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Message-ID: <20240216092439.197072a5@gandalf.local.home>
Date: Fri, 16 Feb 2024 09:24:39 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@...il.com>, Florent Revest
<revest@...omium.org>, linux-trace-kernel@...r.kernel.org, LKML
<linux-kernel@...r.kernel.org>, Martin KaFai Lau <martin.lau@...ux.dev>,
bpf <bpf@...r.kernel.org>, Sven Schnelle <svens@...ux.ibm.com>, Alexei
Starovoitov <ast@...nel.org>, Jiri Olsa <jolsa@...nel.org>, Arnaldo
Carvalho de Melo <acme@...nel.org>, Daniel Borkmann <daniel@...earbox.net>,
Alan Maguire <alan.maguire@...cle.com>, Mark Rutland
<mark.rutland@....com>, Peter Zijlstra <peterz@...radead.org>, Thomas
Gleixner <tglx@...utronix.de>, Guo Ren <guoren@...nel.org>
Subject: Re: [PATCH v7 28/36] tracing: Add ftrace_partial_regs() for
converting ftrace_regs to pt_regs
On Fri, 16 Feb 2024 22:09:02 +0900
Masami Hiramatsu (Google) <mhiramat@...nel.org> wrote:
> On Thu, 15 Feb 2024 11:11:34 -0500
> Steven Rostedt <rostedt@...dmis.org> wrote:
>
> > On Wed, 7 Feb 2024 00:12:40 +0900
> > "Masami Hiramatsu (Google)" <mhiramat@...nel.org> wrote:
> >
> > > From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> > >
> > > Add ftrace_partial_regs() which converts the ftrace_regs to pt_regs.
> > > If the architecture defines its own ftrace_regs, this copies partial
> > > registers to pt_regs and returns it. If not, ftrace_regs is the same as
> > > pt_regs and ftrace_partial_regs() will return ftrace_regs::regs.
> >
> > This says what this patch is doing and not why it is doing it.
>
> Hmm, OK. The reason is the eBPF needs this to keep the same pt_regs
> interface to access registers.
> Thus when replacing the pt_regs with ftrace_regs in fprobes (which is
> used by kprobe_multi eBPF event), this will be required.
> I'll add this to next version.
Thanks, that should go into the change log.
-- Steve
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