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  1. 20 Feb, 2009 14 commits
    • Ingo Molnar's avatar
      x86, mm, kprobes: fault.c, simplify notify_page_fault() · b1801812
      Ingo Molnar authored 
      Impact: cleanup

Remove an #ifdef from notify_page_fault(). The function still
compiles to nothing in the !CONFIG_KPROBES case.

Introduce kprobes_built_in() and kprobe_fault_handler() helpers
to allow this - they returns 0 if !CONFIG_KPROBES.

No code changed:

   text	   data	    bss	    dec	    hex	filename
   4618	     32	     24	   4674	   1242	fault.o.before
   4618	     32	     24	   4674	   1242	fault.o.after

Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      b1801812
    • Ingo Molnar's avatar
      x86, mm: fault.c, simplify kmmio_fault() · b814d41f
      Ingo Molnar authored 
      Impact: cleanup

Remove an #ifdef from kmmio_fault() - we can do this by
providing default implementations for is_kmmio_active()
and kmmio_handler(). The compiler optimizes it all away
in the !CONFIG_MMIOTRACE case.

Also, while at it, clean up mmiotrace.h a bit:

 - standard header guards
 - standard vertical spaces for structure definitions

No code changed (both with mmiotrace on and off in the config):

   text	   data	    bss	    dec	    hex	filename
   2947	     12	     12	   2971	    b9b	fault.o.before
   2947	     12	     12	   2971	    b9b	fault.o.after

Cc: Pekka Paalanen <pq@iki.fi>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      b814d41f
    • Ingo Molnar's avatar
      x86, mm: fault.c, enable PF_RSVD checks on 32-bit too · 121d5d0a
      Ingo Molnar authored 
      Impact: improve page fault handling robustness

The 'PF_RSVD' flag (bit 3) of the page-fault error_code is a
relatively recent addition to x86 CPUs, so the 32-bit do_fault()
implementation never had it. This flag gets set when the CPU
detects nonzero values in any reserved bits of the page directory
entries.

Extend the existing 64-bit check for PF_RSVD in do_page_fault()
to 32-bit too. If we detect such a fault then we print a more
informative oops and the pagetables.

This unifies the code some more, removes an ugly #ifdef and improves
the 32-bit page fault code robustness a bit. It slightly increases
the 32-bit kernel text size.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      121d5d0a
    • Ingo Molnar's avatar
      x86, mm: fault.c, factor out the vm86 fault check · 8c938f9f
      Ingo Molnar authored 
      Impact: cleanup

Instead of an ugly, open-coded, #ifdef-ed vm86 related legacy check
in do_page_fault(), put it into the check_v8086_mode() helper
function and merge it with an existing #ifdef.

Also, simplify the code flow a tiny bit in the helper.

No code changed:

arch/x86/mm/fault.o:

   text	   data	    bss	    dec	    hex	filename
   2711	     12	     12	   2735	    aaf	fault.o.before
   2711	     12	     12	   2735	    aaf	fault.o.after

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      8c938f9f
    • Ingo Molnar's avatar
      x86, mm: fault.c, refactor/simplify the is_prefetch() code · 107a0367
      Ingo Molnar authored 
      Impact: no functionality changed

Factor out the opcode checker into a helper inline.

The code got a tiny bit smaller:

   text	   data	    bss	    dec	    hex	filename
   4632	     32	     24	   4688	   1250	fault.o.before
   4618	     32	     24	   4674	   1242	fault.o.after

And it got cleaner / easier to review as well.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      107a0367
    • Ingo Molnar's avatar
      x86, mm: fault.c cleanup · 2d4a7167
      Ingo Molnar authored 
      Impact: cleanup, no code changed

Clean up various small details, which can be correctness checked
automatically:

 - tidy up the include file section
 - eliminate unnecessary includes
 - introduce show_signal_msg() to clean up code flow
 - standardize the code flow
 - standardize comments and other style details
 - more cleanups, pointed out by checkpatch

No code changed on either 32-bit nor 64-bit:

arch/x86/mm/fault.o:

   text	   data	    bss	    dec	    hex	filename
   4632	     32	     24	   4688	   1250	fault.o.before
   4632	     32	     24	   4688	   1250	fault.o.after

the md5 changed due to a change in a single instruction:

   2e8a8241e7f0d69706776a5a26c90bc0  fault.o.before.asm
   c5c3d36e725586eb74f0e10692f0193e  fault.o.after.asm

Because a __LINE__ reference in a WARN_ONCE() has changed.

On 32-bit a few stack offsets changed - no code size difference
nor any functionality difference.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      2d4a7167
    • Ingo Molnar's avatar
      Merge branch 'tip/x86/urgent' of... · c9e1585b
      Ingo Molnar authored 
      Merge branch 'tip/x86/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into x86/mm
      c9e1585b
    • Ingo Molnar's avatar
      x86, pat: add large-PAT check to split_large_page() · 7a5714e0
      Ingo Molnar authored 
      Impact: future-proof the split_large_page() function

Linus noticed that split_large_page() is not safe wrt. the
PAT bit: it is bit 12 on the 1GB and 2MB page table level
(_PAGE_BIT_PAT_LARGE), and it is bit 7 on the 4K page
table level (_PAGE_BIT_PAT).

Currently it is not a problem because we never set
_PAGE_BIT_PAT_LARGE on any of the large-page mappings - but
should this happen in the future the split_large_page() would
silently lift bit 12 into the lowlevel 4K pte and would start
corrupting the physical page frame offset. Not fun.

So add a debug warning, to make sure if something ever sets
the PAT bit then this function gets updated too.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      7a5714e0
    • Steven Rostedt's avatar
      x86: check PMD in spurious_fault handler · 3c3e5694
      Steven Rostedt authored 
      Impact: fix to prevent hard lockup on bad PMD permissions

If the PMD does not have the correct permissions for a page access,
but the PTE does, the spurious fault handler will mistake the fault
as a lazy TLB transaction. This will result in an infinite loop of:

 fault -> spurious_fault check (pass) -> return to code -> fault

This patch adds a check and a warn on if the PTE passes the permissions
but the PMD does not.

[ Updated: Ingo Molnar suggested using WARN_ONCE with some text ]
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      3c3e5694
    • Ingo Molnar's avatar
      Merge branches 'x86/asm', 'x86/cleanups' and 'x86/headers' into x86/core · 60916285
      Ingo Molnar authored
      60916285
    • Ingo Molnar's avatar
      Merge branch 'x86/urgent' into x86/core · 3b6f7b9b
      Ingo Molnar authored
      3b6f7b9b
    • Vegard Nossum's avatar
      x86: use symbolic constants for MSR_IA32_MISC_ENABLE bits · ecab22aa
      Vegard Nossum authored 
      Impact: Cleanup. No functional changes.
Signed-off-by: default avatarVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      ecab22aa
    • Ingo Molnar's avatar
      x86: use the right protections for split-up pagetables · 07a66d7c
      Ingo Molnar authored 
      Steven Rostedt found a bug in where in his modified kernel
ftrace was unable to modify the kernel text, due to the PMD
itself having been marked read-only as well in
split_large_page().

The fix, suggested by Linus, is to not try to 'clone' the
reference protection of a huge-page, but to use the standard
(and permissive) page protection bits of KERNPG_TABLE.

The 'cloning' makes sense for the ptes but it's a confused and
incorrect concept at the page table level - because the
pagetable entry is a set of all ptes and hence cannot
'clone' any single protection attribute - the ptes can be any
mixture of protections.

With the permissive KERNPG_TABLE, even if the pte protections
get changed after this point (due to ftrace doing code-patching
or other similar activities like kprobes), the resulting combined
protections will still be correct and the pte's restrictive
(or permissive) protections will control it.

Also update the comment.

This bug was there for a long time but has not caused visible
problems before as it needs a rather large read-only area to
trigger. Steve possibly hacked his kernel with some really
large arrays or so. Anyway, the bug is definitely worth fixing.

[ Huang Ying also experienced problems in this area when writing
  the EFI code, but the real bug in split_large_page() was not
  realized back then. ]
Reported-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Reported-by: default avatarHuang Ying <ying.huang@intel.com>
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      07a66d7c
    • Alok N Kataria's avatar
      x86, vmi: TSC going backwards check in vmi clocksource · 48ffc70b
      Alok N Kataria authored 
      Impact: fix time warps under vmware

Similar to the check for TSC going backwards in the TSC clocksource,
we also need this check for VMI clocksource.
Signed-off-by: default avatarAlok N Kataria <akataria@vmware.com>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: stable@kernel.org
      48ffc70b
  3. 19 Feb, 2009 26 commits