<div dir="ltr">Hi All,<div>i looked into this further, generated .c file with expanded macros for debugging</div><div>Some of the function pointer are not populated correctly.</div><div>I have attached the expanded source files which i used.</div><div>Pls see the following GDB analysis:</div><div><br></div><br>(gdb) bt<br>#0 0x00000000 in ?? ()<br>#1 0x080490a0 in __event_probe__sample_tracepoint___message (__tp_data=0x80512d0, <br> text=0x804ca64 "Hello World\n") at sample_tracepoint.c:8567<br><br>#2 0x0804ba23 in __tracepoint_cb_sample_tracepoint___message (<br> text=0x804ca64 "Hello World\n")<br> at <span style="font-size:12.8000001907349px">/build/home/jam/gentp</span>/src/sample.c:4026<br>#3 main (argc=1, argv=0xffffdd74)<br> at <span style="font-size:12.8000001907349px">/build/home/jam/gentp/</span>src/sample.c:4731<br><br><b>***bc_runtime->filter</b> --- is not populated correctly, because of which it crashes<br><b>(gdb) frame 1</b><br>#1 0x080490a0 in __event_probe__sample_tracepoint___message (__tp_data=0x80512d0, <br> text=0x804ca64 "Hello World\n") at sample_tracepoint.c:8567<br>8567 if (__builtin_expect(!!(<b>bc_runtime->filter</b>(bc_runtime, __stackvar.__filter_stack_data) & LTTNG_FILTER_RECORD_FLAG), 0))<br><br><br><b>(gdb) list</b><br>8562 (__stackvar.__filter_stack_data, __tp_data,text);<br>8563 for (bc_runtime = ((__typeof__(*bc_runtime) *) ((char *) ((reinterpret_cast<__typeof__((&__event->bytecode_runtime_head)->next)>(tracepoint_dlopen.rcu_dereference_sym_bp((reinterpret_cast<void *>((&__event->bytecode_runtime_head)->next)))))) - (unsigned long) (&((__typeof__(*bc_runtime) *) 0)->node)));<br>8564 &bc_runtime->node != (&__event->bytecode_runtime_head);<br>8565 bc_runtime = ((__typeof__(*bc_runtime) *) ((char *) ((reinterpret_cast<__typeof__(bc_runtime->node.next)>(tracepoint_dlopen.rcu_dereference_sym_bp((reinterpret_cast<void *>(bc_runtime->node.next)))))) - (unsigned long) (&((__typeof__(*bc_runtime) *) 0)->node))))<br>8566 {<br><b>8567 if (__builtin_expect(!!(bc_runtime->filter(bc_runtime, __stackvar.__filter_stack_data) & LTTNG_FILTER_RECORD_FLAG), 0))</b><br>8568 __filter_record = 1;<br>8569 } if (__builtin_expect(!!(!__filter_record), 1)) return;<br>8570 } __event_len =<br>8571<br><br><br><b>printing bc_runtime shows filter is 0</b><br><b>(gdb) p *bc_runtime </b><br>$3 = {bc = 0x0,<b> filter = 0x0,</b> link_failed = 0, node = {next = 0x8051304, <br> prev = 0x8051304}}<br><br><br><b>also i see __event->bytecode_runtime_head->prev = 0x1 which may be wrong</b><br><b>(gdb) p *__event</b><br>$4 = {id = 2, chan = 0xf6c047c0, enabled = 1, <br> desc = 0x804c700 <__event_desc___sample_tracepoint_message>, _deprecated1 = 0x0, <br> ctx = 0x0, instrumentation = LTTNG_UST_TRACEPOINT, u = {<No data fields>}, node = {<br> next = 0x8051344, prev = 0x0}, _deprecated2 = {next = 0x0, prev = 0x0}, <br> _deprecated3 = 0x0, _deprecated4 = 0, <b>bytecode_runtime_head = {next = 0x8051304, <br> prev = 0x1}</b>, has_enablers_without_bytecode = 134552592, enablers_ref_head = {<br> next = 0x8051c10, prev = 0x0}, hlist = {next = 0xf6c00ea0, prev = 0x1}, <br> registered = 89}<div><br></div><div><br></div><div>I guess this structure is populated in tracepoint_register using urcu.</div><div>Can anyone give me more pointers to debug this. Is this a known issue and is there any patch which i can use</div><div><br></div><div><br></div><div class="gmail_extra"><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr">/Jam</div></div><div dir="ltr"><br></div><div dir="ltr"><br></div></div></div></div>
<br><div class="gmail_quote">On Mon, Aug 3, 2015 at 4:19 PM, jamie explorer <span dir="ltr"><<a href="mailto:jamieexplorer@gmail.com" target="_blank">jamieexplorer@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi,<div>i am trying to run 32-bit application and see crash at the the line where "tracepoint" is used.</div><div>i am using sample application given in lttng-ust-2.6.0/doc/examples/gen-tp/</div><div>Not able to understand why the problem is seen only with 32-bit apps? Can experts here pls help me fix this.</div><div><br></div><div>Have tried using ELF 32-bit app on Intel 80386 and PowerPC and see the crash. Where as 64-bit applications have no problem.</div><div><br></div><div>following is the code where it crashes</div><div><div> for (i = 0; i < 100000; i++) {</div><div> tracepoint(sample_tracepoint, message, "Hello World\n"); <<<< Crash here</div><div> usleep(1); </div><div> }</div></div><div><br></div><div><div><div><div dir="ltr"><div dir="ltr"><br></div><div dir="ltr">/Jam</div></div></div></div>
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