linux-kernel - Re: [PATCH 2/2] ftrace/x86/extable: Add is_ftrace

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Message-ID: <20141118231516.2c3a7bdb@gandalf.local.home>
Date:	Tue, 18 Nov 2014 23:15:16 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, williams@...hat.com,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH 2/2] ftrace/x86/extable: Add is_ftrace_trampoline()
 function

On Tue, 18 Nov 2014 22:33:33 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:


> +/*
> + * This is used by __kernel_text_address() to return true if the
> + * the address is on a dynamically allocated trampoline that would
> + * not return true for either core_kernel_text() or
> + * is_module_text_address().
> + */
> +bool is_ftrace_trampoline(unsigned long addr)
> +{
> +	struct ftrace_ops *op;
> +
> +	do_for_each_ftrace_op(op, ftrace_ops_list) {
> +		/*
> +		 * This is to check for dynamically allocated trampolines.
> +		 * Trampolines that are in kernel text will have
> +		 * core_kernel_text() return true.
> +		 */
> +		if (op->trampoline && op->trampoline_size)
> +			if (addr >= op->trampoline &&
> +			    addr < op->trampoline + op->trampoline_size)
> +				return true;
> +	} while_for_each_ftrace_op(op);
> +
> +	return false;
> +}
> +

Hmm, preemption should be disabled here. We can't guarantee that the
caller will have that. Will update.

-- Steve
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