linux-stable.git/arch/powerpc/kernel, branch v3.12.2

powerpc/pseries: Duplicate dtl entries sometimes sent to userspace

2013-11-29T19:28:08+00:00

commit 84b073868b9d9e754ae48b828337633d1b386482 upstream.

When reading from the dispatch trace log (dtl) userspace interface, I
sometimes see duplicate entries. One example:

# hexdump -C dtl.out

00000000  07 04 00 0c 00 00 48 44  00 00 00 00 00 00 00 00
00000010  00 0c a0 b4 16 83 6d 68  00 00 00 00 00 00 00 00
00000020  00 00 00 00 10 00 13 50  80 00 00 00 00 00 d0 32

00000030  07 04 00 0c 00 00 48 44  00 00 00 00 00 00 00 00
00000040  00 0c a0 b4 16 83 6d 68  00 00 00 00 00 00 00 00
00000050  00 00 00 00 10 00 13 50  80 00 00 00 00 00 d0 32

The problem is in scan_dispatch_log() where we call dtl_consumer()
but bail out before incrementing the index.

To fix this I moved dtl_consumer() after the timebase comparison.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Enable PCI_COMMAND_MASTER for PCI bridges

2013-11-29T19:28:08+00:00

commit bf898ec5cbd33be11147743bee27b66b10cb2f85 upstream.

On PHB3, we will fail to fetch IODA tables without PCI_COMMAND_MASTER
on PCI bridges. According to one experiment I had, the MSIx interrupts
didn't raise from the adapter without the bit applied to all upstream
PCI bridges including root port of the adapter. The patch forces to
have that bit enabled accordingly.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/signals: Mark VSX not saved with small contexts

2013-11-29T19:28:08+00:00

commit c13f20ac48328b05cd3b8c19e31ed6c132b44b42 upstream.

The VSX MSR bit in the user context indicates if the context contains VSX
state.  Currently we set this when the process has touched VSX at any stage.

Unfortunately, if the user has not provided enough space to save the VSX state,
we can't save it but we currently still set the MSR VSX bit.

This patch changes this to clear the MSR VSX bit when the user doesn't provide
enough space.  This indicates that there is no valid VSX state in the user
context.

This is needed to support get/set/make/swapcontext for applications that use
VSX but only provide a small context.  For example, getcontext in glibc
provides a smaller context since the VSX registers don't need to be saved over
the glibc function call.  But since the program calling getcontext may have
used VSX, the kernel currently says the VSX state is valid when it's not.  If
the returned context is then used in setcontext (ie. a small context without
VSX but with MSR VSX set), the kernel will refuse the context.  This situation
has been reported by the glibc community.

Based on patch from Carlos O'Donell.

Tested-by: Haren Myneni 
Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/vio: use strcpy in modalias_show

2013-11-29T19:28:07+00:00

commit 411cabf79e684171669ad29a0628c400b4431e95 upstream.

Commit e82b89a6f19bae73fb064d1b3dd91fcefbb478f4 used strcat instead of
strcpy which can result in an overflow of newlines on the buffer.

Signed-off-by: Prarit Bhargava
Cc: benh@kernel.crashing.org
Cc: ben@decadent.org.uk
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/irq: Don't switch to irq stack from softirq stack

2013-10-07T21:19:39+00:00

irq_exit() is now called on the irq stack, which can trigger a switch to
the softirq stack from the irq stack.  If an interrupt happens at that
point, we will not properly detect the re-entrancy and clobber the
original return context on the irq stack.

This fixes it.  The side effect is to prevent all nesting from softirq
stack to irq stack even in the "safe" case but it's simpler that way and
matches what x86_64 does.

Reported-by: Cédric Le Goater 
Tested-by: Cédric Le Goater 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Linus Torvalds

powerpc/tm: Switch out userspace PPR and DSCR sooner

2013-10-03T07:25:51+00:00

When we do a treclaim or trecheckpoint we end up running with userspace
PPR and DSCR values.  Currently we don't do anything special to avoid
running with user values which could cause a severe performance
degradation.

This patch moves the PPR and DSCR save and restore around treclaim and
trecheckpoint so that we run with user values for a much shorter period.
More care is taken with the PPR as it's impact is greater than the DSCR.

This is similar to user exceptions, where we run HTM_MEDIUM early to
ensure that we don't run with a userspace PPR values in the kernel.

Signed-off-by: Michael Neuling 
Cc:  # 3.9+
Signed-off-by: Benjamin Herrenschmidt

powerpc/tm: Turn interrupts hard off in tm_reclaim()

2013-10-03T07:25:44+00:00

We can't take IRQs in tm_reclaim as we might have a bogus r13 and r1.

This turns IRQs hard off in this function.

Signed-off-by: Michael Neuling 
Cc:  # 3.9+
Signed-off-by: Benjamin Herrenschmidt

powerpc/vio: Fix modalias_show return values

2013-10-03T07:25:16+00:00

modalias_show() should return an empty string on error, not -ENODEV.

This causes the following false and annoying error:

> find /sys/devices -name modalias -print0 | xargs -0 cat >/dev/null
cat: /sys/devices/vio/4000/modalias: No such device
cat: /sys/devices/vio/4001/modalias: No such device
cat: /sys/devices/vio/4002/modalias: No such device
cat: /sys/devices/vio/4004/modalias: No such device
cat: /sys/devices/vio/modalias: No such device

Signed-off-by: Prarit Bhargava 
Signed-off-by: Benjamin Herrenschmidt 
CC:

powerpc/iommu: Use GFP_KERNEL instead of GFP_ATOMIC in iommu_init_table()

2013-10-03T07:24:44+00:00

Under heavy (DLPAR?) stress, we tripped this panic() in
arch/powerpc/kernel/iommu.c::iommu_init_table():

	page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz));
	if (!page)
		panic("iommu_init_table: Can't allocate %ld bytes\n", sz);

Before the panic() we got a page allocation failure for an order-2
allocation. There appears to be memory free, but perhaps not in the
ATOMIC context. I looked through all the call-sites of
iommu_init_table() and didn't see any obvious reason to need an ATOMIC
allocation. Most call-sites in fact have an explicit GFP_KERNEL
allocation shortly before the call to iommu_init_table(), indicating we
are not in an atomic context. There is some indirection for some paths,
but I didn't see any locks indicating that GFP_KERNEL is inappropriate.

With this change under the same conditions, we have not been able to
reproduce the panic.

Signed-off-by: Nishanth Aravamudan 
Signed-off-by: Benjamin Herrenschmidt 
CC:

powerpc/sysfs: Disable writing to PURR in guest mode

2013-10-03T07:22:53+00:00

arch/powerpc/kernel/sysfs.c exports PURR with write permission.
This may be valid for kernel in phyp mode. But writing to
the file in guest mode causes crash due to a priviledge violation

Signed-off-by: Madhavan Srinivasan 
Signed-off-by: Benjamin Herrenschmidt 
CC: