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  1. 19 7月, 2014 1 次提交
    • K
      seccomp: add "seccomp" syscall · 48dc92b9
      由 Kees Cook 提交于 
      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: NKees Cook <keescook@chromium.org>
Reviewed-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NAndy Lutomirski <luto@amacapital.net>
      48dc92b9
  3. 05 6月, 2014 1 次提交
    • F
      sys_sgetmask/sys_ssetmask: add CONFIG_SGETMASK_SYSCALL · f6187769
      由 Fabian Frederick 提交于 
      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: NFabian Frederick <fabf@skynet.be>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f6187769
  5. 04 4月, 2014 2 次提交
  7. 10 5月, 2013 1 次提交
  9. 04 3月, 2013 2 次提交
  11. 14 12月, 2012 1 次提交
    • K
      module: add syscall to load module from fd · 34e1169d
      由 Kees Cook 提交于 
      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: NKees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (merge fixes)
      34e1169d
  13. 01 6月, 2012 1 次提交
    • C
      syscalls, x86: add __NR_kcmp syscall · d97b46a6
      由 Cyrill Gorcunov 提交于 
      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: NCyrill Gorcunov <gorcunov@openvz.org>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Valdis.Kletnieks@vt.edu
Cc: Michal Marek <mmarek@suse.cz>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d97b46a6
  15. 01 11月, 2011 1 次提交
    • C
      Cross Memory Attach · fcf63409
      由 Christopher Yeoh 提交于 
      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.tgzSigned-off-by: NChris Yeoh <yeohc@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: <linux-man@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fcf63409
  17. 27 8月, 2011 1 次提交
  19. 21 5月, 2011 1 次提交
  21. 06 5月, 2011 1 次提交
    • A
      net: Add sendmmsg socket system call · 228e548e
      由 Anton Blanchard 提交于 
      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: NAnton Blanchard <anton@samba.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      228e548e
  23. 15 3月, 2011 2 次提交
  25. 23 9月, 2010 1 次提交
  27. 28 7月, 2010 2 次提交
  29. 13 3月, 2010 1 次提交
    • C
      Add generic sys_ipc wrapper · baed7fc9
      由 Christoph Hellwig 提交于 
      Add a generic implementation of the ipc demultiplexer syscall.  Except for
s390 and sparc64 all implementations of the sys_ipc are nearly identical.

There are slight differences in the types of the parameters, where mips
and powerpc as the only 64-bit architectures with sys_ipc use unsigned
long for the "third" argument as it gets casted to a pointer later, while
it traditionally is an "int" like most other paramters.  frv goes even
further and uses unsigned long for all parameters execept for "ptr" which
is a pointer type everywhere.  The change from int to unsigned long for
"third" and back to "int" for the others on frv should be fine due to the
in-register calling conventions for syscalls (we already had a similar
issue with the generic sys_ptrace), but I'd prefer to have the arch
maintainers looks over this in details.

Except for that h8300, m68k and m68knommu lack an impplementation of the
semtimedop sub call which this patch adds, and various architectures have
gets used - at least on i386 it seems superflous as the compat code on
x86-64 and ia64 doesn't even bother to implement it.

[akpm@linux-foundation.org: add sys_ipc to sys_ni.c]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Reviewed-by: NH. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Acked-by: NJesper Nilsson <jesper.nilsson@axis.com>
Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NKyle McMartin <kyle@mcmartin.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      baed7fc9
  31. 06 11月, 2009 1 次提交
  33. 13 10月, 2009 1 次提交
    • A
      net: Introduce recvmmsg socket syscall · a2e27255
      由 Arnaldo Carvalho de Melo 提交于 
      Meaning receive multiple messages, reducing the number of syscalls and
net stack entry/exit operations.

Next patches will introduce mechanisms where protocols that want to
optimize this operation will provide an unlocked_recvmsg operation.

This takes into account comments made by:

. Paul Moore: sock_recvmsg is called only for the first datagram,
  sock_recvmsg_nosec is used for the rest.

. Caitlin Bestler: recvmmsg now has a struct timespec timeout, that
  works in the same fashion as the ppoll one.

  If the underlying protocol returns a datagram with MSG_OOB set, this
  will make recvmmsg return right away with as many datagrams (+ the OOB
  one) it has received so far.

. Rémi Denis-Courmont & Steven Whitehouse: If we receive N < vlen
  datagrams and then recvmsg returns an error, recvmmsg will return
  the successfully received datagrams, store the error and return it
  in the next call.

This paves the way for a subsequent optimization, sk_prot->unlocked_recvmsg,
where we will be able to acquire the lock only at batch start and end, not at
every underlying recvmsg call.
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a2e27255
  35. 22 9月, 2009 1 次提交
  37. 21 9月, 2009 1 次提交
    • I
      perf: Do the big rename: Performance Counters -> Performance Events · cdd6c482
      由 Ingo Molnar 提交于 
      Bye-bye Performance Counters, welcome Performance Events!

In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.

Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.

All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)

The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.

Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.

User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)

This patch has been generated via the following script:

  FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

  sed -i \
    -e 's/PERF_EVENT_/PERF_RECORD_/g' \
    -e 's/PERF_COUNTER/PERF_EVENT/g' \
    -e 's/perf_counter/perf_event/g' \
    -e 's/nb_counters/nb_events/g' \
    -e 's/swcounter/swevent/g' \
    -e 's/tpcounter_event/tp_event/g' \
    $FILES

  for N in $(find . -name perf_counter.[ch]); do
    M=$(echo $N | sed 's/perf_counter/perf_event/g')
    mv $N $M
  done

  FILES=$(find . -name perf_event.*)

  sed -i \
    -e 's/COUNTER_MASK/REG_MASK/g' \
    -e 's/COUNTER/EVENT/g' \
    -e 's/\<event\>/event_id/g' \
    -e 's/counter/event/g' \
    -e 's/Counter/Event/g' \
    $FILES

... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.

Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.

( NOTE: 'counters' are still the proper terminology when we deal
  with hardware registers - and these sed scripts are a bit
  over-eager in renaming them. I've undone some of that, but
  in case there's something left where 'counter' would be
  better than 'event' we can undo that on an individual basis
  instead of touching an otherwise nicely automated patch. )
Suggested-by: NStephane Eranian <eranian@google.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Reviewed-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      cdd6c482
  39. 14 1月, 2009 1 次提交
  41. 08 12月, 2008 1 次提交
    • T
      performance counters: core code · 0793a61d
      由 Thomas Gleixner 提交于 
      Implement the core kernel bits of Performance Counters subsystem.

The Linux Performance Counter subsystem provides an abstraction of
performance counter hardware capabilities. It provides per task and per
CPU counters, and it provides event capabilities on top of those.

Performance counters are accessed via special file descriptors.
There's one file descriptor per virtual counter used.

The special file descriptor is opened via the perf_counter_open()
system call:

 int
 perf_counter_open(u32 hw_event_type,
                   u32 hw_event_period,
                   u32 record_type,
                   pid_t pid,
                   int cpu);

The syscall returns the new fd. The fd can be used via the normal
VFS system calls: read() can be used to read the counter, fcntl()
can be used to set the blocking mode, etc.

Multiple counters can be kept open at a time, and the counters
can be poll()ed.

See more details in Documentation/perf-counters.txt.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      0793a61d
  43. 20 11月, 2008 1 次提交
    • U
      reintroduce accept4 · de11defe
      由 Ulrich Drepper 提交于 
      Introduce a new accept4() system call.  The addition of this system call
matches analogous changes in 2.6.27 (dup3(), evenfd2(), signalfd4(),
inotify_init1(), epoll_create1(), pipe2()) which added new system calls
that differed from analogous traditional system calls in adding a flags
argument that can be used to access additional functionality.

The accept4() system call is exactly the same as accept(), except that
it adds a flags bit-mask argument.  Two flags are initially implemented.
(Most of the new system calls in 2.6.27 also had both of these flags.)

SOCK_CLOEXEC causes the close-on-exec (FD_CLOEXEC) flag to be enabled
for the new file descriptor returned by accept4().  This is a useful
security feature to avoid leaking information in a multithreaded
program where one thread is doing an accept() at the same time as
another thread is doing a fork() plus exec().  More details here:
http://udrepper.livejournal.com/20407.html "Secure File Descriptor Handling",
Ulrich Drepper).

The other flag is SOCK_NONBLOCK, which causes the O_NONBLOCK flag
to be enabled on the new open file description created by accept4().
(This flag is merely a convenience, saving the use of additional calls
fcntl(F_GETFL) and fcntl (F_SETFL) to achieve the same result.

Here's a test program.  Works on x86-32.  Should work on x86-64, but
I (mtk) don't have a system to hand to test with.

It tests accept4() with each of the four possible combinations of
SOCK_CLOEXEC and SOCK_NONBLOCK set/clear in 'flags', and verifies
that the appropriate flags are set on the file descriptor/open file
description returned by accept4().

I tested Ulrich's patch in this thread by applying against 2.6.28-rc2,
and it passes according to my test program.

/* test_accept4.c

  Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk
       <mtk.manpages@gmail.com>

  Licensed under the GNU GPLv2 or later.
*/
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>

#define PORT_NUM 33333

#define die(msg) do { perror(msg); exit(EXIT_FAILURE); } while (0)

/**********************************************************************/

/* The following is what we need until glibc gets a wrapper for
  accept4() */

/* Flags for socket(), socketpair(), accept4() */
#ifndef SOCK_CLOEXEC
#define SOCK_CLOEXEC    O_CLOEXEC
#endif
#ifndef SOCK_NONBLOCK
#define SOCK_NONBLOCK   O_NONBLOCK
#endif

#ifdef __x86_64__
#define SYS_accept4 288
#elif __i386__
#define USE_SOCKETCALL 1
#define SYS_ACCEPT4 18
#else
#error "Sorry -- don't know the syscall # on this architecture"
#endif

static int
accept4(int fd, struct sockaddr *sockaddr, socklen_t *addrlen, int flags)
{
   printf("Calling accept4(): flags = %x", flags);
   if (flags != 0) {
       printf(" (");
       if (flags & SOCK_CLOEXEC)
           printf("SOCK_CLOEXEC");
       if ((flags & SOCK_CLOEXEC) && (flags & SOCK_NONBLOCK))
           printf(" ");
       if (flags & SOCK_NONBLOCK)
           printf("SOCK_NONBLOCK");
       printf(")");
   }
   printf("\n");

#if USE_SOCKETCALL
   long args[6];

   args[0] = fd;
   args[1] = (long) sockaddr;
   args[2] = (long) addrlen;
   args[3] = flags;

   return syscall(SYS_socketcall, SYS_ACCEPT4, args);
#else
   return syscall(SYS_accept4, fd, sockaddr, addrlen, flags);
#endif
}

/**********************************************************************/

static int
do_test(int lfd, struct sockaddr_in *conn_addr,
       int closeonexec_flag, int nonblock_flag)
{
   int connfd, acceptfd;
   int fdf, flf, fdf_pass, flf_pass;
   struct sockaddr_in claddr;
   socklen_t addrlen;

   printf("=======================================\n");

   connfd = socket(AF_INET, SOCK_STREAM, 0);
   if (connfd == -1)
       die("socket");
   if (connect(connfd, (struct sockaddr *) conn_addr,
               sizeof(struct sockaddr_in)) == -1)
       die("connect");

   addrlen = sizeof(struct sockaddr_in);
   acceptfd = accept4(lfd, (struct sockaddr *) &claddr, &addrlen,
                      closeonexec_flag | nonblock_flag);
   if (acceptfd == -1) {
       perror("accept4()");
       close(connfd);
       return 0;
   }

   fdf = fcntl(acceptfd, F_GETFD);
   if (fdf == -1)
       die("fcntl:F_GETFD");
   fdf_pass = ((fdf & FD_CLOEXEC) != 0) ==
              ((closeonexec_flag & SOCK_CLOEXEC) != 0);
   printf("Close-on-exec flag is %sset (%s); ",
           (fdf & FD_CLOEXEC) ? "" : "not ",
           fdf_pass ? "OK" : "failed");

   flf = fcntl(acceptfd, F_GETFL);
   if (flf == -1)
       die("fcntl:F_GETFD");
   flf_pass = ((flf & O_NONBLOCK) != 0) ==
              ((nonblock_flag & SOCK_NONBLOCK) !=0);
   printf("nonblock flag is %sset (%s)\n",
           (flf & O_NONBLOCK) ? "" : "not ",
           flf_pass ? "OK" : "failed");

   close(acceptfd);
   close(connfd);

   printf("Test result: %s\n", (fdf_pass && flf_pass) ? "PASS" : "FAIL");
   return fdf_pass && flf_pass;
}

static int
create_listening_socket(int port_num)
{
   struct sockaddr_in svaddr;
   int lfd;
   int optval;

   memset(&svaddr, 0, sizeof(struct sockaddr_in));
   svaddr.sin_family = AF_INET;
   svaddr.sin_addr.s_addr = htonl(INADDR_ANY);
   svaddr.sin_port = htons(port_num);

   lfd = socket(AF_INET, SOCK_STREAM, 0);
   if (lfd == -1)
       die("socket");

   optval = 1;
   if (setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &optval,
                  sizeof(optval)) == -1)
       die("setsockopt");

   if (bind(lfd, (struct sockaddr *) &svaddr,
            sizeof(struct sockaddr_in)) == -1)
       die("bind");

   if (listen(lfd, 5) == -1)
       die("listen");

   return lfd;
}

int
main(int argc, char *argv[])
{
   struct sockaddr_in conn_addr;
   int lfd;
   int port_num;
   int passed;

   passed = 1;

   port_num = (argc > 1) ? atoi(argv[1]) : PORT_NUM;

   memset(&conn_addr, 0, sizeof(struct sockaddr_in));
   conn_addr.sin_family = AF_INET;
   conn_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
   conn_addr.sin_port = htons(port_num);

   lfd = create_listening_socket(port_num);

   if (!do_test(lfd, &conn_addr, 0, 0))
       passed = 0;
   if (!do_test(lfd, &conn_addr, SOCK_CLOEXEC, 0))
       passed = 0;
   if (!do_test(lfd, &conn_addr, 0, SOCK_NONBLOCK))
       passed = 0;
   if (!do_test(lfd, &conn_addr, SOCK_CLOEXEC, SOCK_NONBLOCK))
       passed = 0;

   close(lfd);

   exit(passed ? EXIT_SUCCESS : EXIT_FAILURE);
}

[mtk.manpages@gmail.com: rewrote changelog, updated test program]
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Tested-by: NMichael Kerrisk <mtk.manpages@gmail.com>
Acked-by: NMichael Kerrisk <mtk.manpages@gmail.com>
Cc: <linux-api@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      de11defe
  45. 17 10月, 2008 1 次提交
  47. 30 9月, 2008 1 次提交
    • T
      Configure out file locking features · bfcd17a6
      由 Thomas Petazzoni 提交于 
      This patch adds the CONFIG_FILE_LOCKING option which allows to remove
support for advisory locks. With this patch enabled, the flock()
system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl()
and NFS support are disabled. These features are not necessarly needed
on embedded systems. It allows to save ~11 Kb of kernel code and data:

   text          data     bss     dec     hex filename
1125436        118764  212992 1457192  163c28 vmlinux.old
1114299        118564  212992 1445855  160fdf vmlinux
 -11137    -200       0  -11337   -2C49 +/-

This patch has originally been written by Matt Mackall
<mpm@selenic.com>, and is part of the Linux Tiny project.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Cc: matthew@wil.cx
Cc: linux-fsdevel@vger.kernel.org
Cc: mpm@selenic.com
Cc: akpm@linux-foundation.org
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      bfcd17a6
  49. 26 7月, 2008 3 次提交
  51. 25 7月, 2008 4 次提交
    • U
      flag parameters: inotify_init · 4006553b
      由 Ulrich Drepper 提交于 
      This patch introduces the new syscall inotify_init1 (note: the 1 stands for
the one parameter the syscall takes, as opposed to no parameter before).  The
values accepted for this parameter are function-specific and defined in the
inotify.h header.  Here the values must match the O_* flags, though.  In this
patch CLOEXEC support is introduced.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_inotify_init1
# ifdef __x86_64__
#  define __NR_inotify_init1 294
# elif defined __i386__
#  define __NR_inotify_init1 332
# else
#  error "need __NR_inotify_init1"
# endif
#endif

#define IN_CLOEXEC O_CLOEXEC

int
main (void)
{
  int fd;
  fd = syscall (__NR_inotify_init1, 0);
  if (fd == -1)
    {
      puts ("inotify_init1(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("inotify_init1(0) set close-on-exit");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_inotify_init1, IN_CLOEXEC);
  if (fd == -1)
    {
      puts ("inotify_init1(IN_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("inotify_init1(O_CLOEXEC) does not set close-on-exit");
      return 1;
    }
  close (fd);

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[akpm@linux-foundation.org: add sys_ni stub]
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4006553b
    • U
      flag parameters: eventfd · b087498e
      由 Ulrich Drepper 提交于 
      This patch adds the new eventfd2 syscall.  It extends the old eventfd
syscall by one parameter which is meant to hold a flag value.  In this
patch the only flag support is EFD_CLOEXEC which causes the close-on-exec
flag for the returned file descriptor to be set.

A new name EFD_CLOEXEC is introduced which in this implementation must
have the same value as O_CLOEXEC.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_eventfd2
# ifdef __x86_64__
#  define __NR_eventfd2 290
# elif defined __i386__
#  define __NR_eventfd2 328
# else
#  error "need __NR_eventfd2"
# endif
#endif

#define EFD_CLOEXEC O_CLOEXEC

int
main (void)
{
  int fd = syscall (__NR_eventfd2, 1, 0);
  if (fd == -1)
    {
      puts ("eventfd2(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("eventfd2(0) sets close-on-exec flag");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_eventfd2, 1, EFD_CLOEXEC);
  if (fd == -1)
    {
      puts ("eventfd2(EFD_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("eventfd2(EFD_CLOEXEC) does not set close-on-exec flag");
      return 1;
    }
  close (fd);

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[akpm@linux-foundation.org: add sys_ni stub]
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b087498e
    • U
      flag parameters: signalfd · 9deb27ba
      由 Ulrich Drepper 提交于 
      This patch adds the new signalfd4 syscall.  It extends the old signalfd
syscall by one parameter which is meant to hold a flag value.  In this
patch the only flag support is SFD_CLOEXEC which causes the close-on-exec
flag for the returned file descriptor to be set.

A new name SFD_CLOEXEC is introduced which in this implementation must
have the same value as O_CLOEXEC.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_signalfd4
# ifdef __x86_64__
#  define __NR_signalfd4 289
# elif defined __i386__
#  define __NR_signalfd4 327
# else
#  error "need __NR_signalfd4"
# endif
#endif

#define SFD_CLOEXEC O_CLOEXEC

int
main (void)
{
  sigset_t ss;
  sigemptyset (&ss);
  sigaddset (&ss, SIGUSR1);
  int fd = syscall (__NR_signalfd4, -1, &ss, 8, 0);
  if (fd == -1)
    {
      puts ("signalfd4(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("signalfd4(0) set close-on-exec flag");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_signalfd4, -1, &ss, 8, SFD_CLOEXEC);
  if (fd == -1)
    {
      puts ("signalfd4(SFD_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("signalfd4(SFD_CLOEXEC) does not set close-on-exec flag");
      return 1;
    }
  close (fd);

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[akpm@linux-foundation.org: add sys_ni stub]
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9deb27ba
    • U
      flag parameters: paccept · aaca0bdc
      由 Ulrich Drepper 提交于 
      This patch is by far the most complex in the series.  It adds a new syscall
paccept.  This syscall differs from accept in that it adds (at the userlevel)
two additional parameters:

- a signal mask
- a flags value

The flags parameter can be used to set flag like SOCK_CLOEXEC.  This is
imlpemented here as well.  Some people argued that this is a property which
should be inherited from the file desriptor for the server but this is against
POSIX.  Additionally, we really want the signal mask parameter as well
(similar to pselect, ppoll, etc).  So an interface change in inevitable.

The flag value is the same as for socket and socketpair.  I think diverging
here will only create confusion.  Similar to the filesystem interfaces where
the use of the O_* constants differs, it is acceptable here.

The signal mask is handled as for pselect etc.  The mask is temporarily
installed for the thread and removed before the call returns.  I modeled the
code after pselect.  If there is a problem it's likely also in pselect.

For architectures which use socketcall I maintained this interface instead of
adding a system call.  The symmetry shouldn't be broken.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/syscall.h>

#ifndef __NR_paccept
# ifdef __x86_64__
#  define __NR_paccept 288
# elif defined __i386__
#  define SYS_PACCEPT 18
#  define USE_SOCKETCALL 1
# else
#  error "need __NR_paccept"
# endif
#endif

#ifdef USE_SOCKETCALL
# define paccept(fd, addr, addrlen, mask, flags) \
  ({ long args[6] = { \
       (long) fd, (long) addr, (long) addrlen, (long) mask, 8, (long) flags }; \
     syscall (__NR_socketcall, SYS_PACCEPT, args); })
#else
# define paccept(fd, addr, addrlen, mask, flags) \
  syscall (__NR_paccept, fd, addr, addrlen, mask, 8, flags)
#endif

#define PORT 57392

#define SOCK_CLOEXEC O_CLOEXEC

static pthread_barrier_t b;

static void *
tf (void *arg)
{
  pthread_barrier_wait (&b);
  int s = socket (AF_INET, SOCK_STREAM, 0);
  struct sockaddr_in sin;
  sin.sin_family = AF_INET;
  sin.sin_addr.s_addr = htonl (INADDR_LOOPBACK);
  sin.sin_port = htons (PORT);
  connect (s, (const struct sockaddr *) &sin, sizeof (sin));
  close (s);

  pthread_barrier_wait (&b);
  s = socket (AF_INET, SOCK_STREAM, 0);
  sin.sin_port = htons (PORT);
  connect (s, (const struct sockaddr *) &sin, sizeof (sin));
  close (s);
  pthread_barrier_wait (&b);

  pthread_barrier_wait (&b);
  sleep (2);
  pthread_kill ((pthread_t) arg, SIGUSR1);

  return NULL;
}

static void
handler (int s)
{
}

int
main (void)
{
  pthread_barrier_init (&b, NULL, 2);

  struct sockaddr_in sin;
  pthread_t th;
  if (pthread_create (&th, NULL, tf, (void *) pthread_self ()) != 0)
    {
      puts ("pthread_create failed");
      return 1;
    }

  int s = socket (AF_INET, SOCK_STREAM, 0);
  int reuse = 1;
  setsockopt (s, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof (reuse));
  sin.sin_family = AF_INET;
  sin.sin_addr.s_addr = htonl (INADDR_LOOPBACK);
  sin.sin_port = htons (PORT);
  bind (s, (struct sockaddr *) &sin, sizeof (sin));
  listen (s, SOMAXCONN);

  pthread_barrier_wait (&b);

  int s2 = paccept (s, NULL, 0, NULL, 0);
  if (s2 < 0)
    {
      puts ("paccept(0) failed");
      return 1;
    }

  int coe = fcntl (s2, F_GETFD);
  if (coe & FD_CLOEXEC)
    {
      puts ("paccept(0) set close-on-exec-flag");
      return 1;
    }
  close (s2);

  pthread_barrier_wait (&b);

  s2 = paccept (s, NULL, 0, NULL, SOCK_CLOEXEC);
  if (s2 < 0)
    {
      puts ("paccept(SOCK_CLOEXEC) failed");
      return 1;
    }

  coe = fcntl (s2, F_GETFD);
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("paccept(SOCK_CLOEXEC) does not set close-on-exec flag");
      return 1;
    }
  close (s2);

  pthread_barrier_wait (&b);

  struct sigaction sa;
  sa.sa_handler = handler;
  sa.sa_flags = 0;
  sigemptyset (&sa.sa_mask);
  sigaction (SIGUSR1, &sa, NULL);

  sigset_t ss;
  pthread_sigmask (SIG_SETMASK, NULL, &ss);
  sigaddset (&ss, SIGUSR1);
  pthread_sigmask (SIG_SETMASK, &ss, NULL);

  sigdelset (&ss, SIGUSR1);
  alarm (4);
  pthread_barrier_wait (&b);

  errno = 0 ;
  s2 = paccept (s, NULL, 0, &ss, 0);
  if (s2 != -1 || errno != EINTR)
    {
      puts ("paccept did not fail with EINTR");
      return 1;
    }

  close (s);

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[akpm@linux-foundation.org: make it compile]
[akpm@linux-foundation.org: add sys_ni stub]
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Roland McGrath <roland@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      aaca0bdc
  53. 23 7月, 2008 1 次提交
  55. 06 2月, 2008 1 次提交
    • D
      timerfd: new timerfd API · 4d672e7a
      由 Davide Libenzi 提交于 
      This is the new timerfd API as it is implemented by the following patch:

int timerfd_create(int clockid, int flags);
int timerfd_settime(int ufd, int flags,
		    const struct itimerspec *utmr,
		    struct itimerspec *otmr);
int timerfd_gettime(int ufd, struct itimerspec *otmr);

The timerfd_create() API creates an un-programmed timerfd fd.  The "clockid"
parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME.

The timerfd_settime() API give new settings by the timerfd fd, by optionally
retrieving the previous expiration time (in case the "otmr" parameter is not
NULL).

The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit
is set in the "flags" parameter.  Otherwise it's a relative time.

The timerfd_gettime() API returns the next expiration time of the timer, or
{0, 0} if the timerfd has not been set yet.

Like the previous timerfd API implementation, read(2) and poll(2) are
supported (with the same interface).  Here's a simple test program I used to
exercise the new timerfd APIs:

http://www.xmailserver.org/timerfd-test2.c

[akpm@linux-foundation.org: coding-style cleanups]
[akpm@linux-foundation.org: fix ia64 build]
[akpm@linux-foundation.org: fix m68k build]
[akpm@linux-foundation.org: fix mips build]
[akpm@linux-foundation.org: fix alpha, arm, blackfin, cris, m68k, s390, sparc and sparc64 builds]
[heiko.carstens@de.ibm.com: fix s390]
[akpm@linux-foundation.org: fix powerpc build]
[akpm@linux-foundation.org: fix sparc64 more]
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4d672e7a
  57. 24 1月, 2008 1 次提交
    • P
      [POWERPC] Provide a way to protect 4k subpages when using 64k pages · fa28237c
      由 Paul Mackerras 提交于 
      Using 64k pages on 64-bit PowerPC systems makes life difficult for
emulators that are trying to emulate an ISA, such as x86, which use a
smaller page size, since the emulator can no longer use the MMU and
the normal system calls for controlling page protections.  Of course,
the emulator can emulate the MMU by checking and possibly remapping
the address for each memory access in software, but that is pretty
slow.

This provides a facility for such programs to control the access
permissions on individual 4k sub-pages of 64k pages.  The idea is
that the emulator supplies an array of protection masks to apply to a
specified range of virtual addresses.  These masks are applied at the
level where hardware PTEs are inserted into the hardware page table
based on the Linux PTEs, so the Linux PTEs are not affected.  Note
that this new mechanism does not allow any access that would otherwise
be prohibited; it can only prohibit accesses that would otherwise be
allowed.  This new facility is only available on 64-bit PowerPC and
only when the kernel is configured for 64k pages.

The masks are supplied using a new subpage_prot system call, which
takes a starting virtual address and length, and a pointer to an array
of protection masks in memory.  The array has a 32-bit word per 64k
page to be protected; each 32-bit word consists of 16 2-bit fields,
for which 0 allows any access (that is otherwise allowed), 1 prevents
write accesses, and 2 or 3 prevent any access.

Implicit in this is that the regions of the address space that are
protected are switched to use 4k hardware pages rather than 64k
hardware pages (on machines with hardware 64k page support).  In fact
the whole process is switched to use 4k hardware pages when the
subpage_prot system call is used, but this could be improved in future
to switch only the affected segments.

The subpage protection bits are stored in a 3 level tree akin to the
page table tree.  The top level of this tree is stored in a structure
that is appended to the top level of the page table tree, i.e., the
pgd array.  Since it will often only be 32-bit addresses (below 4GB)
that are protected, the pointers to the first four bottom level pages
are also stored in this structure (each bottom level page contains the
protection bits for 1GB of address space), so the protection bits for
addresses below 4GB can be accessed with one fewer loads than those
for higher addresses.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
      fa28237c
  59. 31 10月, 2007 1 次提交
  61. 17 10月, 2007 1 次提交