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  1. 07 Jan, 2010 3 commits
    • Mike Frysinger's avatar
      NOMMU: Avoiding duplicate icache flushes of shared maps · cfe79c00
      Mike Frysinger authored 
      When working with FDPIC, there are many shared mappings of read-only
code regions between applications (the C library, applet packages like
busybox, etc.), but the current do_mmap_pgoff() function will issue an
icache flush whenever a VMA is added to an MM instead of only doing it
when the map is initially created.

The flush can instead be done when a region is first mmapped PROT_EXEC.
Note that we may not rely on the first mapping of a region being
executable - it's possible for it to be PROT_READ only, so we have to
remember whether we've flushed the region or not, and then flush the
entire region when a bit of it is made executable.

However, this also affects the brk area.  That will no longer be
executable.  We can mprotect() it to PROT_EXEC on MPU-mode kernels, but
for NOMMU mode kernels, when it increases the brk allocation, making
sys_brk() flush the extra from the icache should suffice.  The brk area
probably isn't used by NOMMU programs since the brk area can only use up
the leavings from the stack allocation, where the stack allocation is
larger than requested.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      cfe79c00
    • Mike Frysinger's avatar
      FDPIC: Respect PT_GNU_STACK exec protection markings when creating NOMMU stack · 04e4f2b1
      Mike Frysinger authored 
      The current code will load the stack size and protection markings, but
then only use the markings in the MMU code path.  The NOMMU code path
always passes PROT_EXEC to the mmap() call.  While this doesn't matter
to most people whilst the code is running, it will cause a pointless
icache flush when starting every FDPIC application.  Typically this
icache flush will be of a region on the order of 128KB in size, or may
be the entire icache, depending on the facilities available on the CPU.

In the case where the arch default behaviour seems to be desired
(EXSTACK_DEFAULT), we probe VM_STACK_FLAGS for VM_EXEC to determine
whether we should be setting PROT_EXEC or not.

For arches that support an MPU (Memory Protection Unit - an MMU without
the virtual mapping capability), setting PROT_EXEC or not will make an
important difference.

It should be noted that this change also affects the executability of
the brk region, since ELF-FDPIC has that share with the stack.  However,
this is probably irrelevant as NOMMU programs aren't likely to use the
brk region, preferring instead allocation via mmap().
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      04e4f2b1
    • Linus Torvalds's avatar
      Merge branch 'for-2.6.33' of git://linux-nfs.org/~bfields/linux · 93939f4e
      Linus Torvalds authored 
      * 'for-2.6.33' of git://linux-nfs.org/~bfields/linux:
  sunrpc: fix peername failed on closed listener
  nfsd: make sure data is on disk before calling ->fsync
  nfsd: fix "insecure" export option
      93939f4e
  3. 06 Jan, 2010 16 commits
  5. 05 Jan, 2010 8 commits
  7. 04 Jan, 2010 13 commits