linux-toradex.git/arch/powerpc/kernel, branch v3.2.54

powerpc/signals: Improved mark VSX not saved with small contexts fix

2014-01-03T04:33:24+00:00

commit ec67ad82814bee92251fd963bf01c7a173856555 upstream.

In a recent patch:
  commit c13f20ac48328b05cd3b8c19e31ed6c132b44b42
  Author: Michael Neuling 
  powerpc/signals: Mark VSX not saved with small contexts

We fixed an issue but an improved solution was later discussed after the patch
was merged.

Firstly, this patch doesn't handle the 64bit signals case, which could also hit
this issue (but has never been reported).

Secondly, the original patch isn't clear what MSR VSX should be set to.  The
new approach below always clears the MSR VSX bit (to indicate no VSX is in the
context) and sets it only in the specific case where VSX is available (ie. when
VSX has been used and the signal context passed has space to provide the
state).

This reverts the original patch and replaces it with the improved solution.  It
also adds a 64 bit version.

Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

powerpc/signals: Mark VSX not saved with small contexts

2014-01-03T04:33:23+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: Ben Hutchings

powerpc/pseries: Duplicate dtl entries sometimes sent to userspace

2014-01-03T04:33:23+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 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

powerpc/vio: use strcpy in modalias_show

2014-01-03T04:33:16+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: Ben Hutchings

powerpc/vio: Fix modalias_show return values

2014-01-03T04:33:16+00:00

commit e82b89a6f19bae73fb064d1b3dd91fcefbb478f4 upstream.

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 
Signed-off-by: Ben Hutchings

powerpc/pseries/lparcfg: Fix possible overflow are more than 1026

2013-10-26T20:06:11+00:00

commit 5676005acf26ab7e924a8438ea4746e47d405762 upstream.

need set '\0' for 'local_buffer'.

SPLPAR_MAXLENGTH is 1026, RTAS_DATA_BUF_SIZE is 4096. so the contents of
rtas_data_buf may truncated in memcpy.

if contents are really truncated.
  the splpar_strlen is more than 1026. the next while loop checking will
  not find the end of buffer. that will cause memory access violation.

Signed-off-by: Chen Gang 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

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

2013-10-26T20:06:08+00:00

commit 1cf389df090194a0976dc867b7fffe99d9d490cb upstream.

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 
Signed-off-by: Ben Hutchings

powerpc/sysfs: Disable writing to PURR in guest mode

2013-10-26T20:06:07+00:00

commit d1211af3049f4c9c1d8d4eb8f8098cc4f4f0d0c7 upstream.

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 
[bwh: Backported to 3.2:
 - Adjust context
 - CPUs are sysdev and we must use the sysdev API]
Signed-off-by: Ben Hutchings

powerpc: Handle unaligned ldbrx/stdbrx

2013-10-26T20:05:58+00:00

commit 230aef7a6a23b6166bd4003bfff5af23c9bd381f upstream.

Normally when we haven't implemented an alignment handler for
a load or store instruction the process will be terminated.

The alignment handler uses the DSISR (or a pseudo one) to locate
the right handler. Unfortunately ldbrx and stdbrx overlap lfs and
stfs so we incorrectly think ldbrx is an lfs and stdbrx is an
stfs.

This bug is particularly nasty - instead of terminating the
process we apply an incorrect fixup and continue on.

With more and more overlapping instructions we should stop
creating a pseudo DSISR and index using the instruction directly,
but for now add a special case to catch ldbrx/stdbrx.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

powerpc: Don't Oops when accessing /proc/powerpc/lparcfg without hypervisor

2013-09-10T00:57:33+00:00

commit f5f6cbb61610b7bf9d9d96db9c3979d62a424bab upstream.

/proc/powerpc/lparcfg is an ancient facility (though still actively used)
which allows access to some informations relative to the partition when
running underneath a PAPR compliant hypervisor.

It makes no sense on non-pseries machines. However, currently, not only
can it be created on these if the kernel has pseries support, but accessing
it on such a machine will crash due to trying to do hypervisor calls.

In fact, it should also not do HV calls on older pseries that didn't have
an hypervisor either.

Finally, it has the plumbing to be a module but is a "bool" Kconfig option.

This fixes the whole lot by turning it into a machine_device_initcall
that is only created on pseries, and adding the necessary hypervisor
check before calling the H_GET_EM_PARMS hypercall

Signed-off-by: Benjamin Herrenschmidt 
[bwh: Backported to 3.2: lparcfg_cleanup() was a bit different]
Signed-off-by: Ben Hutchings