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Date: Mon, 2 Aug 2010 04:28:42 +0200 From: Frederic Weisbecker <fweisbec@...il.com> To: Srikar Dronamraju <srikar@...ux.vnet.ibm.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>, Randy Dunlap <rdunlap@...otime.net>, Arnaldo Carvalho de Melo <acme@...radead.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Christoph Hellwig <hch@...radead.org>, Oleg Nesterov <oleg@...hat.com>, Mark Wielaard <mjw@...hat.com>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Andrew Morton <akpm@...ux-foundation.org>, Naren A Devaiah <naren.devaiah@...ibm.com>, Jim Keniston <jkenisto@...ux.vnet.ibm.com>, "Frank Ch. Eigler" <fche@...hat.com>, Ananth N Mavinakayanahalli <ananth@...ibm.com>, LKML <linux-kernel@...r.kernel.org>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, 2nddept-manager@....hitachi.co.jp Subject: Re: [PATCHv10 2.6.35-rc6-tip 9/14] trace: uprobes trace_event interface On Thu, Jul 29, 2010 at 07:45:24PM +0530, Srikar Dronamraju wrote: > > > > Possible enhancement: Moving this config right after KPROBE_EVENT, because > > those two provide similar dynamic events. > > > > Masami, > Below patch should address the comments raised by you. > > -- > Thanks and Regards > Srikar > > --- > From: Srikar Dronamraju <srikar@...ux.vnet.ibm.com> > > > Implements trace_event support for uprobes. In its > current form it can be used to put probes at a specified text address > in a process and dump the required registers when the code flow reaches > the probed address. > > TODO: Documentation/trace/uprobetrace.txt > > Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com> > --- > > Changelog from v5: Addressed comments from Masami Hiramatsu and Steven > Rostedt. Some changes because of changes in common probe events. > > Changelog from v4: (Merged to 2.6.35-rc3-tip) > > Changelog from v2/v3: (Addressing comments from Steven Rostedt > and Frederic Weisbecker) > * removed pit field from uprobe_trace_entry. > * share common parts with kprobe trace events. > * use trace_create_file instead of debugfs_create_file. > > > The following example shows how to dump the instruction pointer and %ax a > register at the probed text address. > > Start a process to trace. Get the address to trace. > [Here pid is asssumed as 6016] > [Address to trace is 0x0000000000446420] > [Registers to be dumped are %ip and %ax] > > # cd /sys/kernel/debug/tracing/ > # echo 'p 6016:0x0000000000446420 %ip %ax' > uprobe_events > # cat uprobe_events > p:uprobes/p_6016_0x0000000000446420 6016:0x0000000000446420 %ip=%ip %ax=%ax > # cat events/uprobes/p_6016_0x0000000000446420/enable > 0 > [enable the event] > # echo 1 > events/uprobes/p_6016_0x0000000000446420/enable > # cat events/uprobes/p_6016_0x0000000000446420/enable > 1 > # #### do some activity on the program so that it hits the breakpoint > # cat uprobe_profile > 6016 p_6016_0x0000000000446420 234 > # tracer: nop > # > # TASK-PID CPU# TIMESTAMP FUNCTION > # | | | | | > zsh-6016 [004] 227931.093579: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > zsh-6016 [005] 227931.097541: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > zsh-6016 [000] 227931.124909: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > zsh-6016 [001] 227933.128565: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > zsh-6016 [004] 227933.132756: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > zsh-6016 [000] 227933.158802: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > zsh-6016 [001] 227935.161602: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > zsh-6016 [004] 227935.165229: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79 > > arch/Kconfig | 11 - > kernel/trace/Kconfig | 16 + > kernel/trace/Makefile | 1 > kernel/trace/trace.h | 5 > kernel/trace/trace_probe.h | 2 > kernel/trace/trace_uprobe.c | 739 +++++++++++++++++++++++++++++++++++++++++++ > 6 files changed, 764 insertions(+), 10 deletions(-) > create mode 100644 kernel/trace/trace_uprobe.c > > > diff --git a/arch/Kconfig b/arch/Kconfig > index c8c8e3f..af167f8 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -48,16 +48,7 @@ config OPTPROBES > select KALLSYMS_ALL > > config UPROBES > - bool "User-space probes (EXPERIMENTAL)" > - default n > - depends on ARCH_SUPPORTS_UPROBES > - depends on MMU > - help > - Uprobes enables kernel subsystems to establish probepoints > - in user applications and execute handler functions when > - the probepoints are hit. For more information, refer to > - Documentation/uprobes.txt. > - If in doubt, say "N". > + def_bool n > > config HAVE_EFFICIENT_UNALIGNED_ACCESS > bool > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index c681fa7..c77ba2d 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -377,6 +377,22 @@ config KPROBE_EVENT > This option is also required by perf-probe subcommand of perf tools. > If you want to use perf tools, this option is strongly recommended. > > +config UPROBE_EVENT > + bool "Enable uprobes-based dynamic events" > + depends on ARCH_SUPPORTS_UPROBES > + depends on MMU > + select UPROBES > + select PROBE_EVENTS > + select TRACING > + default n > + help > + This allows the user to add tracing events on top of userspace dynamic > + events (similar to tracepoints) on the fly via the traceevents interface. > + Those events can be inserted wherever uprobes can probe, and record > + various registers. > + This option is required if you plan to use perf-probe subcommand of perf > + tools on user space applications. > + Why did you split CONFIG_UPROBES and CONFIG_UPROBE_EVENT? Is there another kind of use of uprobes than through "trace events"? Hmm, speaking about it, I think kprobes has the same problem. In fact now I remember I noticed it by the past but we found another user of kprobes, mostly unused I guess. Anyway, uprobes config itself doesn't need to be split from uprobes events. Also, what about the "Dynamic Probes" menu I proposed? (it's possibly a crappy idea, I don't know). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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