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* perf probe: Ignore tail calls to probed functionsNaveen N. Rao2015-05-141-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | perf probe currently errors out if there are any tail calls to probed functions: [root@rhel71be]# perf probe do_fork Failed to find probe point in any functions. Error: Failed to add events. Fix this by teaching perf to ignore tail calls. Without patch: [root@rhel71be perf]# ./perf probe -v do_fork probe-definition(0): do_fork symbol:do_fork file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Looking at the vmlinux_path (7 entries long) symsrc__init: build id mismatch for /boot/vmlinux. Using /usr/lib/debug/lib/modules/3.10.0-201.el7.ppc64/vmlinux for symbols Open Debuginfo file: /usr/lib/debug/lib/modules/3.10.0-201.el7.ppc64/vmlinux Try to find probe point from debuginfo. found inline addr: 0xc0000000000bb9b0 Probe point found: do_fork+0 found inline addr: 0xc0000000000bbe20 Probe point found: kernel_thread+48 found inline addr: 0xc0000000000bbe5c Probe point found: sys_fork+28 found inline addr: 0xc0000000000bbfac Probe point found: sys_vfork+44 found inline addr: 0xc0000000000bc27c Failed to find probe point in any functions. An error occurred in debuginfo analysis (-2). Error: Failed to add events. Reason: No such file or directory (Code: -2) With patch: [root@rhel71be perf]# ./perf probe -v do_fork probe-definition(0): do_fork symbol:do_fork file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Looking at the vmlinux_path (7 entries long) symsrc__init: build id mismatch for /boot/vmlinux. Using /usr/lib/debug/lib/modules/3.10.0-201.el7.ppc64/vmlinux for symbols Open Debuginfo file: /usr/lib/debug/lib/modules/3.10.0-201.el7.ppc64/vmlinux Try to find probe point from debuginfo. found inline addr: 0xc0000000000bb9b0 Probe point found: do_fork+0 found inline addr: 0xc0000000000bbe20 Probe point found: kernel_thread+48 found inline addr: 0xc0000000000bbe5c Probe point found: sys_fork+28 found inline addr: 0xc0000000000bbfac Probe point found: sys_vfork+44 found inline addr: 0xc0000000000bc27c Ignoring tail call from SyS_clone Found 4 probe_trace_events. Opening /sys/kernel/debug/tracing/kprobe_events write=1 No kprobe blacklist support, ignored Added new events: Writing event: p:probe/do_fork _text+768432 Failed to write event: Invalid argument Error: Failed to add events. Reason: Invalid argument (Code: -22) [Ignore the error about failure to write event - this kernel is missing a patch to resolve _text properly] The reason to ignore tail calls is that the address does not belong to any function frame. In the example above, the address in SyS_clone is 0xc0000000000bc27c, but looking at the debug-info: <1><830081>: Abbrev Number: 133 (DW_TAG_subprogram) <830083> DW_AT_external : 1 <830083> DW_AT_name : (indirect string, offset: 0x3cea3): SyS_clone <830087> DW_AT_decl_file : 7 <830088> DW_AT_decl_line : 1689 <83008a> DW_AT_prototyped : 1 <83008a> DW_AT_type : <0x8110eb> <83008e> DW_AT_low_pc : 0xc0000000000bc270 <830096> DW_AT_high_pc : 0xc <83009e> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) <8300a0> DW_AT_GNU_all_call_sites: 1 <8300a0> DW_AT_sibling : <0x830178> <snip> <3><830147>: Abbrev Number: 125 (DW_TAG_GNU_call_site) <830148> DW_AT_low_pc : 0xc0000000000bc27c <830150> DW_AT_GNU_tail_call: 1 <830150> DW_AT_abstract_origin: <0x82e7e1> The frame ends at 0xc0000000000bc27c. I suppose this is why this particular call is a "tail" call. FWIW, systemtap seems to ignore these as well and requires users to explicitly place probes at these call sites if necessary. I print out the caller so that users know. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Link: http://lkml.kernel.org/r/1430394151-15928-1-git-send-email-naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Add --range option to show a variable's location rangeHe Kuang2015-05-121-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It is not easy for users to get the accurate byte offset or the line number where a local variable can be probed. With '--range' option, local variables in the scope of the probe point are showed with a byte offset range, and can be added according to this range information. For example, there are some variables in the function generic_perform_write(): <generic_perform_write@mm/filemap.c:0> 0 ssize_t generic_perform_write(struct file *file, 1 struct iov_iter *i, loff_t pos) 2 { 3 struct address_space *mapping = file->f_mapping; 4 const struct address_space_operations *a_ops = mapping->a_ops; ... 42 status = a_ops->write_begin(file, mapping, pos, bytes, flags, &page, &fsdata); 44 if (unlikely(status < 0)) But we fail when we try to probe the variable 'a_ops' at line 42 or 44. $ perf probe --add 'generic_perform_write:42 a_ops' Failed to find the location of a_ops at this address. Perhaps, it has been optimized out. This is because the source code do not match the assembly, so a variable may not be available in the source code line where it appears. After this patch, we can lookup the accurate byte offset range of a variable, 'INV' indicates that this variable is not valid at the given point, but available in the scope: $ perf probe --vars 'generic_perform_write:42' --range Available variables at generic_perform_write:42 @<generic_perform_write+141> [INV] ssize_t written @<generic_perform_write+[324-331]> [INV] struct address_space_operations* a_ops @<generic_perform_write+[55-61,170-176,223-246]> [VAL] (unknown_type) fsdata @<generic_perform_write+[70-307,346-411]> [VAL] loff_t pos @<generic_perform_write+[0-286,286-336,346-411]> [VAL] long int status @<generic_perform_write+[83-342,346-411]> [VAL] long unsigned int bytes @<generic_perform_write+[122-311,320-338,346-403,403-411]> [VAL] struct address_space* mapping @<generic_perform_write+[35-344,346-411]> [VAL] struct iov_iter* i @<generic_perform_write+[0-340,346-411]> [VAL] struct page* page @<generic_perform_write+[70-307,346-411]> Then it is more clear for us to add a probe with this variable: $ perf probe --add 'generic_perform_write+170 a_ops' Added new event: probe:generic_perform_write (on generic_perform_write+170 with a_ops) Signed-off-by: He Kuang <hekuang@huawei.com> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/r/1431336304-16863-2-git-send-email-hekuang@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Remove length limitation for showing available variablesHe Kuang2015-05-121-2/+2
| | | | | | | | | | | | | | | Use struct strbuf instead of bare char[] to remove the length limitation of variables in variable_list, so they will not disappear due to overlength, and make preparation for adding more description for variables. Signed-off-by: He Kuang <hekuang@huawei.com> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/r/1431336304-16863-1-git-send-email-hekuang@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Support glob wildcards for function nameMasami Hiramatsu2015-05-081-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Support glob wildcards for function name when adding new probes. This will allow us to build caches of function-entry level information with $params. e.g. ---- # perf probe --no-inlines --add 'kmalloc* $params' Added new events: probe:kmalloc_slab (on kmalloc* with $params) probe:kmalloc_large_node (on kmalloc* with $params) probe:kmalloc_order_trace (on kmalloc* with $params) You can now use it in all perf tools, such as: perf record -e probe:kmalloc_order_trace -aR sleep 1 # perf probe --list probe:kmalloc_large_node (on kmalloc_large_node@mm/slub.c with size flags node) probe:kmalloc_order_trace (on kmalloc_order_trace@mm/slub.c with size flags order) probe:kmalloc_slab (on kmalloc_slab@mm/slab_common.c with size flags) ---- Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: David Ahern <dsahern@gmail.com> Cc: Hemant Kumar <hemant@linux.vnet.ibm.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20150508010335.24812.19972.stgit@localhost.localdomain Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Fix to handle optimized not-inlined functionsMasami Hiramatsu2015-02-061-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix to handle optimized no-inline functions which have only function definition but no actual instance at that point. To fix this problem, we need to find actual instance of the function. Without this patch: ---- # perf probe -a __up Failed to get entry address of __up. Error: Failed to add events. # perf probe -L __up Specified source line is not found. Error: Failed to show lines. ---- With this patch: ---- # perf probe -a __up Added new event: probe:__up (on __up) You can now use it in all perf tools, such as: perf record -e probe:__up -aR sleep 1 # perf probe -L __up <__up@/home/fedora/ksrc/linux-3/kernel/locking/semaphore.c:0> 0 static noinline void __sched __up(struct semaphore *sem) { struct semaphore_waiter *waiter = list_first_entry(&sem->wait_ struct semaphore_waite 4 list_del(&waiter->list); 5 waiter->up = true; 6 wake_up_process(waiter->task); 7 } ---- Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20150130093744.30575.43290.stgit@localhost.localdomain Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Fix to find line information for probe listMasami Hiramatsu2013-10-041-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix to find the correct (as much as possible) line information for listing probes. Without this fix, perf probe --list action will show incorrect line information as below; probe:getname_flags (on getname_flags@ksrc/linux-3/fs/namei.c) probe:getname_flags_1 (on getname:-89@x86/include/asm/current.h) probe:getname_flags_2 (on user_path_at_empty:-2054@x86/include/asm/current.h) The minus line number is obviously wrong, and current.h is not related to the probe point. Deeper investigation discovered that there were 2 issues related to this bug, and minor typos too. The 1st issue is the rack of considering about nested inlined functions, which causes the wrong (relative) line number. The 2nd issue is that the dwarf line info is not correct at those points. It points 14th line of current.h. Since it seems that the line info includes somewhat unreliable information, this fixes perf to try to find correct line information from both of debuginfo and line info as below. 1) Probe address is the entry of a function instance In this case, the line is set as the function declared line. 2) Probe address is the entry of an expanded inline function block In this case, the line is set as the function call-site line. This means that the line number is relative from the entry line of caller function (which can be an inlined function if nested) 3) Probe address is inside a function instance or an expanded inline function block In this case, perf probe queries the line number from lineinfo and verify the function declared file is same as the file name queried from lineinfo. If the file name is different, it is a failure case. The probe address is shown as symbol+offset. 4) Probe address is not in the any function instance This is a failure case, the probe address is shown as symbol+offset. With this fix, perf probe -l shows correct probe lines as below; probe:getname_flags (on getname_flags@ksrc/linux-3/fs/namei.c) probe:getname_flags_1 (on getname:2@ksrc/linux-3/fs/namei.c) probe:getname_flags_2 (on user_path_at_empty:4@ksrc/linux-3/fs/namei.c) Changes at v2: - Fix typos in the function comments. (Thanks to Namhyung Kim) - Use die_find_top_inlinefunc instead of die_find_inlinefunc_next. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130930092144.1693.11058.stgit@udc4-manage.rcp.hitachi.co.jp Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Fix finder to find lines of given functionMasami Hiramatsu2013-09-191-0/+3
| | | | | | | | | | | | | | | | | The commit ba28c59bc9ed8fb7b9a753cd88ee54a2c4f6265b fixed a declaration entry bug in probe_point_search_cb(). There are same bugs in line finder and call_probe_finder(). This introduces a new dwarf utility function to determine given DIE is a function definition, not declaration. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20120423032435.8737.80064.stgit@localhost.localdomain Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Search concrete out-of-line instancesMasami Hiramatsu2011-08-121-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | gcc 4.6 generates a concrete out-of-line instance when there is a function which is implicitly inlined somewhere but also has its own instance. The concrete out-of-line instance means that it has an abstract origin of the function which is referred by not only inlined-subroutines but also a concrete subprogram. Since current dwarf_func_inline_instances() can find only instances of inlined-subroutines, this introduces new die_walk_instances() to find both of subprogram and inlined-subroutines. e.g. without this, Available variables at sched_group_rt_period @<cpu_rt_period_read_uint+9> struct task_group* tg perf probe failed to find actual subprogram instance of sched_group_rt_period(). With this, Available variables at sched_group_rt_period @<cpu_rt_period_read_uint+9> struct task_group* tg @<sched_group_rt_period+0> struct task_group* tg Now it found the sched_group_rt_period() itself. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20110811110311.19900.63997.stgit@fedora15 Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Fix to search local variables in appropriate scopeMasami Hiramatsu2011-08-121-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix perf probe to search local variables in appropriate local inlined function scope. For example, pre_schedule() has only 2 local variables, as below; $ perf probe -L pre_schedule <pre_schedule@/home/mhiramat/ksrc/linux-2.6/kernel/sched.c:0> 0 static inline void pre_schedule(struct rq *rq, struct task_struct *prev) { 2 if (prev->sched_class->pre_schedule) 3 prev->sched_class->pre_schedule(rq, prev); } However, current perf probe shows 4 local variables on pre_schedule(), because it searches variables in the caller(schedule()) scope. $ perf probe -V pre_schedule Available variables at pre_schedule @<schedule+445> int cpu long unsigned int* switch_count struct rq* rq struct task_struct* prev This patch fixes this issue by searching variables in the local scope of the instance of inlined function. Here is the result. $ perf probe -V pre_schedule Available variables at pre_schedule @<schedule+445> struct rq* rq struct task_struct* prev Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20110811110259.19900.85664.stgit@fedora15 Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf probe: Fix to search nested inlined functions in CUMasami Hiramatsu2011-08-121-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix perf probe to walk through the lines of all nested inlined function call sites and declared lines when a whole CU is passed to the line walker. The die_walk_lines() can have two different type of DIEs, subprogram (or inlined-subroutine) DIE and CU DIE. If a caller passes a subprogram DIE, this means that the walker walk on lines of given subprogram. In this case, it just needs to search on direct children of DIE tree for finding call-site information of inlined function which directly called from given subprogram. On the other hand, if a caller passes a CU DIE to the walker, this means that the walker have to walk on all lines in the source files included in given CU DIE. In this case, it has to search whole DIE trees of all subprograms to find the call-site information of all nested inlined functions. Without this patch: $ perf probe --line kernel/cpu.c:151-157 </home/mhiramat/ksrc/linux-2.6/kernel/cpu.c:151> static int cpu_notify(unsigned long val, void *v) { 154 return __cpu_notify(val, v, -1, NULL); } With this: $ perf probe --line kernel/cpu.c:151-157 </home/mhiramat/ksrc/linux-2.6/kernel/cpu.c:151> 152 static int cpu_notify(unsigned long val, void *v) { 154 return __cpu_notify(val, v, -1, NULL); } As you can see, --line option with source line range shows the declared lines as probe-able. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20110811110241.19900.34994.stgit@fedora15 Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* perf-probe: Move dwarf library routines to dwarf-aux.{c, h}Masami Hiramatsu2011-07-151-0/+100
Move dwarf library related routines to dwarf-aux.{c,h}. This includes several minor changes. - Add simple documents for each API. - Rename die_find_real_subprogram() to die_find_realfunc() - Rename line_walk_handler_t to line_walk_callback_t. - Minor cleanups. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/20110627072727.6528.57647.stgit@fedora15 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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