| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20111208171044.GC2499@redhat.com> Date: Thu, 8 Dec 2011 12:10:44 -0500 From: Jason Baron <jbaron@...hat.com> To: jim.cromie@...il.com Cc: greg@...ah.com, joe@...ches.com, bart.vanassche@...il.com, linux-kernel@...r.kernel.org, Thomas Renninger <trenn@...e.de>, Rusty Russell <rusty@...tcorp.com.au> Subject: Re: [PATCH 18/25] dynamic_debug: Introduce global fake module param $module.dyndbg On Tue, Dec 06, 2011 at 12:11:28PM -0700, jim.cromie@...il.com wrote: > From: Jim Cromie <jim.cromie@...il.com> > > Rework Thomas Renninger's $module.ddebug boot-time debugging feature, > from https://lkml.org/lkml/2010/9/15/397 > > Extend dynamic-debug facility to work during module initialization: > > foo.dyndbg bar.dyndbg="$bar-query-string" > > This patch introduces a 'fake' module parameter: $module.ddebug for > all modules. It is not explicitly added to each module, but is > implemented as an unknown-parameter callback invoked by kernel/param's > parse_one(), and it applies each module's query-string as if it were > written to the $DBGFS/dynamic_debug/control file. > > The module-name is added to the unknown-parameter callback signature > and to its caller: parse_one(). This lets the common callback know > what module its handling a common parameter for. > > If no value is given (as in foo.dyndbg example above), "+p" is > assumed, which enables all pr_debug callsites in the module. > > The parameter is not shown in /sys/module/*/parameters, thus it does > not use any resources. Changes to the parameter are made via the > control file. > > Signed-off-by: Jim Cromie <jim.cromie@...il.com> > CC: Thomas Renninger <trenn@...e.de> > CC: Rusty Russell <rusty@...tcorp.com.au> > --- > Documentation/dynamic-debug-howto.txt | 52 ++++++++++++++++++++++++++++++++- > include/linux/dynamic_debug.h | 11 +++++++ > include/linux/moduleparam.h | 2 +- > init/main.c | 7 ++-- > kernel/module.c | 3 +- > kernel/params.c | 10 ++++-- > lib/dynamic_debug.c | 16 +++++++++- > 7 files changed, 89 insertions(+), 12 deletions(-) > > diff --git a/Documentation/dynamic-debug-howto.txt b/Documentation/dynamic-debug-howto.txt > index 989a892..56e496a 100644 > --- a/Documentation/dynamic-debug-howto.txt > +++ b/Documentation/dynamic-debug-howto.txt > @@ -219,7 +219,7 @@ Note also that there is no convenient syntax to remove all > the flags at once, you need to use "-flmpt". > > > -Debug messages during boot process > +Debug messages during Boot Process > ================================== > > To be able to activate debug messages during the boot process, > @@ -238,6 +238,45 @@ PCI (or other devices) initialization also is a hot candidate for using > this boot parameter for debugging purposes. > > > +Debug Messages at Module Initialization Time > +============================================ > + > +Enabling a module's debug messages via debug control file only works > +once the module is loaded; too late for callsites in init functions. > +And when module is unloaded, debug flag settings for the module are > +lost. Instead, a "dyndbg" module parameter can be passed: > + > + - via kernel boot parameter: (this form works on built-ins too) > + module.dyndbg=+mfp > + module.dyndbg # defaults to +p > + > + - as an ordinary module parameter via modprobe > + modprobe module dyndbg=+pmfl > + modprobe module dyndbg # defaults to +p > + > + - or the parameter can be used permanently via modprobe.conf(.local) > + options module dyndbg=+pmflt > + options module dyndbg # defaults to +p > + > +The $modname.dyndbg="value" should exclude "module $modname", as the > +$modname is taken from the param-name, and only 1 spec of each type is > +allowed. > + > +The dyndbg option is not implemented as an ordinary module parameter > +and thus will not show up in /sys/module/module_name/parameters/dyndbg > +The settings can be reverted later via the sysfs interface if the > +debug messages are no longer needed: > + > + echo "module module_name -p" > <debugfs>/dynamic_debug/control > + > +$module.dyndbg="..." on boot-line works on built-in modules as well as > +those loaded by modprobe (from either early or normal userspace), and > +somewhat overlaps debug_query functionality. > + > +Modprobed modules get dyndbg flags given on boot-line after those > +given via modprobe (either explicitly, or from /etc/modprobe.d/*). > +This can surprise if boot-line arg subtracts flags. > + > Examples > ======== > > @@ -264,3 +303,14 @@ nullarbor:~ # echo -n 'func svc_process -p' > > // enable messages for NFS calls READ, READLINK, READDIR and READDIR+. > nullarbor:~ # echo -n 'format "nfsd: READ" +p' > > <debugfs>/dynamic_debug/control > + > +// boot-args example, with newlines and comments > +Kernel command line: ... > + ddebug_query="func i2c_del_adapter +p; func tboot_probe +p" > + dynamic_debug.verbose=1 // see whats going on > + nouveau.dyndbg // implicit =+p > + tsc_sync.dyndbg=+p // builtin on my kernel > + i2c_core.dyndbg=+p // loaded by udev > + *.dyndbg="=_" // wildcard applies to builtins > + k10temp.dyndbg="+p # comment in query is stripped " > + pnp.dyndbg="func pnpacpi_get_resources +p; func pnp_assign_mem +p" # multi I see you've added docs for the 'dyndbg' kernel command-line options, but then I don't see any changes in the code to 'unkown_bootoption'. What am I missing? Thanks, -Jason -- 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/
Powered by blists - more mailing lists