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From: Mark Rutland <mark.rutland@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, will@kernel.org,
	rostedt@goodmis.org, samitolvanen@google.com,
	keescook@chromium.org, mhiramat@kernel.org
Subject: Re: [PATCH] ftrace: Allow WITH_ARGS flavour of graph tracer with shadow call stack
Date: Fri, 9 Dec 2022 14:40:25 +0000	[thread overview]
Message-ID: <Y5NI2TKtGbDKyt53@FVFF77S0Q05N> (raw)
In-Reply-To: <20221209143402.3332369-1-ardb@kernel.org>

On Fri, Dec 09, 2022 at 03:34:02PM +0100, Ard Biesheuvel wrote:
> The recent switch on arm64 from DYNAMIC_FTRACE_WITH_REGS to
> DYNAMIC_FTRACE_WITH_ARGS failed to take into account that we currently
> require the former in order to allow the function graph tracer to be
> enabled in combination with shadow call stacks. This means that this is
> no longer permitted at all, in spite of the fact that either flavour of
> ftrace works perfectly fine in this combination.
> 
> Given that arm64 is the only arch that implements shadow call stacks in
> the first place, let's update the condition to just reflect the arm64
> change. When other architectures adopt shadow call stack support, this
> can be revisited if needed.
> 
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

My bad; sorry about this, and thanks for the fix!

Acked-by: Mark Rutland <mark.rutland@arm.com>

We should probably also add:

Fixes: 26299b3f6ba26bfc ("ftrace: arm64: move from REGS to ARGS")

Mark.

> ---
>  arch/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 072a1b39e3afd0d1..683f365b5e31c856 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -635,7 +635,7 @@ config ARCH_SUPPORTS_SHADOW_CALL_STACK
>  config SHADOW_CALL_STACK
>  	bool "Shadow Call Stack"
>  	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
> -	depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
> +	depends on DYNAMIC_FTRACE_WITH_ARGS || !FUNCTION_GRAPH_TRACER
>  	help
>  	  This option enables the compiler's Shadow Call Stack, which
>  	  uses a shadow stack to protect function return addresses from
> -- 
> 2.35.1
> 

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WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, will@kernel.org,
	rostedt@goodmis.org, samitolvanen@google.com,
	keescook@chromium.org, mhiramat@kernel.org
Subject: Re: [PATCH] ftrace: Allow WITH_ARGS flavour of graph tracer with shadow call stack
Date: Fri, 9 Dec 2022 14:40:25 +0000	[thread overview]
Message-ID: <Y5NI2TKtGbDKyt53@FVFF77S0Q05N> (raw)
In-Reply-To: <20221209143402.3332369-1-ardb@kernel.org>

On Fri, Dec 09, 2022 at 03:34:02PM +0100, Ard Biesheuvel wrote:
> The recent switch on arm64 from DYNAMIC_FTRACE_WITH_REGS to
> DYNAMIC_FTRACE_WITH_ARGS failed to take into account that we currently
> require the former in order to allow the function graph tracer to be
> enabled in combination with shadow call stacks. This means that this is
> no longer permitted at all, in spite of the fact that either flavour of
> ftrace works perfectly fine in this combination.
> 
> Given that arm64 is the only arch that implements shadow call stacks in
> the first place, let's update the condition to just reflect the arm64
> change. When other architectures adopt shadow call stack support, this
> can be revisited if needed.
> 
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

My bad; sorry about this, and thanks for the fix!

Acked-by: Mark Rutland <mark.rutland@arm.com>

We should probably also add:

Fixes: 26299b3f6ba26bfc ("ftrace: arm64: move from REGS to ARGS")

Mark.

> ---
>  arch/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 072a1b39e3afd0d1..683f365b5e31c856 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -635,7 +635,7 @@ config ARCH_SUPPORTS_SHADOW_CALL_STACK
>  config SHADOW_CALL_STACK
>  	bool "Shadow Call Stack"
>  	depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
> -	depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
> +	depends on DYNAMIC_FTRACE_WITH_ARGS || !FUNCTION_GRAPH_TRACER
>  	help
>  	  This option enables the compiler's Shadow Call Stack, which
>  	  uses a shadow stack to protect function return addresses from
> -- 
> 2.35.1
> 

  reply	other threads:[~2022-12-09 14:41 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-09 14:34 [PATCH] ftrace: Allow WITH_ARGS flavour of graph tracer with shadow call stack Ard Biesheuvel
2022-12-09 14:34 ` Ard Biesheuvel
2022-12-09 14:40 ` Mark Rutland [this message]
2022-12-09 14:40   ` Mark Rutland
2022-12-09 21:51   ` Steven Rostedt
2022-12-09 21:51     ` Steven Rostedt
2022-12-12 10:36     ` Mark Rutland
2022-12-12 10:36       ` Mark Rutland
2022-12-13 11:36       ` Will Deacon
2022-12-13 11:36         ` Will Deacon
2022-12-11  3:27 ` Masami Hiramatsu
2022-12-11  3:27   ` Masami Hiramatsu
2022-12-12 10:46   ` Mark Rutland
2022-12-12 10:46     ` Mark Rutland

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