This patch adds the ability to be able to save the FPU registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.
This patch optimises the thread copy path (as a result of a fork() or
clone()) so that the parent thread can return to userspace with hot
registers avoiding a possibly pointless reload of FPU register state.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This prepares for the decoupling of saving {fpu,altivec,vsx} registers and
marking {fpu,altivec,vsx} as being unused by a thread.
Currently giveup_{fpu,altivec,vsx}() does both however optimisations to
task switching can be made if these two operations are decoupled.
save_all() will permit the saving of registers to thread structs and leave
threads MSR with bits enabled.
This patch introduces no functional change.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently the FPU, VEC and VSX facilities are lazily loaded. This is not
a problem unless a process is using these facilities.
Modern versions of GCC are very good at automatically vectorising code,
new and modernised workloads make use of floating point and vector
facilities, even the kernel makes use of vectorised memcpy.
All this combined greatly increases the cost of a syscall since the
kernel uses the facilities sometimes even in syscall fast-path making it
increasingly common for a thread to take an *_unavailable exception soon
after a syscall, not to mention potentially taking all three.
The obvious overcompensation to this problem is to simply always load
all the facilities on every exit to userspace. Loading up all FPU, VEC
and VSX registers every time can be expensive and if a workload does
avoid using them, it should not be forced to incur this penalty.
An 8bit counter is used to detect if the registers have been used in the
past and the registers are always loaded until the value wraps to back
to zero.
Several versions of the assembly in entry_64.S were tested:
1. Always calling C.
2. Performing a common case check and then calling C.
3. A complex check in asm.
After some benchmarking it was determined that avoiding C in the common
case is a performance benefit (option 2). The full check in asm (option
3) greatly complicated that codepath for a negligible performance gain
and the trade-off was deemed not worth it.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
[mpe: Move load_vec in the struct to fill an existing hole, reword change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
fixup
Currently when threads get scheduled off they always giveup the FPU,
Altivec (VMX) and Vector (VSX) units if they were using them. When they are
scheduled back on a fault is then taken to enable each facility and load
registers. As a result explicitly disabling FPU/VMX/VSX has not been
necessary.
Future changes and optimisations remove this mandatory giveup and fault
which could cause calls such as clone() and fork() to copy threads and run
them later with FPU/VMX/VSX enabled but no registers loaded.
This patch starts the process of having MSR_{FP,VEC,VSX} mean that a
threads registers are hot while not having MSR_{FP,VEC,VSX} means that the
registers must be loaded. This allows for a smarter return to userspace.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Load up the non volatile FPU and VMX regs and ensure that they are the
expected value in a signal handler
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Loop in assembly checking the registers with many threads.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Test that the non volatile floating point and Altivec registers get
correctly preserved across the fork() syscall.
fork() works nicely for this purpose, the registers should be the same for
both parent and child
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
[mpe: Add include guards to basic_asm.h, minor formatting]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
LTO can cause GCC to inline some functions which have attributes set.
The act of inlining the functions can lead to GCC forgetting about the
attributes which leads to incorrect tests.
Notable example being: __attribute__((__target__("no-vsx")))
LTO can also interact strangely with custom assembly functions and cause
tests to intermittently fail.
Both these cases are hard to detect and require manual inspection of
binaries which is unlikely to happen for all tests. Furthermore, LTO
optimisations are not necessary for selftests and correctness is
paramount and as such it is best to disable LTO.
LTO can be enabled on a per test basis.
A pseries_le_defconfig kernel on a POWER8 was used to determine that the
same subset of selftests pass and fail with and without -flto in the
common Makefile.
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Gcc helpfully points out that we're accessing past the end of the gprs
array:
tm-signal-msr-resv.c: In function 'signal_usr1':
tm-signal-msr-resv.c:43:37: error: array subscript is above array bounds [-Werror=array-bounds]
ucp->uc_mcontext.regs->gpr[PT_MSR] |= (7ULL);
We haven't noticed previously because -flto was hiding it somehow.
The code is confused, PT_MSR isn't a gpr, instead it's in
uc_regs->gregs, so fix it.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
htab_get_table_size() either retrieve the size of the hash page table (HPT)
from the device tree - if the HPT size is determined by firmware - or
uses a heuristic to determine a good size based on RAM size if the kernel
is responsible for allocating the HPT.
To support a PAPR extension allowing resizing of the HPT, we're going to
want the memory size -> HPT size logic elsewhere, so split it out into a
helper function.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This makes a number of cleanups to handling of mapping failures during
memory hotplug on Power:
For errors creating the linear mapping for the hot-added region:
* This is now reported with EFAULT which is more appropriate than the
previous EINVAL (the failure is unlikely to be related to the
function's parameters)
* An error in this path now prints a warning message, rather than just
silently failing to add the extra memory.
* Previously a failure here could result in the region being partially
mapped. We now clean up any partial mapping before failing.
For errors creating the vmemmap for the hot-added region:
* This is now reported with EFAULT instead of causing a BUG() - this
could happen for external reason (e.g. full hash table) so it's better
to handle this non-fatally
* An error message is also printed, so the failure won't be silent
* As above a failure could cause a partially mapped region, we now
clean this up. [mpe: move htab_remove_mapping() out of #ifdef
CONFIG_MEMORY_HOTPLUG to enable this]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
At the moment the hpte_removebolted callback in ppc_md returns void and
will BUG_ON() if the hpte it's asked to remove doesn't exist in the first
place. This is awkward for the case of cleaning up a mapping which was
partially made before failing.
So, we add a return value to hpte_removebolted, and have it return ENOENT
in the case that the HPTE to remove didn't exist in the first place.
In the (sole) caller, we propagate errors in hpte_removebolted to its
caller to handle. However, we handle ENOENT specially, continuing to
complete the unmapping over the specified range before returning the error
to the caller.
This means that htab_remove_mapping() will work sanely on a partially
present mapping, removing any HPTEs which are present, while also returning
ENOENT to its caller in case it's important there.
There are two callers of htab_remove_mapping():
- In remove_section_mapping() we already WARN_ON() any error return,
which is reasonable - in this case the mapping should be fully
present
- In vmemmap_remove_mapping() we BUG_ON() any error. We change that to
just a WARN_ON() in the case of ENOENT, since failing to remove a
mapping that wasn't there in the first place probably shouldn't be
fatal.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently, the only error that htab_remove_mapping() can report is -EINVAL,
if removal of bolted HPTEs isn't implemeted for this platform. We make
a few clean ups to the handling of this:
* EINVAL isn't really the right code - there's nothing wrong with the
function's arguments - use ENODEV instead
* We were also printing a warning message, but that's a decision better
left up to the callers, so remove it
* One caller is vmemmap_remove_mapping(), which will just BUG_ON() on
error, making the warning message redundant, so no change is needed
there.
* The other caller is remove_section_mapping(). This is called in the
memory hot remove path at a point after vmemmap_remove_mapping() so
if hpte_removebolted isn't implemented, we'd expect to have already
BUG()ed anyway. Put a WARN_ON() here, in lieu of a printk() since this
really shouldn't be happening.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Instead of defining a local version of struct udphdr use the standard
definition from <linux/udp.h>.
The 'src' field is named 'source' in the <linux/udp.h> definition.
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Instead of defining a local version of struct iphdr use the standard
definition from <linux/ip.h>.
Several fields in the <linux/ip.h> definition have different names:
- proto -> protocol
- src -> saddr
- dest -> daddr
- total_length -> tot_len
- checksum -> check
Also, 'ver_len' is composed by 'version' and 'ihl' in <linux/ip.h>.
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Instead of defining the local struct vlantag use the standard definition
of vlan_hdr from <linux/if_vlan.h>.
The fields in the <linux/if_vlan.h> definition have different names:
- vlan -> h_vlan_TCI
- subtype -> h_vlan_encapsulated_proto
While there, use also the ETH_P_IP macro instead of an hard-coded 0x0800
value.
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Instead of defining a local version of struct ethhdr use the standard
definition from <linux/if_ether.h>.
The fields in the <linux/if_ether.h> definition have different names:
- dest -> h_dest
- src -> h_source
- type -> h_proto
While there, use a few other standard functions/macros:
- eth_broadcast_addr (instead of a memset)
- ETH_ALEN
- ETH_P_8021Q
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Now that other PTE fields have been moved out of the way, we can
expand the RPN field of the PTE on 64-bit Book 3S systems and align
it with the RPN field in the radix PTE format used by PowerISA v3.0
CPUs in radix mode. For 64k page size, this means we need to move
the _PAGE_COMBO and _PAGE_4K_PFN bits.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This moves the _PAGE_SPECIAL and _PAGE_SOFT_DIRTY bits in the Linux
PTE on 64-bit Book 3S systems to bit positions which are designated
for software use in the radix PTE format used by PowerISA v3.0 CPUs
in radix mode.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This moves the _PAGE_EXEC, _PAGE_RW and _PAGE_USER bits around in
the Linux PTE on 64-bit Book 3S systems to correspond with the bit
positions used in radix mode by PowerISA v3.0 CPUs. This also adds
a _PAGE_READ bit corresponding to the read permission bit in the
radix PTE. _PAGE_READ is currently unused but could possibly be used
in future to improve pte_protnone().
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This moves the _PAGE_HASHPTE, _PAGE_F_GIX and _PAGE_F_SECOND fields in
the Linux PTE on 64-bit Book 3S systems to the most significant byte.
Of the 5 bits, one is a software-use bit and the other four are
reserved bit positions in the PowerISA v3.0 radix PTE format.
Using these bits is OK because these bits are all to do with tracking
the HPTE(s) associated with the Linux PTE, and therefore won't be
needed in radix mode. This frees up bit positions in the lower two
bytes.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This changes _PAGE_PTE for 64-bit Book 3S processors from 0x1 to
0x4000_0000_0000_0000, because that bit is used as the L (leaf)
bit by PowerISA v3.0 CPUs in radix mode. The "leaf" bit indicates
that the PTE points to a page directly rather than another radix
level, which is what the _PAGE_PTE bit means.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This changes _PAGE_PRESENT for 64-bit Book 3S processors from 0x2 to
0x8000_0000_0000_0000, because that is where PowerISA v3.0 CPUs in
radix mode will expect to find it.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This changes the Linux page tables to store physical addresses
rather than kernel virtual addresses in the upper levels of the
tree (pgd, pud and pmd) for 64-bit Book 3S machines.
This also changes the hugepd pointers used to implement hugepages
when the base page size is 4k to store physical addresses rather than
virtual addresses (again just for 64-bit Book3S machines).
This frees up some high order bits, and will be needed with
PowerISA v3.0 machines which read the page table tree in hardware
in radix mode.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This frees up bits 57-63 in the Linux PTE on 64-bit Book 3S machines.
In the 4k page case, this is done just by reducing the size of the
RPN field to 39 bits, giving 51-bit real addresses. In the 64k page
case, we had 10 unused bits in the middle of the PTE, so this moves
the RPN field down 10 bits to make use of those unused bits. This
means the RPN field is now 3 bits larger at 37 bits, giving 53-bit
real addresses in the normal case, or 49-bit real addresses for the
special 4k PFN case.
We are doing this in order to be able to move some other PTE bits
into the positions where PowerISA V3.0 processors will expect to
find them in radix-tree mode. Ultimately we will be able to move
the RPN field to lower bit positions and make it larger.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
- eeh: Fix partial hotplug criterion from Gavin Shan
- mm: Clear the invalid slot information correctly from Aneesh Kumar K.V
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Merge tag 'powerpc-4.5-4' into next
Pull in our current fixes from 4.5, in particular the "Fix Multi hit
ERAT" bug is causing folks some grief when testing next.
I ran into this issue while debugging an early boot problem. The system
hit a BUG_ON() but report bug failed to print the line number and file
name. The reason being that the system was running in real mode and
report_bug() searches for addresses in the PAGE_OFFSET+ region.
Suggested-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
__xchg_called_with_bad_pointer() can't tell us which code uses {cmp}xchg
with an unsupported size, and no error is reported until the link stage.
To make such problems easier to debug, use BUILD_BUG_ON_MSG() instead.
Signed-off-by: pan xinhui <xinhui.pan@linux.vnet.ibm.com>
[mpe: Tweak change log wording & add relaxed/acquire]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
fixup
Most current OpenPOWER platforms have an AST BMC, so add graphics
support via the AST DRM driver.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There are a few firmware-provided interfaces for OpenPOWER platforms:
the PRD infrastructure, IPMI support, and MTD access to the PNOR flash.
This change adds these to powernv_defconfig
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This change adds a defconfig for the non-virtualised power platforms,
based on pseries_defconfig, but without pseries, and little-endian,
and no OF trampoline.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add a cputable entry for POWER9. More code is required to actually
boot and run on a POWER9 but this gets the base piece in which we can
start building on.
Copies over from POWER8 except for:
- Adds a new CPU_FTR_ARCH_300 bit to start hanging new architecture
features from (in subsequent patches).
- Advertises new user features bits PPC_FEATURE2_ARCH_3_00 &
HAS_IEEE128 when on POWER9.
- Drops CPU_FTR_SUBCORE.
- Drops PMU code and machine check.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Use defines for literals __init_tlb_power[78] rather than hand coding
them.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Subcores isn't really part of the 2.07 architecture but currently we
turn it on using the 2.07 feature bit. Subcores is really a POWER8
specific feature.
This adds a new CPU_FTR bit just for subcores and moves the subcore
init code over to use this.
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When initialising OPAL interfaces, there is a possibility that
opal_msglog_init() may fail to initialise the msglog/memory console.
Fix opal_msglog_sysfs_init() so it doesn't try to create sysfs entry for
the msglog if this occurs.
Suggested-by: Joel Stanley <joel@jms.id.au>
Fixes: 9b4fffa149 ("powerpc/powernv: new function to access OPAL msglog")
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We can get a hash pte fault with 4k base page size and find the pte
already inserted with 64K base page size. In that case we need to clear
the existing slot information from the old pte. Fix this correctly
With THP, we also clear the slot information with respect to all
the 64K hash pte mapping that 16MB page. They are all invalid
now. This make sure we don't find the slot valid when we fault with
4k base page size. Finding the slot valid should not result in any wrong
behavior because we do check again in hash page table for the validity.
But we can avoid that check completely.
Fixes: a43c0eb836 ("powerpc/mm: Convert 4k hash insert to C")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
During error recovery, the device could be removed as part of the
partial hotplug. The criterion used to come with partial hotplug
is: if the device driver provides error_detected(), slot_reset()
and resume() callbacks, it's immune from hotplug. Otherwise,
it's going to experience partial hotplug during EEH recovery. But
the criterion isn't correct enough: mlx4_core driver for Mellanox
adapters provides error_detected(), slot_reset() callbacks, but
resume() isn't there. Those Mellanox adapters won't be to involved
in the partial hotplug.
This fixes the criterion to a practical one: adpater with driver
that provides error_detected(), slot_reset() will be immune from
partial hotplug. resume() isn't mandatory.
Fixes: f2da4ccf ("powerpc/eeh: More relaxed hotplug criterion")
Cc: stable@vger.kernel.org #v4.4+
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Implement cmpxchg{,64}_relaxed and atomic{,64}_cmpxchg_relaxed, based on
which _release variants can be built.
To avoid superfluous barriers in _acquire variants, we implement these
operations with assembly code rather use __atomic_op_acquire() to build
them automatically.
For the same reason, we keep the assembly implementation of fully
ordered cmpxchg operations.
However, we don't do the similar for _release, because that will require
putting barriers in the middle of ll/sc loops, which is probably a bad
idea.
Note cmpxchg{,64}_relaxed and atomic{,64}_cmpxchg_relaxed are not
compiler barriers.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Implement xchg{,64}_relaxed and atomic{,64}_xchg_relaxed, based on these
_relaxed variants, release/acquire variants and fully ordered versions
can be built.
Note that xchg{,64}_relaxed and atomic_{,64}_xchg_relaxed are not
compiler barriers.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
On powerpc, acquire and release semantics can be achieved with
lightweight barriers("lwsync" and "ctrl+isync"), which can be used to
implement __atomic_op_{acquire,release}.
For release semantics, since we only need to ensure all memory accesses
that issue before must take effects before the -store- part of the
atomics, "lwsync" is what we only need. On the platform without
"lwsync", "sync" should be used. Therefore in __atomic_op_release() we
use PPC_RELEASE_BARRIER.
For acquire semantics, "lwsync" is what we only need for the similar
reason. However on the platform without "lwsync", we can use "isync"
rather than "sync" as an acquire barrier. Therefore in
__atomic_op_acquire() we use PPC_ACQUIRE_BARRIER, which is barrier() on
UP, "lwsync" if available and "isync" otherwise.
Implement atomic{,64}_{add,sub,inc,dec}_return_relaxed, and build other
variants with these helpers.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Some architectures may have their special barriers for acquire, release
and fence semantics, so that general memory barriers(smp_mb__*_atomic())
in the default __atomic_op_*() may be too strong, so allow architectures
to define their own helpers which can overwrite the default helpers.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Enhanced Error Handling could mean anything in the context of the entire
kernel, so change the name to reference that it is both for PCI and
powerpc.
EEH covers a bit more than the previously listed files, so add the headers
and platform-specific code to the EEH maintained section.
In addition, I am taking over the maintainership.
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
I spent some time trying to use kgdb and debugged my inability to
resume from kgdb_handle_breakpoint(). NIP is not incremented
and that leads to a loop in the debugger.
I've tested this lightly on a virtual instance with KDB enabled.
After the patch, I am able to get the "go" command to work as
expected.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Quite often drivers set only "write" permission assuming that this
includes "read" permission as well and this works on plenty of
platforms. However IODA2 is strict about this and produces an EEH when
"read" permission is not set and reading happens.
This adds a workaround in the IODA code to always add the "read" bit
when the "write" bit is set.
Fixes: 10b35b2b74 ("powerpc/powernv: Do not set "read" flag if direction==DMA_NONE")
Cc: stable@vger.kernel.org # 4.2+
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Tested-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
With ppc64 we use the deposited pgtable_t to store the hash pte slot
information. We should not withdraw the deposited pgtable_t without
marking the pmd none. This ensure that low level hash fault handling
will skip this huge pte and we will handle them at upper levels.
Recent change to pmd splitting changed the above in order to handle the
race between pmd split and exit_mmap. The race is explained below.
Consider following race:
CPU0 CPU1
shrink_page_list()
add_to_swap()
split_huge_page_to_list()
__split_huge_pmd_locked()
pmdp_huge_clear_flush_notify()
// pmd_none() == true
exit_mmap()
unmap_vmas()
zap_pmd_range()
// no action on pmd since pmd_none() == true
pmd_populate()
As result the THP will not be freed. The leak is detected by check_mm():
BUG: Bad rss-counter state mm:ffff880058d2e580 idx:1 val:512
The above required us to not mark pmd none during a pmd split.
The fix for ppc is to clear the huge pte of _PAGE_USER, so that low
level fault handling code skip this pte. At higher level we do take ptl
lock. That should serialze us against the pmd split. Once the lock is
acquired we do check the pmd again using pmd_same. That should always
return false for us and hence we should retry the access. We do the
pmd_same check in all case after taking plt with
THP (do_huge_pmd_wp_page, do_huge_pmd_numa_page and
huge_pmd_set_accessed)
Also make sure we wait for irq disable section in other cpus to finish
before flipping a huge pte entry with a regular pmd entry. Code paths
like find_linux_pte_or_hugepte depend on irq disable to get
a stable pte_t pointer. A parallel thp split need to make sure we
don't convert a pmd pte to a regular pmd entry without waiting for the
irq disable section to finish.
Fixes: eef1b3ba05 ("thp: implement split_huge_pmd()")
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When PCI bus is unplugged during full hotplug for EEH recovery,
the platform PE instance (struct pnv_ioda_pe) isn't released and
it dereferences the stale PCI bus that has been released. It leads
to kernel crash when referring to the stale PCI bus.
This fixes the issue by correcting the PE's primary bus when it's
oneline at plugging time, in pnv_pci_dma_bus_setup() which is to
be called by pcibios_fixup_bus().
Cc: stable@vger.kernel.org # v4.1+
Reported-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reported-by: Pradipta Ghosh <pradghos@in.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When PE is created, its primary bus is cached to pe->bus. At later
point, the cached primary bus is returned from eeh_pe_bus_get().
However, we could get stale cached primary bus and run into kernel
crash in one case: full hotplug as part of fenced PHB error recovery
releases all PCI busses under the PHB at unplugging time and recreate
them at plugging time. pe->bus is still dereferencing the PCI bus
that was released.
This adds another PE flag (EEH_PE_PRI_BUS) to represent the validity
of pe->bus. pe->bus is updated when its first child EEH device is
online and the flag is set. Before unplugging in full hotplug for
error recovery, the flag is cleared.
Fixes: 8cdb2833 ("powerpc/eeh: Trace PCI bus from PE")
Cc: stable@vger.kernel.org #v3.11+
Reported-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reported-by: Pradipta Ghosh <pradghos@in.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
If a cpu is hotplugged while the hcall trace points are active, it's
possible to hit a warning from RCU due to the trace points calling into
RCU from an offline cpu, eg:
RCU used illegally from offline CPU!
rcu_scheduler_active = 1, debug_locks = 1
Make the hypervisor tracepoints conditional by using
TRACE_EVENT_FN_COND.
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Cyril Bur