linux.git/arch/powerpc/perf, branch v3.18.64

powerpc/perf: Fix book3s kernel to userspace backtraces

2015-07-04T03:02:22+00:00

[ Upstream commit 72e349f1124a114435e599479c9b8d14bfd1ebcd ]

When we take a PMU exception or a software event we call
perf_read_regs(). This overloads regs->result with a boolean that
describes if we should use the sampled instruction address register
(SIAR) or the regs.

If the exception is in kernel, we start with the kernel regs and
backtrace through the kernel stack. At this point we switch to the
userspace regs and backtrace the user stack with perf_callchain_user().

Unfortunately these regs have not got the perf_read_regs() treatment,
so regs->result could be anything. If it is non zero,
perf_instruction_pointer() decides to use the SIAR, and we get issues
like this:

0.11%  qemu-system-ppc  [kernel.kallsyms]        [k] _raw_spin_lock_irqsave
       |
       ---_raw_spin_lock_irqsave
          |
          |--52.35%-- 0
          |          |
          |          |--46.39%-- __hrtimer_start_range_ns
          |          |          kvmppc_run_core
          |          |          kvmppc_vcpu_run_hv
          |          |          kvmppc_vcpu_run
          |          |          kvm_arch_vcpu_ioctl_run
          |          |          kvm_vcpu_ioctl
          |          |          do_vfs_ioctl
          |          |          sys_ioctl
          |          |          system_call
          |          |          |
          |          |          |--67.08%-- _raw_spin_lock_irqsave <--- hi mum
          |          |          |          |
          |          |          |           --100.00%-- 0x7e714
          |          |          |                     0x7e714

Notice the bogus _raw_spin_irqsave when we transition from kernel
(system_call) to userspace (0x7e714). We inserted what was in the SIAR.

Add a check in regs_use_siar() to check that the regs in question
are from a PMU exception. With this fix the backtrace makes sense:

     0.47%  qemu-system-ppc  [kernel.vmlinux]         [k] _raw_spin_lock_irqsave
            |
            ---_raw_spin_lock_irqsave
               |
               |--53.83%-- 0
               |          |
               |          |--44.73%-- hrtimer_try_to_cancel
               |          |          kvmppc_start_thread
               |          |          kvmppc_run_core
               |          |          kvmppc_vcpu_run_hv
               |          |          kvmppc_vcpu_run
               |          |          kvm_arch_vcpu_ioctl_run
               |          |          kvm_vcpu_ioctl
               |          |          do_vfs_ioctl
               |          |          sys_ioctl
               |          |          system_call
               |          |          __ioctl
               |          |          0x7e714
               |          |          0x7e714

Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin

powerpc/perf: Cap 64bit userspace backtraces to PERF_MAX_STACK_DEPTH

2015-05-17T23:12:09+00:00

[ Upstream commit 9a5cbce421a283e6aea3c4007f141735bf9da8c3 ]

We cap 32bit userspace backtraces to PERF_MAX_STACK_DEPTH
(currently 127), but we forgot to do the same for 64bit backtraces.

Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin

powerpc/perf/hv-24x7: Use per-cpu page buffer

2015-01-16T14:59:46+00:00

commit f34b6c72c3ebaa286d3311a825ef79eccbcca82f upstream.

The 24x7 counters are continuously running and not updated on an
interrupt. So we record the event counts when stopping the event or
deleting it.

But to "read" a single counter in 24x7, we allocate a page and pass it
into the hypervisor (The HV returns the page full of counters from which
we extract the specific counter for this event).

We allocate a page using GFP_USER and when deleting the event, we end up
with the following warning because we are blocking in interrupt context.

  [  698.641709] BUG: scheduling while atomic: swapper/0/0/0x10010000

We could use GFP_ATOMIC but that could result in failures. Pre-allocate
a buffer so we don't have to allocate in interrupt context. Further as
Michael Ellerman suggested, use Per-CPU buffer so we only need to
allocate once per CPU.

Signed-off-by: Sukadev Bhattiprolu 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

perf: Fix and clean up initialization of pmu::event_idx

2014-10-28T09:51:01+00:00

Andy reported that the current state of event_idx is rather confused.
So remove all but the x86_pmu implementation and change the default to
return 0 (the safe option).

Reported-by: Andy Lutomirski 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Benjamin Herrenschmidt 
Cc: Christoph Lameter 
Cc: Cody P Schafer 
Cc: Cody P Schafer 
Cc: Heiko Carstens 
Cc: Hendrik Brueckner 
Cc: Himangi Saraogi 
Cc: Linus Torvalds 
Cc: Martin Schwidefsky 
Cc: Michael Ellerman 
Cc: Paul Gortmaker 
Cc: Paul Mackerras 
Cc: sukadev@linux.vnet.ibm.com 
Cc: Thomas Huth 
Cc: Vince Weaver 
Cc: linux390@de.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Signed-off-by: Ingo Molnar

powerpc/perf/hv-24x7: Simplify catalog_read()

2014-10-07T05:57:10+00:00

catalog_read() implements the read interface for the sysfs file

	/sys/bus/event_source/devices/hv_24x7/interface/catalog

It essentially takes a buffer, an offset and count as parameters
to the read() call.  It makes a hypervisor call to read a specific
page from the catalog and copy the required bytes into the given
buffer. Each call to catalog_read() returns at most one 4K page.

Given these requirements, we should be able to simplify the
catalog_read().

Signed-off-by: Sukadev Bhattiprolu 
Signed-off-by: Michael Ellerman

powerpc/perf/hv-24x7: use kmem_cache instead of aligned stack allocations

2014-10-07T05:52:58+00:00

Ian pointed out the use of __aligned(4096) caused rather large stack
consumption in single_24x7_request(), so use the kmem_cache
hv_page_cache (which we've already got set up for other allocations)
insead of allocating locally.

CC: Haren Myneni 
Reported-by: Ian Munsie 
Signed-off-by: Cody P Schafer 
Signed-off-by: Sukadev Bhattiprolu 
Signed-off-by: Michael Ellerman

powerpc: Make a bunch of things static

2014-09-25T13:14:41+00:00

Signed-off-by: Anton Blanchard 
Signed-off-by: Michael Ellerman

powerpc/perf: Fix ABIv2 kernel backtraces

2014-09-09T09:02:45+00:00

ABIv2 kernels are failing to backtrace through the kernel. An example:

39.30%  readseek2_proce  [kernel.kallsyms]    [k] find_get_entry
            |
            --- find_get_entry
               __GI___libc_read

The problem is in valid_next_sp() where we check that the new stack
pointer is at least STACK_FRAME_OVERHEAD below the previous one.

ABIv1 has a minimum stack frame size of 112 bytes consisting of 48 bytes
and 64 bytes of parameter save area. ABIv2 changes that to 32 bytes
with no paramter save area.

STACK_FRAME_OVERHEAD is in theory the minimum stack frame size,
but we over 240 uses of it, some of which assume that it includes
space for the parameter area.

We need to work through all our stack defines and rationalise them
but let's fix perf now by creating STACK_FRAME_MIN_SIZE and using
in valid_next_sp(). This fixes the issue:

30.64%  readseek2_proce  [kernel.kallsyms]    [k] find_get_entry
            |
            --- find_get_entry
               pagecache_get_page
               generic_file_read_iter
               new_sync_read
               vfs_read
               sys_read
               syscall_exit
               __GI___libc_read

Cc: stable@vger.kernel.org # 3.16+
Reported-by: Aneesh Kumar K.V 
Signed-off-by: Anton Blanchard

powerpc/perf/hv-24x7: Use kmem_cache_free

2014-08-13T05:14:04+00:00

Free memory allocated using kmem_cache_zalloc using kmem_cache_free
rather than kfree.

The Coccinelle semantic patch that makes this change is as follows:

// 
@@
expression x,E,c;
@@

 x = \(kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache_alloc_node\)(c,...)
 ... when != x = E
     when != &x
?-kfree(x)
+kmem_cache_free(c,x)
// 

Signed-off-by: Himangi Saraogi 
Acked-by: Julia Lawall 
Signed-off-by: Benjamin Herrenschmidt

Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

2014-08-07T15:50:34+00:00

Pull powerpc updates from Ben Herrenschmidt:
 "This is the powerpc new goodies for 3.17.  The short story:

  The biggest bit is Michael removing all of pre-POWER4 processor
  support from the 64-bit kernel.  POWER3 and rs64.  This gets rid of a
  ton of old cruft that has been bitrotting in a long while.  It was
  broken for quite a few versions already and nobody noticed.  Nobody
  uses those machines anymore.  While at it, he cleaned up a bunch of
  old dusty cabinets, getting rid of a skeletton or two.

  Then, we have some base VFIO support for KVM, which allows assigning
  of PCI devices to KVM guests, support for large 64-bit BARs on
  "powernv" platforms, support for HMI (Hardware Management Interrupts)
  on those same platforms, some sparse-vmemmap improvements (for memory
  hotplug),

  There is the usual batch of Freescale embedded updates (summary in the
  merge commit) and fixes here or there, I think that's it for the
  highlights"

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (102 commits)
  powerpc/eeh: Export eeh_iommu_group_to_pe()
  powerpc/eeh: Add missing #ifdef CONFIG_IOMMU_API
  powerpc: Reduce scariness of interrupt frames in stack traces
  powerpc: start loop at section start of start in vmemmap_populated()
  powerpc: implement vmemmap_free()
  powerpc: implement vmemmap_remove_mapping() for BOOK3S
  powerpc: implement vmemmap_list_free()
  powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE
  powerpc/book3s: Fix endianess issue for HMI handling on napping cpus.
  powerpc/book3s: handle HMIs for cpus in nap mode.
  powerpc/powernv: Invoke opal call to handle hmi.
  powerpc/book3s: Add basic infrastructure to handle HMI in Linux.
  powerpc/iommu: Fix comments with it_page_shift
  powerpc/powernv: Handle compound PE in config accessors
  powerpc/powernv: Handle compound PE for EEH
  powerpc/powernv: Handle compound PE
  powerpc/powernv: Split ioda_eeh_get_state()
  powerpc/powernv: Allow to freeze PE
  powerpc/powernv: Enable M64 aperatus for PHB3
  powerpc/eeh: Aux PE data for error log
  ...