From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rabin Vincent Subject: Re: [PATCH 2/2] ftrace - add ftrace function_graph support on ARM Date: Mon, 11 Oct 2010 03:36:03 +0530 Message-ID: <20101010220603.GA2723@debian> References: <4B91A39F.8050502@am.sony.com> <20100306201849.GD13262@n2100.arm.linux.org.uk> <20101009193757.GB28183@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:33137 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751886Ab0JJWGN (ORCPT ); Sun, 10 Oct 2010 18:06:13 -0400 Received: by pwj4 with SMTP id 4so729705pwj.19 for ; Sun, 10 Oct 2010 15:06:11 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20101009193757.GB28183@n2100.arm.linux.org.uk> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Russell King - ARM Linux Cc: Tim Bird , linux-omap , "linux-arm-kernel@lists.infradead.org" On Sat, Oct 09, 2010 at 08:37:57PM +0100, Russell King - ARM Linux wrote: > On Sat, Oct 09, 2010 at 11:20:50PM +0530, Rabin Vincent wrote: > > It's used just for the C entry functions for interrupts: asm_do_IRQ() > > and the IPI and local timer functions. > > > > AFAICS __exception seems to be used only for is_exception_text(). If > > that's the case, would it be OK to just place those functions in > > __irq_entry if ftrace is built and have is_exception_text() check that > > section too? > > No. is_exception_text() is used to detect those functions which have > a specific stack layout - which is that there's a pt_regs struct on the > stack. Grouping other functions into that violates the expectation. I'm not sure I follow. These functions (asm_do_IRQ(), do_IPI(), and do_local_timer()) will be the only ones in __irq_entry. iow, __irq_entry will contain nothing else except these functions. So we woudn't be grouping other functions; it's just that some of the __exception functions would be moved to the new section so that __exception and __irq_entry combined will contain the functions with the specific stack layout (and only those functions).