1. 28 11月, 2014 1 次提交
    • A
      arm64: ptrace: add NT_ARM_SYSTEM_CALL regset · 766a85d7
      AKASHI Takahiro 提交于
      This regeset is intended to be used to get and set a system call number
      while tracing.
      There was some discussion about possible approaches to do so:
      
      (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly,
          and update regs->syscallno later on in syscall_trace_enter(), or
      (2) define a dedicated regset for this purpose as on s390, or
      (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm
      
      Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to
      tracer as well as that secure_computing() expects a changed syscall number,
      especially case of -1, to be visible before this function returns in
      syscall_trace_enter(), (1) doesn't work well.
      We will take (2) since it looks much cleaner.
      Signed-off-by: NAKASHI Takahiro <takahiro.akashi@linaro.org>
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      766a85d7
  2. 27 11月, 2014 2 次提交
    • L
      arm64: Move some head.text functions to executable section · 034edabe
      Laura Abbott 提交于
      The head.text section is intended to be run at early bootup
      before any of the regular kernel mappings have been setup.
      Parts of head.text may be freed back into the buddy allocator
      due to TEXT_OFFSET so for security requirements this memory
      must not be executable. The suspend/resume/hotplug code path
      requires some of these head.S functions to run however which
      means they need to be executable. Support these conflicting
      requirements by moving the few head.text functions that need
      to be executable to the text section which has the appropriate
      page table permissions.
      Tested-by: NKees Cook <keescook@chromium.org>
      Reviewed-by: NMark Rutland <mark.rutland@arm.com>
      Tested-by: NMark Rutland <mark.rutland@arm.com>
      Signed-off-by: NLaura Abbott <lauraa@codeaurora.org>
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      034edabe
    • M
      arm64: jump labels: NOP out NOP -> NOP replacement · 6ddae418
      Mark Rutland 提交于
      In the arm64 arch_static_branch implementation we place an A64 NOP into
      the instruction stream and log relevant details to a jump_entry in a
      __jump_table section. Later this may be replaced with an immediate
      branch without link to the code for the unlikely case.
      
      At init time, the core calls arch_jump_label_transform_static to
      initialise the NOPs. On x86 this involves inserting the optimal NOP for
      a given microarchitecture, but on arm64 we only use the architectural
      NOP, and hence replace each NOP with the exact same NOP. This is
      somewhat pointless.
      
      Additionally, at module load time we don't call jump_label_apply_nops to
      patch the optimal NOPs in, unlike other architectures, but get away with
      this because we only use the architectural NOP anyway. A later notifier
      will patch NOPs with branches as required.
      
      Similarly to x86 commit 11570da1 (x86/jump-label: Do not bother
      updating NOPs if they are correct), we can avoid patching NOPs with
      identical NOPs. Given that we only use a single NOP encoding, this means
      we can NOP-out the body of arch_jump_label_transform_static entirely. As
      the default __weak arch_jump_label_transform_static implementation
      performs a patch, we must use an empty function to achieve this.
      
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Jiang Liu <liuj97@gmail.com>
      Cc: Laura Abbott <lauraa@codeaurora.org>
      Acked-by: NWill Deacon <will.deacon@arm.com>
      Signed-off-by: NMark Rutland <mark.rutland@arm.com>
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      6ddae418
  3. 26 11月, 2014 1 次提交
  4. 25 11月, 2014 16 次提交
  5. 21 11月, 2014 6 次提交
  6. 17 11月, 2014 1 次提交
  7. 14 11月, 2014 3 次提交
    • W
      arm64: entry: use ldp/stp instead of push/pop when saving/restoring regs · 63648dd2
      Will Deacon 提交于
      The push/pop instructions can be suboptimal when saving/restoring large
      amounts of data to/from the stack, for example on entry/exit from the
      kernel. This is because:
      
        (1) They act on descending addresses (i.e. the newly decremented sp),
            which may defeat some hardware prefetchers
      
        (2) They introduce an implicit dependency between each instruction, as
            the sp has to be updated in order to resolve the address of the
            next access.
      
      This patch removes the push/pop instructions from our kernel entry/exit
      macros in favour of ldp/stp plus offset.
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      63648dd2
    • W
      arm64: entry: avoid writing lr explicitly for constructing return paths · d54e81f9
      Will Deacon 提交于
      Using an explicit adr instruction to set the link register to point at
      ret_fast_syscall/ret_to_user can defeat branch and return stack predictors.
      
      Instead, use the standard calling instructions (bl, blr) and have an
      unconditional branch as the following instruction.
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      d54e81f9
    • M
      arm64: Fix up /proc/cpuinfo · 44b82b77
      Mark Rutland 提交于
      Commit d7a49086 (arm64: cpuinfo: print info for all CPUs)
      attempted to clean up /proc/cpuinfo, but due to concerns regarding
      further changes was reverted in commit 5e39977e (Revert "arm64:
      cpuinfo: print info for all CPUs").
      
      There are two major issues with the arm64 /proc/cpuinfo format
      currently:
      
      * The "Features" line describes (only) the 64-bit hwcaps, which is
        problematic for some 32-bit applications which attempt to parse it. As
        the same names are used for analogous ISA features (e.g. aes) despite
        these generally being architecturally unrelated, it is not possible to
        simply append the 64-bit and 32-bit hwcaps in a manner that might not
        be misleading to some applications.
      
        Various potential solutions have appeared in vendor kernels. Typically
        the format of the Features line varies depending on whether the task
        is 32-bit.
      
      * Information is only printed regarding a single CPU. This does not
        match the ARM format, and does not provide sufficient information in
        big.LITTLE systems where CPUs are heterogeneous. The CPU information
        printed is queried from the current CPU's registers, which is racy
        w.r.t. cross-cpu migration.
      
      This patch attempts to solve these issues. The following changes are
      made:
      
      * When a task with a LINUX32 personality attempts to read /proc/cpuinfo,
        the "Features" line contains the decoded 32-bit hwcaps, as with the
        arm port. Otherwise, the decoded 64-bit hwcaps are shown. This aligns
        with the behaviour of COMPAT_UTS_MACHINE and COMPAT_ELF_PLATFORM. In
        the absense of compat support, the Features line is empty.
      
        The set of hwcaps injected into a task's auxval are unaffected.
      
      * Properties are printed per-cpu, as with the ARM port. The per-cpu
        information is queried from pre-recorded cpu information (as used by
        the sanity checks).
      
      * As with the previous attempt at fixing up /proc/cpuinfo, the hardware
        field is removed. The only users so far are 32-bit applications tied
        to particular boards, so no portable applications should be affected,
        and this should prevent future tying to particular boards.
      
      The following differences remain:
      
      * No model_name is printed, as this cannot be queried from the hardware
        and cannot be provided in a stable fashion. Use of the CPU
        {implementor,variant,part,revision} fields is sufficient to identify a
        CPU and is portable across arm and arm64.
      
      * The following system-wide properties are not provided, as they are not
        possible to provide generally. Programs relying on these are already
        tied to particular (32-bit only) boards:
        - Hardware
        - Revision
        - Serial
      
      No software has yet been identified for which these remaining
      differences are problematic.
      
      Cc: Greg Hackmann <ghackmann@google.com>
      Cc: Ian Campbell <ijc@hellion.org.uk>
      Cc: Serban Constantinescu <serban.constantinescu@arm.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: cross-distro@lists.linaro.org
      Cc: linux-api@vger.kernel.org
      Cc: linux-arm-kernel@lists.infradead.org
      Cc: linux-kernel@vger.kernel.org
      Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
      Signed-off-by: NMark Rutland <mark.rutland@arm.com>
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      44b82b77
  8. 07 11月, 2014 4 次提交
  9. 05 11月, 2014 6 次提交