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  1. May 09, 2018
  2. May 08, 2018
  3. Apr 04, 2018
  4. Mar 27, 2018
  5. Mar 26, 2018
    • Suzuki K Poulose's avatar
      arm64: Add work around for Arm Cortex-A55 Erratum 1024718 · ece1397c
      Suzuki K Poulose authored
      
      
      Some variants of the Arm Cortex-55 cores (r0p0, r0p1, r1p0) suffer
      from an erratum 1024718, which causes incorrect updates when DBM/AP
      bits in a page table entry is modified without a break-before-make
      sequence. The work around is to skip enabling the hardware DBM feature
      on the affected cores. The hardware Access Flag management features
      is not affected. There are some other cores suffering from this
      errata, which could be added to the midr_list to trigger the work
      around.
      
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: ckadabi@codeaurora.org
      Reviewed-by: default avatarDave Martin <dave.martin@arm.com>
      Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      ece1397c
    • Dave Martin's avatar
      arm64/sve: Document firmware support requirements in Kconfig · 5043694e
      Dave Martin authored
      
      
      Use of SVE by EL2 and below requires explicit support in the
      firmware.  There is no means to hide the presence of SVE from EL2,
      so a kernel configured with CONFIG_ARM64_SVE=y will typically not
      work correctly on SVE capable hardware unless the firmware does
      include the appropriate support.
      
      This is not expected to pose a problem in the wild, since platform
      integrators are responsible for ensuring that they ship up-to-date
      firmware to support their hardware.  However, developers may hit
      the issue when using mismatched compoments.
      
      In order to draw attention to the issue and how to solve it, this
      patch adds some Kconfig text giving a brief explanation and details
      of compatible firmware versions.
      
      Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
      Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      5043694e
  6. Mar 19, 2018
  7. Mar 09, 2018
    • Ard Biesheuvel's avatar
      arm64/kernel: don't ban ADRP to work around Cortex-A53 erratum #843419 · a257e025
      Ard Biesheuvel authored
      
      
      Working around Cortex-A53 erratum #843419 involves special handling of
      ADRP instructions that end up in the last two instruction slots of a
      4k page, or whose output register gets overwritten without having been
      read. (Note that the latter instruction sequence is never emitted by
      a properly functioning compiler, which is why it is disregarded by the
      handling of the same erratum in the bfd.ld linker which we rely on for
      the core kernel)
      
      Normally, this gets taken care of by the linker, which can spot such
      sequences at final link time, and insert a veneer if the ADRP ends up
      at a vulnerable offset. However, linux kernel modules are partially
      linked ELF objects, and so there is no 'final link time' other than the
      runtime loading of the module, at which time all the static relocations
      are resolved.
      
      For this reason, we have implemented the #843419 workaround for modules
      by avoiding ADRP instructions altogether, by using the large C model,
      and by passing -mpc-relative-literal-loads to recent versions of GCC
      that may emit adrp/ldr pairs to perform literal loads. However, this
      workaround forces us to keep literal data mixed with the instructions
      in the executable .text segment, and literal data may inadvertently
      turn into an exploitable speculative gadget depending on the relative
      offsets of arbitrary symbols.
      
      So let's reimplement this workaround in a way that allows us to switch
      back to the small C model, and to drop the -mpc-relative-literal-loads
      GCC switch, by patching affected ADRP instructions at runtime:
      - ADRP instructions that do not appear at 4k relative offset 0xff8 or
        0xffc are ignored
      - ADRP instructions that are within 1 MB of their target symbol are
        converted into ADR instructions
      - remaining ADRP instructions are redirected via a veneer that performs
        the load using an unaffected movn/movk sequence.
      
      Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
      [will: tidied up ADRP -> ADR instruction patching.]
      [will: use ULL suffix for 64-bit immediate]
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      a257e025
  8. Mar 08, 2018
    • Ard Biesheuvel's avatar
      arm64/kernel: kaslr: reduce module randomization range to 4 GB · f2b9ba87
      Ard Biesheuvel authored
      
      
      We currently have to rely on the GCC large code model for KASLR for
      two distinct but related reasons:
      - if we enable full randomization, modules will be loaded very far away
        from the core kernel, where they are out of range for ADRP instructions,
      - even without full randomization, the fact that the 128 MB module region
        is now no longer fully reserved for kernel modules means that there is
        a very low likelihood that the normal bottom-up allocation of other
        vmalloc regions may collide, and use up the range for other things.
      
      Large model code is suboptimal, given that each symbol reference involves
      a literal load that goes through the D-cache, reducing cache utilization.
      But more importantly, literals are not instructions but part of .text
      nonetheless, and hence mapped with executable permissions.
      
      So let's get rid of our dependency on the large model for KASLR, by:
      - reducing the full randomization range to 4 GB, thereby ensuring that
        ADRP references between modules and the kernel are always in range,
      - reduce the spillover range to 4 GB as well, so that we fallback to a
        region that is still guaranteed to be in range
      - move the randomization window of the core kernel to the middle of the
        VMALLOC space
      
      Note that KASAN always uses the module region outside of the vmalloc space,
      so keep the kernel close to that if KASAN is enabled.
      
      Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      f2b9ba87
  9. Mar 06, 2018
    • Catalin Marinas's avatar
      arm64: Revert L1_CACHE_SHIFT back to 6 (64-byte cache line size) · 1f85b42a
      Catalin Marinas authored
      
      
      Commit 97303480 ("arm64: Increase the max granular size") increased
      the cache line size to 128 to match Cavium ThunderX, apparently for some
      performance benefit which could not be confirmed. This change, however,
      has an impact on the network packets allocation in certain
      circumstances, requiring slightly over a 4K page with a significant
      performance degradation.
      
      This patch reverts L1_CACHE_SHIFT back to 6 (64-byte cache line) while
      keeping ARCH_DMA_MINALIGN at 128. The cache_line_size() function was
      changed to default to ARCH_DMA_MINALIGN in the absence of a meaningful
      CTR_EL0.CWG bit field.
      
      In addition, if a system with ARCH_DMA_MINALIGN < CTR_EL0.CWG is
      detected, the kernel will force swiotlb bounce buffering for all
      non-coherent devices since DMA cache maintenance on sub-CWG ranges is
      not safe, leading to data corruption.
      
      Cc: Tirumalesh Chalamarla <tchalamarla@cavium.com>
      Cc: Timur Tabi <timur@codeaurora.org>
      Cc: Florian Fainelli <f.fainelli@gmail.com>
      Acked-by: default avatarRobin Murphy <robin.murphy@arm.com>
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      1f85b42a
  10. Feb 06, 2018
    • Shanker Donthineni's avatar
      arm64: Add software workaround for Falkor erratum 1041 · 3060e9f0
      Shanker Donthineni authored
      
      
      The ARM architecture defines the memory locations that are permitted
      to be accessed as the result of a speculative instruction fetch from
      an exception level for which all stages of translation are disabled.
      Specifically, the core is permitted to speculatively fetch from the
      4KB region containing the current program counter 4K and next 4K.
      
      When translation is changed from enabled to disabled for the running
      exception level (SCTLR_ELn[M] changed from a value of 1 to 0), the
      Falkor core may errantly speculatively access memory locations outside
      of the 4KB region permitted by the architecture. The errant memory
      access may lead to one of the following unexpected behaviors.
      
      1) A System Error Interrupt (SEI) being raised by the Falkor core due
         to the errant memory access attempting to access a region of memory
         that is protected by a slave-side memory protection unit.
      2) Unpredictable device behavior due to a speculative read from device
         memory. This behavior may only occur if the instruction cache is
         disabled prior to or coincident with translation being changed from
         enabled to disabled.
      
      The conditions leading to this erratum will not occur when either of the
      following occur:
       1) A higher exception level disables translation of a lower exception level
         (e.g. EL2 changing SCTLR_EL1[M] from a value of 1 to 0).
       2) An exception level disabling its stage-1 translation if its stage-2
          translation is enabled (e.g. EL1 changing SCTLR_EL1[M] from a value of 1
          to 0 when HCR_EL2[VM] has a value of 1).
      
      To avoid the errant behavior, software must execute an ISB immediately
      prior to executing the MSR that will change SCTLR_ELn[M] from 1 to 0.
      
      Signed-off-by: default avatarShanker Donthineni <shankerd@codeaurora.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      3060e9f0
  11. Feb 05, 2018
  12. Jan 16, 2018
  13. Jan 15, 2018
  14. Jan 08, 2018
  15. Dec 22, 2017
  16. Dec 12, 2017
    • Shanker Donthineni's avatar
      arm64: Add software workaround for Falkor erratum 1041 · 932b50c7
      Shanker Donthineni authored
      
      
      The ARM architecture defines the memory locations that are permitted
      to be accessed as the result of a speculative instruction fetch from
      an exception level for which all stages of translation are disabled.
      Specifically, the core is permitted to speculatively fetch from the
      4KB region containing the current program counter 4K and next 4K.
      
      When translation is changed from enabled to disabled for the running
      exception level (SCTLR_ELn[M] changed from a value of 1 to 0), the
      Falkor core may errantly speculatively access memory locations outside
      of the 4KB region permitted by the architecture. The errant memory
      access may lead to one of the following unexpected behaviors.
      
      1) A System Error Interrupt (SEI) being raised by the Falkor core due
         to the errant memory access attempting to access a region of memory
         that is protected by a slave-side memory protection unit.
      2) Unpredictable device behavior due to a speculative read from device
         memory. This behavior may only occur if the instruction cache is
         disabled prior to or coincident with translation being changed from
         enabled to disabled.
      
      The conditions leading to this erratum will not occur when either of the
      following occur:
       1) A higher exception level disables translation of a lower exception level
         (e.g. EL2 changing SCTLR_EL1[M] from a value of 1 to 0).
       2) An exception level disabling its stage-1 translation if its stage-2
          translation is enabled (e.g. EL1 changing SCTLR_EL1[M] from a value of 1
          to 0 when HCR_EL2[VM] has a value of 1).
      
      To avoid the errant behavior, software must execute an ISB immediately
      prior to executing the MSR that will change SCTLR_ELn[M] from 1 to 0.
      
      Signed-off-by: default avatarShanker Donthineni <shankerd@codeaurora.org>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      932b50c7
  17. Dec 11, 2017
  18. Nov 16, 2017
    • Will Deacon's avatar
      arm64/mm/kasan: don't use vmemmap_populate() to initialize shadow · e17d8025
      Will Deacon authored
      The kasan shadow is currently mapped using vmemmap_populate() since that
      provides a semi-convenient way to map pages into init_top_pgt.  However,
      since that no longer zeroes the mapped pages, it is not suitable for
      kasan, which requires zeroed shadow memory.
      
      Add kasan_populate_shadow() interface and use it instead of
      vmemmap_populate().  Besides, this allows us to take advantage of
      gigantic pages and use them to populate the shadow, which should save us
      some memory wasted on page tables and reduce TLB pressure.
      
      Link: http://lkml.kernel.org/r/20171103185147.2688-3-pasha.tatashin@oracle.com
      
      
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Steven Sistare <steven.sistare@oracle.com>
      Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
      Cc: Bob Picco <bob.picco@oracle.com>
      Cc: Michal Hocko <mhocko@suse.com>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Christian Borntraeger <borntraeger@de.ibm.com>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Matthew Wilcox <willy@infradead.org>
      Cc: Mel Gorman <mgorman@techsingularity.net>
      Cc: Michal Hocko <mhocko@kernel.org>
      Cc: Sam Ravnborg <sam@ravnborg.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e17d8025
  19. Nov 13, 2017
    • Dave Martin's avatar
      arm64: Make ARMV8_DEPRECATED depend on SYSCTL · 6cfa7cc4
      Dave Martin authored
      
      
      If CONFIG_SYSCTL=n and CONFIG_ARMV8_DEPRECATED=y, the deprecated
      instruction emulation code currently leaks some memory at boot
      time, and won't have any runtime control interface.  This does
      not feel like useful or intended behaviour...
      
      This patch adds a dependency on CONFIG_SYSCTL, so that such a
      kernel can't be built in the first place.
      
      It's probably not worth adding the error-handling / cleanup code
      that would be needed to deal with this otherwise: people who
      desperately need the emulation can still enable SYSCTL.
      
      Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      6cfa7cc4
  20. Nov 03, 2017
  21. Oct 25, 2017
  22. Oct 19, 2017
  23. Oct 12, 2017
  24. Oct 04, 2017
  25. Oct 02, 2017
  26. Aug 15, 2017
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