android_kernel_samsung_univ.../Documentation/ABI/testing/sysfs-module
Mathieu Desnoyers 66cc69e34e Fix: module signature vs tracepoints: add new TAINT_UNSIGNED_MODULE
Users have reported being unable to trace non-signed modules loaded
within a kernel supporting module signature.

This is caused by tracepoint.c:tracepoint_module_coming() refusing to
take into account tracepoints sitting within force-loaded modules
(TAINT_FORCED_MODULE). The reason for this check, in the first place, is
that a force-loaded module may have a struct module incompatible with
the layout expected by the kernel, and can thus cause a kernel crash
upon forced load of that module on a kernel with CONFIG_TRACEPOINTS=y.

Tracepoints, however, specifically accept TAINT_OOT_MODULE and
TAINT_CRAP, since those modules do not lead to the "very likely system
crash" issue cited above for force-loaded modules.

With kernels having CONFIG_MODULE_SIG=y (signed modules), a non-signed
module is tainted re-using the TAINT_FORCED_MODULE taint flag.
Unfortunately, this means that Tracepoints treat that module as a
force-loaded module, and thus silently refuse to consider any tracepoint
within this module.

Since an unsigned module does not fit within the "very likely system
crash" category of tainting, add a new TAINT_UNSIGNED_MODULE taint flag
to specifically address this taint behavior, and accept those modules
within Tracepoints. We use the letter 'X' as a taint flag character for
a module being loaded that doesn't know how to sign its name (proposed
by Steven Rostedt).

Also add the missing 'O' entry to trace event show_module_flags() list
for the sake of completeness.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
NAKed-by: Ingo Molnar <mingo@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: David Howells <dhowells@redhat.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-03-13 12:11:51 +10:30

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What: /sys/module/pch_phub/drivers/.../pch_mac
Date: August 2010
KernelVersion: 2.6.35
Contact: masa-korg@dsn.okisemi.com
Description: Write/read GbE MAC address.
What: /sys/module/pch_phub/drivers/.../pch_firmware
Date: August 2010
KernelVersion: 2.6.35
Contact: masa-korg@dsn.okisemi.com
Description: Write/read Option ROM data.
What: /sys/module/ehci_hcd/drivers/.../uframe_periodic_max
Date: July 2011
KernelVersion: 3.1
Contact: Kirill Smelkov <kirr@mns.spb.ru>
Description: Maximum time allowed for periodic transfers per microframe (μs)
[ USB 2.0 sets maximum allowed time for periodic transfers per
microframe to be 80%, that is 100 microseconds out of 125
microseconds (full microframe).
However there are cases, when 80% max isochronous bandwidth is
too limiting. For example two video streams could require 110
microseconds of isochronous bandwidth per microframe to work
together. ]
Through this setting it is possible to raise the limit so that
the host controller would allow allocating more than 100
microseconds of periodic bandwidth per microframe.
Beware, non-standard modes are usually not thoroughly tested by
hardware designers, and the hardware can malfunction when this
setting differ from default 100.
What: /sys/module/*/{coresize,initsize}
Date: Jan 2012
KernelVersion:»·3.3
Contact: Kay Sievers <kay.sievers@vrfy.org>
Description: Module size in bytes.
What: /sys/module/*/taint
Date: Jan 2012
KernelVersion:»·3.3
Contact: Kay Sievers <kay.sievers@vrfy.org>
Description: Module taint flags:
P - proprietary module
O - out-of-tree module
F - force-loaded module
C - staging driver module
X - unsigned module