Messages in this thread | | | Date | Mon, 7 Mar 2022 08:24:50 -0500 | From | Steven Rostedt <> | Subject | Re: ftrace bug |
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On Mon, 7 Mar 2022 12:26:45 +0100 Arend van Spriel <arend.vanspriel@broadcom.com> wrote:
> Hi Steven, > > I wanted to use FTRACE on an ARM platform and I hit the following > warning which results in ftrace bug. This happens upon loading a module. > Looking up the warning I suspect the branch target is too far off. The > module is quite large and therefor not loaded in the modules section. Is > there a way to exclude a module. In ftrace_module_init I see a check for > !mod->num_ftrace_callsites. Is there a way to avoid creating ftrace > callsites in a module?
Are you sure it's the size. Just want to make sure that's the reason before going with different solutions.
> > Regards, > Arend > > ------------[ cut here ]------------ > > WARNING: CPU: 2 PID: 1525 at arch/arm/kernel/insn.c:47 > __arm_gen_branch+0x70/0x78 > > CPU: 2 PID: 1525 Comm: insmod Tainted: P 4.19.183 #2 > > Hardware name: Generic DT based system > > [<c02139e4>] (unwind_backtrace) from [<c020d4f8>] (show_stack+0x20/0x24) > > [<c020d4f8>] (show_stack) from [<c0922aec>] (dump_stack+0x98/0xac) > > [<c0922aec>] (dump_stack) from [<c0919b98>] (__warn.part.0+0xcc/0xe8) > > [<c0919b98>] (__warn.part.0) from [<c0919d4c>] > (warn_slowpath_null+0x54/0x74) > [<c0919d4c>] (warn_slowpath_null) from [<c021225c>] > (__arm_gen_branch+0x70/0x78) > [<c021225c>] (__arm_gen_branch) from [<c02120e4>] > (ftrace_make_nop+0x64/0xec) > [<c02120e4>] (ftrace_make_nop) from [<c02ac2b0>] > (ftrace_process_locs+0x370/0x4b4) > > [<c02ac2b0>] (ftrace_process_locs) from [<c02af538>] > (ftrace_module_init+0x38/0x3c) > > [<c02af538>] (ftrace_module_init) from [<c02a47d8>] > (load_module+0x18d0/0x2570) > [<c02a47d8>] (load_module) from [<c02a56f8>] > (sys_finit_module+0xe0/0xf8) > [<c02a56f8>] (sys_finit_module) from [<c0201000>] > (ret_fast_syscall+0x0/0x58) > Exception stack(0xd9b1bfa8 to 0xd9b1bff0) > > bfa0: 01170228 00000000 00000003 01170228 00000000 > beb7ceb3 > bfc0: 01170228 00000000 beb7cdc4 0000017b 00127010 00000000 00000000 > 00000000 > bfe0: beb7cc38 beb7cc28 0001a0dc 00012890 > > ---[ end trace f48808a851a4544a ]--- > > ------------[ cut here ]------------ > > WARNING: CPU: 2 PID: 1525 at kernel/trace/ftrace.c:2034 > ftrace_bug+0xfc/0x394
Three should be more content after the "cut here" that is very relevant (I hate that cut here, because I constantly need to tell people to show me more :-p I need to add a "ftrace bug cut here" line.)
Could you show me the output right after that.
-- Steve
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