It should be ALTIVEC, not ALIVEC.
Cyril explains: If a thread performs a transaction with altivec and then
gets preempted for whatever reason, this bug may cause the kernel to not
re-enable altivec when that thread runs again. This will result in an
altivec unavailable fault, when that fault happens inside a user
transaction the kernel has no choice but to enable altivec and doom the
transaction.
The result is that transactions using altivec may get aborted more often
than they should.
The difficulty in catching this with a selftest is my deliberate use of
the word may above. Optimisations to avoid FPU/altivec/VSX faults mean
that the kernel will always leave them on for 255 switches. This code
prevents the kernel turning it off if it got to the 256th switch (and
userspace was transactional).
Fixes: dc16b553c9 ("powerpc: Always restore FPU/VEC/VSX if hardware transactional memory in use")
Reviewed-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently the MSR TM bit is always set if the hardware is TM capable.
This adds extra overhead as it means the TM SPRS (TFHAR, TEXASR and
TFAIR) must be swapped for each process regardless of if they use TM.
For processes that don't use TM the TM MSR bit can be turned off
allowing the kernel to avoid the expensive swap of the TM registers.
A TM unavailable exception will occur if a thread does use TM and the
kernel will enable MSR_TM and leave it so for some time afterwards.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Make the structures being used for checkpointed state named
consistently with the pt_regs/ckpt_regs.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There is currently an inconsistency as to how the entire CPU register
state is saved and restored when a thread uses transactional memory
(TM).
Using transactional memory results in the CPU having duplicated
(almost) all of its register state. This duplication results in a set
of registers which can be considered 'live', those being currently
modified by the instructions being executed and another set that is
frozen at a point in time.
On context switch, both sets of state have to be saved and (later)
restored. These two states are often called a variety of different
things. Common terms for the state which only exists after the CPU has
entered a transaction (performed a TBEGIN instruction) in hardware are
'transactional' or 'speculative'.
Between a TBEGIN and a TEND or TABORT (or an event that causes the
hardware to abort), regardless of the use of TSUSPEND the
transactional state can be referred to as the live state.
The second state is often to referred to as the 'checkpointed' state
and is a duplication of the live state when the TBEGIN instruction is
executed. This state is kept in the hardware and will be rolled back
to on transaction failure.
Currently all the registers stored in pt_regs are ALWAYS the live
registers, that is, when a thread has transactional registers their
values are stored in pt_regs and the checkpointed state is in
ckpt_regs. A strange opposite is true for fp_state/vr_state. When a
thread is non transactional fp_state/vr_state holds the live
registers. When a thread has initiated a transaction fp_state/vr_state
holds the checkpointed state and transact_fp/transact_vr become the
structure which holds the live state (at this point it is a
transactional state).
This method creates confusion as to where the live state is, in some
circumstances it requires extra work to determine where to put the
live state and prevents the use of common functions designed (probably
before TM) to save the live state.
With this patch pt_regs, fp_state and vr_state all represent the
same thing and the other structures [pending rename] are for
checkpointed state.
Acked-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
After a thread is reclaimed from its active or suspended transactional
state the checkpointed state exists on CPU, this state (along with the
live/transactional state) has been saved in its entirety by the
reclaiming process.
There exists a sequence of events that would cause the kernel to call
one of enable_kernel_fp(), enable_kernel_altivec() or
enable_kernel_vsx() after a thread has been reclaimed. These functions
save away any user state on the CPU so that the kernel can use the
registers. Not only is this saving away unnecessary at this point, it
is actually incorrect. It causes a save of the checkpointed state to
the live structures within the thread struct thus destroying the true
live state for that thread.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
msr_check_and_set() always performs a mfmsr() to determine if it needs
to perform an mtmsr(), as mfmsr() can be a costly operation
msr_check_and_set() could return the MSR now on the CPU to avoid
callers of msr_check_and_set having to make their own mfmsr() call.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
giveup_all() causes FPU/VMX/VSX facilities to be disabled in a threads
MSR. If the thread performing the giveup was transactional, the kernel
must record which facilities were in use before the giveup as the
thread must have these facilities re-enabled on return to userspace.
>From process.c:
/*
* This is called if we are on the way out to userspace and the
* TIF_RESTORE_TM flag is set. It checks if we need to reload
* FP and/or vector state and does so if necessary.
* If userspace is inside a transaction (whether active or
* suspended) and FP/VMX/VSX instructions have ever been enabled
* inside that transaction, then we have to keep them enabled
* and keep the FP/VMX/VSX state loaded while ever the transaction
* continues. The reason is that if we didn't, and subsequently
* got a FP/VMX/VSX unavailable interrupt inside a transaction,
* we don't know whether it's the same transaction, and thus we
* don't know which of the checkpointed state and the transactional
* state to use.
*/
Calling check_if_tm_restore_required() will set TIF_RESTORE_TM and
save the MSR if needed.
Fixes: c208505 ("powerpc: create giveup_all()")
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Comment from arch/powerpc/kernel/process.c:967:
If userspace is inside a transaction (whether active or
suspended) and FP/VMX/VSX instructions have ever been enabled
inside that transaction, then we have to keep them enabled
and keep the FP/VMX/VSX state loaded while ever the transaction
continues. The reason is that if we didn't, and subsequently
got a FP/VMX/VSX unavailable interrupt inside a transaction,
we don't know whether it's the same transaction, and thus we
don't know which of the checkpointed state and the ransactional
state to use.
restore_math() restore_fp() and restore_altivec() currently may not
restore the registers. It doesn't appear that this is more serious
than a performance penalty. If the math registers aren't restored the
userspace thread will still be run with the facility disabled.
Userspace will not be able to read invalid values. On the first access
it will take an facility unavailable exception and the kernel will
detected an active transaction, at which point it will abort the
transaction. There is the possibility for a pathological case
preventing any progress by transactions, however, transactions
are never guaranteed to make progress.
Fixes: 70fe3d9 ("powerpc: Restore FPU/VEC/VSX if previously used")
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Another set of things that are only called from assembler and so need
prototypes to keep sparse happy.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Commit 8d460f6156 ("powerpc/process: Add the function
flush_tmregs_to_thread") added flush_tmregs_to_thread() and included
the assumption that it would only be called for a task which is not
current.
Although this is correct for ptrace, when generating a core dump, some
of the routines which call flush_tmregs_to_thread() are called. This
leads to a WARNing such as:
Not expecting ptrace on self: TM regs may be incorrect
------------[ cut here ]------------
WARNING: CPU: 123 PID: 7727 at arch/powerpc/kernel/process.c:1088 flush_tmregs_to_thread+0x78/0x80
CPU: 123 PID: 7727 Comm: libvirtd Not tainted 4.8.0-rc1-gcc6x-g61e8a0d #1
task: c000000fe631b600 task.stack: c000000fe63b0000
NIP: c00000000001a1a8 LR: c00000000001a1a4 CTR: c000000000717780
REGS: c000000fe63b3420 TRAP: 0700 Not tainted (4.8.0-rc1-gcc6x-g61e8a0d)
MSR: 900000010282b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 28004222 XER: 20000000
...
NIP [c00000000001a1a8] flush_tmregs_to_thread+0x78/0x80
LR [c00000000001a1a4] flush_tmregs_to_thread+0x74/0x80
Call Trace:
flush_tmregs_to_thread+0x74/0x80 (unreliable)
vsr_get+0x64/0x1a0
elf_core_dump+0x604/0x1430
do_coredump+0x5fc/0x1200
get_signal+0x398/0x740
do_signal+0x54/0x2b0
do_notify_resume+0x98/0xb0
ret_from_except_lite+0x70/0x74
So fix flush_tmregs_to_thread() to detect the case where it is called on
current, and a transaction is active, and in that case flush the TM regs
to the thread_struct.
This patch also moves flush_tmregs_to_thread() into ptrace.c as it is
only called from that file.
Fixes: 8d460f6156 ("powerpc/process: Add the function flush_tmregs_to_thread")
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
[mpe: Flesh out change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch creates a function flush_tmregs_to_thread which
will then be used by subsequent patches in this series. The
function checks for self tracing ptrace interface attempts
while in the TM context and logs appropriate warning message.
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We plan to use jump label for cpu_has_feature(). In order to implement
this we need to include the linux/jump_label.h in asm/cputable.h.
Unfortunately if we do that it leads to an include loop. The root of the
problem seems to be that reg.h needs cputable.h (for CPU_FTRs), and then
cputable.h via jump_label.h eventually pulls in hw_irq.h which needs
reg.h (for MSR_EE).
So move cpu_has_feature() to a separate file on its own.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[mpe: Rename to cpu_has_feature.h and flesh out change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
- tm: Always reclaim in start_thread() for exec() class syscalls from Cyril Bur
- tm: Avoid SLB faults in treclaim/trecheckpoint when RI=0 from Michael Neuling
- eeh: Fix wrong argument passed to eeh_rmv_device() from Gavin Shan
- Initialise pci_io_base as early as possible from Darren Stevens
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Merge tag 'powerpc-4.7-5' into next
Pull in the fixes we sent during 4.7, we have code we want to merge into
next that depends on some of them.
Userspace can quite legitimately perform an exec() syscall with a
suspended transaction. exec() does not return to the old process, rather
it load a new one and starts that, the expectation therefore is that the
new process starts not in a transaction. Currently exec() is not treated
any differently to any other syscall which creates problems.
Firstly it could allow a new process to start with a suspended
transaction for a binary that no longer exists. This means that the
checkpointed state won't be valid and if the suspended transaction were
ever to be resumed and subsequently aborted (a possibility which is
exceedingly likely as exec()ing will likely doom the transaction) the
new process will jump to invalid state.
Secondly the incorrect attempt to keep the transactional state while
still zeroing state for the new process creates at least two TM Bad
Things. The first triggers on the rfid to return to userspace as
start_thread() has given the new process a 'clean' MSR but the suspend
will still be set in the hardware MSR. The second TM Bad Thing triggers
in __switch_to() as the processor is still transactionally suspended but
__switch_to() wants to zero the TM sprs for the new process.
This is an example of the outcome of calling exec() with a suspended
transaction. Note the first 700 is likely the first TM bad thing
decsribed earlier only the kernel can't report it as we've loaded
userspace registers. c000000000009980 is the rfid in
fast_exception_return()
Bad kernel stack pointer 3fffcfa1a370 at c000000000009980
Oops: Bad kernel stack pointer, sig: 6 [#1]
CPU: 0 PID: 2006 Comm: tm-execed Not tainted
NIP: c000000000009980 LR: 0000000000000000 CTR: 0000000000000000
REGS: c00000003ffefd40 TRAP: 0700 Not tainted
MSR: 8000000300201031 <SF,ME,IR,DR,LE,TM[SE]> CR: 00000000 XER: 00000000
CFAR: c0000000000098b4 SOFTE: 0
PACATMSCRATCH: b00000010000d033
GPR00: 0000000000000000 00003fffcfa1a370 0000000000000000 0000000000000000
GPR04: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR12: 00003fff966611c0 0000000000000000 0000000000000000 0000000000000000
NIP [c000000000009980] fast_exception_return+0xb0/0xb8
LR [0000000000000000] (null)
Call Trace:
Instruction dump:
f84d0278 e9a100d8 7c7b03a6 e84101a0 7c4ff120 e8410170 7c5a03a6 e8010070
e8410080 e8610088 e8810090 e8210078 <4c000024> 48000000 e8610178 88ed023b
Kernel BUG at c000000000043e80 [verbose debug info unavailable]
Unexpected TM Bad Thing exception at c000000000043e80 (msr 0x201033)
Oops: Unrecoverable exception, sig: 6 [#2]
CPU: 0 PID: 2006 Comm: tm-execed Tainted: G D
task: c0000000fbea6d80 ti: c00000003ffec000 task.ti: c0000000fb7ec000
NIP: c000000000043e80 LR: c000000000015a24 CTR: 0000000000000000
REGS: c00000003ffef7e0 TRAP: 0700 Tainted: G D
MSR: 8000000300201033 <SF,ME,IR,DR,RI,LE,TM[SE]> CR: 28002828 XER: 00000000
CFAR: c000000000015a20 SOFTE: 0
PACATMSCRATCH: b00000010000d033
GPR00: 0000000000000000 c00000003ffefa60 c000000000db5500 c0000000fbead000
GPR04: 8000000300001033 2222222222222222 2222222222222222 00000000ff160000
GPR08: 0000000000000000 800000010000d033 c0000000fb7e3ea0 c00000000fe00004
GPR12: 0000000000002200 c00000000fe00000 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 c0000000fbea7410 00000000ff160000
GPR24: c0000000ffe1f600 c0000000fbea8700 c0000000fbea8700 c0000000fbead000
GPR28: c000000000e20198 c0000000fbea6d80 c0000000fbeab680 c0000000fbea6d80
NIP [c000000000043e80] tm_restore_sprs+0xc/0x1c
LR [c000000000015a24] __switch_to+0x1f4/0x420
Call Trace:
Instruction dump:
7c800164 4e800020 7c0022a6 f80304a8 7c0222a6 f80304b0 7c0122a6 f80304b8
4e800020 e80304a8 7c0023a6 e80304b0 <7c0223a6> e80304b8 7c0123a6 4e800020
This fixes CVE-2016-5828.
Fixes: bc2a9408fa ("powerpc: Hook in new transactional memory code")
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This enables new registers, LMRR and LMSER, that can trigger an EBB in
userspace code when a monitored load (via the new ldmx instruction)
loads memory from a monitored space. This facility is controlled by a
new FSCR bit, LM.
This patch disables the FSCR LM control bit on task init and enables
that bit when a load monitor facility unavailable exception is taken
for using it. On context switch, this bit is then used to determine
whether the two relevant registers are saved and restored. This is
done lazily for performance reasons.
Signed-off-by: Jack Miller <jack@codezen.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This fixes a few issues with FSCR init and switching.
In commit 152d523e63 ("powerpc: Create context switch helpers
save_sprs() and restore_sprs()") we moved the setting of the FSCR
register from inside an CPU_FTR_ARCH_207S section to inside just a
CPU_FTR_ARCH_DSCR section. Hence we are setting FSCR on POWER6/7 where
the FSCR doesn't exist. This is harmless but we shouldn't do it.
Also, we can simplify the FSCR context switch. We don't need to go
through the calculation involving dscr_inherit. We can just restore
what we saved last time.
We also set an initial value in INIT_THREAD, so that pid 1 which is
cloned from that gets a sane value.
Based on patch by Jack Miller.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In both __giveup_fpu() and __giveup_altivec() we make two modifications
to tsk->thread.regs->msr. gcc decides to do a read/modify/write of
each change, so we end up with a load hit store:
ld r9,264(r10)
rldicl r9,r9,50,1
rotldi r9,r9,14
std r9,264(r10)
...
ld r9,264(r10)
rldicl r9,r9,40,1
rotldi r9,r9,24
std r9,264(r10)
Fix this by using a temporary.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Define HAVE_EXIT_THREAD for archs which want to do something in
exit_thread. For others, let's define exit_thread as an empty inline.
This is a cleanup before we change the prototype of exit_thread to
accept a task parameter.
[akpm@linux-foundation.org: fix mips]
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Howells <dhowells@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We also use MMU_FTR_RADIX to branch out from code path specific to
hash.
No functionality change.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In order to support live patching we need to maintain an alternate
stack of TOC & LR values. We use the base of the stack for this, and
store the "live patch stack pointer" in struct thread_info.
Unlike the other fields of thread_info, we can not statically initialise
that value, so it must be done at run time.
This patch just adds the code to support that, it is not enabled until
the next patch which actually adds live patch support.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Sometimes when sparse warns about undefined symbols, it isn't
because they should have 'static' added, it's because they're
overriding __weak symbols defined elsewhere, and the header has
been missed.
Fix a few of them by adding appropriate headers.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In save_sprs() in process.c contains the following test:
if (cpu_has_feature(cpu_has_feature(CPU_FTR_ALTIVEC)))
t->vrsave = mfspr(SPRN_VRSAVE);
CPU feature with the mask 0x1 is CPU_FTR_COHERENT_ICACHE so the test
is equivilent to:
if (cpu_has_feature(CPU_FTR_ALTIVEC) &&
cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
On CPUs without support for both (i.e G5) this results in vrsave not
being saved between context switches. The vector register save/restore
code doesn't use VRSAVE to determine which registers to save/restore,
but the value of VRSAVE is used to determine if altivec is being used
in several code paths.
Fixes: 152d523e63 ("powerpc: Create context switch helpers save_sprs() and restore_sprs()")
Cc: stable@vger.kernel.org
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Highlights:
- Restructure Linux PTE on Book3S/64 to Radix format from Paul Mackerras
- Book3s 64 MMU cleanup in preparation for Radix MMU from Aneesh Kumar K.V
- Add POWER9 cputable entry from Michael Neuling
- FPU/Altivec/VSX save/restore optimisations from Cyril Bur
- Add support for new ftrace ABI on ppc64le from Torsten Duwe
Various cleanups & minor fixes from:
- Adam Buchbinder, Andrew Donnellan, Balbir Singh, Christophe Leroy, Cyril
Bur, Luis Henriques, Madhavan Srinivasan, Pan Xinhui, Russell Currey,
Sukadev Bhattiprolu, Suraj Jitindar Singh.
General:
- atomics: Allow architectures to define their own __atomic_op_* helpers from
Boqun Feng
- Implement atomic{, 64}_*_return_* variants and acquire/release/relaxed
variants for (cmp)xchg from Boqun Feng
- Add powernv_defconfig from Jeremy Kerr
- Fix BUG_ON() reporting in real mode from Balbir Singh
- Add xmon command to dump OPAL msglog from Andrew Donnellan
- Add xmon command to dump process/task similar to ps(1) from Douglas Miller
- Clean up memory hotplug failure paths from David Gibson
pci/eeh:
- Redesign SR-IOV on PowerNV to give absolute isolation between VFs from Wei
Yang.
- EEH Support for SRIOV VFs from Wei Yang and Gavin Shan.
- PCI/IOV: Rename and export virtfn_{add, remove} from Wei Yang
- PCI: Add pcibios_bus_add_device() weak function from Wei Yang
- MAINTAINERS: Update EEH details and maintainership from Russell Currey
cxl:
- Support added to the CXL driver for running on both bare-metal and
hypervisor systems, from Christophe Lombard and Frederic Barrat.
- Ignore probes for virtual afu pci devices from Vaibhav Jain
perf:
- Export Power8 generic and cache events to sysfs from Sukadev Bhattiprolu
- hv-24x7: Fix usage with chip events, display change in counter values,
display domain indices in sysfs, eliminate domain suffix in event names,
from Sukadev Bhattiprolu
Freescale:
- Updates from Scott: "Highlights include 8xx optimizations, 32-bit checksum
optimizations, 86xx consolidation, e5500/e6500 cpu hotplug, more fman and
other dt bits, and minor fixes/cleanup."
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Merge tag 'powerpc-4.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"This was delayed a day or two by some build-breakage on old toolchains
which we've now fixed.
There's two PCI commits both acked by Bjorn.
There's one commit to mm/hugepage.c which is (co)authored by Kirill.
Highlights:
- Restructure Linux PTE on Book3S/64 to Radix format from Paul
Mackerras
- Book3s 64 MMU cleanup in preparation for Radix MMU from Aneesh
Kumar K.V
- Add POWER9 cputable entry from Michael Neuling
- FPU/Altivec/VSX save/restore optimisations from Cyril Bur
- Add support for new ftrace ABI on ppc64le from Torsten Duwe
Various cleanups & minor fixes from:
- Adam Buchbinder, Andrew Donnellan, Balbir Singh, Christophe Leroy,
Cyril Bur, Luis Henriques, Madhavan Srinivasan, Pan Xinhui, Russell
Currey, Sukadev Bhattiprolu, Suraj Jitindar Singh.
General:
- atomics: Allow architectures to define their own __atomic_op_*
helpers from Boqun Feng
- Implement atomic{, 64}_*_return_* variants and acquire/release/
relaxed variants for (cmp)xchg from Boqun Feng
- Add powernv_defconfig from Jeremy Kerr
- Fix BUG_ON() reporting in real mode from Balbir Singh
- Add xmon command to dump OPAL msglog from Andrew Donnellan
- Add xmon command to dump process/task similar to ps(1) from Douglas
Miller
- Clean up memory hotplug failure paths from David Gibson
pci/eeh:
- Redesign SR-IOV on PowerNV to give absolute isolation between VFs
from Wei Yang.
- EEH Support for SRIOV VFs from Wei Yang and Gavin Shan.
- PCI/IOV: Rename and export virtfn_{add, remove} from Wei Yang
- PCI: Add pcibios_bus_add_device() weak function from Wei Yang
- MAINTAINERS: Update EEH details and maintainership from Russell
Currey
cxl:
- Support added to the CXL driver for running on both bare-metal and
hypervisor systems, from Christophe Lombard and Frederic Barrat.
- Ignore probes for virtual afu pci devices from Vaibhav Jain
perf:
- Export Power8 generic and cache events to sysfs from Sukadev
Bhattiprolu
- hv-24x7: Fix usage with chip events, display change in counter
values, display domain indices in sysfs, eliminate domain suffix in
event names, from Sukadev Bhattiprolu
Freescale:
- Updates from Scott: "Highlights include 8xx optimizations, 32-bit
checksum optimizations, 86xx consolidation, e5500/e6500 cpu
hotplug, more fman and other dt bits, and minor fixes/cleanup"
* tag 'powerpc-4.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (179 commits)
powerpc: Fix unrecoverable SLB miss during restore_math()
powerpc/8xx: Fix do_mtspr_cpu6() build on older compilers
powerpc/rcpm: Fix build break when SMP=n
powerpc/book3e-64: Use hardcoded mttmr opcode
powerpc/fsl/dts: Add "jedec,spi-nor" flash compatible
powerpc/T104xRDB: add tdm riser card node to device tree
powerpc32: PAGE_EXEC required for inittext
powerpc/mpc85xx: Add pcsphy nodes to FManV3 device tree
powerpc/mpc85xx: Add MDIO bus muxing support to the board device tree(s)
powerpc/86xx: Introduce and use common dtsi
powerpc/86xx: Update device tree
powerpc/86xx: Move dts files to fsl directory
powerpc/86xx: Switch to kconfig fragments approach
powerpc/86xx: Update defconfigs
powerpc/86xx: Consolidate common platform code
powerpc32: Remove one insn in mulhdu
powerpc32: small optimisation in flush_icache_range()
powerpc: Simplify test in __dma_sync()
powerpc32: move xxxxx_dcache_range() functions inline
powerpc32: Remove clear_pages() and define clear_page() inline
...
This patch adds the ability to be able to save the VSX registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.
This patch builds on a previous optimisation for the FPU and VEC registers
in the thread copy path to avoid a possibly pointless reload of VSX state.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch adds the ability to be able to save the VEC registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.
This patch builds on a previous optimisation for the FPU registers in the
thread copy path to avoid a possibly pointless reload of VEC state.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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>
Replace calls to get_random_int() followed by a cast to (unsigned long)
with calls to get_random_long(). Also address shifting bug which, in
case of x86 removed entropy mask for mmap_rnd_bits values > 31 bits.
Signed-off-by: Daniel Cashman <dcashman@android.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nick Kralevich <nnk@google.com>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- tm: Block signal return from setting invalid MSR state from Michael Neuling
- tm: Check for already reclaimed tasks from Michael Neuling
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Merge tag 'powerpc-4.4-3' into next
Merge the two TM fixes we merged in 4.4. We are about to merge selftests
for these, and without the fixes the selftests will oops.
powerpc fixes for 4.4 #2
- tm: Block signal return from setting invalid MSR state from Michael Neuling
- tm: Check for already reclaimed tasks from Michael Neuling
Print MSR TM bits in oops messages. This appends them to the end
like this:
MSR: 8000000502823031 <SF,VEC,VSX,FP,ME,IR,DR,LE,TM[TE]>
You get the TM[] only if at least one TM MSR bit is set. Inside the
TM[], E means Enabled (bit 32), S means Suspended (bit 33), and T
means Transactional (bit 34)
If no bits are set, you get no TM[] output.
Include rework of printbits() to handle this case.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Two DSCR tests have a hack in them:
/*
* XXX: Force a context switch out so that DSCR
* current value is copied into the thread struct
* which is required for the child to inherit the
* changed value.
*/
sleep(1);
We should not be working around this in the testcase, it is a kernel bug.
Fix it by copying the current DSCR to the child, instead of what we
had in the thread struct at last context switch.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
commit 152d523e63 ("powerpc: Create context switch helpers save_sprs()
and restore_sprs()") moved the restore of SPRs after the call to _switch().
There is an issue with this approach - new tasks do not return through
_switch(), they are set up by copy_thread() to directly return through
ret_from_fork() or ret_from_kernel_thread(). This means restore_sprs() is
not getting called for new tasks.
Fix this by moving restore_sprs() before _switch().
Fixes: 152d523e63 ("powerpc: Create context switch helpers save_sprs() and restore_sprs()")
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Commit a0e72cf12b ("powerpc: Create msr_check_and_{set,clear}()")
removed a call to check_if_tm_restore_required() in the
enable_kernel_*() functions. Add them back in.
Fixes: a0e72cf12b ("powerpc: Create msr_check_and_{set,clear}()")
Reported-by: Rashmica Gupta <rashmicy@gmail.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Remove a bunch of unnecessary fallback functions and group
things in a more logical way.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Most of __switch_to() is housekeeping, TLB batching, timekeeping etc.
Move these away from the more complex and critical context switching
code.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Create a single function that flushes everything (FP, VMX, VSX, SPE).
Doing this all at once means we only do one MSR write.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Create a single function that gives everything up (FP, VMX, VSX, SPE).
Doing this all at once means we only do one MSR write.
A context switch microbenchmark using yield():
http://ozlabs.org/~anton/junkcode/context_switch2.c
./context_switch2 --test=yield --fp --altivec --vector 0 0
shows an improvement of 3% on POWER8.
Signed-off-by: Anton Blanchard <anton@samba.org>
[mpe: giveup_all() needs to be EXPORT_SYMBOL'ed]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
More consolidation of our MSR available bit handling.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add a boot option that strictly manages the MSR unavailable bits.
This catches kernel uses of FP/Altivec/SPE that would otherwise
corrupt user state.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Create helper functions to set and clear MSR bits after first
checking if they are already set. Grouping them will make it
easy to avoid the MSR writes in a subsequent optimisation.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move the MSR modification into c. Removing it from the assembly
function will allow us to avoid costly MSR writes by batching them
up.
Check the FP and VMX bits before calling the relevant giveup_*()
function. This makes giveup_vsx() and flush_vsx_to_thread() perform
more like their sister functions, and allows us to use
flush_vsx_to_thread() in the signal code.
Move the check_if_tm_restore_required() check in.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move the MSR modification into new c functions. Removing it from
the low level functions will allow us to avoid costly MSR writes
by batching them up.
Move the check_if_tm_restore_required() check into these new functions.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
mtmsrd_isync() will do an mtmsrd followed by an isync on older
processors. On newer processors we avoid the isync via a feature fixup.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Instead of having multiple giveup_*_maybe_transactional() functions,
separate out the TM check into a new function called
check_if_tm_restore_required().
This will make it easier to optimise the giveup_*() functions in a
subsequent patch.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The UP only lazy floating point and vector optimisations were written
back when SMP was not common, and neither glibc nor gcc used vector
instructions. Now SMP is very common, glibc aggressively uses vector
instructions and gcc autovectorises.
We want to add new optimisations that apply to both UP and SMP, but
in preparation for that remove these UP only optimisations.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move all our context switch SPR save and restore code into two
helpers. We do a few optimisations:
- Group all mfsprs and all mtsprs. In many cases an mtspr sets a
scoreboarding bit that an mfspr waits on, so the current practise of
mfspr A; mtspr A; mfpsr B; mtspr B is the worst scheduling we can
do.
- SPR writes are slow, so check that the value is changing before
writing it.
A context switch microbenchmark using yield():
http://ozlabs.org/~anton/junkcode/context_switch2.c
./context_switch2 --test=yield 0 0
shows an improvement of almost 10% on POWER8.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
