1. 19 4月, 2017 8 次提交
    • M
      powerpc/perf: Export memory hierarchy info to user space · 79e96f8f
      Madhavan Srinivasan 提交于
      The LDST field and DATA_SRC in SIER identifies the memory hierarchy level
      (eg: L1, L2 etc), from which a data-cache miss for a marked instruction
      was satisfied. Use the 'perf_mem_data_src' object to export this
      hierarchy level to user space.
      Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
      Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      79e96f8f
    • S
      powerpc/perf: Define big-endian version of perf_mem_data_src · 8c5073db
      Sukadev Bhattiprolu 提交于
      perf_mem_data_src is a union that is initialized in the kernel via the ->val
      field and accessed by userspace via the mem_xxx bitfields. For this to work
      correctly on big endian platforms, we need a big-endian definition for the
      bitfields.
      
      Currently on a big endian system, if a user requests PERF_SAMPLE_DATA_SRC (perf
      report -d), they will get the default value from perf_sample_data_init(), which
      is PERF_MEM_NA. The value for PERF_MEM_NA is constructed using shifts:
      
        /* TLB access */
        #define PERF_MEM_TLB_NA		0x01 /* not available */
        ...
        #define PERF_MEM_TLB_SHIFT	26
      
        #define PERF_MEM_S(a, s) \
      	(((__u64)PERF_MEM_##a##_##s) << PERF_MEM_##a##_SHIFT)
      
        #define PERF_MEM_NA (PERF_MEM_S(OP, NA)   |\
      		    PERF_MEM_S(LVL, NA)   |\
      		    PERF_MEM_S(SNOOP, NA) |\
      		    PERF_MEM_S(LOCK, NA)  |\
      		    PERF_MEM_S(TLB, NA))
      
      Which works out as:
      
        ((0x01 << 0) | (0x01 << 5) | (0x01 << 19) | (0x01 << 24) | (0x01 << 26))
      
      Which means the PERF_MEM_NA value comes out of the kernel as 0x5080021
      in CPU endian.
      
      But then in the perf tool, the code uses the bitfields to inspect the value, and
      currently the bitfields are defined using little endian ordering.
      
      So eg. in perf_mem__tlb_scnprintf() we see:
        data_src->val = 0x5080021
                   op = 0x0
                  lvl = 0x0
                snoop = 0x0
                 lock = 0x0
                 dtlb = 0x0
                 rsvd = 0x5080021
      
      Because of the way the perf tool code is written this is still displayed to the
      user as "N/A", so there is no bug visible at the UI level.
      
      Currently there are no big endian architectures which export a meaningful
      value (ie. other than PERF_MEM_NA), so the extent of the bug on big endian
      platforms is that the PERF_MEM_NA value is exported incorrectly as described
      above. Subsequent patches will add support on big endian powerpc for populating
      the data source value.
      
      This patch does a minimal fix of adding big endian definition of the bitfields
      to match the values that are already exported by the kernel on big endian. And
      it makes no change on little endian.
      Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
      Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
      Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      8c5073db
    • A
      powerpc/iommu: Do not call PageTransHuge() on tail pages · e889e96e
      Alexey Kardashevskiy 提交于
      The CMA pages migration code does not support compound pages at
      the moment so it performs few tests before proceeding to actual page
      migration.
      
      One of the tests - PageTransHuge() - has VM_BUG_ON_PAGE(PageTail()) as
      it is designed to be called on head pages only. Since we also test for
      PageCompound(), and it contains PageTail() and PageHead(), we can
      simplify the check by leaving just PageCompound() and therefore avoid
      possible VM_BUG_ON_PAGE.
      
      Fixes: 2e5bbb54 ("KVM: PPC: Book3S HV: Migrate pinned pages out of CMA")
      Cc: stable@vger.kernel.org # v4.9+
      Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
      Acked-by: NBalbir Singh <bsingharora@gmail.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      e889e96e
    • A
      powerpc/mmap: Any hint > 128TB searches the full VA space · 321f7d29
      Aneesh Kumar K.V 提交于
      As part of the new large address space support, processes start out life with a
      128TB virtual address space. However when calling mmap() a process can pass a
      hint address, and if that hint is > 128TB the kernel will use the full 512TB
      address space to try and satisfy the mmap() request.
      
      Currently we have a check that the hint is > 128TB and < 512TB (TASK_SIZE),
      which was added as an optimisation to avoid updating addr_limit unnecessarily
      and also to avoid calling slice_flush_segments() on all CPUs more than
      necessary.
      
      However this has the user-visible side effect that an mmap() hint above 512TB
      does not search the full address space unless a preceding mmap() used a hint
      value > 128TB && < 512TB.
      
      So fix it to treat any hint above 128TB as a hint to search the full address
      space, instead of checking the hint against TASK_SIZE, we instead check if the
      addr_limit is already == TASK_SIZE.
      
      This also brings the ABI in-line with what is proposed on x86. ie, that a hint
      address above 128TB up to and including (2^64)-1 is an indication to search the
      full address space.
      
      Fixes: f4ea6dcb (powerpc/mm: Enable mappings above 128TB)
      Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      321f7d29
    • M
      cxl: Enable PCI device IDs for future IBM CXL adapters · 41e20d95
      Matthew R. Ochs 提交于
      Add support for future IBM Coherent Accelerator (CXL) devices
      with an IDs of 0x0623 and 0x0628.
      Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
      Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
      Acked-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      41e20d95
    • N
      powerpc/64s: Minor fix for MCE TLB flush for radix · 95dbdf4f
      Nicholas Piggin 提交于
      The TLB flush for radix first flushes TLB for radix configuration,
      then flushes for hash configuration. The second flush is unnecessary
      but does not affect correctness.
      
      Fixes: 1a472c9d ("powerpc/mm/radix: Add tlbflush routines")
      Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
      Reviewed-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      95dbdf4f
    • A
      powerpc/mm/radix: Use mm->task_size for boundary checking instead of addr_limit · be77e999
      Aneesh Kumar K.V 提交于
      We don't init addr_limit correctly for 32 bit applications. So default to using
      mm->task_size for boundary condition checking. We use addr_limit to only control
      free space search. This makes sure that we do the right thing with 32 bit
      applications.
      
      We should consolidate the usage of TASK_SIZE/mm->task_size and
      mm->context.addr_limit later.
      
      This partially reverts commit fbfef902 (powerpc/mm: Switch some
      TASK_SIZE checks to use mm_context addr_limit).
      
      Fixes: fbfef902 ("powerpc/mm: Switch some TASK_SIZE checks to use mm_context addr_limit")
      Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      be77e999
    • N
      powerpc/64s: Revert setting of LPCR[LPES] on POWER9 · 8d1b48ef
      Nicholas Piggin 提交于
      The XIVE enablement patches included a change to set the LPES (Logical
      Partitioning Environment Selector) bit (bit # 3) in LPCR (Logical Partitioning
      Control Register) on POWER9 hosts. This bit sets external interrupts to guest
      delivery mode, which uses SRR0/1. The host's EE interrupt handler is written to
      expect HSRR0/1 (for earlier CPUs). This should be fine because XIVE is
      configured not to deliver EEs to the host (Hypervisor Virtulization Interrupt is
      used instead) so the EE handler should never be executed.
      
      However a bug in interrupt controller code, hardware, or odd configuration of a
      simulator could result in the host getting an EE incorrectly. Keeping the EE
      delivery mode matching the host EE handler prevents strange crashes due to using
      the wrong exception registers.
      
      KVM will configure the LPCR to set LPES prior to running a guest so that EEs are
      delivered to the guest using SRR0/1.
      
      Fixes: 08a1e650 ("powerpc: Fixup LPCR:PECE and HEIC setting on POWER9")
      Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
      [mpe: Massage change log to avoid referring to LPES0 which is now renamed LPES]
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      8d1b48ef
  2. 13 4月, 2017 18 次提交
  3. 12 4月, 2017 6 次提交
    • R
      powerpc/mm: Fix hash table dump when memory is not contiguous · 9e4114b3
      Rashmica Gupta 提交于
      The current behaviour of the hash table dump assumes that memory is contiguous
      and iterates from the start of memory to (start + size of memory). When memory
      isn't physically contiguous, this doesn't work.
      
      If memory exists at 0-5 GB and 6-10 GB then the current approach will check if
      entries exist in the hash table from 0GB to 9GB. This patch changes the
      behaviour to iterate over any holes up to the end of memory.
      
      Fixes: 1515ab93 ("powerpc/mm: Dump hash table")
      Signed-off-by: NRashmica Gupta <rashmica.g@gmail.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      9e4114b3
    • O
      powerpc/mm: Add physical address to Linux page table dump · aaa22952
      Oliver O'Halloran 提交于
      The current page table dumper scans the Linux page tables and coalesces mappings
      with adjacent virtual addresses and similar PTE flags. This behaviour is
      somewhat broken when you consider the IOREMAP space where entirely unrelated
      mappings will appear to be virtually contiguous. This patch modifies the range
      coalescing so that only ranges that are both physically and virtually contiguous
      are combined. This patch also adds to the dump output the physical address at
      the start of each range.
      
      Fixes: 8eb07b18 ("powerpc/mm: Dump linux pagetables")
      Signed-off-by: NOliver O'Halloran <oohall@gmail.com>
      [mpe: Print the physicall address with 0x like the other addresses]
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      aaa22952
    • O
      powerpc/mm: Fix missing _PAGE_NON_IDEMPOTENT in pgtable dump · 70538eaa
      Oliver O'Halloran 提交于
      On Book3s we have two PTE flags used to mark cache-inhibited mappings:
      _PAGE_TOLERANT and _PAGE_NON_IDEMPOTENT. Currently the kernel page table dumper
      only looks at the generic _PAGE_NO_CACHE which is defined to be _PAGE_TOLERANT.
      This patch modifies the dumper so both flags are shown in the dump.
      
      Fixes: 8eb07b18 ("powerpc/mm: Dump linux pagetables")
      Signed-off-by: NOliver O'Halloran <oohall@gmail.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      70538eaa
    • B
      powerpc/tracing: Allow tracing of mmap syscalls · 9c355917
      Balbir Singh 提交于
      Currently sys_mmap() and sys_mmap2() (32-bit only), are not visible to the
      syscall tracing machinery. This means users are not able to see the execution of
      mmap() syscalls using the syscall tracer.
      
      Fix that by using SYSCALL_DEFINE6 for sys_mmap() and sys_mmap2() so that the
      meta-data associated with these syscalls is visible to the syscall tracer.
      
      A side-effect of this change is that the return type has changed from unsigned
      long to long. However this should have no effect, the only code in the kernel
      which uses the result of these syscalls is in the syscall return path, which is
      written in asm and treats the result as unsigned regardless.
      
      Example output:
        cat-3399  [001] ....   196.542410: sys_mmap(addr: 7fff922a0000, len: 20000, prot: 3, flags: 812, fd: 3, offset: 1b0000)
        cat-3399  [001] ....   196.542443: sys_mmap -> 0x7fff922a0000
        cat-3399  [001] ....   196.542668: sys_munmap(addr: 7fff922c0000, len: 6d2c)
        cat-3399  [001] ....   196.542677: sys_munmap -> 0x0
      Signed-off-by: NBalbir Singh <bsingharora@gmail.com>
      [mpe: Massage change log, add detail on return type change]
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      9c355917
    • M
      powerpc/mm: Fix swapper_pg_dir size on 64-bit hash w/64K pages · 03dfee6d
      Michael Ellerman 提交于
      Recently in commit f6eedbba ("powerpc/mm/hash: Increase VA range to 128TB"),
      we increased H_PGD_INDEX_SIZE to 15 when we're building with 64K pages. This
      makes it larger than RADIX_PGD_INDEX_SIZE (13), which means the logic to
      calculate MAX_PGD_INDEX_SIZE in book3s/64/pgtable.h is wrong.
      
      The end result is that the PGD (Page Global Directory, ie top level page table)
      of the kernel (aka. swapper_pg_dir), is too small.
      
      This generally doesn't lead to a crash, as we don't use the full range in normal
      operation. However if we try to dump the kernel pagetables we can trigger a
      crash because we walk off the end of the pgd into other memory and eventually
      try to dereference something bogus:
      
        $ cat /sys/kernel/debug/kernel_pagetables
        Unable to handle kernel paging request for data at address 0xe8fece0000000000
        Faulting instruction address: 0xc000000000072314
        cpu 0xc: Vector: 380 (Data SLB Access) at [c0000000daa13890]
            pc: c000000000072314: ptdump_show+0x164/0x430
            lr: c000000000072550: ptdump_show+0x3a0/0x430
           dar: e802cf0000000000
        seq_read+0xf8/0x560
        full_proxy_read+0x84/0xc0
        __vfs_read+0x6c/0x1d0
        vfs_read+0xbc/0x1b0
        SyS_read+0x6c/0x110
        system_call+0x38/0xfc
      
      The root cause is that MAX_PGD_INDEX_SIZE isn't actually computed to be
      the max of H_PGD_INDEX_SIZE or RADIX_PGD_INDEX_SIZE. To fix that move
      the calculation into asm-offsets.c where we can do it easily using
      max().
      
      Fixes: f6eedbba ("powerpc/mm/hash: Increase VA range to 128TB")
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      03dfee6d
    • M
      Merge branch 'topic/xive' (early part) into next · 3c19d5ad
      Michael Ellerman 提交于
      This merges the arch part of the XIVE support, leaving the final commit
      with the KVM specific pieces dangling on the branch for Paul to merge
      via the kvm-ppc tree.
      3c19d5ad
  4. 11 4月, 2017 8 次提交
    • G
      powerpc/powernv: Recover correct PACA on wakeup from a stop on P9 DD1 · 17ed4c8f
      Gautham R. Shenoy 提交于
      POWER9 DD1.0 hardware has a bug where the SPRs of a thread waking up
      from stop 0,1,2 with ESL=1 can endup being misplaced in the core. Thus
      the HSPRG0 of a thread waking up from can contain the paca pointer of
      its sibling.
      
      This patch implements a context recovery framework within threads of a
      core, by provisioning space in paca_struct for saving every sibling
      threads's paca pointers. Basically, we should be able to arrive at the
      right paca pointer from any of the thread's existing paca pointer.
      
      At bootup, during powernv idle-init, we save the paca address of every
      CPU in each one its siblings paca_struct in the slot corresponding to
      this CPU's index in the core.
      
      On wakeup from a stop, the thread will determine its index in the core
      from the TIR register and recover its PACA pointer by indexing into
      the correct slot in the provisioned space in the current PACA.
      
      Furthermore, ensure that the NVGPRs are restored from the stack on the
      way out by setting the NAPSTATELOST in paca.
      
      [Changelog written with inputs from svaidy@linux.vnet.ibm.com]
      Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
      Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
      [mpe: Call it a bug]
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      17ed4c8f
    • G
      powerpc/powernv/idle: Don't override default/deepest directly in kernel · f3b3f284
      Gautham R. Shenoy 提交于
      Currently during idle-init on power9, if we don't find suitable stop
      states in the device tree that can be used as the
      default_stop/deepest_stop, we set stop0 (ESL=1,EC=1) as the default
      stop state psscr to be used by power9_idle and deepest stop state
      which is used by CPU-Hotplug.
      
      However, if the platform firmware has not configured or enabled a stop
      state, the kernel should not make any assumptions and fallback to a
      default choice.
      
      If the kernel uses a stop state that is not configured by the platform
      firmware, it may lead to further failures which should be avoided.
      
      In this patch, we modify the init code to ensure that the kernel uses
      only the stop states exposed by the firmware through the device
      tree. When a suitable default stop state isn't found, we disable
      ppc_md.power_save for power9. Similarly, when a suitable
      deepest_stop_state is not found in the device tree exported by the
      firmware, fall back to the default busy-wait loop in the CPU-Hotplug
      code.
      
      [Changelog written with inputs from svaidy@linux.vnet.ibm.com]
      Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
      Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      f3b3f284
    • G
      powerpc/powernv/smp: Add busy-wait loop as fall back for CPU-Hotplug · 90061231
      Gautham R. Shenoy 提交于
      Currently, the powernv cpu-offline function assumes that platform idle
      states such as stop on POWER9, winkle/sleep/nap on POWER8 are always
      available. On POWER8, it picks nap as the default state if other deep
      idle states like sleep/winkle are not available and enabled in the
      platform.
      
      On POWER9, nap is not available and all idle states are managed by
      STOP instruction.  The parameters to the idle state are passed through
      processor stop status control register (PSSCR).  Hence as such
      executing STOP would take parameters from current PSSCR. We do not
      want to make any assumptions in kernel on what STOP states and PSSCR
      features are configured by the platform.
      
      Ideally platform will configure a good set of stop states that can be
      used in the kernel.  We would like to start with a clean slate, if the
      platform choose to not configure any state or there is an error in
      platform firmware that lead to no stop states being configured or
      allowed to be requested.
      
      This patch adds a fallback method for CPU-Hotplug that is similar to
      snooze loop at idle where the threads are left to spin at low priority
      and hence reduce the cycles consumed.
      
      This is a safe fallback mechanism in the case when no stop state would
      be requested if the platform firmware did not configure them most
      likely due to an error condition.
      
      Requesting a stop state when the platform has not configured them or
      enabled them would lead to further error conditions which could be
      difficult to debug.
      
      [Changelog written with inputs from svaidy@linux.vnet.ibm.com]
      Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
      Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      90061231
    • G
      powerpc/powernv: Move CPU-Offline idle state invocation from smp.c to idle.c · a7cd88da
      Gautham R. Shenoy 提交于
      Move the piece of code in powernv/smp.c::pnv_smp_cpu_kill_self() which
      transitions the CPU to the deepest available platform idle state to a
      new function named pnv_cpu_offline() in powernv/idle.c. The rationale
      behind this code movement is that the data required to determine the
      deepest available platform state resides in powernv/idle.c.
      Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
      Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      a7cd88da
    • A
      powerpc/hugetlb: Add ABI defines for supported HugeTLB page sizes · 2c9faa76
      Anshuman Khandual 提交于
      Add user space exported API definitions for 512KB, 1MB, 2MB, 8MB, 16MB,
      1GB, 16GB non default huge page sizes to be used with mmap() system
      call.
      Signed-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
      [mpe: Reword the comment to emphasise that these are only needed to use
       the non-default huge page size, and updated the change log.]
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      2c9faa76
    • A
      powerpc/mm: Remove reduntant initmem information from log · ea614555
      Anshuman Khandual 提交于
      Generic core VM already prints these information in the log
      buffer, hence there is no need for a second print. This just
      removes the second print from arch powerpc NUMA init path.
      
      Before the patch:
      
        $ dmesg | grep "Initmem"
      
        numa: Initmem setup node 0 [mem 0x00000000-0xffffffff]
        numa: Initmem setup node 1 [mem 0x100000000-0x1ffffffff]
        numa: Initmem setup node 2 [mem 0x200000000-0x2ffffffff]
        numa: Initmem setup node 3 [mem 0x300000000-0x3ffffffff]
        numa: Initmem setup node 4 [mem 0x400000000-0x4ffffffff]
        numa: Initmem setup node 5 [mem 0x500000000-0x5ffffffff]
        numa: Initmem setup node 6 [mem 0x600000000-0x6ffffffff]
        numa: Initmem setup node 7 [mem 0x700000000-0x7ffffffff]
        Initmem setup node 0 [mem 0x0000000000000000-0x00000000ffffffff]
        Initmem setup node 1 [mem 0x0000000100000000-0x00000001ffffffff]
        Initmem setup node 2 [mem 0x0000000200000000-0x00000002ffffffff]
        Initmem setup node 3 [mem 0x0000000300000000-0x00000003ffffffff]
        Initmem setup node 4 [mem 0x0000000400000000-0x00000004ffffffff]
        Initmem setup node 5 [mem 0x0000000500000000-0x00000005ffffffff]
        Initmem setup node 6 [mem 0x0000000600000000-0x00000006ffffffff]
        Initmem setup node 7 [mem 0x0000000700000000-0x00000007ffffffff]
      
      After the patch just the latter set is printed.
      Signed-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      ea614555
    • M
      powerpc: Make sparsemem the default on 64-bit Book3S · 7b3912f4
      Michael Ellerman 提交于
      Make sparsemem the default on all 64-bit Book3S platforms. It already is
      for pseries and ps3, and we need to enable it for powernv because on
      POWER9 memory between chips is discontiguous.
      
      For the other platforms sparsemem should work fine, though it might add
      a small amount of overhead. We can always force FLATMEM in the
      defconfigs if necessary.
      Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      7b3912f4
    • M
      powerpc/nohash: Fix use of mmu_has_feature() in setup_initial_memory_limit() · 4868e350
      Michael Ellerman 提交于
      setup_initial_memory_limit() is called from early_init_devtree(), which
      runs prior to feature patching. If the kernel is built with CONFIG_JUMP_LABEL=y
      and CONFIG_JUMP_LABEL_FEATURE_CHECKS=y then we will potentially get the
      wrong value.
      
      If we also have CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG=y we get a warning
      and backtrace:
      
        Warning! mmu_has_feature() used prior to jump label init!
        CPU: 0 PID: 0 Comm: swapper Not tainted 4.11.0-rc4-gccN-next-20170331-g6af2434 #1
        Call Trace:
        [c000000000fc3d50] [c000000000a26c30] .dump_stack+0xa8/0xe8 (unreliable)
        [c000000000fc3de0] [c00000000002e6b8] .setup_initial_memory_limit+0xa4/0x104
        [c000000000fc3e60] [c000000000d5c23c] .early_init_devtree+0xd0/0x2f8
        [c000000000fc3f00] [c000000000d5d3b0] .early_setup+0x90/0x11c
        [c000000000fc3f90] [c000000000000520] start_here_multiplatform+0x68/0x80
      
      Fix it by using early_mmu_has_feature().
      
      Fixes: c12e6f24 ("powerpc: Add option to use jump label for mmu_has_feature()")
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      4868e350