From: Mark Rutland <mark.rutland@arm.com>
To: Chengming Zhou <zhouchengming@bytedance.com>
Cc: rostedt@goodmis.org, mingo@redhat.com, catalin.marinas@arm.com,
will@kernel.org, tglx@linutronix.de, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
broonie@kernel.org, ardb@kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, duanxiongchun@bytedance.com,
songmuchun@bytedance.com
Subject: Re: [PATCH v4 1/2] ftrace: cleanup ftrace_graph_caller enable and disable
Date: Tue, 19 Apr 2022 12:41:05 +0100 [thread overview]
Message-ID: <Yl6f0XKoRxNhgGPv@FVFF77S0Q05N> (raw)
In-Reply-To: <20220409153554.14470-1-zhouchengming@bytedance.com>
On Sat, Apr 09, 2022 at 11:35:53PM +0800, Chengming Zhou wrote:
> The ftrace_[enable,disable]_ftrace_graph_caller() are used to do
> special hooks for graph tracer, which are not needed on some ARCHs
> that use graph_ops:func function to install return_hooker.
>
> So introduce the weak version in ftrace core code to cleanup
> in x86.
>
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
> ---
> v4:
> - put weak ftrace_enable,disable_ftrace_graph_caller() in
> fgraph.c instead of ftrace.c as suggested by Steve.
>
> v3:
> - consolidate two #if into a single #if, suggested by Steve. Thanks.
> ---
> arch/x86/kernel/ftrace.c | 17 ++---------------
> kernel/trace/fgraph.c | 18 ++++++++++++++++++
> 2 files changed, 20 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 1e31c7d21597..b09d73c2ba89 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -579,9 +579,7 @@ void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
>
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
>
> -#ifdef CONFIG_DYNAMIC_FTRACE
> -
> -#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
> +#if defined(CONFIG_DYNAMIC_FTRACE) && !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS)
> extern void ftrace_graph_call(void);
> static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
> {
> @@ -610,18 +608,7 @@ int ftrace_disable_ftrace_graph_caller(void)
>
> return ftrace_mod_jmp(ip, &ftrace_stub);
> }
> -#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
> -int ftrace_enable_ftrace_graph_caller(void)
> -{
> - return 0;
> -}
> -
> -int ftrace_disable_ftrace_graph_caller(void)
> -{
> - return 0;
> -}
> -#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
> -#endif /* !CONFIG_DYNAMIC_FTRACE */
> +#endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
>
> /*
> * Hook the return address and push it in the stack of return addrs
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 8f4fb328133a..289311680c29 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -30,6 +30,24 @@ int ftrace_graph_active;
> /* Both enabled by default (can be cleared by function_graph tracer flags */
> static bool fgraph_sleep_time = true;
>
> +/*
> + * archs can override this function if they must do something
> + * to enable hook for graph tracer.
> + */
> +int __weak ftrace_enable_ftrace_graph_caller(void)
> +{
> + return 0;
> +}
> +
> +/*
> + * archs can override this function if they must do something
> + * to disable hook for graph tracer.
> + */
> +int __weak ftrace_disable_ftrace_graph_caller(void)
> +{
> + return 0;
> +}
IIUC an arch should either:
* Have ftrace_graph_call()
* Have both ftrace_enable_ftrace_graph_caller() and
ftrace_disable_ftrace_graph_caller()
... and I can't think of a reason an arch would need both ftrace_graph_call()
*and* the enable/disable functions.
Given that, could we drop the `__weak` and place these within ifdeffery, i.e.
make the above:
| #ifndef ftrace_graph_call
| int ftrace_enable_ftrace_graph_caller(void) { return 0; }
| int ftrace_disable_ftrace_graph_caller(void) { return 0; }
| #endif /* ftrace_graph_call *.
That way we'd catch cases when:
* An architecture meant to provide one of these functions, but forgot (e.g. the
name got typo'd)
* An architecture provides an unnecessary implementation of either of these
functions.
Regardless, this looks ok to me. Steve, are you happy with this? I suspect we'd
need to take this via the arm64 tree with the next patch, so we'd need your Ack.
Thanks,
Mark.
> +
> /**
> * ftrace_graph_stop - set to permanently disable function graph tracing
> *
> --
> 2.35.1
>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-04-19 12:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-09 15:35 [PATCH v4 1/2] ftrace: cleanup ftrace_graph_caller enable and disable Chengming Zhou
2022-04-09 15:35 ` [PATCH v4 2/2] arm64/ftrace: Make function graph use ftrace directly Chengming Zhou
2022-04-19 12:55 ` Mark Rutland
2022-04-19 13:27 ` [External] " Chengming Zhou
2022-04-18 13:24 ` [PATCH v4 1/2] ftrace: cleanup ftrace_graph_caller enable and disable Chengming Zhou
2022-04-19 11:41 ` Mark Rutland [this message]
2022-04-20 15:30 ` [External] " Chengming Zhou
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Yl6f0XKoRxNhgGPv@FVFF77S0Q05N \
--to=mark.rutland@arm.com \
--cc=ardb@kernel.org \
--cc=bp@alien8.de \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=dave.hansen@linux.intel.com \
--cc=duanxiongchun@bytedance.com \
--cc=hpa@zytor.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=rostedt@goodmis.org \
--cc=songmuchun@bytedance.com \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
--cc=x86@kernel.org \
--cc=zhouchengming@bytedance.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).