From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754383Ab0C1AZm (ORCPT ); Sat, 27 Mar 2010 20:25:42 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:39234 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754289Ab0C1AZl (ORCPT ); Sat, 27 Mar 2010 20:25:41 -0400 Date: Sat, 27 Mar 2010 17:25:33 -0700 From: "Paul E. McKenney" To: Mathieu Desnoyers Cc: akpm@linux-foundation.org, Ingo Molnar , linux-kernel@vger.kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, adobriyan@gmail.com, rusty@rustcorp.co.au Subject: Re: [RFC patch] extable and module add object is static Message-ID: <20100328002533.GN2343@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20100327153233.993367557@efficios.com> <20100327224606.GK2343@linux.vnet.ibm.com> <20100327231421.GA4685@Krystal> <20100327232024.GB4685@Krystal> <20100327234314.GL2343@linux.vnet.ibm.com> <20100328000234.GA4924@Krystal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100328000234.GA4924@Krystal> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 27, 2010 at 08:02:34PM -0400, Mathieu Desnoyers wrote: > * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote: > > On Sat, Mar 27, 2010 at 07:20:24PM -0400, Mathieu Desnoyers wrote: > [...] > > > Something close to "object_is_static()" would be "kernel_text_address()", but it > > > only considers the text section addresses. I'd need something that would be > > > broader than that, containing all core kernel and module bss and data sections. > > > > > > Still looking... > > > > I was actually feeling pretty good about remembering object_is_on_stack() > > and finding it again. ;-) > > > > I am not seeing anything the identifies data or bss, and in any case, > > other situations such as per-CPU, __read_mostly, and who knows what all > > else would also need to be handled. So in the short term, my guess would > > be that it would be best to provide the three functions (possibly renaming > > them as noted above), but to leave the responsibility for figuring out > > which to invoke with the caller. Always happy to be proven wrong, of > > course! > > > > Thanx, Paul > > I think I found a neat way to do object_is_static(), which is all we need here. > Can you have a look at the following patch ? If you think it's right, I'll add > it to the patchset for the next submission. Looks plausible to me! Rusty, any thoughts? Thanx, Paul > extable and module add object is static > > Adds an API to extable.c to check if an object is statically defined. This > permits, along with object_is_on_stack(), to figure out is an object is either > statically defined (object_is_static()) or allocated on the stack > (object_is_on_stack()). > > Signed-off-by: Mathieu Desnoyers > CC: "Paul E. McKenney" > CC: David S. Miller > CC: akpm@linux-foundation.org > CC: mingo@elte.hu > CC: laijs@cn.fujitsu.com > CC: dipankar@in.ibm.com > CC: josh@joshtriplett.org > CC: dvhltc@us.ibm.com > CC: niv@us.ibm.com > CC: tglx@linutronix.de > CC: peterz@infradead.org > CC: rostedt@goodmis.org > CC: Valdis.Kletnieks@vt.edu > CC: dhowells@redhat.com > CC: eric.dumazet@gmail.com > CC: Alexey Dobriyan > --- > include/linux/kernel.h | 2 + > kernel/extable.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 54 insertions(+) > > Index: linux.trees.git/include/linux/kernel.h > =================================================================== > --- linux.trees.git.orig/include/linux/kernel.h 2010-03-27 19:27:02.000000000 -0400 > +++ linux.trees.git/include/linux/kernel.h 2010-03-27 19:28:02.000000000 -0400 > @@ -218,6 +218,8 @@ extern int __kernel_text_address(unsigne > extern int kernel_text_address(unsigned long addr); > extern int func_ptr_is_kernel_text(void *ptr); > > +extern int object_is_static(void *obj); > + > struct pid; > extern struct pid *session_of_pgrp(struct pid *pgrp); > > Index: linux.trees.git/kernel/extable.c > =================================================================== > --- linux.trees.git.orig/kernel/extable.c 2010-03-27 19:28:06.000000000 -0400 > +++ linux.trees.git/kernel/extable.c 2010-03-27 19:54:40.000000000 -0400 > @@ -60,6 +60,14 @@ static inline int init_kernel_text(unsig > return 0; > } > > +static inline int init_kernel_text_or_data(unsigned long addr) > +{ > + if (addr >= (unsigned long)__init_begin && > + addr <= (unsigned long)__init_end) > + return 1; > + return 0; > +} > + > int core_kernel_text(unsigned long addr) > { > if (addr >= (unsigned long)_stext && > @@ -113,3 +121,47 @@ int func_ptr_is_kernel_text(void *ptr) > return 1; > return is_module_text_address(addr); > } > + > +/* > + * Taking the safe approach to refer to each section individually rather than > + * just taking a range between _stext and _end, just in case an architecture > + * would decide to override the standard linker scripts and put a section > + * outside of this range. > + * > + * Should be kept in sync with linux/section.h and asm-generic/vmlinux.lds.h. > + */ > +static int core_object_is_static(void *obj) > +{ > + unsigned long addr = (unsigned long) obj; > + > + if (addr >= (unsigned long)_sdata && > + addr <= (unsigned long)_edata) > + return 1; > + if (addr >= (unsigned long)__bss_start && > + addr <= (unsigned long)__bss_stop) > + return 1; > + if (addr >= (unsigned long)__per_cpu_start && > + addr <= (unsigned long)__per_cpu_end) > + return 1; > + if (addr >= (unsigned long)__start_rodata && > + addr <= (unsigned long)__end_rodata) > + return 1; > + if (system_state == SYSTEM_BOOTING && > + init_kernel_text_or_data(addr)) > + return 1; > + if (core_kernel_text(addr)) > + return 1; > + return 0; > +} > + > +/* > + * object_is_static - returns true is an object is statically defined > + */ > +int object_is_static(void *obj) > +{ > + if (core_object_is_static(obj)) > + return 1; > + if (is_module_address((unsigned long) obj)) > + return 1; > + return 0; > +} > > > -- > Mathieu Desnoyers > Operating System Efficiency R&D Consultant > EfficiOS Inc. > http://www.efficios.com