Since the system reset interrupt began to use its own stack, and
machine check interrupts have done so for some time, r1 can be
changed without clearing MSR[RI], provided no other interrupts
(including SLB misses) are taken.

MSR[RI] does have to be cleared when using SCRATCH0, however.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Merge our fixes branch. It has a few important fixes that are needed for
futher testing and also some commits that will conflict with content in
next.

The comments in this file don't conform to the coding style so take
them to "Comment Formatting Re-Education Camp".

Suggested-by: Michael "Camp Drill Sergeant" Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Neuling <mikey@neuling.org>
[mpe: Reflow some comments and add full stops, fix spelling of Sergeant.]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Current we store the userspace r1 to PACATMSCRATCH before finally
saving it to the thread struct.

In theory an exception could be taken here (like a machine check or
SLB miss) that could write PACATMSCRATCH and hence corrupt the
userspace r1. The SLB fault currently doesn't touch PACATMSCRATCH, but
others do.

We've never actually seen this happen but it's theoretically
possible. Either way, the code is fragile as it is.

This patch saves r1 to the kernel stack (which can't fault) before we
turn MSR[RI] back on. PACATMSCRATCH is still used but only with
MSR[RI] off. We then copy r1 from the kernel stack to the thread
struct once we have MSR[RI] back on.

Suggested-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

When we treclaim we store the userspace checkpointed r13 to a scratch
SPR and then later save the scratch SPR to the user thread struct.

Unfortunately, this doesn't work as accessing the user thread struct
can take an SLB fault and the SLB fault handler will write the same
scratch SPRG that now contains the userspace r13.

To fix this, we store r13 to the kernel stack (which can't fault)
before we access the user thread struct.

Found by running P8 guest + powervm + disable_1tb_segments + TM. Seen
as a random userspace segfault with r13 looking like a kernel address.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This patch simply fix part of the documentation on the HTM code.

This fixes reference to old fields that were renamed in commit
000ec280e3dd ("powerpc: tm: Rename transct_(*) to ck(\1)_state")

It also documents better the flow after commit eb5c3f1c8647 ("powerpc:
Always save/restore checkpointed regs during treclaim/trecheckpoint"),
where tm_recheckpoint can recheckpoint what is in ck{fp,vr}_state
blindly.

Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

files not using feature fixup don't need asm/feature-fixups.h
files using feature fixup need asm/feature-fixups.h

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit eb5c3f1c8647 ("powerpc: Always save/restore checkpointed regs
during treclaim/trecheckpoint") __tm_recheckpoint was modified to no
longer take the second parameter 'unsigned long orig_msr' as part of a
TM rewrite to simplify the reclaiming/recheckpointing process.

There is a comment in the asm file where the function is delcared which
has an incorrect prototype with the 'orig_msr' parameter.

This patch corrects the comment.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This patch exports tm_enable()/tm_disable/tm_abort() APIs, which
will be used for PR KVM transactional memory logic.

Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Reviewed-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Pull powerpc updates from Michael Ellerman:
 "A bit of a small release, I suspect in part due to me travelling for
  KS. But my backlog of patches to review is smaller than usual, so I
  think in part folks just didn't send as much this cycle.

  Non-highlights:

   - Five fixes for the >128T address space handling, both to fix bugs
     in our implementation and to bring the semantics exactly into line
     with x86.

  Highlights:

   - Support for a new OPAL call on bare metal machines which gives us a
     true NMI (ie. is not masked by MSR[EE]=0) for debugging etc.

   - Support for Power9 DD2 in the CXL driver.

   - Improvements to machine check handling so that uncorrectable errors
     can be reported into the generic memory_failure() machinery.

   - Some fixes and improvements for VPHN, which is used under PowerVM
     to notify the Linux partition of topology changes.

   - Plumbing to enable TM (transactional memory) without suspend on
     some Power9 processors (PPC_FEATURE2_HTM_NO_SUSPEND).

   - Support for emulating vector loads form cache-inhibited memory, on
     some Power9 revisions.

   - Disable the fast-endian switch "syscall" by default (behind a
     CONFIG), we believe it has never had any users.

   - A major rework of the API drivers use when initiating and waiting
     for long running operations performed by OPAL firmware, and changes
     to the powernv_flash driver to use the new API.

   - Several fixes for the handling of FP/VMX/VSX while processes are
     using transactional memory.

   - Optimisations of TLB range flushes when using the radix MMU on
     Power9.

   - Improvements to the VAS facility used to access coprocessors on
     Power9, and related improvements to the way the NX crypto driver
     handles requests.

   - Implementation of PMEM_API and UACCESS_FLUSHCACHE for 64-bit.

  Thanks to: Alexey Kardashevskiy, Alistair Popple, Allen Pais, Andrew
  Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Balbir Singh, Benjamin
  Herrenschmidt, Breno Leitao, Christophe Leroy, Christophe Lombard,
  Cyril Bur, Frederic Barrat, Gautham R. Shenoy, Geert Uytterhoeven,
  Guilherme G. Piccoli, Gustavo Romero, Haren Myneni, Joel Stanley,
  Kamalesh Babulal, Kautuk Consul, Markus Elfring, Masami Hiramatsu,
  Michael Bringmann, Michael Neuling, Michal Suchanek, Naveen N. Rao,
  Nicholas Piggin, Oliver O'Halloran, Paul Mackerras, Pedro Miraglia
  Franco de Carvalho, Philippe Bergheaud, Sandipan Das, Seth Forshee,
  Shriya, Stephen Rothwell, Stewart Smith, Sukadev Bhattiprolu, Tyrel
  Datwyler, Vaibhav Jain, Vaidyanathan Srinivasan, and William A.
  Kennington III"

* tag 'powerpc-4.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (151 commits)
  powerpc/64s: Fix Power9 DD2.0 workarounds by adding DD2.1 feature
  powerpc/64s: Fix masking of SRR1 bits on instruction fault
  powerpc/64s: mm_context.addr_limit is only used on hash
  powerpc/64s/radix: Fix 128TB-512TB virtual address boundary case allocation
  powerpc/64s/hash: Allow MAP_FIXED allocations to cross 128TB boundary
  powerpc/64s/hash: Fix fork() with 512TB process address space
  powerpc/64s/hash: Fix 128TB-512TB virtual address boundary case allocation
  powerpc/64s/hash: Fix 512T hint detection to use >= 128T
  powerpc: Fix DABR match on hash based systems
  powerpc/signal: Properly handle return value from uprobe_deny_signal()
  powerpc/fadump: use kstrtoint to handle sysfs store
  powerpc/lib: Implement UACCESS_FLUSHCACHE API
  powerpc/lib: Implement PMEM API
  powerpc/powernv/npu: Don't explicitly flush nmmu tlb
  powerpc/powernv/npu: Use flush_all_mm() instead of flush_tlb_mm()
  powerpc/powernv/idle: Round up latency and residency values
  powerpc/kprobes: refactor kprobe_lookup_name for safer string operations
  powerpc/kprobes: Blacklist emulate_update_regs() from kprobes
  powerpc/kprobes: Do not disable interrupts for optprobes and kprobes_on_ftrace
  powerpc/kprobes: Disable preemption before invoking probe handler for optprobes
  ...