Commit graph

405 commits

Author SHA1 Message Date
Nicholas Piggin
2275d7b575 powerpc/64s/radix: introduce options to disable use of the tlbie instruction
Introduce two options to control the use of the tlbie instruction. A
boot time option which completely disables the kernel using the
instruction, this is currently incompatible with HASH MMU, KVM, and
coherent accelerators.

And a debugfs option can be switched at runtime and avoids using tlbie
for invalidating CPU TLBs for normal process and kernel address
mappings. Coherent accelerators are still managed with tlbie, as will
KVM partition scope translations.

Cross-CPU TLB flushing is implemented with IPIs and tlbiel. This is a
basic implementation which does not attempt to make any optimisation
beyond the tlbie implementation.

This is useful for performance testing among other things. For example
in certain situations on large systems, using IPIs may be faster than
tlbie as they can be directed rather than broadcast. Later we may also
take advantage of the IPIs to do more interesting things such as trim
the mm cpumask more aggressively.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190902152931.17840-7-npiggin@gmail.com
2019-09-05 14:22:41 +10:00
Nicholas Piggin
99161de3a2 powerpc/64s/radix: tidy up TLB flushing code
There should be no functional changes.

- Use calls to existing radix_tlb.c functions in flush_partition.

- Rename radix__flush_tlb_lpid to radix__flush_all_lpid and similar,
  because they flush everything, matching flush_all_mm rather than
  flush_tlb_mm for the lpid.

- Remove some unused radix_tlb.c flush primitives.

Signed-off: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190902152931.17840-3-npiggin@gmail.com
2019-09-05 14:22:40 +10:00
Nicholas Piggin
ed6546bdc6 powerpc/64s: remove register_process_table callback
This callback is only required because the partition table init comes
before process table allocation on powernv (aka bare metal aka native).

Change the order to allocate the process table first, and remove the
callback.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190902152931.17840-2-npiggin@gmail.com
2019-09-05 14:22:40 +10:00
Christoph Hellwig
f2902a2fb4 powerpc: use the generic dma coherent remap allocator
This switches to using common code for the DMA allocations, including
potential use of the CMA allocator if configured.

Switching to the generic code enables DMA allocations from atomic
context, which is required by the DMA API documentation, and also
adds various other minor features drivers start relying upon.  It
also makes sure we have on tested code base for all architectures
that require uncached pte bits for coherent DMA allocations.

Another advantage is that consistent memory allocations now share
the general vmalloc pool instead of needing an explicit careout
from it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Christophe Leroy <christophe.leroy@c-s.fr> # tested on 8xx
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190814132230.31874-2-hch@lst.de
2019-08-28 23:19:34 +10:00
Christophe Leroy
4a45b7460c powerpc/mm: refactor ioremap vm area setup.
PPC32 and PPC64 are doing the same once SLAB is available.
Create a do_ioremap() function that calls get_vm_area and
do the mapping.

For PPC64, we add the 4K PFN hack sanity check to __ioremap_caller()
in order to avoid using __ioremap_at(). Other checks in __ioremap_at()
are irrelevant for __ioremap_caller().

On PPC64, VM area is allocated in the range [ioremap_bot ; IOREMAP_END]
On PPC32, VM area is allocated in the range [VMALLOC_START ; VMALLOC_END]

Lets define IOREMAP_START is ioremap_bot for PPC64, and alias
IOREMAP_START/END to VMALLOC_START/END on PPC32

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/42e7e36ad32e0fdf76692426cc642799c9f689b8.1566309263.git.christophe.leroy@c-s.fr
2019-08-27 13:03:35 +10:00
Christophe Leroy
191e42063a powerpc/mm: refactor ioremap_range() and use ioremap_page_range()
book3s64's ioremap_range() is almost same as fallback ioremap_range(),
except that it calls radix__ioremap_range() when radix is enabled.

radix__ioremap_range() is also very similar to the other ones, expect
that it calls ioremap_page_range when slab is available.

PPC32 __ioremap_caller() have a loop doing the same thing as
ioremap_range() so use it on PPC32 as well.

Lets keep only one version of ioremap_range() which calls
ioremap_page_range() on all platforms when slab is available.

At the same time, drop the nid parameter which is not used.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4b1dca7096b01823b101be7338983578641547f1.1566309263.git.christophe.leroy@c-s.fr
2019-08-27 13:03:35 +10:00
Christophe Leroy
7cd9b317b6 powerpc/mm: make ioremap_bot common to all
Drop multiple definitions of ioremap_bot and make one common to
all subarches.

Only CONFIG_PPC_BOOK3E_64 had a global static init value for
ioremap_bot. Now ioremap_bot is set in early_init_mmu_global().

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/920eebfd9f36f14c79d1755847f5bf7c83703bdd.1566309262.git.christophe.leroy@c-s.fr
2019-08-27 13:03:34 +10:00
Nicholas Piggin
6bb25170d7 powerpc/64s/radix: Remove redundant pfn_pte bitop, add VM_BUG_ON
pfn_pte is never given a pte above the addressable physical memory
limit, so the masking is redundant. In case of a software bug, it
is not obviously better to silently truncate the pfn than to corrupt
the pte (either one will result in memory corruption or crashes),
so there is no reason to add this to the fast path.

Add VM_BUG_ON to catch cases where the pfn is invalid. These would
catch the create_section_mapping bug fixed by a previous commit.

  [16885.256466] ------------[ cut here ]------------
  [16885.256492] kernel BUG at arch/powerpc/include/asm/book3s/64/pgtable.h:612!
  cpu 0x0: Vector: 700 (Program Check) at [c0000000ee0a36d0]
      pc: c000000000080738: __map_kernel_page+0x248/0x6f0
      lr: c000000000080ac0: __map_kernel_page+0x5d0/0x6f0
      sp: c0000000ee0a3960
     msr: 9000000000029033
    current = 0xc0000000ec63b400
    paca    = 0xc0000000017f0000   irqmask: 0x03   irq_happened: 0x01
      pid   = 85, comm = sh
  kernel BUG at arch/powerpc/include/asm/book3s/64/pgtable.h:612!
  Linux version 5.3.0-rc1-00001-g0fe93e5f3394
  enter ? for help
  [c0000000ee0a3a00] c000000000d37378 create_physical_mapping+0x260/0x360
  [c0000000ee0a3b10] c000000000d370bc create_section_mapping+0x1c/0x3c
  [c0000000ee0a3b30] c000000000071f54 arch_add_memory+0x74/0x130

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190724084638.24982-5-npiggin@gmail.com
2019-08-20 21:22:20 +10:00
Christophe Leroy
d964211791 powerpc/mm: define empty update_mmu_cache() as static inline
Only BOOK3S and FSL_BOOK3E have a usefull update_mmu_cache().

For the others, just define it static inline.

In the meantime, simplify the FSL_BOOK3E related ifdef as
book3e_hugetlb_preload() only exists when CONFIG_PPC_FSL_BOOK3E
is selected.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/668aba4db6b9af6d8a151174e11a4289f1a6bbcd.1565933217.git.christophe.leroy@c-s.fr
2019-08-20 21:22:14 +10:00
Robin Murphy
175967318c mm: introduce ARCH_HAS_PTE_DEVMAP
ARCH_HAS_ZONE_DEVICE is somewhat meaningless in itself, and combined
with the long-out-of-date comment can lead to the impression than an
architecture may just enable it (since __add_pages() now "comprehends
device memory" for itself) and expect things to work.

In practice, however, ZONE_DEVICE users have little chance of
functioning correctly without __HAVE_ARCH_PTE_DEVMAP, so let's clean
that up the same way as ARCH_HAS_PTE_SPECIAL and make it the proper
dependency so the real situation is clearer.

Link: http://lkml.kernel.org/r/87554aa78478a02a63f2c4cf60a847279ae3eb3b.1558547956.git.robin.murphy@arm.com
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-16 19:23:25 -07:00
Linus Torvalds
192f0f8e9d powerpc updates for 5.3
Notable changes:
 
  - Removal of the NPU DMA code, used by the out-of-tree Nvidia driver, as well
    as some other functions only used by drivers that haven't (yet?) made it
    upstream.
 
  - A fix for a bug in our handling of hardware watchpoints (eg. perf record -e
    mem: ...) which could lead to register corruption and kernel crashes.
 
  - Enable HAVE_ARCH_HUGE_VMAP, which allows us to use large pages for vmalloc
    when using the Radix MMU.
 
  - A large but incremental rewrite of our exception handling code to use gas
    macros rather than multiple levels of nested CPP macros.
 
 And the usual small fixes, cleanups and improvements.
 
 Thanks to:
   Alastair D'Silva, Alexey Kardashevskiy, Andreas Schwab, Aneesh Kumar K.V, Anju
   T Sudhakar, Anton Blanchard, Arnd Bergmann, Athira Rajeev, Cédric Le Goater,
   Christian Lamparter, Christophe Leroy, Christophe Lombard, Christoph Hellwig,
   Daniel Axtens, Denis Efremov, Enrico Weigelt, Frederic Barrat, Gautham R.
   Shenoy, Geert Uytterhoeven, Geliang Tang, Gen Zhang, Greg Kroah-Hartman, Greg
   Kurz, Gustavo Romero, Krzysztof Kozlowski, Madhavan Srinivasan, Masahiro
   Yamada, Mathieu Malaterre, Michael Neuling, Nathan Lynch, Naveen N. Rao,
   Nicholas Piggin, Nishad Kamdar, Oliver O'Halloran, Qian Cai, Ravi Bangoria,
   Sachin Sant, Sam Bobroff, Satheesh Rajendran, Segher Boessenkool, Shaokun
   Zhang, Shawn Anastasio, Stewart Smith, Suraj Jitindar Singh, Thiago Jung
   Bauermann, YueHaibing.
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Merge tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:
 "Notable changes:

   - Removal of the NPU DMA code, used by the out-of-tree Nvidia driver,
     as well as some other functions only used by drivers that haven't
     (yet?) made it upstream.

   - A fix for a bug in our handling of hardware watchpoints (eg. perf
     record -e mem: ...) which could lead to register corruption and
     kernel crashes.

   - Enable HAVE_ARCH_HUGE_VMAP, which allows us to use large pages for
     vmalloc when using the Radix MMU.

   - A large but incremental rewrite of our exception handling code to
     use gas macros rather than multiple levels of nested CPP macros.

  And the usual small fixes, cleanups and improvements.

  Thanks to: Alastair D'Silva, Alexey Kardashevskiy, Andreas Schwab,
  Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann,
  Athira Rajeev, Cédric Le Goater, Christian Lamparter, Christophe
  Leroy, Christophe Lombard, Christoph Hellwig, Daniel Axtens, Denis
  Efremov, Enrico Weigelt, Frederic Barrat, Gautham R. Shenoy, Geert
  Uytterhoeven, Geliang Tang, Gen Zhang, Greg Kroah-Hartman, Greg Kurz,
  Gustavo Romero, Krzysztof Kozlowski, Madhavan Srinivasan, Masahiro
  Yamada, Mathieu Malaterre, Michael Neuling, Nathan Lynch, Naveen N.
  Rao, Nicholas Piggin, Nishad Kamdar, Oliver O'Halloran, Qian Cai, Ravi
  Bangoria, Sachin Sant, Sam Bobroff, Satheesh Rajendran, Segher
  Boessenkool, Shaokun Zhang, Shawn Anastasio, Stewart Smith, Suraj
  Jitindar Singh, Thiago Jung Bauermann, YueHaibing"

* tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (163 commits)
  powerpc/powernv/idle: Fix restore of SPRN_LDBAR for POWER9 stop state.
  powerpc/eeh: Handle hugepages in ioremap space
  ocxl: Update for AFU descriptor template version 1.1
  powerpc/boot: pass CONFIG options in a simpler and more robust way
  powerpc/boot: add {get, put}_unaligned_be32 to xz_config.h
  powerpc/irq: Don't WARN continuously in arch_local_irq_restore()
  powerpc/module64: Use symbolic instructions names.
  powerpc/module32: Use symbolic instructions names.
  powerpc: Move PPC_HA() PPC_HI() and PPC_LO() to ppc-opcode.h
  powerpc/module64: Fix comment in R_PPC64_ENTRY handling
  powerpc/boot: Add lzo support for uImage
  powerpc/boot: Add lzma support for uImage
  powerpc/boot: don't force gzipped uImage
  powerpc/8xx: Add microcode patch to move SMC parameter RAM.
  powerpc/8xx: Use IO accessors in microcode programming.
  powerpc/8xx: replace #ifdefs by IS_ENABLED() in microcode.c
  powerpc/8xx: refactor programming of microcode CPM params.
  powerpc/8xx: refactor printing of microcode patch name.
  powerpc/8xx: Refactor microcode write
  powerpc/8xx: refactor writing of CPM microcode arrays
  ...
2019-07-13 16:08:36 -07:00
Aneesh Kumar K.V
d6eacedd1f powerpc/book3s: Use config independent helpers for page table walk
Even when we have HugeTLB and THP disabled, kernel linear map can still be
mapped with hugepages. This is only an issue with radix translation because hash
MMU doesn't map kernel linear range in linux page table and other kernel
map areas are not mapped using hugepage.

Add config independent helpers and put WARN_ON() when we don't expect things
to be mapped via hugepages.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-07-05 00:43:50 +10:00
Aneesh Kumar K.V
b8c8a524cc powerpc/mm: Remove unused variable declaration
Since commit 0034d395f8 ("powerpc/mm/hash64: Map all the kernel
regions in the same 0xc range") __kernel_virt_size is not used
anymore.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-07-05 00:20:42 +10:00
Christoph Hellwig
7eb3cf7619 powerpc/powernv: remove unused NPU DMA code
None of these routines were ever used anywhere in the kernel tree
since they were added to the kernel.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-07-01 16:26:55 +10:00
Michael Ellerman
8b8dc69514 Merge branch 'fixes' into next
Merge our fixes branch into next, this brings in a number of commits
that fix bugs we don't want to hit in next, in particular the fix for
CVE-2019-12817.
2019-07-01 14:04:39 +10:00
Nicholas Piggin
d909f9109c powerpc/64s/radix: Enable HAVE_ARCH_HUGE_VMAP
This sets the HAVE_ARCH_HUGE_VMAP option, and defines the required
page table functions.

This enables huge (2MB and 1GB) ioremap mappings. I don't have a
benchmark for this change, but huge vmap will be used by a later core
kernel change to enable huge vmalloc memory mappings. This improves
cached `git diff` performance by about 5% on a 2-node POWER9 with 32MB
size dentry cache hash.

  Profiling git diff dTLB misses with a vanilla kernel:

  81.75%  git      [kernel.vmlinux]    [k] __d_lookup_rcu
   7.21%  git      [kernel.vmlinux]    [k] strncpy_from_user
   1.77%  git      [kernel.vmlinux]    [k] find_get_entry
   1.59%  git      [kernel.vmlinux]    [k] kmem_cache_free

            40,168      dTLB-miss
       0.100342754 seconds time elapsed

  With powerpc huge vmalloc:

             2,987      dTLB-miss
       0.095933138 seconds time elapsed

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-06-19 20:05:09 +10:00
Nicholas Piggin
d38153f9cc powerpc/64s/radix: ioremap use ioremap_page_range
Radix can use ioremap_page_range for ioremap, after slab is available.
This makes it possible to enable huge ioremap mapping support.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-06-19 20:05:09 +10:00
Linus Torvalds
fa1827d773 powerpc fixes for 5.2 #4
One fix for a regression introduced by our 32-bit KASAN support, which broke
 booting on machines with "bootx" early debugging enabled.
 
 A fix for a bug which broke kexec on 32-bit, introduced by changes to the 32-bit
 STRICT_KERNEL_RWX support in v5.1.
 
 Finally two fixes going to stable for our THP split/collapse handling,
 discovered by Nick. The first fixes random crashes and/or corruption in guests
 under sufficient load.
 
 Thanks to:
   Nicholas Piggin, Christophe Leroy, Aaro Koskinen, Mathieu Malaterre.
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Merge tag 'powerpc-5.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 "One fix for a regression introduced by our 32-bit KASAN support, which
  broke booting on machines with "bootx" early debugging enabled.

  A fix for a bug which broke kexec on 32-bit, introduced by changes to
  the 32-bit STRICT_KERNEL_RWX support in v5.1.

  Finally two fixes going to stable for our THP split/collapse handling,
  discovered by Nick. The first fixes random crashes and/or corruption
  in guests under sufficient load.

  Thanks to: Nicholas Piggin, Christophe Leroy, Aaro Koskinen, Mathieu
  Malaterre"

* tag 'powerpc-5.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/32s: fix booting with CONFIG_PPC_EARLY_DEBUG_BOOTX
  powerpc/64s: __find_linux_pte() synchronization vs pmdp_invalidate()
  powerpc/64s: Fix THP PMD collapse serialisation
  powerpc: Fix kexec failure on book3s/32
2019-06-15 07:29:32 -10:00
Nicholas Piggin
33258a1db1 powerpc/64s: Fix THP PMD collapse serialisation
Commit 1b2443a547 ("powerpc/book3s64: Avoid multiple endian
conversion in pte helpers") changed the actual bitwise tests in
pte_access_permitted by using pte_write() and pte_present() helpers
rather than raw bitwise testing _PAGE_WRITE and _PAGE_PRESENT bits.

The pte_present() change now returns true for PTEs which are
!_PAGE_PRESENT and _PAGE_INVALID, which is the combination used by
pmdp_invalidate() to synchronize access from lock-free lookups.
pte_access_permitted() is used by pmd_access_permitted(), so allowing
GUP lock free access to proceed with such PTEs breaks this
synchronisation.

This bug has been observed on a host using the hash page table MMU,
with random crashes and corruption in guests, usually together with
bad PMD messages in the host.

Fix this by adding an explicit check in pmd_access_permitted(), and
documenting the condition explicitly.

The pte_write() change should be okay, and would prevent GUP from
falling back to the slow path when encountering savedwrite PTEs, which
matches what x86 (that does not implement savedwrite) does.

Fixes: 1b2443a547 ("powerpc/book3s64: Avoid multiple endian conversion in pte helpers")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-06-07 16:26:44 +10:00
Thomas Gleixner
2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00
Linus Torvalds
86a78a8b8d powerpc fixes for 5.2 #2
One fix going back to stable, for a bug on 32-bit introduced when we added
 support for THREAD_INFO_IN_TASK.
 
 A fix for a typo in a recent rework of our hugetlb code that leads to crashes on
 64-bit when using hugetlbfs with a 4K PAGE_SIZE.
 
 Two fixes for our recent rework of the address layout on 64-bit hash CPUs, both
 only triggered when userspace tries to access addresses outside the user or
 kernel address ranges.
 
 Finally a fix for a recently introduced double free in an error path in our
 cacheinfo code.
 
 Thanks to:
   Aneesh Kumar K.V, Christophe Leroy, Sachin Sant, Tobin C. Harding.
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Merge tag 'powerpc-5.2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 "One fix going back to stable, for a bug on 32-bit introduced when we
  added support for THREAD_INFO_IN_TASK.

  A fix for a typo in a recent rework of our hugetlb code that leads to
  crashes on 64-bit when using hugetlbfs with a 4K PAGE_SIZE.

  Two fixes for our recent rework of the address layout on 64-bit hash
  CPUs, both only triggered when userspace tries to access addresses
  outside the user or kernel address ranges.

  Finally a fix for a recently introduced double free in an error path
  in our cacheinfo code.

  Thanks to: Aneesh Kumar K.V, Christophe Leroy, Sachin Sant, Tobin C.
  Harding"

* tag 'powerpc-5.2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/cacheinfo: Remove double free
  powerpc/mm/hash: Fix get_region_id() for invalid addresses
  powerpc/mm: Drop VM_BUG_ON in get_region_id()
  powerpc/mm: Fix crashes with hugepages & 4K pages
  powerpc/32s: fix flush_hash_pages() on SMP
2019-05-19 10:10:15 -07:00
Aneesh Kumar K.V
c179976cf4 powerpc/mm/hash: Fix get_region_id() for invalid addresses
Accesses by userspace to random addresses outside the user or kernel
address range will generate an SLB fault. When we handle that fault we
classify the effective address into several classes, eg. user, kernel
linear, kernel virtual etc.

For addresses that are completely outside of any valid range, we
should not insert an SLB entry at all, and instead immediately an
exception.

In the past this was handled in two ways. Firstly we would check the
top nibble of the address (using REGION_ID(ea)) and that would tell us
if the address was user (0), kernel linear (c), kernel virtual (d), or
vmemmap (f). If the address didn't match any of these it was invalid.

Then for each type of address we would do a secondary check. For the
user region we check against H_PGTABLE_RANGE, for kernel linear we
would mask the top nibble of the address and then check the address
against MAX_PHYSMEM_BITS.

As part of commit 0034d395f8 ("powerpc/mm/hash64: Map all the kernel
regions in the same 0xc range") we replaced REGION_ID() with
get_region_id() and changed the masking of the top nibble to only mask
the top two bits, which introduced a bug.

Addresses less than (4 << 60) are still handled correctly, they are
either less than (1 << 60) in which case they are subject to the
H_PGTABLE_RANGE check, or they are correctly checked against
MAX_PHYSMEM_BITS.

However addresses from (4 << 60) to ((0xc << 60) - 1), are incorrectly
treated as kernel linear addresses in get_region_id(). Then the top
two bits are cleared by EA_MASK in slb_allocate_kernel() and the
address is checked against MAX_PHYSMEM_BITS, which it passes due to
the masking. The end result is we incorrectly insert SLB entries for
those addresses.

That is not actually catastrophic, having inserted the SLB entry we
will then go on to take a page fault for the address and at that point
we detect the problem and report it as a bad fault.

Still we should not be inserting those entries, or treating them as
kernel linear addresses in the first place. So fix get_region_id() to
detect addresses in that range and return an invalid region id, which
we cause use to not insert an SLB entry and directly report an
exception.

Fixes: 0034d395f8 ("powerpc/mm/hash64: Map all the kernel regions in the same 0xc range")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
[mpe: Drop change to EA_MASK for now, rewrite change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-17 22:57:40 +10:00
Aneesh Kumar K.V
6457f42eb3 powerpc/mm: Drop VM_BUG_ON in get_region_id()
We call get_region_id() without validating the ea value. That means
with a wrong ea value we hit the BUG as below.

  kernel BUG at arch/powerpc/include/asm/book3s/64/hash.h:129!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  CPU: 0 PID: 3937 Comm: access_tests Not tainted 5.1.0
  ....
  NIP [c00000000007ba20] do_slb_fault+0x70/0x320
  LR [c00000000000896c] data_access_slb_common+0x15c/0x1a0

Fix this by removing the VM_BUG_ON. All callers make sure the returned
region id is valid and error out otherwise.

Fixes: 0034d395f8 ("powerpc/mm/hash64: Map all the kernel regions in the same 0xc range")
Reported-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-17 00:40:01 +10:00
Alexandre Ghiti
4eb0716e86 hugetlb: allow to free gigantic pages regardless of the configuration
On systems without CONTIG_ALLOC activated but that support gigantic pages,
boottime reserved gigantic pages can not be freed at all.  This patch
simply enables the possibility to hand back those pages to memory
allocator.

Link: http://lkml.kernel.org/r/20190327063626.18421-5-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: David S. Miller <davem@davemloft.net> [sparc]
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
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>
2019-05-14 09:47:47 -07:00
Michael Ellerman
8150a153c0 powerpc/64s: Use early_mmu_has_feature() in set_kuap()
When implementing the KUAP support on Radix we fixed one case where
mmu_has_feature() was being called too early in boot via
__put_user_size().

However since then some new code in linux-next has created a new path
via which we can end up calling mmu_has_feature() too early.

On P9 this leads to crashes early in boot if we have both PPC_KUAP and
CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG enabled. Our early boot code
calls printk() which calls probe_kernel_read(), that does a
__copy_from_user_inatomic() which calls into set_kuap() and that uses
mmu_has_feature().

At that point in boot we haven't patched MMU features yet so the debug
code in mmu_has_feature() complains, and calls printk(). At that point
we recurse, eg:

  ...
  dump_stack+0xdc
  probe_kernel_read+0x1a4
  check_pointer+0x58
  ...
  printk+0x40
  dump_stack_print_info+0xbc
  dump_stack+0x8
  probe_kernel_read+0x1a4
  probe_kernel_read+0x19c
  check_pointer+0x58
  ...
  printk+0x40
  cpufeatures_process_feature+0xc8
  scan_cpufeatures_subnodes+0x380
  of_scan_flat_dt_subnodes+0xb4
  dt_cpu_ftrs_scan_callback+0x158
  of_scan_flat_dt+0xf0
  dt_cpu_ftrs_scan+0x3c
  early_init_devtree+0x360
  early_setup+0x9c

And so on for infinity, symptom is a dead system.

Even more fun is what happens when using the hash MMU (ie. p8 or p9
with Radix disabled), and when we don't have
CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG enabled. With the debug disabled
we don't check if static keys have been initialised, we just rely on
the jump label. But the jump label defaults to true so we just whack
the AMR even though Radix is not enabled.

Clearing the AMR is fine, but after we've done the user copy we write
(0b11 << 62) into AMR. When using hash that makes all pages with key
zero no longer readable or writable. All kernel pages implicitly have
key zero, and so all of a sudden the kernel can't read or write any of
its memory. Again dead system.

In the medium term we have several options for fixing this.
probe_kernel_read() doesn't need to touch AMR at all, it's not doing a
user access after all, but it uses __copy_from_user_inatomic() just
because it's easy, we could fix that.

It would also be safe to default to not writing to the AMR during
early boot, until we've detected features. But it's not clear that
flipping all the MMU features to static_key_false won't introduce
other bugs.

But for now just switch to early_mmu_has_feature() in set_kuap(), that
avoids all the problems with jump labels. It adds the overhead of a
global lookup and test, but that's probably trivial compared to the
writes to the AMR anyway.

Fixes: 890274c2dc ("powerpc/64s: Implement KUAP for Radix MMU")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Russell Currey <ruscur@russell.cc>
2019-05-09 14:28:56 +10:00
Rick Lindsley
f39356261c powerpc/book3s/64: check for NULL pointer in pgd_alloc()
When the memset code was added to pgd_alloc(), it failed to consider
that kmem_cache_alloc() can return NULL. It's uncommon, but not
impossible under heavy memory contention. Example oops:

  Unable to handle kernel paging request for data at address 0x00000000
  Faulting instruction address: 0xc0000000000a4000
  Oops: Kernel access of bad area, sig: 11 [#1]
  LE SMP NR_CPUS=2048 NUMA pSeries
  CPU: 70 PID: 48471 Comm: entrypoint.sh Kdump: loaded Not tainted 4.14.0-115.6.1.el7a.ppc64le #1
  task: c000000334a00000 task.stack: c000000331c00000
  NIP:  c0000000000a4000 LR: c00000000012f43c CTR: 0000000000000020
  REGS: c000000331c039c0 TRAP: 0300   Not tainted  (4.14.0-115.6.1.el7a.ppc64le)
  MSR:  800000010280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]>  CR: 44022840  XER: 20040000
  CFAR: c000000000008874 DAR: 0000000000000000 DSISR: 42000000 SOFTE: 1
  ...
  NIP [c0000000000a4000] memset+0x68/0x104
  LR [c00000000012f43c] mm_init+0x27c/0x2f0
  Call Trace:
    mm_init+0x260/0x2f0 (unreliable)
    copy_mm+0x11c/0x638
    copy_process.isra.28.part.29+0x6fc/0x1080
    _do_fork+0xdc/0x4c0
    ppc_clone+0x8/0xc
  Instruction dump:
  409e000c b0860000 38c60002 409d000c 90860000 38c60004 78a0d183 78a506a0
  7c0903a6 41820034 60000000 60420000 <f8860000> f8860008 f8860010 f8860018

Fixes: fc5c2f4a55 ("powerpc/mm/hash64: Zero PGD pages on allocation")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Rick Lindsley <ricklind@vnet.linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-07 13:24:31 +10:00
Christophe Leroy
a67beca077 powerpc/32: make KVIRT_TOP dependent on FIXMAP_START
When we add KASAN shadow area, KVIRT_TOP can't be anymore fixed
at 0xfe000000.

This patch uses FIXADDR_START to define KVIRT_TOP.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:26 +10:00
Christophe Leroy
8a2cc87a24 powerpc/mm: refactor pmd_pgtable()
pmd_pgtable() is identical on the 4 subarches, refactor it.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:25 +10:00
Christophe Leroy
e80789a3c1 powerpc/mm: refactor definition of pgtable_cache[]
pgtable_cache[] is the same for the 4 subarches, lets make it common.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:25 +10:00
Christophe Leroy
dc096864ba powerpc/mm: refactor pte_alloc_one() and pte_free() families definition.
Functions pte_alloc_one(), pte_alloc_one_kernel(), pte_free(),
pte_free_kernel() are identical for the four subarches.

This patch moves their definition in a common place.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:25 +10:00
Christophe Leroy
b0124ff57e powerpc/mm: inline pte_alloc_one_kernel() and pte_alloc_one() on PPC32
pte_alloc_one_kernel() and pte_alloc_one() are simple calls to
pte_fragment_alloc(), so they are good candidates for inlining as
already done on PPC64.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:25 +10:00
Christophe Leroy
696dffa24b powerpc/mm: move pgtable_t in asm/mmu.h
pgtable_t is now identical for all subarches, move it to the
top level asm/mmu.h

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:24 +10:00
Christophe Leroy
447def3b06 powerpc/mm: drop __bad_pte()
This has never been called (since Kernel has been in git at least),
drop it.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:24 +10:00
Christophe Leroy
723f268f19 powerpc/mm: cleanup ifdef mess in add_huge_page_size()
Introduce a subarch specific helper check_and_get_huge_psize()
to check the huge page sizes and cleanup the ifdef mess in
add_huge_page_size()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:23 +10:00
Christophe Leroy
5fb84fec46 powerpc/mm: add a helper to populate hugepd
This patchs adds a subarch helper to populate hugepd.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:23 +10:00
Christophe Leroy
8197af22be powerpc/mm: split asm/hugetlb.h into dedicated subarch files
Three subarches support hugepages:
  - fsl book3e
  - book3s/64
  - 8xx

This patch splits asm/hugetlb.h to reduce the #ifdef mess.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:23 +10:00
Christophe Leroy
5953fb4f46 powerpc/mm: define subarch SLB_ADDR_LIMIT_DEFAULT
This patch defines a subarch specific SLB_ADDR_LIMIT_DEFAULT
to remove the #ifdefs around the setup of mm->context.slb_addr_limit

It also generalises the use of mm_ctx_set_slb_addr_limit() helper.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:23 +10:00
Christophe Leroy
877461210e powerpc/mm: get rid of mm_ctx_slice_mask_xxx()
Now that slice_mask_for_size() is in mmu.h, the mm_ctx_slice_mask_xxx()
are not needed anymore, so drop them. Note that the 8xx ones where
not used anyway.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:22 +10:00
Christophe Leroy
fca5c1e9eb powerpc/mm: move slice_mask_for_size() into mmu.h
Move slice_mask_for_size() into subarch mmu.h

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
[mpe: Retain the BUG_ON()s, rather than converting to VM_BUG_ON()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-05-03 01:20:22 +10:00
Aneesh Kumar K.V
5f53d28608 powerpc/mm/hash: Rename KERNEL_REGION_ID to LINEAR_MAP_REGION_ID
The region actually point to linear map. Rename the #define to
clarify thati.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:40 +10:00
Aneesh Kumar K.V
1c946c1b7f powerpc/mm/hash: Simplify the region id calculation.
This reduces multiple comparisons in get_region_id to a bit shift operation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:40 +10:00
Aneesh Kumar K.V
0034d395f8 powerpc/mm/hash64: Map all the kernel regions in the same 0xc range
This patch maps vmalloc, IO and vmemap regions in the 0xc address range
instead of the current 0xd and 0xf range. This brings the mapping closer
to radix translation mode.

With hash 64K page size each of this region is 512TB whereas with 4K config
we are limited by the max page table range of 64TB and hence there regions
are of 16TB size.

The kernel mapping is now:

 On 4K hash

     kernel_region_map_size = 16TB
     kernel vmalloc start   = 0xc000100000000000
     kernel IO start        = 0xc000200000000000
     kernel vmemmap start   = 0xc000300000000000

64K hash, 64K radix and 4k radix:

     kernel_region_map_size = 512TB
     kernel vmalloc start   = 0xc008000000000000
     kernel IO start        = 0xc00a000000000000
     kernel vmemmap start   = 0xc00c000000000000

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:39 +10:00
Aneesh Kumar K.V
a35a3c6f60 powerpc/mm/hash64: Add a variable to track the end of IO mapping
This makes it easy to update the region mapping in the later patch

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:39 +10:00
Aneesh Kumar K.V
ef629cc5bf powerc/mm/hash: Reduce hash_mm_context size
Allocate subpage protect related variables only if we use the feature.
This helps in reducing the hash related mm context struct by around 4K

Before the patch
sizeof(struct hash_mm_context)  = 8288

After the patch
sizeof(struct hash_mm_context) = 4160

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:39 +10:00
Aneesh Kumar K.V
701101865f powerpc/mm: Reduce memory usage for mm_context_t for radix
Currently, our mm_context_t on book3s64 include all hash specific
context details like slice mask and subpage protection details. We
can skip allocating these with radix translation. This will help us to save
8K per mm_context with radix translation.

With the patch applied we have

sizeof(mm_context_t)  = 136
sizeof(struct hash_mm_context)  = 8288

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:39 +10:00
Aneesh Kumar K.V
60458fba46 powerpc/mm: Add helpers for accessing hash translation related variables
We want to switch to allocating them runtime only when hash translation is
enabled. Add helpers so that both book3s and nohash can be adapted to
upcoming change easily.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:38 +10:00
Aneesh Kumar K.V
4f40b15f33 powerpc/mm: Remove PPC_MM_SLICES #ifdef for book3s64
Book3s64 always have PPC_MM_SLICES enabled. So remove the unncessary #ifdef

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:38 +10:00
Aneesh Kumar K.V
6161a37307 powerpc/mm: Fix build error with FLATMEM book3s64 config
The current value of MAX_PHYSMEM_BITS cannot work with 32 bit configs.
We used to have MAX_PHYSMEM_BITS not defined without SPARSEMEM and 32
bit configs never expected a value to be set for MAX_PHYSMEM_BITS.

Dependent code such as zsmalloc derived the right values based on other
fields. Instead of finding a value that works with different configs,
use new values only for book3s_64. For 64 bit booke, use the definition
of MAX_PHYSMEM_BITS as per commit a7df61a0e2 ("[PATCH] ppc64: Increase sparsemem defaults")
That change was done in 2005 and hopefully will work with book3e 64.

Fixes: 8bc0868998 ("powerpc/mm: Only define MAX_PHYSMEM_BITS in SPARSEMEM configurations")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:12:38 +10:00
Christophe Leroy
a68c31fc01 powerpc/32s: Implement Kernel Userspace Access Protection
This patch implements Kernel Userspace Access Protection for
book3s/32.

Due to limitations of the processor page protection capabilities,
the protection is only against writing. read protection cannot be
achieved using page protection.

The previous patch modifies the page protection so that RW user
pages are RW for Key 0 and RO for Key 1, and it sets Key 0 for
both user and kernel.

This patch changes userspace segment registers are set to Ku 0
and Ks 1. When kernel needs to write to RW pages, the associated
segment register is then changed to Ks 0 in order to allow write
access to the kernel.

In order to avoid having the read all segment registers when
locking/unlocking the access, some data is kept in the thread_struct
and saved on stack on exceptions. The field identifies both the
first unlocked segment and the first segment following the last
unlocked one. When no segment is unlocked, it contains value 0.

As the hash_page() function is not able to easily determine if a
protfault is due to a bad kernel access to userspace, protfaults
need to be handled by handle_page_fault when KUAP is set.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Drop allow_read/write_to/from_user() as they're now in kup.h,
      and adapt allow_user_access() to do nothing when to == NULL]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:11:47 +10:00
Christophe Leroy
f342adca3a powerpc/32s: Prepare Kernel Userspace Access Protection
This patch prepares Kernel Userspace Access Protection for
book3s/32.

Due to limitations of the processor page protection capabilities,
the protection is only against writing. read protection cannot be
achieved using page protection.

book3s/32 provides the following values for PP bits:

PP00 provides RW for Key 0 and NA for Key 1
PP01 provides RW for Key 0 and RO for Key 1
PP10 provides RW for all
PP11 provides RO for all

Today PP10 is used for RW pages and PP11 for RO pages, and user
segment register's Kp and Ks are set to 1. This patch modifies
page protection to use PP01 for RW pages and sets user segment
registers to Kp 0 and Ks 0.

This will allow to setup Userspace write access protection by
settng Ks to 1 in the following patch.

Kernel space segment registers remain unchanged.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-04-21 23:11:46 +10:00