11 Jun, 2018
1 commit
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Pull restartable sequence support from Thomas Gleixner:
"The restartable sequences syscall (finally):After a lot of back and forth discussion and massive delays caused by
the speculative distraction of maintainers, the core set of
restartable sequences has finally reached a consensus.It comes with the basic non disputed core implementation along with
support for arm, powerpc and x86 and a full set of selftestsIt was exposed to linux-next earlier this week, so it does not fully
comply with the merge window requirements, but there is really no
point to drag it out for yet another cycle"* 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rseq/selftests: Provide Makefile, scripts, gitignore
rseq/selftests: Provide parametrized tests
rseq/selftests: Provide basic percpu ops test
rseq/selftests: Provide basic test
rseq/selftests: Provide rseq library
selftests/lib.mk: Introduce OVERRIDE_TARGETS
powerpc: Wire up restartable sequences system call
powerpc: Add syscall detection for restartable sequences
powerpc: Add support for restartable sequences
x86: Wire up restartable sequence system call
x86: Add support for restartable sequences
arm: Wire up restartable sequences system call
arm: Add syscall detection for restartable sequences
arm: Add restartable sequences support
rseq: Introduce restartable sequences system call
uapi/headers: Provide types_32_64.h
08 Jun, 2018
1 commit
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Pull powerpc updates from Michael Ellerman:
"Notable changes:- Support for split PMD page table lock on 64-bit Book3S (Power8/9).
- Add support for HAVE_RELIABLE_STACKTRACE, so we properly support
live patching again.- Add support for patching barrier_nospec in copy_from_user() and
syscall entry.- A couple of fixes for our data breakpoints on Book3S.
- A series from Nick optimising TLB/mm handling with the Radix MMU.
- Numerous small cleanups to squash sparse/gcc warnings from Mathieu
Malaterre.- Several series optimising various parts of the 32-bit code from
Christophe Leroy.- Removal of support for two old machines, "SBC834xE" and "C2K"
("GEFanuc,C2K"), which is why the diffstat has so many deletions.And many other small improvements & fixes.
There's a few out-of-area changes. Some minor ftrace changes OK'ed by
Steve, and a fix to our powernv cpuidle driver. Then there's a series
touching mm, x86 and fs/proc/task_mmu.c, which cleans up some details
around pkey support. It was ack'ed/reviewed by Ingo & Dave and has
been in next for several weeks.Thanks to: Akshay Adiga, Alastair D'Silva, Alexey Kardashevskiy, Al
Viro, Andrew Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Arnd
Bergmann, Balbir Singh, Cédric Le Goater, Christophe Leroy, Christophe
Lombard, Colin Ian King, Dave Hansen, Fabio Estevam, Finn Thain,
Frederic Barrat, Gautham R. Shenoy, Haren Myneni, Hari Bathini, Ingo
Molnar, Jonathan Neuschäfer, Josh Poimboeuf, Kamalesh Babulal,
Madhavan Srinivasan, Mahesh Salgaonkar, Mark Greer, Mathieu Malaterre,
Matthew Wilcox, Michael Neuling, Michal Suchanek, Naveen N. Rao,
Nicholas Piggin, Nicolai Stange, Olof Johansson, Paul Gortmaker, Paul
Mackerras, Peter Rosin, Pridhiviraj Paidipeddi, Ram Pai, Rashmica
Gupta, Ravi Bangoria, Russell Currey, Sam Bobroff, Samuel
Mendoza-Jonas, Segher Boessenkool, Shilpasri G Bhat, Simon Guo,
Souptick Joarder, Stewart Smith, Thiago Jung Bauermann, Torsten Duwe,
Vaibhav Jain, Wei Yongjun, Wolfram Sang, Yisheng Xie, YueHaibing"* tag 'powerpc-4.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (251 commits)
powerpc/64s/radix: Fix missing ptesync in flush_cache_vmap
cpuidle: powernv: Fix promotion from snooze if next state disabled
powerpc: fix build failure by disabling attribute-alias warning in pci_32
ocxl: Fix missing unlock on error in afu_ioctl_enable_p9_wait()
powerpc-opal: fix spelling mistake "Uniterrupted" -> "Uninterrupted"
powerpc: fix spelling mistake: "Usupported" -> "Unsupported"
powerpc/pkeys: Detach execute_only key on !PROT_EXEC
powerpc/powernv: copy/paste - Mask SO bit in CR
powerpc: Remove core support for Marvell mv64x60 hostbridges
powerpc/boot: Remove core support for Marvell mv64x60 hostbridges
powerpc/boot: Remove support for Marvell mv64x60 i2c controller
powerpc/boot: Remove support for Marvell MPSC serial controller
powerpc/embedded6xx: Remove C2K board support
powerpc/lib: optimise PPC32 memcmp
powerpc/lib: optimise 32 bits __clear_user()
powerpc/time: inline arch_vtime_task_switch()
powerpc/Makefile: set -mcpu=860 flag for the 8xx
powerpc: Implement csum_ipv6_magic in assembly
powerpc/32: Optimise __csum_partial()
powerpc/lib: Adjust .balign inside string functions for PPC32
...
06 Jun, 2018
1 commit
-
Expose a new system call allowing each thread to register one userspace
memory area to be used as an ABI between kernel and user-space for two
purposes: user-space restartable sequences and quick access to read the
current CPU number value from user-space.* Restartable sequences (per-cpu atomics)
Restartables sequences allow user-space to perform update operations on
per-cpu data without requiring heavy-weight atomic operations.The restartable critical sections (percpu atomics) work has been started
by Paul Turner and Andrew Hunter. It lets the kernel handle restart of
critical sections. [1] [2] The re-implementation proposed here brings a
few simplifications to the ABI which facilitates porting to other
architectures and speeds up the user-space fast path.Here are benchmarks of various rseq use-cases.
Test hardware:
arm32: ARMv7 Processor rev 4 (v7l) "Cubietruck", 2-core
x86-64: Intel E5-2630 v3@2.40GHz, 16-core, hyperthreadingThe following benchmarks were all performed on a single thread.
* Per-CPU statistic counter increment
getcpu+atomic (ns/op) rseq (ns/op) speedup
arm32: 344.0 31.4 11.0
x86-64: 15.3 2.0 7.7* LTTng-UST: write event 32-bit header, 32-bit payload into tracer
per-cpu buffergetcpu+atomic (ns/op) rseq (ns/op) speedup
arm32: 2502.0 2250.0 1.1
x86-64: 117.4 98.0 1.2* liburcu percpu: lock-unlock pair, dereference, read/compare word
getcpu+atomic (ns/op) rseq (ns/op) speedup
arm32: 751.0 128.5 5.8
x86-64: 53.4 28.6 1.9* jemalloc memory allocator adapted to use rseq
Using rseq with per-cpu memory pools in jemalloc at Facebook (based on
rseq 2016 implementation):The production workload response-time has 1-2% gain avg. latency, and
the P99 overall latency drops by 2-3%.* Reading the current CPU number
Speeding up reading the current CPU number on which the caller thread is
running is done by keeping the current CPU number up do date within the
cpu_id field of the memory area registered by the thread. This is done
by making scheduler preemption set the TIF_NOTIFY_RESUME flag on the
current thread. Upon return to user-space, a notify-resume handler
updates the current CPU value within the registered user-space memory
area. User-space can then read the current CPU number directly from
memory.Keeping the current cpu id in a memory area shared between kernel and
user-space is an improvement over current mechanisms available to read
the current CPU number, which has the following benefits over
alternative approaches:- 35x speedup on ARM vs system call through glibc
- 20x speedup on x86 compared to calling glibc, which calls vdso
executing a "lsl" instruction,
- 14x speedup on x86 compared to inlined "lsl" instruction,
- Unlike vdso approaches, this cpu_id value can be read from an inline
assembly, which makes it a useful building block for restartable
sequences.
- The approach of reading the cpu id through memory mapping shared
between kernel and user-space is portable (e.g. ARM), which is not the
case for the lsl-based x86 vdso.On x86, yet another possible approach would be to use the gs segment
selector to point to user-space per-cpu data. This approach performs
similarly to the cpu id cache, but it has two disadvantages: it is
not portable, and it is incompatible with existing applications already
using the gs segment selector for other purposes.Benchmarking various approaches for reading the current CPU number:
ARMv7 Processor rev 4 (v7l)
Machine model: Cubietruck
- Baseline (empty loop): 8.4 ns
- Read CPU from rseq cpu_id: 16.7 ns
- Read CPU from rseq cpu_id (lazy register): 19.8 ns
- glibc 2.19-0ubuntu6.6 getcpu: 301.8 ns
- getcpu system call: 234.9 nsx86-64 Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz:
- Baseline (empty loop): 0.8 ns
- Read CPU from rseq cpu_id: 0.8 ns
- Read CPU from rseq cpu_id (lazy register): 0.8 ns
- Read using gs segment selector: 0.8 ns
- "lsl" inline assembly: 13.0 ns
- glibc 2.19-0ubuntu6 getcpu: 16.6 ns
- getcpu system call: 53.9 ns- Speed (benchmark taken on v8 of patchset)
Running 10 runs of hackbench -l 100000 seems to indicate, contrary to
expectations, that enabling CONFIG_RSEQ slightly accelerates the
scheduler:Configuration: 2 sockets * 8-core Intel(R) Xeon(R) CPU E5-2630 v3 @
2.40GHz (directly on hardware, hyperthreading disabled in BIOS, energy
saving disabled in BIOS, turboboost disabled in BIOS, cpuidle.off=1
kernel parameter), with a Linux v4.6 defconfig+localyesconfig,
restartable sequences series applied.* CONFIG_RSEQ=n
avg.: 41.37 s
std.dev.: 0.36 s* CONFIG_RSEQ=y
avg.: 40.46 s
std.dev.: 0.33 s- Size
On x86-64, between CONFIG_RSEQ=n/y, the text size increase of vmlinux is
567 bytes, and the data size increase of vmlinux is 5696 bytes.[1] https://lwn.net/Articles/650333/
[2] http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1695/original/LPC%20-%20PerCpu%20Atomics.pdfSigned-off-by: Mathieu Desnoyers
Signed-off-by: Thomas Gleixner
Acked-by: Peter Zijlstra (Intel)
Cc: Joel Fernandes
Cc: Catalin Marinas
Cc: Dave Watson
Cc: Will Deacon
Cc: Andi Kleen
Cc: "H . Peter Anvin"
Cc: Chris Lameter
Cc: Russell King
Cc: Andrew Hunter
Cc: Michael Kerrisk
Cc: "Paul E . McKenney"
Cc: Paul Turner
Cc: Boqun Feng
Cc: Josh Triplett
Cc: Steven Rostedt
Cc: Ben Maurer
Cc: Alexander Viro
Cc: linux-api@vger.kernel.org
Cc: Andy Lutomirski
Cc: Andrew Morton
Cc: Linus Torvalds
Link: http://lkml.kernel.org/r/20151027235635.16059.11630.stgit@pjt-glaptop.roam.corp.google.com
Link: http://lkml.kernel.org/r/20150624222609.6116.86035.stgit@kitami.mtv.corp.google.com
Link: https://lkml.kernel.org/r/20180602124408.8430-3-mathieu.desnoyers@efficios.com
10 May, 2018
1 commit
-
Signed-off-by: Al Viro
[mpe: Update sys_ni.c for s/ppc_rtas/sys_rtas/]
Signed-off-by: Michael Ellerman
03 May, 2018
1 commit
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This is the io_getevents equivalent of ppoll/pselect and allows to
properly mix signals and aio completions (especially with IOCB_CMD_POLL)
and atomically executes the following sequence:sigset_t origmask;
pthread_sigmask(SIG_SETMASK, &sigmask, &origmask);
ret = io_getevents(ctx, min_nr, nr, events, timeout);
pthread_sigmask(SIG_SETMASK, &origmask, NULL);Note that unlike many other signal related calls we do not pass a sigmask
size, as that would get us to 7 arguments, which aren't easily supported
by the syscall infrastructure. It seems a lot less painful to just add a
new syscall variant in the unlikely case we're going to increase the
sigset size.Signed-off-by: Christoph Hellwig
Reviewed-by: Greg Kroah-Hartman
Reviewed-by: Darrick J. Wong
05 Apr, 2018
1 commit
-
It may be useful for an architecture to override the definitions of the
COMPAT_SYSCALL_DEFINE0() and __COMPAT_SYSCALL_DEFINEx() macros in
, in particular to use a different calling convention
for syscalls. This patch provides a mechanism to do so, based on the
previously introduced CONFIG_ARCH_HAS_SYSCALL_WRAPPER. If it is enabled,
is included in and may be used
to define the macros mentioned above. Moreover, as the syscall calling
convention may be different if CONFIG_ARCH_HAS_SYSCALL_WRAPPER is set,
the compat syscall function prototypes in are #ifndef'd
out in that case.As some of the syscalls and/or compat syscalls may not be present,
the COND_SYSCALL() and COND_SYSCALL_COMPAT() macros in kernel/sys_ni.c
as well as the SYS_NI() and COMPAT_SYS_NI() macros in
kernel/time/posix-stubs.c can be re-defined in iff
CONFIG_ARCH_HAS_SYSCALL_WRAPPER is enabled.Signed-off-by: Dominik Brodowski
Acked-by: Linus Torvalds
Cc: Al Viro
Cc: Andrew Morton
Cc: Andy Lutomirski
Cc: Borislav Petkov
Cc: Brian Gerst
Cc: Denys Vlasenko
Cc: H. Peter Anvin
Cc: Josh Poimboeuf
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/20180405095307.3730-5-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar
03 Apr, 2018
3 commits
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This keeps it in line with the SYSCALL_DEFINEx() / COMPAT_SYSCALL_DEFINEx()
calling convention.Signed-off-by: Dominik Brodowski
-
Shuffle the cond_syscall() entries in kernel/sys_ni.c around so that they
are kept in the same order as in include/uapi/asm-generic/unistd.h. For
better structuring, add the same comments as in that file, but keep a few
additional comments and extend the commentary where it seems useful.Signed-off-by: Dominik Brodowski
-
While sys32_quotactl() is only needed on x86, it can use the recommended
COMPAT_SYSCALL_DEFINEx() machinery for its setup.Acked-by: Jan Kara
Cc: Christoph Hellwig
Signed-off-by: Dominik Brodowski
02 Nov, 2017
1 commit
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
23 Dec, 2016
1 commit
-
... and fix the minor buglet in compat io_submit() - native one
kills ioctx as cleanup when put_user() fails. Get rid of
bogus compat_... in !CONFIG_AIO case, while we are at it - they
should simply fail with ENOSYS, same as for native counterparts.Signed-off-by: Al Viro
13 Sep, 2016
1 commit
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Guenter Roeck reported breakage on the h8300 and c6x architectures (among
others) caused by the new memory protection keys syscalls. This patch does
what Arnd suggested and adds them to kernel/sys_ni.c.Fixes: a60f7b69d92c ("generic syscalls: Wire up memory protection keys syscalls")
Reported-and-tested-by: Guenter Roeck
Signed-off-by: Dave Hansen
Acked-by: Arnd Bergmann
Cc: linux-arch@vger.kernel.org
Cc: Dave Hansen
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/20160912203842.48E7AC50@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner
02 Dec, 2015
1 commit
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Add a copy_file_range() system call for offloading copies between
regular files.This gives an interface to underlying layers of the storage stack which
can copy without reading and writing all the data. There are a few
candidates that should support copy offloading in the nearer term:- btrfs shares extent references with its clone ioctl
- NFS has patches to add a COPY command which copies on the server
- SCSI has a family of XCOPY commands which copy in the deviceThis system call avoids the complexity of also accelerating the creation
of the destination file by operating on an existing destination file
descriptor, not a path.Currently the high level vfs entry point limits copy offloading to files
on the same mount and super (and not in the same file). This can be
relaxed if we get implementations which can copy between file systems
safely.Signed-off-by: Zach Brown
[Anna Schumaker: Change -EINVAL to -EBADF during file verification,
Change flags parameter from int to unsigned int,
Add function to include/linux/syscalls.h,
Check copy len after file open mode,
Don't forbid ranges inside the same file,
Use rw_verify_area() to veriy ranges,
Use file_out rather than file_in,
Add COPY_FR_REFLINK flag]
Signed-off-by: Anna Schumaker
Reviewed-by: Christoph Hellwig
Signed-off-by: Al Viro
06 Nov, 2015
1 commit
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With the refactored mlock code, introduce a new system call for mlock.
The new call will allow the user to specify what lock states are being
added. mlock2 is trivial at the moment, but a follow on patch will add a
new mlock state making it useful.Signed-off-by: Eric B Munson
Acked-by: Michal Hocko
Acked-by: Vlastimil Babka
Cc: Heiko Carstens
Cc: Geert Uytterhoeven
Cc: Catalin Marinas
Cc: Stephen Rothwell
Cc: Guenter Roeck
Cc: Jonathan Corbet
Cc: Kirill A. Shutemov
Cc: Michael Kerrisk
Cc: Ralf Baechle
Cc: Shuah Khan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Sep, 2015
1 commit
-
Here is an implementation of a new system call, sys_membarrier(), which
executes a memory barrier on all threads running on the system. It is
implemented by calling synchronize_sched(). It can be used to
distribute the cost of user-space memory barriers asymmetrically by
transforming pairs of memory barriers into pairs consisting of
sys_membarrier() and a compiler barrier. For synchronization primitives
that distinguish between read-side and write-side (e.g. userspace RCU
[1], rwlocks), the read-side can be accelerated significantly by moving
the bulk of the memory barrier overhead to the write-side.The existing applications of which I am aware that would be improved by
this system call are as follows:* Through Userspace RCU library (http://urcu.so)
- DNS server (Knot DNS) https://www.knot-dns.cz/
- Network sniffer (http://netsniff-ng.org/)
- Distributed object storage (https://sheepdog.github.io/sheepdog/)
- User-space tracing (http://lttng.org)
- Network storage system (https://www.gluster.org/)
- Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf)
- Financial software (https://lkml.org/lkml/2015/3/23/189)Those projects use RCU in userspace to increase read-side speed and
scalability compared to locking. Especially in the case of RCU used by
libraries, sys_membarrier can speed up the read-side by moving the bulk of
the memory barrier cost to synchronize_rcu().* Direct users of sys_membarrier
- core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198)Microsoft core dotnet GC developers are planning to use the mprotect()
side-effect of issuing memory barriers through IPIs as a way to implement
Windows FlushProcessWriteBuffers() on Linux. They are referring to
sys_membarrier in their github thread, specifically stating that
sys_membarrier() is what they are looking for.To explain the benefit of this scheme, let's introduce two example threads:
Thread A (non-frequent, e.g. executing liburcu synchronize_rcu())
Thread B (frequent, e.g. executing liburcu
rcu_read_lock()/rcu_read_unlock())In a scheme where all smp_mb() in thread A are ordering memory accesses
with respect to smp_mb() present in Thread B, we can change each
smp_mb() within Thread A into calls to sys_membarrier() and each
smp_mb() within Thread B into compiler barriers "barrier()".Before the change, we had, for each smp_mb() pairs:
Thread A Thread B
previous mem accesses previous mem accesses
smp_mb() smp_mb()
following mem accesses following mem accessesAfter the change, these pairs become:
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accessesAs we can see, there are two possible scenarios: either Thread B memory
accesses do not happen concurrently with Thread A accesses (1), or they
do (2).1) Non-concurrent Thread A vs Thread B accesses:
Thread A Thread B
prev mem accesses
sys_membarrier()
follow mem accesses
prev mem accesses
barrier()
follow mem accessesIn this case, thread B accesses will be weakly ordered. This is OK,
because at that point, thread A is not particularly interested in
ordering them with respect to its own accesses.2) Concurrent Thread A vs Thread B accesses
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accessesIn this case, thread B accesses, which are ensured to be in program
order thanks to the compiler barrier, will be "upgraded" to full
smp_mb() by synchronize_sched().* Benchmarks
On Intel Xeon E5405 (8 cores)
(one thread is calling sys_membarrier, the other 7 threads are busy
looping)1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call.
* User-space user of this system call: Userspace RCU library
Both the signal-based and the sys_membarrier userspace RCU schemes
permit us to remove the memory barrier from the userspace RCU
rcu_read_lock() and rcu_read_unlock() primitives, thus significantly
accelerating them. These memory barriers are replaced by compiler
barriers on the read-side, and all matching memory barriers on the
write-side are turned into an invocation of a memory barrier on all
active threads in the process. By letting the kernel perform this
synchronization rather than dumbly sending a signal to every process
threads (as we currently do), we diminish the number of unnecessary wake
ups and only issue the memory barriers on active threads. Non-running
threads do not need to execute such barrier anyway, because these are
implied by the scheduler context switches.Results in liburcu:
Operations in 10s, 6 readers, 2 writers:
memory barriers in reader: 1701557485 reads, 2202847 writes
signal-based scheme: 9830061167 reads, 6700 writes
sys_membarrier: 9952759104 reads, 425 writes
sys_membarrier (dyn. check): 7970328887 reads, 425 writesThe dynamic sys_membarrier availability check adds some overhead to
the read-side compared to the signal-based scheme, but besides that,
sys_membarrier slightly outperforms the signal-based scheme. However,
this non-expedited sys_membarrier implementation has a much slower grace
period than signal and memory barrier schemes.Besides diminishing the number of wake-ups, one major advantage of the
membarrier system call over the signal-based scheme is that it does not
need to reserve a signal. This plays much more nicely with libraries,
and with processes injected into for tracing purposes, for which we
cannot expect that signals will be unused by the application.An expedited version of this system call can be added later on to speed
up the grace period. Its implementation will likely depend on reading
the cpu_curr()->mm without holding each CPU's rq lock.This patch adds the system call to x86 and to asm-generic.
[1] http://urcu.so
membarrier(2) man page:
MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2)
NAME
membarrier - issue memory barriers on a set of threadsSYNOPSIS
#includeint membarrier(int cmd, int flags);
DESCRIPTION
The cmd argument is one of the following:MEMBARRIER_CMD_QUERY
Query the set of supported commands. It returns a bitmask of
supported commands.MEMBARRIER_CMD_SHARED
Execute a memory barrier on all threads running on the system.
Upon return from system call, the caller thread is ensured that
all running threads have passed through a state where all memory
accesses to user-space addresses match program order between
entry to and return from the system call (non-running threads
are de facto in such a state). This covers threads from all pro=E2=80=90
cesses running on the system. This command returns 0.The flags argument needs to be 0. For future extensions.
All memory accesses performed in program order from each targeted
thread is guaranteed to be ordered with respect to sys_membarrier(). If
we use the semantic "barrier()" to represent a compiler barrier forcing
memory accesses to be performed in program order across the barrier,
and smp_mb() to represent explicit memory barriers forcing full memory
ordering across the barrier, we have the following ordering table for
each pair of barrier(), sys_membarrier() and smp_mb():The pair ordering is detailed as (O: ordered, X: not ordered):
barrier() smp_mb() sys_membarrier()
barrier() X X O
smp_mb() X O O
sys_membarrier() O O ORETURN VALUE
On success, these system calls return zero. On error, -1 is returned,
and errno is set appropriately. For a given command, with flags
argument set to 0, this system call is guaranteed to always return the
same value until reboot.ERRORS
ENOSYS System call is not implemented.EINVAL Invalid arguments.
Linux 2015-04-15 MEMBARRIER(2)
Signed-off-by: Mathieu Desnoyers
Reviewed-by: Paul E. McKenney
Reviewed-by: Josh Triplett
Cc: KOSAKI Motohiro
Cc: Steven Rostedt
Cc: Nicholas Miell
Cc: Ingo Molnar
Cc: Alan Cox
Cc: Lai Jiangshan
Cc: Stephen Hemminger
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: David Howells
Cc: Pranith Kumar
Cc: Michael Kerrisk
Cc: Shuah Khan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Sep, 2015
1 commit
-
This activates the userfaultfd syscall.
[sfr@canb.auug.org.au: activate syscall fix]
[akpm@linux-foundation.org: don't enable userfaultfd on powerpc]
Signed-off-by: Andrea Arcangeli
Acked-by: Pavel Emelyanov
Cc: Sanidhya Kashyap
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov"
Cc: Andres Lagar-Cavilla
Cc: Dave Hansen
Cc: Paolo Bonzini
Cc: Rik van Riel
Cc: Mel Gorman
Cc: Andy Lutomirski
Cc: Hugh Dickins
Cc: Peter Feiner
Cc: "Dr. David Alan Gilbert"
Cc: Johannes Weiner
Cc: "Huangpeng (Peter)"
Signed-off-by: Stephen Rothwell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
31 Jul, 2015
1 commit
-
The modify_ldt syscall exposes a large attack surface and is
unnecessary for modern userspace. Make it optional.Signed-off-by: Andy Lutomirski
Reviewed-by: Kees Cook
Cc: Andrew Cooper
Cc: Andy Lutomirski
Cc: Boris Ostrovsky
Cc: Borislav Petkov
Cc: Brian Gerst
Cc: Denys Vlasenko
Cc: H. Peter Anvin
Cc: Jan Beulich
Cc: Konrad Rzeszutek Wilk
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Sasha Levin
Cc: Steven Rostedt
Cc: Thomas Gleixner
Cc: security@kernel.org
Cc: xen-devel
Link: http://lkml.kernel.org/r/a605166a771c343fd64802dece77a903507333bd.1438291540.git.luto@kernel.org
[ Made MATH_EMULATION dependent on MODIFY_LDT_SYSCALL. ]
Signed-off-by: Ingo Molnar
16 Apr, 2015
1 commit
-
There are a lot of embedded systems that run most or all of their
functionality in init, running as root:root. For these systems,
supporting multiple users is not necessary.This patch adds a new symbol, CONFIG_MULTIUSER, that makes support for
non-root users, non-root groups, and capabilities optional. It is enabled
under CONFIG_EXPERT menu.When this symbol is not defined, UID and GID are zero in any possible case
and processes always have all capabilities.The following syscalls are compiled out: setuid, setregid, setgid,
setreuid, setresuid, getresuid, setresgid, getresgid, setgroups,
getgroups, setfsuid, setfsgid, capget, capset.Also, groups.c is compiled out completely.
In kernel/capability.c, capable function was moved in order to avoid
adding two ifdef blocks.This change saves about 25 KB on a defconfig build. The most minimal
kernels have total text sizes in the high hundreds of kB rather than
low MB. (The 25k goes down a bit with allnoconfig, but not that much.The kernel was booted in Qemu. All the common functionalities work.
Adding users/groups is not possible, failing with -ENOSYS.Bloat-o-meter output:
add/remove: 7/87 grow/shrink: 19/397 up/down: 1675/-26325 (-24650)[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Iulia Manda
Reviewed-by: Josh Triplett
Acked-by: Geert Uytterhoeven
Tested-by: Paul E. McKenney
Reviewed-by: Paul E. McKenney
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Dec, 2014
1 commit
-
This patchset adds execveat(2) for x86, and is derived from Meredydd
Luff's patch from Sept 2012 (https://lkml.org/lkml/2012/9/11/528).The primary aim of adding an execveat syscall is to allow an
implementation of fexecve(3) that does not rely on the /proc filesystem,
at least for executables (rather than scripts). The current glibc version
of fexecve(3) is implemented via /proc, which causes problems in sandboxed
or otherwise restricted environments.Given the desire for a /proc-free fexecve() implementation, HPA suggested
(https://lkml.org/lkml/2006/7/11/556) that an execveat(2) syscall would be
an appropriate generalization.Also, having a new syscall means that it can take a flags argument without
back-compatibility concerns. The current implementation just defines the
AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW flags, but other flags could be
added in future -- for example, flags for new namespaces (as suggested at
https://lkml.org/lkml/2006/7/11/474).Related history:
- https://lkml.org/lkml/2006/12/27/123 is an example of someone
realizing that fexecve() is likely to fail in a chroot environment.
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514043 covered
documenting the /proc requirement of fexecve(3) in its manpage, to
"prevent other people from wasting their time".
- https://bugzilla.redhat.com/show_bug.cgi?id=241609 described a
problem where a process that did setuid() could not fexecve()
because it no longer had access to /proc/self/fd; this has since
been fixed.This patch (of 4):
Add a new execveat(2) system call. execveat() is to execve() as openat()
is to open(): it takes a file descriptor that refers to a directory, and
resolves the filename relative to that.In addition, if the filename is empty and AT_EMPTY_PATH is specified,
execveat() executes the file to which the file descriptor refers. This
replicates the functionality of fexecve(), which is a system call in other
UNIXen, but in Linux glibc it depends on opening "/proc/self/fd/" (and
so relies on /proc being mounted).The filename fed to the executed program as argv[0] (or the name of the
script fed to a script interpreter) will be of the form "/dev/fd/"
(for an empty filename) or "/dev/fd//", effectively
reflecting how the executable was found. This does however mean that
execution of a script in a /proc-less environment won't work; also, script
execution via an O_CLOEXEC file descriptor fails (as the file will not be
accessible after exec).Based on patches by Meredydd Luff.
Signed-off-by: David Drysdale
Cc: Meredydd Luff
Cc: Shuah Khan
Cc: "Eric W. Biederman"
Cc: Andy Lutomirski
Cc: Alexander Viro
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Kees Cook
Cc: Arnd Bergmann
Cc: Rich Felker
Cc: Christoph Hellwig
Cc: Michael Kerrisk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
19 Nov, 2014
1 commit
-
Add the new __NR_s390_pci_mmio_write and __NR_s390_pci_mmio_read
system calls to allow user space applications to access device PCI I/O
memory pages on s390x platform.[ Martin Schwidefsky: some code beautification ]
Signed-off-by: Alexey Ishchuk
Signed-off-by: Martin Schwidefsky
09 Oct, 2014
1 commit
-
Pull networking updates from David Miller:
"Most notable changes in here:1) By far the biggest accomplishment, thanks to a large range of
contributors, is the addition of multi-send for transmit. This is
the result of discussions back in Chicago, and the hard work of
several individuals.Now, when the ->ndo_start_xmit() method of a driver sees
skb->xmit_more as true, it can choose to defer the doorbell
telling the driver to start processing the new TX queue entires.skb->xmit_more means that the generic networking is guaranteed to
call the driver immediately with another SKB to send.There is logic added to the qdisc layer to dequeue multiple
packets at a time, and the handling mis-predicted offloads in
software is now done with no locks held.Finally, pktgen is extended to have a "burst" parameter that can
be used to test a multi-send implementation.Several drivers have xmit_more support: i40e, igb, ixgbe, mlx4,
virtio_netAdding support is almost trivial, so export more drivers to
support this optimization soon.I want to thank, in no particular or implied order, Jesper
Dangaard Brouer, Eric Dumazet, Alexander Duyck, Tom Herbert, Jamal
Hadi Salim, John Fastabend, Florian Westphal, Daniel Borkmann,
David Tat, Hannes Frederic Sowa, and Rusty Russell.2) PTP and timestamping support in bnx2x, from Michal Kalderon.
3) Allow adjusting the rx_copybreak threshold for a driver via
ethtool, and add rx_copybreak support to enic driver. From
Govindarajulu Varadarajan.4) Significant enhancements to the generic PHY layer and the bcm7xxx
driver in particular (EEE support, auto power down, etc.) from
Florian Fainelli.5) Allow raw buffers to be used for flow dissection, allowing drivers
to determine the optimal "linear pull" size for devices that DMA
into pools of pages. The objective is to get exactly the
necessary amount of headers into the linear SKB area pre-pulled,
but no more. The new interface drivers use is eth_get_headlen().
From WANG Cong, with driver conversions (several had their own
by-hand duplicated implementations) by Alexander Duyck and Eric
Dumazet.6) Support checksumming more smoothly and efficiently for
encapsulations, and add "foo over UDP" facility. From Tom
Herbert.7) Add Broadcom SF2 switch driver to DSA layer, from Florian
Fainelli.8) eBPF now can load programs via a system call and has an extensive
testsuite. Alexei Starovoitov and Daniel Borkmann.9) Major overhaul of the packet scheduler to use RCU in several major
areas such as the classifiers and rate estimators. From John
Fastabend.10) Add driver for Intel FM10000 Ethernet Switch, from Alexander
Duyck.11) Rearrange TCP_SKB_CB() to reduce cache line misses, from Eric
Dumazet.12) Add Datacenter TCP congestion control algorithm support, From
Florian Westphal.13) Reorganize sk_buff so that __copy_skb_header() is significantly
faster. From Eric Dumazet"* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1558 commits)
netlabel: directly return netlbl_unlabel_genl_init()
net: add netdev_txq_bql_{enqueue, complete}_prefetchw() helpers
net: description of dma_cookie cause make xmldocs warning
cxgb4: clean up a type issue
cxgb4: potential shift wrapping bug
i40e: skb->xmit_more support
net: fs_enet: Add NAPI TX
net: fs_enet: Remove non NAPI RX
r8169:add support for RTL8168EP
net_sched: copy exts->type in tcf_exts_change()
wimax: convert printk to pr_foo()
af_unix: remove 0 assignment on static
ipv6: Do not warn for informational ICMP messages, regardless of type.
Update Intel Ethernet Driver maintainers list
bridge: Save frag_max_size between PRE_ROUTING and POST_ROUTING
tipc: fix bug in multicast congestion handling
net: better IFF_XMIT_DST_RELEASE support
net/mlx4_en: remove NETDEV_TX_BUSY
3c59x: fix bad split of cpu_to_le32(pci_map_single())
net: bcmgenet: fix Tx ring priority programming
...
27 Sep, 2014
1 commit
-
done as separate commit to ease conflict resolution
Signed-off-by: Alexei Starovoitov
Signed-off-by: David S. Miller
18 Aug, 2014
1 commit
-
Many embedded systems will not need these syscalls, and omitting them
saves space. Add a new EXPERT config option CONFIG_ADVISE_SYSCALLS
(default y) to support compiling them out.bloat-o-meter:
add/remove: 0/3 grow/shrink: 0/0 up/down: 0/-2250 (-2250)
function old new delta
sys_fadvise64 57 - -57
sys_fadvise64_64 691 - -691
sys_madvise 1502 - -1502Signed-off-by: Josh Triplett
09 Aug, 2014
2 commits
-
This is the new syscall kexec_file_load() declaration/interface. I have
reserved the syscall number only for x86_64 so far. Other architectures
(including i386) can reserve syscall number when they enable the support
for this new syscall.Signed-off-by: Vivek Goyal
Cc: Michael Kerrisk
Cc: Borislav Petkov
Cc: Yinghai Lu
Cc: Eric Biederman
Cc: H. Peter Anvin
Cc: Matthew Garrett
Cc: Greg Kroah-Hartman
Cc: Dave Young
Cc: WANG Chao
Cc: Baoquan He
Cc: Andy Lutomirski
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
memfd_create() is similar to mmap(MAP_ANON), but returns a file-descriptor
that you can pass to mmap(). It can support sealing and avoids any
connection to user-visible mount-points. Thus, it's not subject to quotas
on mounted file-systems, but can be used like malloc()'ed memory, but with
a file-descriptor to it.memfd_create() returns the raw shmem file, so calls like ftruncate() can
be used to modify the underlying inode. Also calls like fstat() will
return proper information and mark the file as regular file. If you want
sealing, you can specify MFD_ALLOW_SEALING. Otherwise, sealing is not
supported (like on all other regular files).Compared to O_TMPFILE, it does not require a tmpfs mount-point and is not
subject to a filesystem size limit. It is still properly accounted to
memcg limits, though, and to the same overcommit or no-overcommit
accounting as all user memory.Signed-off-by: David Herrmann
Acked-by: Hugh Dickins
Cc: Michael Kerrisk
Cc: Ryan Lortie
Cc: Lennart Poettering
Cc: Daniel Mack
Cc: Andy Lutomirski
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
19 Jul, 2014
1 commit
-
This adds the new "seccomp" syscall with both an "operation" and "flags"
parameter for future expansion. The third argument is a pointer value,
used with the SECCOMP_SET_MODE_FILTER operation. Currently, flags must
be 0. This is functionally equivalent to prctl(PR_SET_SECCOMP, ...).In addition to the TSYNC flag later in this patch series, there is a
non-zero chance that this syscall could be used for configuring a fixed
argument area for seccomp-tracer-aware processes to pass syscall arguments
in the future. Hence, the use of "seccomp" not simply "seccomp_add_filter"
for this syscall. Additionally, this syscall uses operation, flags,
and user pointer for arguments because strictly passing arguments via
a user pointer would mean seccomp itself would be unable to trivially
filter the seccomp syscall itself.Signed-off-by: Kees Cook
Reviewed-by: Oleg Nesterov
Reviewed-by: Andy Lutomirski
05 Jun, 2014
1 commit
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sys_sgetmask and sys_ssetmask are obsolete system calls no longer
supported in libc.This patch replaces architecture related __ARCH_WANT_SYS_SGETMAX by expert
mode configuration.That option is enabled by default for those
architectures.Signed-off-by: Fabian Frederick
Cc: Steven Miao
Cc: Mikael Starvik
Cc: Jesper Nilsson
Cc: David Howells
Cc: Geert Uytterhoeven
Cc: Michal Simek
Cc: Ralf Baechle
Cc: Koichi Yasutake
Cc: "James E.J. Bottomley"
Cc: Helge Deller
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: "David S. Miller"
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Greg Ungerer
Cc: Heiko Carstens
Cc: Oleg Nesterov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Apr, 2014
2 commits
-
uselib hasn't been used since libc5; glibc does not use it. Support
turning it off.When disabled, also omit the load_elf_library implementation from
binfmt_elf.c, which only uselib invokes.bloat-o-meter:
add/remove: 0/4 grow/shrink: 0/1 up/down: 0/-785 (-785)
function old new delta
padzero 39 36 -3
uselib_flags 20 - -20
sys_uselib 168 - -168
SyS_uselib 168 - -168
load_elf_library 426 - -426The new CONFIG_USELIB defaults to `y'.
Signed-off-by: Josh Triplett
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
sys_sysfs is an obsolete system call no longer supported by libc.
- This patch adds a default CONFIG_SYSFS_SYSCALL=y
- Option can be turned off in expert mode.
- cond_syscall added to kernel/sys_ni.c
[akpm@linux-foundation.org: tweak Kconfig help text]
Signed-off-by: Fabian Frederick
Cc: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
10 May, 2013
1 commit
-
Signed-off-by: Al Viro
04 Mar, 2013
2 commits
-
Signed-off-by: Al Viro
-
Signed-off-by: Al Viro
14 Dec, 2012
1 commit
-
As part of the effort to create a stronger boundary between root and
kernel, Chrome OS wants to be able to enforce that kernel modules are
being loaded only from our read-only crypto-hash verified (dm_verity)
root filesystem. Since the init_module syscall hands the kernel a module
as a memory blob, no reasoning about the origin of the blob can be made.Earlier proposals for appending signatures to kernel modules would not be
useful in Chrome OS, since it would involve adding an additional set of
keys to our kernel and builds for no good reason: we already trust the
contents of our root filesystem. We don't need to verify those kernel
modules a second time. Having to do signature checking on module loading
would slow us down and be redundant. All we need to know is where a
module is coming from so we can say yes/no to loading it.If a file descriptor is used as the source of a kernel module, many more
things can be reasoned about. In Chrome OS's case, we could enforce that
the module lives on the filesystem we expect it to live on. In the case
of IMA (or other LSMs), it would be possible, for example, to examine
extended attributes that may contain signatures over the contents of
the module.This introduces a new syscall (on x86), similar to init_module, that has
only two arguments. The first argument is used as a file descriptor to
the module and the second argument is a pointer to the NULL terminated
string of module arguments.Signed-off-by: Kees Cook
Cc: Andrew Morton
Signed-off-by: Rusty Russell (merge fixes)
01 Jun, 2012
1 commit
-
While doing the checkpoint-restore in the user space one need to determine
whether various kernel objects (like mm_struct-s of file_struct-s) are
shared between tasks and restore this state.The 2nd step can be solved by using appropriate CLONE_ flags and the
unshare syscall, while there's currently no ways for solving the 1st one.One of the ways for checking whether two tasks share e.g. mm_struct is to
provide some mm_struct ID of a task to its proc file, but showing such
info considered to be not that good for security reasons.Thus after some debates we end up in conclusion that using that named
'comparison' syscall might be the best candidate. So here is it --
__NR_kcmp.It takes up to 5 arguments - the pids of the two tasks (which
characteristics should be compared), the comparison type and (in case of
comparison of files) two file descriptors.Lookups for pids are done in the caller's PID namespace only.
At moment only x86 is supported and tested.
[akpm@linux-foundation.org: fix up selftests, warnings]
[akpm@linux-foundation.org: include errno.h]
[akpm@linux-foundation.org: tweak comment text]
Signed-off-by: Cyrill Gorcunov
Acked-by: "Eric W. Biederman"
Cc: Pavel Emelyanov
Cc: Andrey Vagin
Cc: KOSAKI Motohiro
Cc: Ingo Molnar
Cc: H. Peter Anvin
Cc: Thomas Gleixner
Cc: Glauber Costa
Cc: Andi Kleen
Cc: Tejun Heo
Cc: Matt Helsley
Cc: Pekka Enberg
Cc: Eric Dumazet
Cc: Vasiliy Kulikov
Cc: Alexey Dobriyan
Cc: Valdis.Kletnieks@vt.edu
Cc: Michal Marek
Cc: Frederic Weisbecker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Nov, 2011
1 commit
-
The basic idea behind cross memory attach is to allow MPI programs doing
intra-node communication to do a single copy of the message rather than a
double copy of the message via shared memory.The following patch attempts to achieve this by allowing a destination
process, given an address and size from a source process, to copy memory
directly from the source process into its own address space via a system
call. There is also a symmetrical ability to copy from the current
process's address space into a destination process's address space.- Use of /proc/pid/mem has been considered, but there are issues with
using it:
- Does not allow for specifying iovecs for both src and dest, assuming
preadv or pwritev was implemented either the area read from or
written to would need to be contiguous.
- Currently mem_read allows only processes who are currently
ptrace'ing the target and are still able to ptrace the target to read
from the target. This check could possibly be moved to the open call,
but its not clear exactly what race this restriction is stopping
(reason appears to have been lost)
- Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix
domain socket is a bit ugly from a userspace point of view,
especially when you may have hundreds if not (eventually) thousands
of processes that all need to do this with each other
- Doesn't allow for some future use of the interface we would like to
consider adding in the future (see below)
- Interestingly reading from /proc/pid/mem currently actually
involves two copies! (But this could be fixed pretty easily)As mentioned previously use of vmsplice instead was considered, but has
problems. Since you need the reader and writer working co-operatively if
the pipe is not drained then you block. Which requires some wrapping to
do non blocking on the send side or polling on the receive. In all to all
communication it requires ordering otherwise you can deadlock. And in the
example of many MPI tasks writing to one MPI task vmsplice serialises the
copying.There are some cases of MPI collectives where even a single copy interface
does not get us the performance gain we could. For example in an
MPI_Reduce rather than copy the data from the source we would like to
instead use it directly in a mathops (say the reduce is doing a sum) as
this would save us doing a copy. We don't need to keep a copy of the data
from the source. I haven't implemented this, but I think this interface
could in the future do all this through the use of the flags - eg could
specify the math operation and type and the kernel rather than just
copying the data would apply the specified operation between the source
and destination and store it in the destination.Although we don't have a "second user" of the interface (though I've had
some nibbles from people who may be interested in using it for intra
process messaging which is not MPI). This interface is something which
hardware vendors are already doing for their custom drivers to implement
fast local communication. And so in addition to this being useful for
OpenMPI it would mean the driver maintainers don't have to fix things up
when the mm changes.There was some discussion about how much faster a true zero copy would
go. Here's a link back to the email with some testing I did on that:http://marc.info/?l=linux-mm&m=130105930902915&w=2
There is a basic man page for the proposed interface here:
http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt
This has been implemented for x86 and powerpc, other architecture should
mainly (I think) just need to add syscall numbers for the process_vm_readv
and process_vm_writev. There are 32 bit compatibility versions for
64-bit kernels.For arch maintainers there are some simple tests to be able to quickly
verify that the syscalls are working correctly here:http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgz
Signed-off-by: Chris Yeoh
Cc: Ingo Molnar
Cc: "H. Peter Anvin"
Cc: Thomas Gleixner
Cc: Arnd Bergmann
Cc: Paul Mackerras
Cc: Benjamin Herrenschmidt
Cc: David Howells
Cc: James Morris
Cc:
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Aug, 2011
1 commit
-
The nfsservctl system call is now gone, so we should remove all
linkage for it.Signed-off-by: NeilBrown
Signed-off-by: J. Bruce Fields
Signed-off-by: Linus Torvalds
21 May, 2011
1 commit
-
When building with:
CONFIG_64BIT=y
CONFIG_MIPS32_COMPAT=y
CONFIG_COMPAT=y
CONFIG_MIPS32_O32=y
CONFIG_MIPS32_N32=y
CONFIG_SYSVIPC is not set
(and implicitly: CONFIG_SYSVIPC_COMPAT is not set)the final link fails with unresolved symbols for:
compat_sys_semctl, compat_sys_msgsnd, compat_sys_msgrcv,
compat_sys_shmctl, compat_sys_msgctl, compat_sys_semtimedopThe fix is to add cond_syscall declarations for all syscalls in
ipc/compat.cSigned-off-by: Kevin Cernekee
Acked-by: Ralf Baechle
Acked-by: Arnd Bergmann
Cc: Andrew Morton
Cc: Al Viro
Cc: Stephen Rothwell
Signed-off-by: Linus Torvalds
06 May, 2011
1 commit
-
This patch adds a multiple message send syscall and is the send
version of the existing recvmmsg syscall. This is heavily
based on the patch by Arnaldo that added recvmmsg.I wrote a microbenchmark to test the performance gains of using
this new syscall:http://ozlabs.org/~anton/junkcode/sendmmsg_test.c
The test was run on a ppc64 box with a 10 Gbit network card. The
benchmark can send both UDP and RAW ethernet packets.64B UDP
batch pkts/sec
1 804570
2 872800 (+ 8 %)
4 916556 (+14 %)
8 939712 (+17 %)
16 952688 (+18 %)
32 956448 (+19 %)
64 964800 (+20 %)64B raw socket
batch pkts/sec
1 1201449
2 1350028 (+12 %)
4 1461416 (+22 %)
8 1513080 (+26 %)
16 1541216 (+28 %)
32 1553440 (+29 %)
64 1557888 (+30 %)We see a 20% improvement in throughput on UDP send and 30%
on raw socket send.[ Add sparc syscall entries. -DaveM ]
Signed-off-by: Anton Blanchard
Signed-off-by: David S. Miller
15 Mar, 2011
2 commits
-
[AV: duplicate of open() guts removed; file_open_root() used instead]
Signed-off-by: Aneesh Kumar K.V
Signed-off-by: Al Viro -
The syscall also return mount id which can be used
to lookup file system specific information such as uuid
in /proc//mountinfoSigned-off-by: Aneesh Kumar K.V
Signed-off-by: Al Viro
