16 Oct, 2016
1 commit
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Pull gcc plugins update from Kees Cook:
"This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot
time as possible, hoping to capitalize on any possible variation in
CPU operation (due to runtime data differences, hardware differences,
SMP ordering, thermal timing variation, cache behavior, etc).At the very least, this plugin is a much more comprehensive example
for how to manipulate kernel code using the gcc plugin internals"* tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
latent_entropy: Mark functions with __latent_entropy
gcc-plugins: Add latent_entropy plugin
15 Oct, 2016
2 commits
-
Pull misc kbuild changes from Michal Marek:
"Just a few patches on the kbuild.git#misc branch this time:- New Coccinelle patch by Nicholas Mc Guire
- Existing patch fixes by Julia Lawall
- Minor comment fix by Markus Elfring"* 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
Coccinelle: flag conditions with no effect
scripts/coccicheck: Update reference for the corresponding documentation
Coccinelle: pm_runtime: ensure relevance of pm_runtime reports
Coccinelle: limit memdup_user transformation to GFP_KERNEL case -
Pull kbuild updates from Michal Marek:
- EXPORT_SYMBOL for asm source by Al Viro.
This does bring a regression, because genksyms no longer generates
checksums for these symbols (CONFIG_MODVERSIONS). Nick Piggin is
working on a patch to fix this.Plus, we are talking about functions like strcpy(), which rarely
change prototypes.- Fixes for PPC fallout of the above by Stephen Rothwell and Nick
Piggin- fixdep speedup by Alexey Dobriyan.
- preparatory work by Nick Piggin to allow architectures to build with
-ffunction-sections, -fdata-sections and --gc-sections- CONFIG_THIN_ARCHIVES support by Stephen Rothwell
- fix for filenames with colons in the initramfs source by me.
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (22 commits)
initramfs: Escape colons in depfile
ppc: there is no clear_pages to export
powerpc/64: whitelist unresolved modversions CRCs
kbuild: -ffunction-sections fix for archs with conflicting sections
kbuild: add arch specific post-link Makefile
kbuild: allow archs to select link dead code/data elimination
kbuild: allow architectures to use thin archives instead of ld -r
kbuild: Regenerate genksyms lexer
kbuild: genksyms fix for typeof handling
fixdep: faster CONFIG_ search
ia64: move exports to definitions
sparc32: debride memcpy.S a bit
[sparc] unify 32bit and 64bit string.h
sparc: move exports to definitions
ppc: move exports to definitions
arm: move exports to definitions
s390: move exports to definitions
m68k: move exports to definitions
alpha: move exports to actual definitions
x86: move exports to actual definitions
...
12 Oct, 2016
14 commits
-
Vim, with the omnicppcomplete(#1) plugin, can do code completion using
information build by ctags. Add flags needed by omnicppcomplete(#2) to
have completion on member of structure.1: https://github.com/vim-scripts/omnicppcomplete
2: https://github.com/vim-scripts/OmniCppComplete/blob/master/doc/omnicppcomplete.txt#L93Link: http://lkml.kernel.org/r/20160830191546.4469-1-mathieu.maret@gmail.com
Signed-off-by: Mathieu Maret
Cc: Michal Marek
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The function calls with octal permissions commonly span multiple lines.
The current test is line oriented and fails to find some matches.Make the test use the $stat variable instead of the $line variable to span
multiple lines.Also add a few functions to the known functions with permissions list.
Move the SYMBOLIC_PERMS test to a separate section to find all the S_
permissions in any form not just those that have specific function names.This can now find and fix permissions uses like:
.mode = S_ | S_;Link: http://lkml.kernel.org/r/b51bab60530912aae4ac420119d465c5b206f19f.1475030406.git.joe@perches.com
Signed-off-by: Joe Perches
Tested-by: Ramiro Oliveira
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Function definitions without identifiers like
int foo(int)
are not preferred. Emit a warning when they occur.Link: http://lkml.kernel.org/r/94fe6378504745991b650f48fc92bb4648f25706.1474925354.git.joe@perches.com
Signed-off-by: Joe Perches
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
It is possible for a multiple line macro definition to have a false positive
report when an argument is used on a line after a continuation \.This line might have a leading '+' as the initial character that could be
confused by checkpatch as an operator.Avoid the leading character on multiple line macro definitions.
Link: http://lkml.kernel.org/r/60229d13399f9b6509db5a32e30d4c16951a60cd.1473836073.git.joe@perches.com
Signed-off-by: Joe Perches
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add a test for macro arguents that have a non-comma leading or trailing
operator where the argument isn't parenthesized to avoid possible precedence
issues.Link: http://lkml.kernel.org/r/47715508972f8d786f435e583ff881dbeee3a114.1473745855.git.joe@perches.com
Signed-off-by: Joe Perches
Cc: Andy Whitcroft
Cc: Julia Lawall
Cc: Dan Carpenter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
If a macro argument is used multiple times in the macro definition, the
macro argument may have an unexpected side-effect.Add a test (MACRO_ARG_REUSE) for that condition which is only
emitted with command-line option --strict.Link: http://lkml.kernel.org/r/b6d67a87cafcafd15499e91780dc63b15dec0aa0.1473744906.git.joe@perches.com
Signed-off-by: Joe Perches
Cc: Andy Whitcroft
Cc: Julia Lawall
Cc: Dan Carpenter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
An "uninitialized value" is emitted when a block comment starts on
the same line as a statement.Fix this and make the test use a little fewer cpu cycles too.
Link: http://lkml.kernel.org/r/3c9993320c2182d37f53ac540878cfef59c3f62d.1473365956.git.joe@perches.com
Signed-off-by: Joe Perches
Reported-by: Charlemagne Lasse
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Adding -f to the get_maintainer.pl invocation means git isn't invoked
by get_maintainer.pl for known filenames.This reduces the overall time to run checkpatch.
Link: http://lkml.kernel.org/r/22991e3a295aeb399b43af0478b6e5809106ccee.1472684066.git.joe@perches.com
Signed-off-by: Joe Perches
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Using const is generally a good idea.
Julia Lawall has created a list of always const and almost always const
structs in the kernel sources.Link: https://lkml.org/lkml/2016/8/28/95
Add the most frequently used (> 50 cases) that are almost always or
always const.Link: http://lkml.kernel.org/r/1e16020f8027654db0095bbfbcc11da51025365c.1472664220.git.joe@perches.com
Signed-off-by: Joe Perches
Acked-by: Kees Cook
Cc: Julia Lawall
Cc: Andy Whitcroft
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Make it easier to add new structs that should be const.
Link: http://lkml.kernel.org/r/e5a8da43e7c11525bafbda1ca69a8323614dd942.1472664220.git.joe@perches.com
Signed-off-by: Joe Perches
Cc: Julia Lawall
Cc: Kees Cook
Cc: Andy Whitcroft
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
< sigh > Comment these tests out.
These are just too enticing to people that don't verify that
both source and dest addresses really must be __aligned(2).It helps make Dan Carpenter happy too.
Link: http://lkml.kernel.org/r/dc32ec66d24647f4cdf824c8dfbbc59aa7ce7b7d.1472665676.git.joe@perches.com
Signed-off-by: Joe Perches
Cc: Dan Carpenter
Cc: Greg
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Warn when block comments are not aligned on the *
/*
* block comment, no warning
*//*
* block comment, emit warning
*/Link: http://lkml.kernel.org/r/edb57bd330adfe024b95ec2a807d4aa7f0c8b112.1472261299.git.joe@perches.com
Signed-off-by: Joe Perches
Reported-by: Sudip Mukherjee
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
S_ uses should be avoided where octal is more intelligible.
Linus didst say:
: It's *much* easier to parse and understand the octal numbers, while the
: symbolic macro names are just random line noise and hard as hell to
: understand. You really have to think about it.
:
: So we should rather go the other way: convert existing bad symbolic
: permission bit macro use to just use the octal numbers.
:
: The symbolic names are good for the *other* bits (ie sticky bit, and the
: inode mode _type_ numbers etc), but for the permission bits, the symbolic
: names are just insane crap. Nobody sane should ever use them. Not in the
: kernel, not in user space.
(http://lkml.kernel.org/r/CA+55aFw5v23T-zvDZp-MmD_EYxF8WbafwwB59934FV7g21uMGQ@mail.gmail.com)Link: http://lkml.kernel.org/r/7232ef011d05a92f4caa86a5e9830d87966a2eaf.1470180926.git.joe@perches.com
Signed-off-by: Joe Perches
Cc: Linus Torvalds
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Use get_maintainer to check the status of individual files. If
"obsolete", suggest leaving the files alone.Link: http://lkml.kernel.org/r/7ceaa510dc9d2df05ec4b456baed7bb1415550b3.1471889575.git.joe@perches.com
Signed-off-by: Joe Perches
Cc: SF Markus Elfring
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Oct, 2016
3 commits
-
Report code constructs where the if and else branch are functionally
identical. In cases where this is intended it really should be
documented - most reported cases probably are bugs.Signed-off-by: Nicholas Mc Guire
Signed-off-by: Michal Marek -
Use the current name (in a comment at the beginning of this script) for
the file which was converted to the documentation format "reStructuredText"
in August 2016.Fixes: 4b9033a33494 ("docs: sphinxify coccinelle.txt and add it to dev-tools")
Signed-off-by: Markus Elfring
Acked-by: Julia Lawall
Signed-off-by: Michal Marek -
This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot time as
possible, hoping to capitalize on any possible variation in CPU operation
(due to runtime data differences, hardware differences, SMP ordering,
thermal timing variation, cache behavior, etc).At the very least, this plugin is a much more comprehensive example for
how to manipulate kernel code using the gcc plugin internals.The need for very-early boot entropy tends to be very architecture or
system design specific, so this plugin is more suited for those sorts
of special cases. The existing kernel RNG already attempts to extract
entropy from reliable runtime variation, but this plugin takes the idea to
a logical extreme by permuting a global variable based on any variation
in code execution (e.g. a different value (and permutation function)
is used to permute the global based on loop count, case statement,
if/then/else branching, etc).To do this, the plugin starts by inserting a local variable in every
marked function. The plugin then adds logic so that the value of this
variable is modified by randomly chosen operations (add, xor and rol) and
random values (gcc generates separate static values for each location at
compile time and also injects the stack pointer at runtime). The resulting
value depends on the control flow path (e.g., loops and branches taken).Before the function returns, the plugin mixes this local variable into
the latent_entropy global variable. The value of this global variable
is added to the kernel entropy pool in do_one_initcall() and _do_fork(),
though it does not credit any bytes of entropy to the pool; the contents
of the global are just used to mix the pool.Additionally, the plugin can pre-initialize arrays with build-time
random contents, so that two different kernel builds running on identical
hardware will not have the same starting values.Signed-off-by: Emese Revfy
[kees: expanded commit message and code comments]
Signed-off-by: Kees Cook
08 Oct, 2016
2 commits
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No need to correct the correct.
Link: http://lkml.kernel.org/r/1472490791.3425.38.camel@perches.com
Signed-off-by: Joe Perches
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When doing an nmi backtrace of many cores, most of which are idle, the
output is a little overwhelming and very uninformative. Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the interrupted
PC to see if it lies within that section.This commit suitably tags x86 and tile idle routines, and only adds in
the minimal framework for other architectures.Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com
Signed-off-by: Chris Metcalf
Acked-by: Peter Zijlstra (Intel)
Tested-by: Peter Zijlstra (Intel)
Tested-by: Daniel Thompson [arm]
Tested-by: Petr Mladek
Cc: Aaron Tomlin
Cc: Peter Zijlstra (Intel)
Cc: "Rafael J. Wysocki"
Cc: Russell King
Cc: Thomas Gleixner
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
07 Oct, 2016
1 commit
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Pull tracing updates from Steven Rostedt:
"This release cycle is rather small. Just a few fixes to tracing.The big change is the addition of the hwlat tracer. It not only
detects SMIs, but also other latency that's caused by the hardware. I
have detected some latency from large boxes having bus contention"* tag 'trace-v4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Call traceoff trigger after event is recorded
ftrace/scripts: Add helper script to bisect function tracing problem functions
tracing: Have max_latency be defined for HWLAT_TRACER as well
tracing: Add NMI tracing in hwlat detector
tracing: Have hwlat trace migrate across tracing_cpumask CPUs
tracing: Add documentation for hwlat_detector tracer
tracing: Added hardware latency tracer
ftrace: Access ret_stack->subtime only in the function profiler
function_graph: Handle TRACE_BPUTS in print_graph_comment
tracing/uprobe: Drop isdigit() check in create_trace_uprobe
05 Oct, 2016
2 commits
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Pull s390 updates from Martin Schwidefsky:
"The new features and main improvements in this merge for v4.9- Support for the UBSAN sanitizer
- Set HAVE_EFFICIENT_UNALIGNED_ACCESS, it improves the code in some
places- Improvements for the in-kernel fpu code, in particular the overhead
for multiple consecutive in kernel fpu users is recuded- Add a SIMD implementation for the RAID6 gen and xor operations
- Add RAID6 recovery based on the XC instruction
- The PCI DMA flush logic has been improved to increase the speed of
the map / unmap operations- The time synchronization code has seen some updates
And bug fixes all over the place"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (48 commits)
s390/con3270: fix insufficient space padding
s390/con3270: fix use of uninitialised data
MAINTAINERS: update DASD maintainer
s390/cio: fix accidental interrupt enabling during resume
s390/dasd: add missing \n to end of dev_err messages
s390/config: Enable config options for Docker
s390/dasd: make query host access interruptible
s390/dasd: fix panic during offline processing
s390/dasd: fix hanging offline processing
s390/pci_dma: improve lazy flush for unmap
s390/pci_dma: split dma_update_trans
s390/pci_dma: improve map_sg
s390/pci_dma: simplify dma address calculation
s390/pci_dma: remove dma address range check
iommu/s390: simplify registration of I/O address translation parameters
s390: migrate exception table users off module.h and onto extable.h
s390: export header for CLP ioctl
s390/vmur: fix irq pointer dereference in int handler
s390/dasd: add missing KOBJ_CHANGE event for unformatted devices
s390: enable UBSAN
... -
Pull documentation updates from Jonathan Corbet:
"This is the documentation update pull for the 4.9 merge window.The Sphinx transition is still creating a fair amount of work. Here we
have a number of fixes and, importantly, a proper PDF output solution,
thanks to Jani Nikula, Mauro Carvalho Chehab and Markus Heiser.I've started a couple of new books: a driver API book (based on the
old device-drivers.tmpl) and a development tools book. Both are meant
to show how we can integrate together our existing documentation into
a more coherent and accessible whole. It involves moving some stuff
around and formatting changes, but, I think, the results are worth it.
The good news is that most of our existing Documentation/*.txt files
are *almost* in RST format already; the amount of messing around
required is minimal.And, of course, there's the usual set of updates, typo fixes, and
more"* tag 'docs-4.9' of git://git.lwn.net/linux: (120 commits)
URL changed for Linux Foundation TAB
dax : Fix documentation with respect to struct pages
iio: Documentation: Correct the path used to create triggers.
docs: Remove space-before-label guidance from CodingStyle
docs-rst: add inter-document cross references
Documentation/email-clients.txt: convert it to ReST markup
Documentation/kernel-docs.txt: reorder based on timestamp
Documentation/kernel-docs.txt: Add dates for online docs
Documentation/kernel-docs.txt: get rid of broken docs
Documentation/kernel-docs.txt: move in-kernel docs
Documentation/kernel-docs.txt: remove more legacy references
Documentation/kernel-docs.txt: add two published books
Documentation/kernel-docs.txt: sort books per publication date
Documentation/kernel-docs.txt: adjust LDD references
Documentation/kernel-docs.txt: some improvements on the ReST output
Documentation/kernel-docs.txt: Consistent indenting: 4 spaces
Documentation/kernel-docs.txt: Add 4 paper/book references
Documentation/kernel-docs.txt: Improve layouting of book list
Documentation/kernel-docs.txt: Remove offline or outdated entries
docs: Clean up bare :: lines
...
04 Oct, 2016
1 commit
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Pull char/misc driver updates from Greg KH:
"Here's the "big" char and misc driver update for 4.9-rc1.Lots of little things here, all over the driver tree for subsystems
that flow through me. Nothing major that I can discern, full details
are in the shortlog.All have been in the linux-next tree with no reported issues"
* tag 'char-misc-4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (144 commits)
drivers/misc/hpilo: Changes to support new security states in iLO5 FW
at25: fix debug and error messaging
misc/genwqe: ensure zero initialization
vme: fake: remove unexpected unlock in fake_master_set()
vme: fake: mark symbols static where possible
spmi: pmic-arb: Return an error code if sanity check fails
Drivers: hv: get rid of id in struct vmbus_channel
Drivers: hv: make VMBus bus ids persistent
mcb: Add a dma_device to mcb_device
mcb: Enable PCI bus mastering by default
mei: stop the stall timer worker if not needed
clk: probe common clock drivers earlier
vme: fake: fix build for 64-bit dma_addr_t
ttyprintk: Neaten and simplify printing
mei: me: add kaby point device ids
coresight: tmc: mark symbols static where possible
coresight: perf: deal with error condition properly
Drivers: hv: hv_util: Avoid dynamic allocation in time synch
fpga manager: Add hardware dependency to Zynq driver
Drivers: hv: utils: Support TimeSync version 4.0 protocol samples.
...
02 Oct, 2016
2 commits
-
pm_runtime.cocci starts with one rule that searches for a variety of
functions calls, followed by various rules that report errors. Previously,
the only connection between the first rule and the rest was to check that
the first rule had matched somewhere. Change the rules to propagate a
position from the first rule to the others, to make sure that the sites
reported on are the same as the sites that were identified as having the
relevant functions.Signed-off-by: Julia Lawall
Signed-off-by: Michal Marek -
Memdup_user encapsulates a memory allocation with the flag GFP_KERNEL, so
only allow this flag in the original code.Signed-off-by: Julia Lawall
Signed-off-by: Michal Marek
29 Sep, 2016
1 commit
-
be7635e7287e ("arch, ftrace: for KASAN put hard/soft IRQ entries into
separate sections") added .softirqentry.text section, but it was not added
to recordmcount. So functions in the section are untracable. Add the
section to scripts/recordmcount.c and scripts/recordmcount.pl.Fixes: be7635e7287e ("arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections")
Link: http://lkml.kernel.org/r/1474902626-73468-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov
Acked-by: Steve Rostedt
Cc: [4.6+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Sep, 2016
1 commit
-
Special characters are problematic in depfiles, but we can fix colons
easily.Reported-by: Florian Fainelli
Signed-off-by: Michal Marek
22 Sep, 2016
1 commit
-
Every so often, with a special config or a architecture change, running
function or function_graph tracing can cause the machien to hard reboot,
crash, or simply hard lockup. There's some functions in the function graph
tracer that can not be traced otherwise it causes the function tracer to
recurse before the recursion protection mechanisms are in place.When this occurs, using the dynamic ftrace featuer that allows limiting what
actually gets traced can be used to bisect down to the problem function.
This adds a script that helps with this process in the scripts/tracing
directory, called ftrace-bisect.shThe set up is to read all the functions that can be traced from
available_filter_functions into a file (full_file). Then run this script
passing it the full_file and a "test_file" and "non_test_file", where the
test_file will be add to set_ftrace_filter. What ftarce_bisect.sh does, is
to copy half of the functions in full_file into the test_file and the other
half into the non_test_file. This way, one can cat the test_file into the
set_ftrace_filter functions and only test the functions that are in that
file. If it works, then we run the process again after copying non_test_file
to full_file and repeating the process. If the system crashed, then the bad
function is in the test_file and after a reboot, the test_file becomes the
new full_file in the next iteration.When we get down to a single function in the full_file, then
ftrace_bisect.sh will report that as the bad function.Full documentation of how to use this simple script is within the script
file itself.Link: http://lkml.kernel.org/r/20160920100716.131d3647@gandalf.local.home
Signed-off-by: Steven Rostedt
20 Sep, 2016
3 commits
-
Some architectures use a hardware defined structure at address zero.
Checking for a null pointer will result in many ubsan reports.
Allow users to disable the null sanitizer.Signed-off-by: Christian Borntraeger
Acked-by: Andrey Ryabinin
Signed-off-by: Heiko Carstens
Signed-off-by: Martin Schwidefsky -
Due to our compiler include directives, the build pathnames for header
files often end up being of the form "$srcdir/./include/linux/xyz.h",
which ends up having that extra "." path component after the build base
in it.Teach faddr2line to skip that too, to make code generated in inline
functions in header files match the filename for the regular C files.Rabin Vincent pointed out that I can't make a stricter regexp match by
using the " at " prefix for the pathname, because that ends up being
locale-dependent. But this does require that the path match be preceded
by a space, to make it a bit more strict (that matters mainly if we
didn't find any base_dir at all, and we only end up with the "./" part
of the match)Acked-by: Josh Poimboeuf
Cc: Rabin Vincent
Signed-off-by: Linus Torvalds -
addr2line doesn't work with KASLR addresses. Add a basic addr2line
wrapper script which takes the 'func+offset/size' format as input.Signed-off-by: Josh Poimboeuf
Signed-off-by: Linus Torvalds
09 Sep, 2016
2 commits
-
Allow architectures to create arch/xxx/Makefile.postlink with targets
for vmlinux, modules.ko, and clean, which will be invoked after final
linking of vmlinux and modules.powerpc will use this to check vmlinux linker relocations for sanity,
and may use it to fix up alternate instruction patch branch addresses.Signed-off-by: Nicholas Piggin
Signed-off-by: Michal Marek -
ld -r is an incremental link used to create built-in.o files in build
subdirectories. It produces relocatable object files containing all
its input files, and these are are then pulled together and relocated
in the final link. Aside from the bloat, this constrains the final
link relocations, which has bitten large powerpc builds with
unresolvable relocations in the final link.Alan Modra has recommended the kernel use thin archives for linking.
This is an alternative and means that the linker has more information
available to it when it links the kernel.This patch enables a config option architectures can select, which
causes all built-in.o files to be built as thin archives. built-in.o
files in subdirectories do not get symbol table or index attached,
which improves speed and size. The final link pass creates a
built-in.o archive in the root output directory which includes the
symbol table and index. The linker then uses takes this file to link.The --whole-archive linker option is required, because the linker now
has visibility to every individual object file, and it will otherwise
just completely avoid including those without external references
(consider a file with EXPORT_SYMBOL or initcall or hardware exceptions
as its only entry points). The traditional built works "by luck" as
built-in.o files are large enough that they're going to get external
references. However this optimisation is unpredictable for the kernel
(due to above external references), ineffective at culling unused, and
costly because the .o files have to be searched for references.
Superior alternatives for link-time culling should be used instead.Build characteristics for inclink vs thinarc, on a small powerpc64le
pseries VM with a modest .config:inclink thinarc
sizes
vmlinux 15 618 680 15 625 028
sum of all built-in.o 56 091 808 1 054 334
sum excluding root built-in.o 151 430find -name built-in.o | xargs rm ; time make vmlinux
real 22.772s 21.143s
user 13.280s 13.430s
sys 4.310s 2.750s- Final kernel pulled in only about 6K more, which shows how
ineffective the object file culling is.
- Build performance looks improved due to less pagecache activity.
On IO constrained systems it could be a bigger win.
- Build size saving is significant.Side note, the toochain understands archives, so there's some tricks,
$ ar t built-in.o # list all files you linked with
$ size built-in.o # and their sizes
$ objdump -d built-in.o # disassembly (unrelocated) with filenamesImplementation by sfr, minor tweaks by npiggin.
Signed-off-by: Stephen Rothwell
Signed-off-by: Nicholas Piggin
Signed-off-by: Michal Marek
06 Sep, 2016
3 commits
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Add yet another regex to kernel-doc to trap @param() references separately
and not produce corrupt RST markup.Signed-off-by: Jonathan Corbet
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As far as I can tell, the handling of "..." arguments has never worked
right, so any documentation provided was ignored in favor of "variable
arguments." This makes kernel-doc handle "@...:" as documented. It does
*not* fix spots in kerneldoc comments that don't follow that convention,
but they are no more broken than before.Signed-off-by: Jonathan Corbet
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Pull kbuild fix from Michal Marek:
"Fix for 'make deb-pkg'. The bug got introduced in v4.8-rc1"* 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
builddeb: Skip gcc-plugins when not configured
05 Sep, 2016
1 commit
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We want the fixes in here for merging and testing.
Signed-off-by: Greg Kroah-Hartman
