Skip to content
  1. Jan 31, 2017
  3. Jan 20, 2017
  5. Jan 05, 2017
  7. Jan 04, 2017
  9. Dec 26, 2016
    • Larry Finger's avatar
      powerpc: Fix build warning on 32-bit PPC · 8ae679c4
      Larry Finger authored 
      

I am getting the following warning when I build kernel 4.9-git on my
PowerBook G4 with a 32-bit PPC processor:

    AS      arch/powerpc/kernel/misc_32.o
  arch/powerpc/kernel/misc_32.S:299:7: warning: "CONFIG_FSL_BOOKE" is not defined [-Wundef]

This problem is evident after commit 989cea5c ("kbuild: prevent
lib-ksyms.o rebuilds"); however, this change in kbuild only exposes an
error that has been in the code since 2005 when this source file was
created.  That was with commit 9994a338 ("powerpc: Introduce
entry_{32,64}.S, misc_{32,64}.S, systbl.S").

The offending line does not make a lot of sense.  This error does not
seem to cause any errors in the executable, thus I am not recommending
that it be applied to any stable versions.

Thanks to Nicholas Piggin for suggesting this solution.

Fixes: 9994a338 ("powerpc: Introduce entry_{32,64}.S, misc_{32,64}.S, systbl.S")
Signed-off-by: default avatarLarry Finger <Larry.Finger@lwfinger.net>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8ae679c4
    • Thomas Gleixner's avatar
      ktime: Cleanup ktime_set() usage · 8b0e1953
      Thomas Gleixner authored 
      

ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
      8b0e1953
  11. Dec 25, 2016
  13. Dec 24, 2016
    • Josh Poimboeuf's avatar
      Revert "x86/unwind: Detect bad stack return address" · c280f773
      Josh Poimboeuf authored 
      

Revert the following commit:

  b6959a36 ("x86/unwind: Detect bad stack return address")

... because Andrey Konovalov reported an unwinder warning:

  WARNING: unrecognized kernel stack return address ffffffffa0000001 at ffff88006377fa18 in a.out:4467

The unwind was initiated from an interrupt which occurred while running in the
generated code for a kprobe.  The unwinder printed the warning because it
expected regs->ip to point to a valid text address, but instead it pointed to
the generated code.

Eventually we may want come up with a way to identify generated kprobe
code so the unwinder can know that it's a valid return address.  Until
then, just remove the warning.

Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/02f296848fbf49fb72dfeea706413ecbd9d4caf6.1482418739.git.jpoimboe@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      c280f773
  15. Dec 23, 2016
    • Peter Zijlstra's avatar
      perf/x86: Fix overlap counter scheduling bug · 1134c2b5
      Peter Zijlstra authored 
      

Jiri reported the overlap scheduling exceeding its max stack.

Looking at the constraint that triggered this, it turns out the
overlap marker isn't needed.

The comment with EVENT_CONSTRAINT_OVERLAP states: "This is the case if
the counter mask of such an event is not a subset of any other counter
mask of a constraint with an equal or higher weight".

Esp. that latter part is of interest here I think, our overlapping mask
is 0x0e, that has 3 bits set and is the highest weight mask in on the
PMU, therefore it will be placed last. Can we still create a scenario
where we would need to rewind that?

The scenario for AMD Fam15h is we're having masks like:

	0x3F -- 111111
	0x38 -- 111000
	0x07 -- 000111

	0x09 -- 001001

And we mark 0x09 as overlapping, because it is not a direct subset of
0x38 or 0x07 and has less weight than either of those. This means we'll
first try and place the 0x09 event, then try and place 0x38/0x07 events.
Now imagine we have:

	3 * 0x07 + 0x09

and the initial pick for the 0x09 event is counter 0, then we'll fail to
place all 0x07 events. So we'll pop back, try counter 4 for the 0x09
event, and then re-try all 0x07 events, which will now work.

The masks on the PMU in question are:

  0x01 - 0001
  0x03 - 0011
  0x0e - 1110
  0x0c - 1100

But since all the masks that have overlap (0xe -> {0xc,0x3}) and (0x3 ->
0x1) are of heavier weight, it should all work out.

Reported-by: default avatarJiri Olsa <jolsa@kernel.org>
Tested-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Liang Kan <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vince@deater.net>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20161109155153.GQ3142@twins.programming.kicks-ass.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      1134c2b5
    • Stephane Eranian's avatar
      perf/x86/pebs: Fix handling of PEBS buffer overflows · daa864b8
      Stephane Eranian authored 
      

This patch solves a race condition between PEBS and the PMU handler.

In case multiple PEBS events are sampled at the same time,
it is possible to have GLOBAL_STATUS bit 62 set indicating
PEBS buffer overflow and also seeing at most 3 PEBS counters
having their bits set in the status register. This is a sign
that there was at least one PEBS record pending at the time
of the PMU interrupt. PEBS counters must only be processed
via the drain_pebs() calls, and not via the regular sample
processing loop coming after that the function, otherwise
phony regular samples may be generated in the sampling buffer
not marked with the EXACT tag.

Another possibility is to have one PEBS event and at least
one non-PEBS event whic hoverflows while PEBS has armed. In this
case, bit 62 of GLOBAL_STATUS will not be set, yet the overflow
status bit for the PEBS counter will be on Skylake.

To avoid this problem, we systematically ignore the PEBS-enabled
counters from the GLOBAL_STATUS mask and we always process PEBS
events via drain_pebs().

The problem manifested itself by having non-exact samples when
sampling only PEBS events, i.e., the PERF_SAMPLE_RECORD would
not have the EXACT flag set.

Note that this problem is only present on Skylake processor.
This fix is harmless on older processors.

Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarStephane Eranian <eranian@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1482395366-8992-1-git-send-email-eranian@google.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      daa864b8
    • Peter Zijlstra's avatar
      x86/paravirt: Mark unused patch_default label · cef4402d
      Peter Zijlstra authored 
      

A bugfix commit:

  45dbea5f ("x86/paravirt: Fix native_patch()")

... introduced a harmless warning:

  arch/x86/kernel/paravirt_patch_32.c: In function 'native_patch':
  arch/x86/kernel/paravirt_patch_32.c:71:1: error: label 'patch_default' defined but not used [-Werror=unused-label]

Fix it by annotating the label as __maybe_unused.

Reported-by: default avatarArnd Bergmann <arnd@arndb.de>
Reported-by: default avatarPiotr Gregor <piotrgregor@rsyncme.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 45dbea5f ("x86/paravirt: Fix native_patch()")
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      cef4402d
  17. Dec 21, 2016