 He Kuang
2017-01-24 10:30 ` [PATCH 1/2] perf probe: Fix wrong register name " He Kuang
2017-01-24 19:11 ` Arnaldo Carvalho de Melo
2017-01-25 9:22 ` Will Deacon
2017-01-26 1:24 ` Masami Hiramatsu
2017-01-26 15:28 ` [tip:perf/core] " tip-bot for He Kuang
2017-05-03 8:54 ` [PATCH 1/2] " Pratyush Anand
2017-01-24 10:30 ` [PATCH 2/2] perf tools: Introduce regs_query_register_offset() " He Kuang
2017-01-24 18:25 ` Will Deacon
2017-01-24 19:09 ` Arnaldo Carvalho de Melo
2017-01-25 7:23 ` [PATCH 2/2 v2] perf tools: Enable bpf prologue " He Kuang
2017-01-25 7:23 ` He Kuang
2017-01-25 13:32 ` Will Deacon
2017-01-25 13:32 ` Will Deacon
2017-01-26 1:49 ` Masami Hiramatsu [this message]
2017-01-26 1:49 ` Masami Hiramatsu
2017-01-26 16:52 ` Will Deacon
2017-01-26 16:52 ` Will Deacon
2017-01-26 19:31 ` Arnaldo Carvalho de Melo
2017-01-26 19:31 ` Arnaldo Carvalho de Melo
2017-02-03 11:08 ` Hekuang
2017-02-03 11:08 ` Hekuang
2017-01-26 1:51 ` Masami Hiramatsu
2017-01-26 1:51 ` Masami Hiramatsu
2017-01-25 7:26 ` [PATCH 2/2] perf tools: Introduce regs_query_register_offset() " Hekuang
2017-01-24 15:56 ` [PATCH 0/2] Support bpf prologue " Arnaldo Carvalho de Melo
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