From: Peter Zijlstra <peterz@infradead.org> To: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>, Linux-mm <linux-mm@kvack.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Christoph Hellwig <hch@infradead.org>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Oleg Nesterov <oleg@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, SystemTap <systemtap@sources.redhat.com>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Frederic Weisbecker <fweisbec@gmail.com>, Andi Kleen <andi@firstfloor.org>, LKML <linux-kernel@vger.kernel.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Subject: Re: [RFC] [PATCH 2.6.37-rc5-tip 5/20] 5: Uprobes: register/unregister probes. Date: Wed, 26 Jan 2011 18:12:29 +0100 [thread overview] Message-ID: <1296061949.28776.1343.camel@laptop> (raw) In-Reply-To: <20110126165645.GP19725@linux.vnet.ibm.com> On Wed, 2011-01-26 at 22:26 +0530, Srikar Dronamraju wrote: > > - lookup the vma relating to the address you stored, > > We already do this thro get_user_pages in write_opcode(). Ah, I didn't read that far.. > > - validate that the vma is indeed a map of the right inode > > We can add a check in write_opcode( we need to pass the inode to > write_opcode). sure.. > > - validate that the offset of the probe corresponds with the stored > > address > > I am not clear on this. We would have derived the address from the > offset. So is that we check for > (vaddr == vma->vm_start + uprobe->offset) Sure, but the vma might have changed since you computed the offset -) > > > > Otherwise you can race with unmap/map and end up installing the probe in > > a random location. > > > > Also, I think the whole thing goes funny if someone maps the same text > > twice ;-) > > I am not sure if we can map the same text twice. If something like > this is possible then we would have 2 addresses for each function. > So how does the linker know which address to jump to out of the 2 or > multiple matching addresses. What would be the usecases for same > text being mapped multiple times and both being executable? You can, if only to wreck your thing, you can call mmap() as often as you like (until your virtual memory space runs out) and get many many mapping of the same file. It doesn't need to make sense to the linker, all it needs to do is confuse your code ;-)
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>, Linux-mm <linux-mm@kvack.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Christoph Hellwig <hch@infradead.org>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Oleg Nesterov <oleg@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, SystemTap <systemtap@sources.redhat.com>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Frederic Weisbecker <fweisbec@gmail.com>, Andi Kleen <andi@firstfloor.org>, LKML <linux-kernel@vger.kernel.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Subject: Re: [RFC] [PATCH 2.6.37-rc5-tip 5/20] 5: Uprobes: register/unregister probes. Date: Wed, 26 Jan 2011 18:12:29 +0100 [thread overview] Message-ID: <1296061949.28776.1343.camel@laptop> (raw) In-Reply-To: <20110126165645.GP19725@linux.vnet.ibm.com> On Wed, 2011-01-26 at 22:26 +0530, Srikar Dronamraju wrote: > > - lookup the vma relating to the address you stored, > > We already do this thro get_user_pages in write_opcode(). Ah, I didn't read that far.. > > - validate that the vma is indeed a map of the right inode > > We can add a check in write_opcode( we need to pass the inode to > write_opcode). sure.. > > - validate that the offset of the probe corresponds with the stored > > address > > I am not clear on this. We would have derived the address from the > offset. So is that we check for > (vaddr == vma->vm_start + uprobe->offset) Sure, but the vma might have changed since you computed the offset -) > > > > Otherwise you can race with unmap/map and end up installing the probe in > > a random location. > > > > Also, I think the whole thing goes funny if someone maps the same text > > twice ;-) > > I am not sure if we can map the same text twice. If something like > this is possible then we would have 2 addresses for each function. > So how does the linker know which address to jump to out of the 2 or > multiple matching addresses. What would be the usecases for same > text being mapped multiple times and both being executable? You can, if only to wreck your thing, you can call mmap() as often as you like (until your virtual memory space runs out) and get many many mapping of the same file. It doesn't need to make sense to the linker, all it needs to do is confuse your code ;-) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-01-26 17:17 UTC|newest] Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-12-16 9:57 [RFC] [PATCH 2.6.37-rc5-tip 0/20] 0: Inode based uprobes Srikar Dronamraju 2010-12-16 9:57 ` [RFC] [PATCH 2.6.37-rc5-tip 1/20] 1: mm: Move replace_page() / write_protect_page() to mm/memory.c Srikar Dronamraju 2010-12-16 9:57 ` [RFC] [PATCH 2.6.37-rc5-tip 2/20] 2: X86 specific breakpoint definitions Srikar Dronamraju 2010-12-16 9:57 ` [RFC] [PATCH 2.6.37-rc5-tip 3/20] 3: uprobes: Breakground page replacement Srikar Dronamraju 2010-12-16 9:58 ` [RFC] [PATCH 2.6.37-rc5-tip 4/20] 4: uprobes: Adding and remove a uprobe in a rb tree Srikar Dronamraju 2011-01-25 12:15 ` Peter Zijlstra 2011-01-26 8:37 ` Srikar Dronamraju 2011-01-26 8:37 ` Srikar Dronamraju 2011-01-25 12:15 ` Peter Zijlstra 2011-01-26 8:41 ` Srikar Dronamraju 2011-01-26 10:13 ` Peter Zijlstra 2011-01-25 12:15 ` Peter Zijlstra 2011-01-26 8:38 ` Srikar Dronamraju 2011-01-25 13:56 ` Peter Zijlstra 2011-01-26 8:45 ` Srikar Dronamraju 2011-01-26 10:14 ` Peter Zijlstra 2011-01-26 15:18 ` Srikar Dronamraju 2011-01-26 15:33 ` Peter Zijlstra 2010-12-16 9:58 ` [RFC] [PATCH 2.6.37-rc5-tip 5/20] 5: Uprobes: register/unregister probes Srikar Dronamraju 2011-01-25 12:15 ` Peter Zijlstra 2011-01-26 7:55 ` Srikar Dronamraju 2011-01-26 7:55 ` Srikar Dronamraju 2011-01-26 10:11 ` Peter Zijlstra 2011-01-26 10:11 ` Peter Zijlstra 2011-01-26 15:30 ` Srikar Dronamraju 2011-01-26 15:30 ` Srikar Dronamraju 2011-01-26 15:45 ` Peter Zijlstra 2011-01-26 15:45 ` Peter Zijlstra 2011-01-26 16:56 ` Srikar Dronamraju 2011-01-26 16:56 ` Srikar Dronamraju 2011-01-26 17:12 ` Peter Zijlstra [this message] 2011-01-26 17:12 ` Peter Zijlstra 2011-01-27 10:01 ` Srikar Dronamraju 2011-01-27 10:01 ` Srikar Dronamraju 2011-01-27 10:23 ` Peter Zijlstra 2011-01-27 10:23 ` Peter Zijlstra 2011-01-27 10:25 ` Srikar Dronamraju 2011-01-27 10:25 ` Srikar Dronamraju 2011-01-27 10:41 ` Peter Zijlstra 2011-01-27 10:41 ` Peter Zijlstra 2011-01-27 10:29 ` Peter Zijlstra 2011-01-27 10:29 ` Peter Zijlstra 2011-01-25 12:15 ` Peter Zijlstra 2011-01-26 7:47 ` Srikar Dronamraju 2011-01-26 7:47 ` Srikar Dronamraju 2011-01-26 10:10 ` Peter Zijlstra 2011-01-26 10:10 ` Peter Zijlstra 2010-12-16 9:58 ` [RFC] [PATCH 2.6.37-rc5-tip 6/20] 6: x86: analyze instruction and determine fixups Srikar Dronamraju 2010-12-16 9:58 ` [RFC] [PATCH 2.6.37-rc5-tip 7/20] 7: uprobes: store/restore original instruction Srikar Dronamraju 2011-01-25 12:15 ` Peter Zijlstra 2010-12-16 9:58 ` [RFC] [PATCH 2.6.37-rc5-tip 8/20] 8: uprobes: mmap and fork hooks Srikar Dronamraju 2011-01-25 12:15 ` Peter Zijlstra 2011-01-26 9:03 ` Srikar Dronamraju 2011-01-26 9:03 ` Srikar Dronamraju 2011-01-26 10:20 ` Peter Zijlstra 2011-01-26 10:20 ` Peter Zijlstra 2011-01-26 14:59 ` Srikar Dronamraju 2011-01-26 14:59 ` Srikar Dronamraju 2011-01-26 15:16 ` Peter Zijlstra 2011-01-26 15:16 ` Peter Zijlstra 2011-01-26 16:30 ` Srikar Dronamraju 2011-01-26 16:30 ` Srikar Dronamraju 2011-01-25 12:15 ` Peter Zijlstra 2011-01-25 20:05 ` Steven Rostedt 2011-01-26 9:06 ` Srikar Dronamraju 2011-01-27 17:03 ` Steven Rostedt 2011-01-28 4:53 ` Srikar Dronamraju 2011-01-28 13:57 ` Steven Rostedt 2011-01-28 14:28 ` Steven Rostedt 2011-01-28 14:46 ` Srikar Dronamraju 2011-01-28 15:02 ` Steven Rostedt 2011-01-26 15:09 ` Srikar Dronamraju 2011-01-26 15:09 ` Srikar Dronamraju 2011-01-26 15:20 ` Peter Zijlstra 2011-01-26 15:20 ` Peter Zijlstra 2010-12-16 9:58 ` [RFC] [PATCH 2.6.37-rc5-tip 9/20] 9: x86: architecture specific task information Srikar Dronamraju 2010-12-16 9:59 ` [RFC] [PATCH 2.6.37-rc5-tip 10/20] 10: uprobes: task specific information Srikar Dronamraju 2011-01-25 13:56 ` Peter Zijlstra 2011-01-25 18:38 ` Josh Stone 2011-01-25 18:55 ` Roland McGrath 2011-01-25 19:56 ` Peter Zijlstra 2010-12-16 9:59 ` [RFC] [PATCH 2.6.37-rc5-tip 11/20] 11: uprobes: slot allocation for uprobes Srikar Dronamraju 2011-01-25 13:56 ` Peter Zijlstra 2010-12-16 9:59 ` [RFC] [PATCH 2.6.37-rc5-tip 12/20] 12: uprobes: get the breakpoint address Srikar Dronamraju 2011-01-25 13:56 ` Peter Zijlstra 2010-12-16 9:59 ` [RFC] [PATCH 2.6.37-rc5-tip 13/20] 13: x86: x86 specific probe handling Srikar Dronamraju 2011-01-25 13:56 ` Peter Zijlstra 2011-01-27 9:40 ` Srikar Dronamraju 2011-01-27 10:22 ` Peter Zijlstra 2011-01-27 19:11 ` Roland McGrath 2011-01-28 4:57 ` Srikar Dronamraju 2011-01-28 6:23 ` Roland McGrath 2011-01-28 8:36 ` Peter Zijlstra 2011-01-28 18:23 ` Roland McGrath 2010-12-16 9:59 ` [RFC] [PATCH 2.6.37-rc5-tip 14/20] 14: uprobes: Handing int3 and singlestep exception Srikar Dronamraju 2011-01-25 13:56 ` Peter Zijlstra 2011-01-25 13:56 ` Peter Zijlstra 2011-01-26 8:52 ` Srikar Dronamraju 2011-01-26 8:52 ` Srikar Dronamraju 2011-01-26 10:17 ` Peter Zijlstra 2011-01-26 10:17 ` Peter Zijlstra 2011-01-26 15:14 ` Srikar Dronamraju 2011-01-26 15:14 ` Srikar Dronamraju 2011-01-26 15:29 ` Peter Zijlstra 2011-01-26 15:29 ` Peter Zijlstra 2010-12-16 10:00 ` [RFC] [PATCH 2.6.37-rc5-tip 15/20] 15: x86: uprobes exception notifier for x86 Srikar Dronamraju 2010-12-16 10:00 ` [RFC] [PATCH 2.6.37-rc5-tip 16/20] 16: uprobes: register a notifier for uprobes Srikar Dronamraju 2011-01-25 13:56 ` Peter Zijlstra 2011-01-27 6:50 ` Srikar Dronamraju 2010-12-16 10:00 ` [RFC] [PATCH 2.6.37-rc5-tip 17/20] 17: uprobes: filter chain Srikar Dronamraju 2010-12-16 10:00 ` [RFC] [PATCH 2.6.37-rc5-tip 18/20] 18: uprobes: commonly used filters Srikar Dronamraju 2010-12-17 19:32 ` Valdis.Kletnieks 2010-12-18 3:04 ` Srikar Dronamraju 2010-12-16 10:00 ` [RFC] [PATCH 2.6.37-rc5-tip 19/20] 19: tracing: Extract out common code for kprobes/uprobes traceevents Srikar Dronamraju 2010-12-16 10:01 ` [RFC] [PATCH 2.6.37-rc5-tip 20/20] 20: tracing: uprobes trace_event interface Srikar Dronamraju 2010-12-16 10:07 ` [RFC] [PATCH 2.6.37-rc5-tip 0/20] 0: Inode based uprobes Srikar Dronamraju
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