16 Feb, 2019
1 commit
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The upcoming GCC 9 release extends the -Wmissing-attributes warnings
(enabled by -Wall) to C and aliases: it warns when particular function
attributes are missing in the aliases but not in their target.In particular, it triggers here because crc32_le_base/__crc32c_le_base
aren't __pure while their target crc32_le/__crc32c_le are.These aliases are used by architectures as a fallback in accelerated
versions of CRC32. See commit 9784d82db3eb ("lib/crc32: make core crc32()
routines weak so they can be overridden").Therefore, being fallbacks, it is likely that even if the aliases
were called from C, there wouldn't be any optimizations possible.
Currently, the only user is arm64, which calls this from asm.Still, marking the aliases as __pure makes sense and is a good idea
for documentation purposes and possible future optimizations,
which also silences the warning.Acked-by: Ard Biesheuvel
Tested-by: Laura Abbott
Signed-off-by: Miguel Ojeda
10 Sep, 2018
1 commit
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Allow architectures to drop in accelerated CRC32 routines by making
the crc32_le/__crc32c_le entry points weak, and exposing non-weak
aliases for them that may be used by the accelerated versions as
fallbacks in case the instructions they rely upon are not available.Acked-by: Herbert Xu
Signed-off-by: Ard Biesheuvel
Signed-off-by: Catalin Marinas
27 Jul, 2018
2 commits
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Header was defining CRCPOLY_LE/BE and CRC32C_POLY_LE but in fact all of
them are CRC-32 polynomials so use consistent naming.Signed-off-by: Krzysztof Kozlowski
Signed-off-by: Herbert Xu -
Allow other drivers and parts of kernel to use the same define for
CRC32 polynomial, instead of duplicating it in many places. This code
does not bring any functional changes, except moving existing code.Signed-off-by: Krzysztof Kozlowski
Signed-off-by: Herbert Xu
27 Sep, 2017
1 commit
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Add the rest of the CRC library functions to kernel-api.
- try to clarify crc32() by adding '@' to a function parameter
- reorder kernel-api CRC functions to be less random
- add more CRC functions to kernel-api
- correct the function parameter names in several placesSigned-off-by: Randy Dunlap
Signed-off-by: Jonathan Corbet
25 Feb, 2017
1 commit
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Extract the crc32 test code into its own source file, to allow to
compile it either to a loadable module, or builtin into the kernel.Link: http://lkml.kernel.org/r/1483470276-10517-1-git-send-email-geert@linux-m68k.org
Signed-off-by: Geert Uytterhoeven
Reviewed-by: Andy Shevchenko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
03 Aug, 2016
1 commit
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The crc32 test function measures the elapsed time in nanoseconds, but
uses 'struct timespec' for that. We want to remove timespec from the
kernel for y2038 compatibility, and ktime_get_ns() also helps make the
code simpler here.It is also slightly better to use monontonic time, as we are only
interested in the time difference.Link: http://lkml.kernel.org/r/20160617143932.3289626-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann
Cc: "David S . Miller"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Jun, 2014
3 commits
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In case they help the compiler.
Signed-off-by: George Spelvin
Signed-off-by: Daniel Borkmann
Signed-off-by: David S. Miller -
So it gets discarded after the selftest.
Signed-off-by: George Spelvin
Signed-off-by: Daniel Borkmann
Signed-off-by: David S. Miller -
There's no need for a full 32x32 matrix, when rows before the last are
just shifted copies of the rows after them.There's still room for improvement (especially on X86 processors with
CRC32 and PCLMUL instructions), but this is a large step in the
right direction [which is in particular useful for its current user,
namely SCTP checksumming over multiple skb frags[] entries, i.e. in
IPVS balancing when other CRC32 offloads are not available].The internal primitive is now called crc32_generic_shift and takes one
less argument; the XOR with crc2 is done in inline wrappers.Signed-off-by: George Spelvin
Signed-off-by: Daniel Borkmann
Signed-off-by: David S. Miller
05 Jun, 2014
1 commit
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Use cpu_to_le32 instead of __constant_cpu_to_le32.
Signed-off-by: Fabian Frederick
Cc: "David S. Miller"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Nov, 2013
2 commits
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We can safely reduce the number of test cases by a tenth.
There is no particular need to run as many as we're running
now for crc32{,c}_combine, that gives us still ~8000 tests
we're doing if people run kernels with crc selftests enabled
which is perfectly fine.Signed-off-by: Daniel Borkmann
Signed-off-by: David S. Miller -
Fengguang reports that when crc32 selftests are running on startup, on
some e.g. 32bit systems, we can get a CPU stall like "INFO: rcu_sched
self-detected stall on CPU { 0} (t=2101 jiffies g=4294967081 c=4294967080
q=41)". As this is not intended, add a cond_resched() at the end of a
test case to fix it. Introduced by efba721f63 ("lib: crc32: add test cases
for crc32{, c}_combine routines").Reported-by: Fengguang Wu
Signed-off-by: Daniel Borkmann
Signed-off-by: David S. Miller
04 Nov, 2013
3 commits
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We already have 100 test cases for crcs itself, so split the test
buffer with a-prio known checksums, and test crc of two blocks
against crc of the whole block for the same results.Output/result with CONFIG_CRC32_SELFTEST=y:
[ 2.687095] crc32: CRC_LE_BITS = 64, CRC_BE BITS = 64
[ 2.687097] crc32: self tests passed, processed 225944 bytes in 278177 nsec
[ 2.687383] crc32c: CRC_LE_BITS = 64
[ 2.687385] crc32c: self tests passed, processed 225944 bytes in 141708 nsec
[ 7.336771] crc32_combine: 113072 self tests passed
[ 12.050479] crc32c_combine: 113072 self tests passed
[ 17.633089] alg: No test for crc32 (crc32-pclmul)Signed-off-by: Daniel Borkmann
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller -
This patch adds a combinator to merge two or more crc32{,c}s
into a new one. This is useful for checksum computations of
fragmented skbs that use crc32/crc32c as checksums.The arithmetics for combining both in the GF(2) was taken and
slightly modified from zlib. Only passing two crcs is insufficient
as two crcs and the length of the second piece is needed for
merging. The code is made generic, so that only polynomials
need to be passed for crc32_le resp. crc32c_le.Signed-off-by: Daniel Borkmann
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller -
This is nothing more but a whitepace cleanup, as 80 chars is not a
hard but soft limit, and otherwise makes the test cases array really
look ugly. So fix it up.Signed-off-by: Daniel Borkmann
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller
12 Sep, 2013
1 commit
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[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Gu Zheng
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Oct, 2012
1 commit
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Fix the const sections for the code generated by crc32 table. There's
no ro version of the cacheline aligned section, so we cannot put in
const data without a conflict Just don't make the crc tables const for
now.[ak@linux.intel.com: some fixes and new description]
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Joe Mario
Signed-off-by: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
31 Jul, 2012
1 commit
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Variables t4, t5, t6 and t7 are only used when CRC_LE_BITS != 32. Fix
the following compilation warnings:lib/crc32.c: In function 'crc32_body':
lib/crc32.c:77:55: warning: unused variable 't7'
lib/crc32.c:77:41: warning: unused variable 't6'
lib/crc32.c:77:27: warning: unused variable 't5'
lib/crc32.c:77:13: warning: unused variable 't4'Signed-off-by: Thiago Rafael Becker
Cc: "Darrick J. Wong"
Cc: Bob Pearson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
24 Mar, 2012
11 commits
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Add self-test code for crc32c.
Signed-off-by: Darrick J. Wong
Cc: Bob Pearson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Reuse the existing crc32 code to stamp out a crc32c implementation.
Signed-off-by: Darrick J. Wong
Cc: Herbert Xu
Cc: Bob Pearson
Cc: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add a comment at the top of crc32.c
[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add two changes that improve the performance of x86 systems
1. replace main loop with incrementing counter this change improves
the performance of the selftest by about 5-6% on Nehalem CPUs. The
apparent reason is that the compiler can use the loop index to perform
an indexed memory access. This is reported to make the performance of
PowerPC CPUs to get worse.2. replace the rem_len loop with incrementing counter this change
improves the performance of the selftest, which has more than the usual
number of occurances, by about 1-2% on x86 CPUs. In actual work loads
the length is most often a multiple of 4 bytes and this code does not
get executed as often if at all. Again this change is reported to make
the performance of PowerPC get worse.[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add slicing-by-8 algorithm to the existing slicing-by-4 algorithm. This
consists of:- extend largest BITS size from 32 to 64
- extend tables from tab[4][256] to up to tab[8][256]
- Add code for inner loop.[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
crc32.c provides a choice of one of several algorithms for computing the
LSB and LSB versions of the CRC32 checksum based on the parameters
CRC_LE_BITS and CRC_BE_BITS.In the original version the values 1, 2, 4 and 8 respectively selected
versions of the alrogithm that computed the crc 1, 2, 4 and 32 bits as a
time.This patch series adds a new version that computes the CRC 64 bits at a
time. To make things easier to understand the parameter has been
reinterpreted to actually stand for the number of bits processed in each
step of the algorithm so that the old value 8 has been replaced with the
value 32.This also allows us to add in a widely used crc algorithm that computes
the crc 8 bits at a time called the Sarwate algorithm.[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
crc32.c in its original version freely mixed u32, __le32 and __be32 types
which caused warnings from sparse with __CHECK_ENDIAN__. This patch fixes
these by forcing the types to u32.[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Misc cleanup of lib/crc32.c and related files.
- remove unnecessary header files.
- straighten out some convoluted ifdef's
- rewrite some references to 2 dimensional arrays as 1 dimensional
arrays to make them correct. I.e. replace tab[i] with tab[0][i].- a few trivial whitespace changes
- fix a warning in gen_crc32tables.c caused by a mismatch in the type of
the pointer passed to output table. Since the table is only used at
kernel compile time, it is simpler to make the table big enough to hold
the largest column size used. One cannot make the column size smaller
in output_table because it has to be used by both the le and be tables
and they can have different column sizes.[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Replace the unit test provided in crc32.c, which doesn't have a makefile
and doesn't compile with current headers, with a simpler self test
routine that also gives a measure of performance and runs at module init
time. The self test option can be enabled through a configuration
option CONFIG_CRC32_SELFTEST.The test stresses the pre and post loops and is thus not very realistic
since actual uses will likely have addresses and lengths that are at
least 4 byte aligned. However, the main loop is long enough so that the
performance is dominated by that loop.The expected values for crc32_le and crc32_be were generated with the
original version of crc32.c using CRC_BITS_LE = 8 and CRC_BITS_BE = 8.
These values were then used to check all the values of the BITS
parameters in both the original and new versions.The performance results show some variability from run to run in spite
of attempts to both warm the cache and reduce the amount of OS noise by
limiting interrutps during the test. To get comparable results and to
analyse options wrt performance the best time reported over a small
sample of runs has been taken.[djwong@us.ibm.com: Minor changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Move a long comment from lib/crc32.c to Documentation/crc32.txt where it
will more likely get read.Edited the resulting document to add an explanation of the slicing-by-n
algorithm.[djwong@us.ibm.com: minor changelog tweaks]
[akpm@linux-foundation.org: fix typo, per George]
Signed-off-by: George Spelvin
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patchset (re)uses Bob Pearson's crc32 slice-by-8 code to stamp out
a software crc32c implementation. It removes the crc32c implementation
in crypto/ in favor of using the stamped-out one in lib/. There is also
a change to Kconfig so that the kernel builder can pick an
implementation best suited for the hardware.The motivation for this patchset is that I am working on adding full
metadata checksumming to ext4. As far as performance impact of adding
checksumming goes, I see nearly no change with a standard mail server
ffsb simulation. On a test that involves only file creation and
deletion and extent tree writes, I see a drop of about 50 pcercent with
the current kernel crc32c implementation; this improves to a drop of
about 20 percent with the enclosed crc32c code.When metadata is usually a small fraction of total IO, this new
implementation doesn't help much because metadata is usually a small
fraction of total IO. However, when we are doing IO that is almost all
metadata (such as rm -rf'ing a tree), then this patch speeds up the
operation substantially.Incidentally, given that iscsi, sctp, and btrfs also use crc32c, this
patchset should improve their speed as well. I have not yet quantified
that, however. This latest submission combines Bob's patches from late
August 2011 with mine so that they can be one coherent patch set.
Please excuse my inability to combine some of the patches; I've been
advised to leave Bob's patches alone and build atop them instead. :/Since the last posting, I've also collected some crc32c test results on
a bunch of different x86/powerpc/sparc platforms. The results can be
viewed here: http://goo.gl/sgt3i ; the "crc32-kern-le" and "crc32c"
columns describe the performance of the kernel's current crc32 and
crc32c software implementations. The "crc32c-by8-le" column shows
crc32c performance with this patchset applied. I expect crc32
performance to be roughly the same.The two _boost columns at the right side of the spreadsheet shows how much
faster the new implementation is over the old one. As you can see, crc32
rises substantially, and crc32c experiences a huge increase.This patch:
- remove trailing whitespace from lib/crc32.c
- remove trailing whitespace from lib/crc32defs.h[djwong@us.ibm.com: changelog tweaks]
Signed-off-by: Bob Pearson
Signed-off-by: Darrick J. Wong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Jan, 2012
1 commit
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Taking a pointer reference to each row in the crc table matrix, one can
reduce the inner loop with a few insn'sSigned-off-by: Joakim Tjernlund
Cc: Bob Pearson
Cc: Frank Zago
Cc: Eric Dumazet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Jul, 2011
1 commit
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This allows us to move duplicated code in
(atomic_inc_not_zero() for now) toSigned-off-by: Arun Sharma
Reviewed-by: Eric Dumazet
Cc: Ingo Molnar
Cc: David Miller
Cc: Eric Dumazet
Acked-by: Mike Frysinger
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 May, 2010
1 commit
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It doesn't work on big-endian - those architectures don't define
__LITTLE_ENDIAN.Cc: Joakim Tjernlund
Reported-by: Stephen Rothwell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 May, 2010
2 commits
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Since crc32.c contains a nifty test program that can be executed in user
space, make sure endian detection works reliably in user space too.Signed-off-by: Joakim Tjernlund
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Precompute more crc32 values(0xcc00, 0xcc0000 and 0xcc000000) into tables.
This increases the table size from 1KB to 4KB but the performance benfit
makes it worth it:28% faster on MPC8321, 266 MHz
2x faster on Core 2 Duo, 3.1GHz[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Joakim Tjernlund
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
30 Mar, 2010
1 commit
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…it slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
07 Mar, 2010
1 commit
-
Signed-off-by: Joakim Tjernlund
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Dec, 2009
1 commit
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Move common crc body to new function crc32_body() cleaup and micro
optimize crc32_body for speed and less size.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Joakim Tjernlund
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
03 Feb, 2008
1 commit
-
Signed-off-by: Joe Perches
Signed-off-by: Adrian Bunk
19 Oct, 2007
1 commit
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To be consistent with the use of attributes in the rest of the kernel
replace all use of __attribute_pure__ with __pure and delete the definition
of __attribute_pure__.Signed-off-by: Ralf Baechle
Cc: Russell King
Acked-by: Mauro Carvalho Chehab
Cc: Bryan Wu
Cc: Paul Mackerras
Cc: Benjamin Herrenschmidt
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
