Simplify things considerably by moving all the ppc32 specific
symbol exports into its own file.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move the lib symbol exports closer to their function definitions
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Check that the OPAL_DUMP_READ token exists before initalising the elog
infrastructure.
This avoids littering the OPAL console with:
"OPAL: Called with bad token 91"
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Check that the OPAL_ELOG_READ token exists before initalising the elog
infrastructure.
This avoids littering the OPAL console with:
"OPAL: Called with bad token 74"
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Check that the OPAL_RTC_READ token exists before we use the OPAL RTC.
Refactors the code a little to merge error paths.
This avoids littering the OPAL console with:
"OPAL: Called with bad token 3".
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently there is no way to generically check if an OPAL call exists or not
from the host kernel.
This adds an OPAL call opal_check_token() which tells you if the given token is
present in OPAL or not.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Fix ppc 32 build failure as reported here:
http://kisskb.ellerman.id.au/kisskb/buildresult/11663513/
The error is as follows:
arch/powerpc/include/asm/floppy.h:142:20: error: 'isa_bridge_pcidev' undeclared
(first use in this function)
This is happening since floppy.o is enabled by BLK_DEV_FD which depends on
ARCH_MAY_HAVE_PC_FDC which is in-turn enabled if PPC_PSERIES=n.
The following commit changes the dependency so that ARCH_MAY_HAVE_PC_FDC is
dependent exclusively on PCI since otherwise it will not compile.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
in commit 29f1aff2c (powerpc: Copy bootable images in the default
install script) we changed to copying all the built boot targets based
on the assumption that it's backwards compatible. It turns out that
debian devived installkernel scripts will barf if not given exactly 4
args.
This change reverts make install to just install the vmlinux (we can
change the dfault in a seperate patch) and introduces a new make
zInstall which works with a more flexible installkernel script.
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Presently we only support initiating Service Processor dump from host.
Hence update sysfs message. Also update couple of other error/info
messages.
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Continue is not needed at the bottom of a loop.
The Coccinelle semantic patch implementing this change is:
@@
@@
for (...;...;...) {
...
if (...) {
...
- continue;
}
}
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch wires up three new syscalls for powerpc. The three
new syscalls are seccomp, getrandom and memfd_create.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
CONFIG_FHANDLE is a requirement for systemd and with the increasing
uptake of systemd within distros it makes sense for 64 bit defconfigs
to include it.
Signed-off-by: Cyril Bur <cyril.bur@au1.ibm.com>
As opal_message_init() uses machine_early_initcall(powernv, ), and
opal_hmi_handler_init() depends on that early initcall, so it also needs
use machine_* to check the machine_id.
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
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 <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Values acquired from Open Firmware are in 32-bit big endian format
and need to be handled on little endian architectures. This patch
ensures values are in cpu endian when hotplugging memory.
Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"A smattering of bug fixes across most architectures"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
powerpc/kvm/cma: Fix panic introduces by signed shift operation
KVM: s390/mm: Fix guest storage key corruption in ptep_set_access_flags
KVM: s390/mm: Fix storage key corruption during swapping
arm/arm64: KVM: Complete WFI/WFE instructions
ARM/ARM64: KVM: Nuke Hyp-mode tlbs before enabling MMU
KVM: s390/mm: try a cow on read only pages for key ops
KVM: s390: Fix user triggerable bug in dead code
fc95ca7284 introduces a memset in
kvmppc_alloc_hpt since the general CMA doesn't clear the memory it
allocates.
However, the size argument passed to memset is computed from a signed value
and its signed bit is extended by the cast the compiler is doing. This lead
to extremely large size value when dealing with order value >= 31, and
almost all the memory following the allocated space is cleaned. As a
consequence, the system is panicing and may even fail spawning the kdump
kernel.
This fix makes use of an unsigned value for the memset's size argument to
avoid sign extension. Among this fix, another shift operation which may
lead to signed extended value too is also fixed.
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
New system call depends on crypto. As it did not have a separate config
option, CONFIG_KEXEC was modified to select CRYPTO and CRYPTO_SHA256.
But now previous patch introduced a new config option for new syscall.
So CONFIG_KEXEC does not require crypto. Remove that dependency.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fc95ca7284 claims that there is no
functional change but this is not true as it calls get_order() (which
takes bytes) where it should have called order_base_2() and the kernel
stops on VM_BUG_ON().
This replaces get_order() with order_base_2() (round-up version of ilog2).
Suggested-by: Paul Mackerras <paulus@samba.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull more powerpc updates from Ben Herrenschmidt:
"Here are some more powerpc bits for 3.17, essentially fixes.
The biggest series, also aimed at -stable, is from Aneesh and is the
result of weeks and weeks of debugging to find out why the heck or THP
implementation was occasionally triggering multi-hit errors in our
level 1 TLB. It ended up being a combination of issues including
subtleties as to how we should invalidate those special 'MPSS' pages
we use to allow the use of 16M pages inside 4K/64K "base page size"
segments (you really have to love our MMU !)
Another interesting one in the "OMG" category is the series from
Michael adding memory barriers to spin_is_locked(). That's also the
result of many days of debugging to figure out why the semaphore code
would occasionally crash in ways that made no sense. It ended up
being some creative lock stacking that was defeated by the fact that
our locks allow a load inside the locked section to be re-ordered with
the load of the lock value itself (I'm still of two mind about whether
to kill that once and for all by putting a heavier barrier back into
our lock implementation...). The fixes come with a long explanation
in the cset comments, feel free to read it if you feel like having a
headache today"
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (25 commits)
powerpc/thp: Add tracepoints to track hugepage invalidate
powerpc/mm: Use read barrier when creating real_pte
powerpc/thp: Use ACCESS_ONCE when loading pmdp
powerpc/thp: Invalidate with vpn in loop
powerpc/thp: Handle combo pages in invalidate
powerpc/thp: Invalidate old 64K based hash page mapping before insert of 4k pte
powerpc/thp: Don't recompute vsid and ssize in loop on invalidate
powerpc/thp: Add write barrier after updating the valid bit
powerpc: reorder per-cpu NUMA information's initialization
powerpc/perf/hv-24x7: Use kmem_cache_free
powerpc/pseries/hvcserver: Fix endian issue in hvcs_get_partner_info
powerpc: Hard disable interrupts in xmon
powerpc: remove duplicate definition of TEXASR_FS
powerpc/pseries: Avoid deadlock on removing ddw
powerpc/pseries: Failure on removing device node
powerpc/boot: Use correct zlib types for comparison
powerpc/powernv: Interface to register/unregister opal dump region
printk: Add function to return log buffer address and size
powerpc: Add POWER8 features to CPU_FTRS_POSSIBLE/ALWAYS
powerpc/ppc476: Disable BTAC
...
window:
Group changes to the device tree. In preparation for adding device tree
overlay support, OF_DYNAMIC is reworked so that a set of device tree
changes can be prepared and applied to the tree all at once. OF_RECONFIG
notifiers see the most significant change here so that users always get
a consistent view of the tree. Notifiers generation is moved from before
a change to after it, and notifiers for a group of changes are emitted
after the entire block of changes have been applied
Automatic console selection from DT. Console drivers can now use
of_console_check() to see if the device node is specified as a console
device. If so then it gets added as a preferred console. UART devices
get this support automatically when uart_add_one_port() is called.
DT unit tests no longer depend on pre-loaded data in the device tree.
Data is loaded dynamically at the start of unit tests, and then unloaded
again when the tests have completed.
Also contains a few bugfixes for reserved regions and early memory setup.
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Merge tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux
Pull device tree updates from Grant Likely:
"The branch contains the following device tree changes the v3.17 merge
window:
Group changes to the device tree. In preparation for adding device
tree overlay support, OF_DYNAMIC is reworked so that a set of device
tree changes can be prepared and applied to the tree all at once.
OF_RECONFIG notifiers see the most significant change here so that
users always get a consistent view of the tree. Notifiers generation
is moved from before a change to after it, and notifiers for a group
of changes are emitted after the entire block of changes have been
applied
Automatic console selection from DT. Console drivers can now use
of_console_check() to see if the device node is specified as a console
device. If so then it gets added as a preferred console. UART
devices get this support automatically when uart_add_one_port() is
called.
DT unit tests no longer depend on pre-loaded data in the device tree.
Data is loaded dynamically at the start of unit tests, and then
unloaded again when the tests have completed.
Also contains a few bugfixes for reserved regions and early memory
setup"
* tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux: (21 commits)
of: Fixing OF Selftest build error
drivers: of: add automated assignment of reserved regions to client devices
of: Use proper types for checking memory overflow
of: typo fix in __of_prop_dup()
Adding selftest testdata dynamically into live tree
of: Add todo tasklist for Devicetree
of: Transactional DT support.
of: Reorder device tree changes and notifiers
of: Move dynamic node fixups out of powerpc and into common code
of: Make sure attached nodes don't carry along extra children
of: Make devicetree sysfs update functions consistent.
of: Create unlocked versions of node and property add/remove functions
OF: Utility helper functions for dynamic nodes
of: Move CONFIG_OF_DYNAMIC code into a separate file
of: rename of_aliases_mutex to just of_mutex
of/platform: Fix of_platform_device_destroy iteration of devices
of: Migrate of_find_node_by_name() users to for_each_node_by_name()
tty: Update hypervisor tty drivers to use core stdout parsing code.
arm/versatile: Add the uart as the stdout device.
of: Enable console on serial ports specified by /chosen/stdout-path
...
Add tracepoint to track hugepage invalidate. This help us
in debugging difficult to track bugs.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
On ppc64 we support 4K hash pte with 64K page size. That requires
us to track the hash pte slot information on a per 4k basis. We do that
by storing the slot details in the second half of pte page. The pte bit
_PAGE_COMBO is used to indicate whether the second half need to be
looked while building real_pte. We need to use read memory barrier while
doing that so that load of hidx is not reordered w.r.t _PAGE_COMBO
check. On the store side we already do a lwsync in __hash_page_4K
CC: <stable@vger.kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We would get wrong results in compiler recomputed old_pmd. Avoid
that by using ACCESS_ONCE
CC: <stable@vger.kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
As per ISA, for 4k base page size we compare 14..65 bits of VA specified
with the entry_VA in tlb. That implies we need to make sure we do a
tlbie with all the possible 4k va we used to access the 16MB hugepage.
With 64k base page size we compare 14..57 bits of VA. Hence we cannot
ignore the lower 24 bits of va while tlbie .We also cannot tlb
invalidate a 16MB entry with just one tlbie instruction because
we don't track which va was used to instantiate the tlb entry.
CC: <stable@vger.kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
If we changed base page size of the segment, either via sub_page_protect
or via remap_4k_pfn, we do a demote_segment which doesn't flush the hash
table entries. We do a lazy hash page table flush for all mapped pages
in the demoted segment. This happens when we handle hash page fault for
these pages.
We use _PAGE_COMBO bit along with _PAGE_HASHPTE to indicate whether a
pte is backed by 4K hash pte. If we find _PAGE_COMBO not set on the pte,
that implies that we could possibly have older 64K hash pte entries in
the hash page table and we need to invalidate those entries.
Use _PAGE_COMBO to determine the page size with which we should
invalidate the hash table entries on unmap.
CC: <stable@vger.kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
If we changed base page size of the segment, either via sub_page_protect
or via remap_4k_pfn, we do a demote_segment which doesn't flush the hash
table entries. We do a lazy hash page table flush for all mapped pages
in the demoted segment. This happens when we handle hash page fault
for these pages.
We use _PAGE_COMBO bit along with _PAGE_HASHPTE to indicate whether a
pte is backed by 4K hash pte. If we find _PAGE_COMBO not set on the pte,
that implies that we could possibly have older 64K hash pte entries in
the hash page table and we need to invalidate those entries.
Handle this correctly for 16M pages
CC: <stable@vger.kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The segment identifier and segment size will remain the same in
the loop, So we can compute it outside. We also change the
hugepage_invalidate interface so that we can use it the later patch
CC: <stable@vger.kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
With hugepages, we store the hpte valid information in the pte page
whose address is stored in the second half of the PMD. Use a
write barrier to make sure clearing pmd busy bit and updating
hpte valid info are ordered properly.
CC: <stable@vger.kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
There is an issue currently where NUMA information is used on powerpc
(and possibly ia64) before it has been read from the device-tree, which
leads to large slab consumption with CONFIG_SLUB and memoryless nodes.
NUMA powerpc non-boot CPU's cpu_to_node/cpu_to_mem is only accurate
after start_secondary(), similar to ia64, which is invoked via
smp_init().
Commit 6ee0578b4d ("workqueue: mark init_workqueues() as
early_initcall()") made init_workqueues() be invoked via
do_pre_smp_initcalls(), which is obviously before the secondary
processors are online.
Additionally, the following commits changed init_workqueues() to use
cpu_to_node to determine the node to use for kthread_create_on_node:
bce903809a ("workqueue: add wq_numa_tbl_len and
wq_numa_possible_cpumask[]")
f3f90ad469 ("workqueue: determine NUMA node of workers accourding to
the allowed cpumask")
Therefore, when init_workqueues() runs, it sees all CPUs as being on
Node 0. On LPARs or KVM guests where Node 0 is memoryless, this leads to
a high number of slab deactivations
(http://www.spinics.net/lists/linux-mm/msg67489.html).
Fix this by initializing the powerpc-specific CPU<->node/local memory
node mapping as early as possible, which on powerpc is
do_init_bootmem(). Currently that function initializes the mapping for
the boot CPU, but we extend it to setup the mapping for all possible
CPUs. Then, in smp_prepare_cpus(), we can correspondingly set the
per-cpu values for all possible CPUs. That ensures that before the
early_initcalls run (and really as early as possible), the per-cpu NUMA
mapping is accurate.
While testing memoryless nodes on PowerKVM guests with a fix to the
workqueue logic to use cpu_to_mem() instead of cpu_to_node(), with a
guest topology of:
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
node 0 size: 0 MB
node 0 free: 0 MB
node 1 cpus: 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
node 1 size: 16336 MB
node 1 free: 15329 MB
node distances:
node 0 1
0: 10 40
1: 40 10
the slab consumption decreases from
Slab: 932416 kB
SUnreclaim: 902336 kB
to
Slab: 395264 kB
SUnreclaim: 359424 kB
And we a corresponding increase in the slab efficiency from
slab mem objs slabs
used active active
------------------------------------------------------------
kmalloc-16384 337 MB 11.28% 100.00%
task_struct 288 MB 9.93% 100.00%
to
slab mem objs slabs
used active active
------------------------------------------------------------
kmalloc-16384 37 MB 100.00% 100.00%
task_struct 31 MB 100.00% 100.00%
Powerpc didn't support memoryless nodes until recently (64bb80d87f
"powerpc/numa: Enable CONFIG_HAVE_MEMORYLESS_NODES" and 8c27226119
"powerpc/numa: Enable USE_PERCPU_NUMA_NODE_ID"). Those commits also
helped improve memory consumption with these kind of environments.
Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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:
// <smpl>
@@
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)
// </smpl>
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
A buffer returned by H_VTERM_PARTNER_INFO contains device information
in big endian format, causing problems for little endian architectures.
This patch ensures that they are in cpu endian.
Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
xmon only soft disables interrupts. This seems like a bad idea - we
certainly don't want decrementer and PMU exceptions going off when
we are debugging something inside xmon.
This issue was uncovered when the hard lockup detector went off
inside xmon. To ensure we wont get a spurious hard lockup warning,
I also call touch_nmi_watchdog() when exiting xmon.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
It appears that commits 7f06f21d40 ("powerpc/tm: Add checking to
treclaim/trechkpt") and e4e3812150 ("KVM: PPC: Book3S HV: Add
transactional memory support") both added definitions of TEXASR_FS.
Remove one of them. At the same time, fix the alignment of the remaining
definition (should be tab-separated like the rest of the #defines).
Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Avoids this warning:
arch/powerpc/boot/gunzip_util.c:118:9: warning: comparison of distinct pointer types lacks a cast
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
PowerNV platform is capable of capturing host memory region when system
crashes (because of host/firmware). We have new OPAL API to register/
unregister memory region to be captured when system crashes.
This patch adds support for new API. Also during boot time we register
kernel log buffer and unregister before doing kexec.
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We have been a bit slack about updating the CPU_FTRS_POSSIBLE and
CPU_FTRS_ALWAYS masks. When we added POWER8, and also POWER8E we forgot
to update the ALWAYS mask. And when we added POWER8_DD1 we forgot to
update both the POSSIBLE and ALWAYS masks.
Luckily this hasn't caused any actual bugs AFAICS. Failing to update the
ALWAYS mask just forgoes a potential optimisation opportunity. Failing
to update the POSSIBLE mask for POWER8_DD1 is also OK because it only
removes a bit rather than adding any.
Regardless they should all be in both masks so as to avoid any future
bugs when the set of ALWAYS/POSSIBLE bits changes, or the masks
themselves change.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michael Neuling <mikey@neuling.org>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This patch disables the branch target address CAM which under specific
circumstances may cause the processor to skip execution of 1-4
instructions. This fixes IBM Erratum #47.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When we take full hotplug to recover from EEH errors, PCI buses
could be involved. For the case, the child devices of involved
PCI buses can't be attached to IOMMU group properly, which is
caused by commit 3f28c5a ("powerpc/powernv: Reduce multi-hit of
iommu_add_device()").
When adding the PCI devices of the newly created PCI buses to
the system, the IOMMU group is expected to be added in (C).
(A) fails to bind the IOMMU group because bus->is_added is
false. (B) fails because the device doesn't have binding IOMMU
table yet. bus->is_added is set to true at end of (C) and
pdev->is_added is set to true at (D).
pcibios_add_pci_devices()
pci_scan_bridge()
pci_scan_child_bus()
pci_scan_slot()
pci_scan_single_device()
pci_scan_device()
pci_device_add()
pcibios_add_device() A: Ignore
device_add() B: Ignore
pcibios_fixup_bus()
pcibios_setup_bus_devices()
pcibios_setup_device() C: Hit
pcibios_finish_adding_to_bus()
pci_bus_add_devices()
pci_bus_add_device() D: Add device
If the parent PCI bus isn't involved in hotplug, the IOMMU
group is expected to be bound in (B). (A) should fail as the
sysfs entries aren't populated.
The patch fixes the issue by reverting commit 3f28c5a and remove
WARN_ON() in iommu_add_device() to allow calling the function
even the specified device already has associated IOMMU group.
Cc: <stable@vger.kernel.org> # 3.16+
Reported-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Similar to the previous commit which described why we need to add a
barrier to arch_spin_is_locked(), we have a similar problem with
spin_unlock_wait().
We need a barrier on entry to ensure any spinlock we have previously
taken is visibly locked prior to the load of lock->slock.
It's also not clear if spin_unlock_wait() is intended to have ACQUIRE
semantics. For now be conservative and add a barrier on exit to give it
ACQUIRE semantics.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The kernel defines the function spin_is_locked(), which can be used to
check if a spinlock is currently locked.
Using spin_is_locked() on a lock you don't hold is obviously racy. That
is, even though you may observe that the lock is unlocked, it may become
locked at any time.
There is (at least) one exception to that, which is if two locks are
used as a pair, and the holder of each checks the status of the other
before doing any update.
Assuming *A and *B are two locks, and *COUNTER is a shared non-atomic
value:
The first CPU does:
spin_lock(*A)
if spin_is_locked(*B)
# nothing
else
smp_mb()
LOAD r = *COUNTER
r++
STORE *COUNTER = r
spin_unlock(*A)
And the second CPU does:
spin_lock(*B)
if spin_is_locked(*A)
# nothing
else
smp_mb()
LOAD r = *COUNTER
r++
STORE *COUNTER = r
spin_unlock(*B)
Although this is a strange locking construct, it should work.
It seems to be understood, but not documented, that spin_is_locked() is
not a memory barrier, so in the examples above and below the caller
inserts its own memory barrier before acting on the result of
spin_is_locked().
For now we assume spin_is_locked() is implemented as below, and we break
it out in our examples:
bool spin_is_locked(*LOCK) {
LOAD l = *LOCK
return l.locked
}
Our intuition is that there should be no problem even if the two code
sequences run simultaneously such as:
CPU 0 CPU 1
==================================================
spin_lock(*A) spin_lock(*B)
LOAD b = *B LOAD a = *A
if b.locked # true if a.locked # true
# nothing # nothing
spin_unlock(*A) spin_unlock(*B)
If one CPU gets the lock before the other then it will do the update and
the other CPU will back off:
CPU 0 CPU 1
==================================================
spin_lock(*A)
LOAD b = *B
spin_lock(*B)
if b.locked # false LOAD a = *A
else if a.locked # true
smp_mb() # nothing
LOAD r1 = *COUNTER spin_unlock(*B)
r1++
STORE *COUNTER = r1
spin_unlock(*A)
However in reality spin_lock() itself is not indivisible. On powerpc we
implement it as a load-and-reserve and store-conditional.
Ignoring the retry logic for the lost reservation case, it boils down to:
spin_lock(*LOCK) {
LOAD l = *LOCK
l.locked = true
STORE *LOCK = l
ACQUIRE_BARRIER
}
The ACQUIRE_BARRIER is required to give spin_lock() ACQUIRE semantics as
defined in memory-barriers.txt:
This acts as a one-way permeable barrier. It guarantees that all
memory operations after the ACQUIRE operation will appear to happen
after the ACQUIRE operation with respect to the other components of
the system.
On modern powerpc systems we use lwsync for ACQUIRE_BARRIER. lwsync is
also know as "lightweight sync", or "sync 1".
As described in Power ISA v2.07 section B.2.1.1, in this scenario the
lwsync is not the barrier itself. It instead causes the LOAD of *LOCK to
act as the barrier, preventing any loads or stores in the locked region
from occurring prior to the load of *LOCK.
Whether this behaviour is in accordance with the definition of ACQUIRE
semantics in memory-barriers.txt is open to discussion, we may switch to
a different barrier in future.
What this means in practice is that the following can occur:
CPU 0 CPU 1
==================================================
LOAD a = *A LOAD b = *B
a.locked = true b.locked = true
LOAD b = *B LOAD a = *A
STORE *A = a STORE *B = b
if b.locked # false if a.locked # false
else else
smp_mb() smp_mb()
LOAD r1 = *COUNTER LOAD r2 = *COUNTER
r1++ r2++
STORE *COUNTER = r1
STORE *COUNTER = r2 # Lost update
spin_unlock(*A) spin_unlock(*B)
That is, the load of *B can occur prior to the store that makes *A
visibly locked. And similarly for CPU 1. The result is both CPUs hold
their lock and believe the other lock is unlocked.
The easiest fix for this is to add a full memory barrier to the start of
spin_is_locked(), so adding to our previous definition would give us:
bool spin_is_locked(*LOCK) {
smp_mb()
LOAD l = *LOCK
return l.locked
}
The new barrier orders the store to the lock we are locking vs the load
of the other lock:
CPU 0 CPU 1
==================================================
LOAD a = *A LOAD b = *B
a.locked = true b.locked = true
STORE *A = a STORE *B = b
smp_mb() smp_mb()
LOAD b = *B LOAD a = *A
if b.locked # true if a.locked # true
# nothing # nothing
spin_unlock(*A) spin_unlock(*B)
Although the above example is theoretical, there is code similar to this
example in sem_lock() in ipc/sem.c. This commit in addition to the next
commit appears to be a fix for crashes we are seeing in that code where
we believe this race happens in practice.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Once again, we see
arch/powerpc/kernel/exceptions-64s.S: Assembler messages:
arch/powerpc/kernel/exceptions-64s.S:865: Error: attempt to move .org backwards
arch/powerpc/kernel/exceptions-64s.S:866: Error: attempt to move .org backwards
arch/powerpc/kernel/exceptions-64s.S:890: Error: attempt to move .org backwards
when compiling ppc:allmodconfig.
This time the problem has been caused by to commit 0869b6fd20
("powerpc/book3s: Add basic infrastructure to handle HMI in Linux"),
which adds functions hmi_exception_early and hmi_exception_after_realmode
into a critical (size-limited) code area, even though that does not appear
to be necessary.
Move those functions to a non-critical area of the file.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
__early_init_mmu() does some things that are really only needed by the
boot cpu. On FSL booke, This includes calling
memblock_enforce_memory_limit(), which is labelled __init. Secondary
cpu init code can't be __init as that would break CPU hotplug.
While it's probably a bug that memblock_enforce_memory_limit() isn't
__init_memblock instead, there's no reason why we should be doing this
stuff for secondary cpus in the first place.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
