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  1. 22 Oct, 2007 10 commits
    • Martin Schwidefsky's avatar
      [S390] Cleanup page table definitions. · 3610cce8
      Martin Schwidefsky authored 
      - De-confuse the defines for the address-space-control-elements
  and the segment/region table entries.
- Create out of line functions for page table allocation / freeing.
- Simplify get_shadow_xxx functions.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      3610cce8
    • Martin Schwidefsky's avatar
      [S390] Introduce follow_table in uaccess_pt.c · e4aa402e
      Martin Schwidefsky authored 
      Define and use follow_table inline in uaccess_pt.c to simplify
the code.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      e4aa402e
    • Martin Schwidefsky's avatar
      [S390] Remove unused user_seg from thread structure. · 6f3fa3f0
      Martin Schwidefsky authored 
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      6f3fa3f0
    • Martin Schwidefsky's avatar
      [S390] tlb flush fix. · ba8a9229
      Martin Schwidefsky authored 
      The current tlb flushing code for page table entries violates the
s390 architecture in a small detail. The relevant section from the
principles of operation (SA22-7832-02 page 3-47):

   "A valid table entry must not be changed while it is attached
   to any CPU and may be used for translation by that CPU except to
   (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY or
   INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page-table
   entry, or (3) make a change by means of a COMPARE AND SWAP AND
   PURGE instruction that purges the TLB."

That means if one thread of a multithreaded applciation uses a vma
while another thread does an unmap on it, the page table entries of
that vma needs to get removed with IPTE, IDTE or CSP. In some strange
and rare situations a cpu could check-stop (die) because a entry has
been pushed out of the TLB that is still needed to complete a
(milli-coded) instruction. I've never seen it happen with the current
code on any of the supported machines, so right now this is a
theoretical problem. But I want to fix it nevertheless, to avoid
headaches in the futures.

To get this implemented correctly without changing common code the
primitives ptep_get_and_clear, ptep_get_and_clear_full and
ptep_set_wrprotect need to use the IPTE instruction to invalidate the
pte before the new pte value gets stored. If IPTE is always used for
the three primitives three important operations will have a performace
hit: fork, mprotect and exit_mmap. Time for some workarounds:

* 1: ptep_get_and_clear_full is used in unmap_vmas to remove page
tables entries in a batched tlb gather operation. If the mmu_gather
context passed to unmap_vmas has been started with full_mm_flush==1
or if only one cpu is online or if the only user of a mm_struct is the
current process then the fullmm indication in the mmu_gather context is
set to one. All TLBs for mm_struct are flushed by the tlb_gather_mmu
call. No new TLBs can be created while the unmap is in progress. In
this case ptep_get_and_clear_full clears the ptes with a simple store.

* 2: ptep_get_and_clear is used in change_protection to clear the
ptes from the page tables before they are reentered with the new
access flags. At the end of the update flush_tlb_range clears the
remaining TLBs. In general the ptep_get_and_clear has to issue IPTE
for each pte and flush_tlb_range is a nop. But if there is only one
user of the mm_struct then ptep_get_and_clear uses simple stores
to do the update and flush_tlb_range will flush the TLBs.

* 3: Similar to 2, ptep_set_wrprotect is used in copy_page_range
for a fork to make all ptes of a cow mapping read-only. At the end of
of copy_page_range dup_mmap will flush the TLBs with a call to
flush_tlb_mm.  Check for mm->mm_users and if there is only one user
avoid using IPTE in ptep_set_wrprotect and let flush_tlb_mm clear the
TLBs.

Overall for single threaded programs the tlb flush code now performs
better, for multi threaded programs it is slightly worse. In particular
exit_mmap() now does a single IDTE for the mm and then just frees every
page cache reference and every page table page directly without a delay
over the mmu_gather structure.
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      ba8a9229
    • Michael Holzheu's avatar
      [S390] kernel: Fix dump on panic for DASDs under LPAR. · e3d3683d
      Michael Holzheu authored 
      Currently the ccw method is used to ipl the DASD dump record under LPAR.
This mechanism is not reliable, which can cause dump failures. This fix
now uses the diag 308 ipl method for all machines, which have diag308
subcode 5 and 4 support.
Signed-off-by: default avatarMichael Holzheu <holzheu@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      e3d3683d
    • Cornelia Huck's avatar
      [S390] struct class_device -> struct device conversion. · 7f021ce1
      Cornelia Huck authored 
      Convert struct class_device users under drivers/s390/char to use
struct device.
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      7f021ce1
    • Cornelia Huck's avatar
      [S390] cio: Fix incomplete commit for uevent suppression. · 5bf04b20
      Cornelia Huck authored 
      Commit fa1a8c23 intended to
introduce uevent suppression for subchannels, but half of it was
lost somewhere. Now, we end up with two uevents for every registered
subchannel :( So we should better add the missing part from
http://marc.info/?l=linux-kernel&m=117515953113974&w=2.
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      5bf04b20
    • Cornelia Huck's avatar
      [S390] cio: Use to_channelpath() for device to channel path conversion. · 05469607
      Cornelia Huck authored 
      We already have a macro for that, so let's use it consistently...
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      05469607
    • Heiko Carstens's avatar
      [S390] Add per-cpu idle time / idle count sysfs attributes. · fae8b22d
      Heiko Carstens authored 
      Add two new sysfs entries per cpu: idle_count and idle_time.
idle_count contains the number of times a cpu went into idle state.
idle_time contains the time a cpu spent in idle state in microseconds.
This can be used e.g. by powertop to tell how often idle state is
entered and left.

# cat /sys/devices/system/cpu/cpu0/idle_count
504
# cat /sys/devices/system/cpu/cpu0/idle_time
469734037 us

Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      fae8b22d
    • Martin Schwidefsky's avatar
      [S390] Update default configuration. · 32346f47
      Martin Schwidefsky authored 
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      32346f47
  3. 21 Oct, 2007 29 commits
  5. 20 Oct, 2007 1 commit
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