Re: [PATCH 0/1] RFC: Revamp admin-guide/tainted-kernels.rst to make it more comprehensible

Thorsten Leemhuis
2018-12-21T12:31:40Z

Am 20.12.18 um 21:10 schrieb Randy Dunlap:
> On 12/20/18 10:21 AM, Thorsten Leemhuis wrote:
>> Am 20.12.18 um 17:38 schrieb Randy Dunlap:
>>> On 12/20/18 7:28 AM, Jonathan Corbet wrote:
>>>> On Thu, 20 Dec 2018 16:23:38 +0100
>>>> Thorsten Leemhuis <linux@leemhuis.info> wrote:
>>>>> While at it: Jonathan, you mentioned putting the script in scripts/, but
>>>>> according to the Makefile in that directory it is "for various helper
>>>>> programs used throughout the kernel for the build process". That's one
>>>>> reason why it feels wrong to put it there. Another one: that script
>>>>> targets users and thus we should try to make sure they can access it
>>>>> easily. That's why I'm currently inclined to put it in tools/ somewhere.
>>>> Yeah, tools/ is a better place. Maybe a tools/debugging directory or some
>>>> such?
>>> chktaint
>> BTW, I renamed it to kernel-taintstatus, sounded more appropriate to me.
>> Does anyone mind?
> Not terribly, although that seems too long to me. ;)
> maybe 'taintstatus'?

I settled to "kernel-chktaint" for now. I'm not attached to the name, but IMHO
making it obvious what this tool checks is worth the "kernel-" prefix.

>> BTW, for those following this thread and my earlier quest for a simple
>> cmd to decode /proc/sys/kernel/tainted: looks like @apexo on twitter
>> (thx again!) found a trick to do what I want which should work on most
>> systems out-of-the-box:
>> $ for i in $(seq 18); do echo $i $(($(cat
>> /proc/sys/kernel/tainted)>>($i-1)&1));done
> I think Jon mentioned this: The output should begin with bit #0,
> not bit #1, so it should show bits 0 - 17 (or whatever the max is),
> not 1 - 18.

No worries, replying to that is nearly next on my todo list.

BTW & FYI, find below the patch I have prepared now.

Ciao, Thorsten

commit 2aa04b7a65a5ecceac27a0d9c0d64a4b04ae943a
Author: Thorsten Leemhuis <linux@leemhuis.info>
Date: Fri Dec 21 12:24:19 2018 +0100

tools: create tools/debugging/ and add a script decoding /proc/sys/kernel/tainted

Add a script to the tools/ directory that shows if or why the running kernel was
tainted. The script was mostly written by Randy Dunlap (thx!), who published it
while discussing changes that try to make admin-guide/tainted-kernels.rst more
comprehensible (https://lore.kernel.org/lkml/8f67a8ca-bf64-c537-843a-b03bcfc3dace@infradead.org/);
I enhanced the script a bit and created this patch.

As the script targets users I did not want to add it to scripts/, as according
to its Makefile "contains sources for various helper programs used throughout
the kernel for the build process". The directory tools/scripts/ also did not
look like a good fit, as the stuff that's there already is used for other
purposes. That's why I created a new directory for tools like this; maybe we
should move scripts/decodecode there as well, but that's something for another
day.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>

diff --git a/tools/Makefile b/tools/Makefile
index abb358a70ad0..c0d1e59f5abb 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -12,6 +12,7 @@ help:
@echo ' acpi - ACPI tools'
@echo ' cgroup - cgroup tools'
@echo ' cpupower - a tool for all things x86 CPU power'
+ @echo ' debugging - tools for debugging'
@echo ' firewire - the userspace part of nosy, an IEEE-1394 traffic sniffer'
@echo ' freefall - laptop accelerometer program for disk protection'
@echo ' gpio - GPIO tools'
@@ -60,7 +61,7 @@ acpi: FORCE
cpupower: FORCE
$(call descend,power/$@)

-cgroup firewire hv guest spi usb virtio vm bpf iio gpio objtool leds wmi pci: FORCE
+cgroup firewire hv guest spi usb virtio vm bpf iio gpio objtool leds wmi pci debugging: FORCE
$(call descend,$@)

liblockdep: FORCE
@@ -95,7 +96,8 @@ kvm_stat: FORCE
all: acpi cgroup cpupower gpio hv firewire liblockdep \
perf selftests spi turbostat usb \
virtio vm bpf x86_energy_perf_policy \
- tmon freefall iio objtool kvm_stat wmi pci
+ tmon freefall iio objtool kvm_stat wmi \
+ pci debugging

acpi_install:
$(call descend,power/$(@:_install=),install)
@@ -103,7 +105,7 @@ acpi_install:
cpupower_install:
$(call descend,power/$(@:_install=),install)

-cgroup_install firewire_install gpio_install hv_install iio_install perf_install spi_install usb_install virtio_install vm_install bpf_install objtool_install wmi_install pci_install:
+cgroup_install firewire_install gpio_install hv_install iio_install perf_install spi_install usb_install virtio_install vm_install bpf_install objtool_install wmi_install pci_install debugging_install:
$(call descend,$(@:_install=),install)

liblockdep_install:
@@ -129,7 +131,7 @@ install: acpi_install cgroup_install cpupower_install gpio_install \
perf_install selftests_install turbostat_install usb_install \
virtio_install vm_install bpf_install x86_energy_perf_policy_install \
tmon_install freefall_install objtool_install kvm_stat_install \
- wmi_install pci_install
+ wmi_install pci_install debugging_install

acpi_clean:
$(call descend,power/acpi,clean)
@@ -137,7 +139,7 @@ acpi_clean:
cpupower_clean:
$(call descend,power/cpupower,clean)

-cgroup_clean hv_clean firewire_clean spi_clean usb_clean virtio_clean vm_clean wmi_clean bpf_clean iio_clean gpio_clean objtool_clean leds_clean pci_clean:
+cgroup_clean hv_clean firewire_clean spi_clean usb_clean virtio_clean vm_clean wmi_clean bpf_clean iio_clean gpio_clean objtool_clean leds_clean pci_clean debugging_clean:
$(call descend,$(@:_clean=),clean)

liblockdep_clean:
@@ -175,6 +177,6 @@ clean: acpi_clean cgroup_clean cpupower_clean hv_clean firewire_clean \
perf_clean selftests_clean turbostat_clean spi_clean usb_clean virtio_clean \
vm_clean bpf_clean iio_clean x86_energy_perf_policy_clean tmon_clean \
freefall_clean build_clean libbpf_clean libsubcmd_clean liblockdep_clean \
- gpio_clean objtool_clean leds_clean wmi_clean pci_clean
+ gpio_clean objtool_clean leds_clean wmi_clean pci_clean debugging_clean

.PHONY: FORCE
diff --git a/tools/debugging/Makefile b/tools/debugging/Makefile
new file mode 100644
index 000000000000..e2b7c1a6fb8f
--- /dev/null
+++ b/tools/debugging/Makefile
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for debugging tools
+
+PREFIX ?= /usr
+BINDIR ?= bin
+INSTALL ?= install
+
+TARGET = kernel-chktaint
+
+all: $(TARGET)
+
+clean:
+
+install: kernel-chktaint
+ $(INSTALL) -D -m 755 $(TARGET) $(DESTDIR)$(PREFIX)/$(BINDIR)/$(TARGET)
+
diff --git a/tools/debugging/kernel-chktaint b/tools/debugging/kernel-chktaint
new file mode 100644
index 000000000000..98861858b192
--- /dev/null
+++ b/tools/debugging/kernel-chktaint
@@ -0,0 +1,199 @@
+#! /bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Randy Dunlap <rdunlap@infradead.org>, 2018
+# Thorsten Leemhuis <linux@leemhuis.info>, 2018
+
+usage()
+{
+ cat <<EOF
+usage: ${0##*/}
+ ${0##*/} <int>
+
+Call without parameters to decode /proc/sys/kernel/tainted.
+
+Call with a positive integer as parameter to decode a value you
+retrieved from /proc/sys/kernel/tainted on another system.
+
+EOF
+}
+
+if [ "$1"x != "x" ]; then
+ if [ "$1"x == "--helpx" ] || [ "$1"x == "-hx" ] ; then
+ usage
+ exit 1
+ elif [ $1 -ge 0 ] 2>/dev/null ; then
+ taint=$1
+ else
+ echo "Error: Parameter '$1' not a positive interger. Aborting." >&2
+ exit 1
+ fi
+else
+ TAINTFILE="/proc/sys/kernel/tainted"
+ if [ ! -r $TAINTFILE ]; then
+ echo "No file: $TAINTFILE"
+ exit
+ fi
+
+ taint=`cat $TAINTFILE`
+fi
+
+if [ $taint -eq 0 ]; then
+ echo "Kernel not Tainted"
+ exit
+else
+ echo "Kernel is Tainted for following reasons:"
+fi
+
+T=$taint
+out=
+
+addout() {
+ out=$out$1
+}
+
+if [ `expr $T % 2` -eq 0 ]; then
+ addout "G"
+else
+ addout "P"
+ echo " * Proprietary module was loaded."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "F"
+ echo " * Module was force loaded."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "S"
+ echo " * SMP kernel oops on an officially SMP incapable processor."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "R"
+ echo " * Module was force unloaded."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "M"
+ echo " * Processor reported a Machine Check Exception (MCE)."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "B"
+ echo " * Bad page referenced or some unexpected page flags."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "U"
+ echo " * Taint requested by userspace application."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "D"
+ echo " * Kernel died recently, i.e. there was an OOPS or BUG"
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "A"
+ echo " * ACPI table overridden by user."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "W"
+ echo " * Kernel issued warning."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "C"
+ echo " * Staging driver was loaded."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "I"
+ echo " * Workaround for bug in platform firmware applied."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "O"
+ echo " * Externally-built ('out-of-tree') module was loaded"
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "E"
+ echo " * Unsigned module was loaded."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "L"
+ echo " * Soft lockup occurred."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "K"
+ echo " * Kernel live patched."
+fi
+
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "X"
+ echo " * Auxiliary taint, defined for and used by distros."
+
+fi
+T=`expr $T / 2`
+if [ `expr $T % 2` -eq 0 ]; then
+ addout " "
+else
+ addout "T"
+ echo " * Kernel was built with the struct randomization plugin."
+fi
+
+echo "Raw taint value as int/string: $taint/'$out'"
+#EOF#