1. 28 9月, 2018 11 次提交
  2. 24 8月, 2018 4 次提交
  3. 23 8月, 2018 1 次提交
    • A
      arch: enable relative relocations for arm64, power and x86 · 271ca788
      Ard Biesheuvel 提交于
      Patch series "add support for relative references in special sections", v10.
      
      This adds support for emitting special sections such as initcall arrays,
      PCI fixups and tracepoints as relative references rather than absolute
      references.  This reduces the size by 50% on 64-bit architectures, but
      more importantly, it removes the need for carrying relocation metadata for
      these sections in relocatable kernels (e.g., for KASLR) that needs to be
      fixed up at boot time.  On arm64, this reduces the vmlinux footprint of
      such a reference by 8x (8 byte absolute reference + 24 byte RELA entry vs
      4 byte relative reference)
      
      Patch #3 was sent out before as a single patch.  This series supersedes
      the previous submission.  This version makes relative ksymtab entries
      dependent on the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS rather
      than trying to infer from kbuild test robot replies for which
      architectures it should be blacklisted.
      
      Patch #1 introduces the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS,
      and sets it for the main architectures that are expected to benefit the
      most from this feature, i.e., 64-bit architectures or ones that use
      runtime relocations.
      
      Patch #2 add support for #define'ing __DISABLE_EXPORTS to get rid of
      ksymtab/kcrctab sections in decompressor and EFI stub objects when
      rebuilding existing C files to run in a different context.
      
      Patches #4 - #6 implement relative references for initcalls, PCI fixups
      and tracepoints, respectively, all of which produce sections with order
      ~1000 entries on an arm64 defconfig kernel with tracing enabled.  This
      means we save about 28 KB of vmlinux space for each of these patches.
      
      [From the v7 series blurb, which included the jump_label patches as well]:
      
        For the arm64 kernel, all patches combined reduce the memory footprint
        of vmlinux by about 1.3 MB (using a config copied from Ubuntu that has
        KASLR enabled), of which ~1 MB is the size reduction of the RELA section
        in .init, and the remaining 300 KB is reduction of .text/.data.
      
      This patch (of 6):
      
      Before updating certain subsystems to use place relative 32-bit
      relocations in special sections, to save space and reduce the number of
      absolute relocations that need to be processed at runtime by relocatable
      kernels, introduce the Kconfig symbol and define it for some architectures
      that should be able to support and benefit from it.
      
      Link: http://lkml.kernel.org/r/20180704083651.24360-2-ard.biesheuvel@linaro.orgSigned-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
      Acked-by: NMichael Ellerman <mpe@ellerman.id.au>
      Reviewed-by: NWill Deacon <will.deacon@arm.com>
      Acked-by: NIngo Molnar <mingo@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Thomas Garnier <thgarnie@google.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "Serge E. Hallyn" <serge@hallyn.com>
      Cc: Bjorn Helgaas <bhelgaas@google.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Russell King <linux@armlinux.org.uk>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Petr Mladek <pmladek@suse.com>
      Cc: James Morris <jmorris@namei.org>
      Cc: Nicolas Pitre <nico@linaro.org>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
      Cc: James Morris <james.morris@microsoft.com>
      Cc: Jessica Yu <jeyu@kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      271ca788
  4. 18 8月, 2018 2 次提交
  5. 17 8月, 2018 2 次提交
    • G
      arm64: mm: check for upper PAGE_SHIFT bits in pfn_valid() · 5ad356ea
      Greg Hackmann 提交于
      ARM64's pfn_valid() shifts away the upper PAGE_SHIFT bits of the input
      before seeing if the PFN is valid.  This leads to false positives when
      some of the upper bits are set, but the lower bits match a valid PFN.
      
      For example, the following userspace code looks up a bogus entry in
      /proc/kpageflags:
      
          int pagemap = open("/proc/self/pagemap", O_RDONLY);
          int pageflags = open("/proc/kpageflags", O_RDONLY);
          uint64_t pfn, val;
      
          lseek64(pagemap, [...], SEEK_SET);
          read(pagemap, &pfn, sizeof(pfn));
          if (pfn & (1UL << 63)) {        /* valid PFN */
              pfn &= ((1UL << 55) - 1);   /* clear flag bits */
              pfn |= (1UL << 55);
              lseek64(pageflags, pfn * sizeof(uint64_t), SEEK_SET);
              read(pageflags, &val, sizeof(val));
          }
      
      On ARM64 this causes the userspace process to crash with SIGSEGV rather
      than reading (1 << KPF_NOPAGE).  kpageflags_read() treats the offset as
      valid, and stable_page_flags() will try to access an address between the
      user and kernel address ranges.
      
      Fixes: c1cc1552 ("arm64: MMU initialisation")
      Cc: stable@vger.kernel.org
      Signed-off-by: NGreg Hackmann <ghackmann@google.com>
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      5ad356ea
    • W
      arm64: Avoid calling stop_machine() when patching jump labels · f6cc0c50
      Will Deacon 提交于
      Patching a jump label involves patching a single instruction at a time,
      swizzling between a branch and a NOP. The architecture treats these
      instructions specially, so a concurrently executing CPU is guaranteed to
      see either the NOP or the branch, rather than an amalgamation of the two
      instruction encodings.
      
      However, in order to guarantee that the new instruction is visible, it
      is necessary to send an IPI to the concurrently executing CPU so that it
      discards any previously fetched instructions from its pipeline. This
      operation therefore cannot be completed from a context with IRQs
      disabled, but this is exactly what happens on the jump label path where
      the hotplug lock is held and irqs are subsequently disabled by
      stop_machine_cpuslocked(). This results in a deadlock during boot on
      Hikey-960.
      
      Due to the architectural guarantees around patching NOPs and branches,
      we don't actually need to stop_machine() at all on the jump label path,
      so we can avoid the deadlock by using the "nosync" variant of our
      instruction patching routine.
      
      Fixes: 693350a7 ("arm64: insn: Don't fallback on nosync path for general insn patching")
      Reported-by: NTuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
      Reported-by: NJohn Stultz <john.stultz@linaro.org>
      Tested-by: NValentin Schneider <valentin.schneider@arm.com>
      Tested-by: NTuomas Tynkkynen <tuomas@tuxera.com>
      Tested-by: NJohn Stultz <john.stultz@linaro.org>
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      f6cc0c50
  6. 12 8月, 2018 3 次提交
  7. 09 8月, 2018 1 次提交
  8. 08 8月, 2018 1 次提交
  9. 07 8月, 2018 6 次提交
  10. 06 8月, 2018 1 次提交
  11. 03 8月, 2018 5 次提交
  12. 02 8月, 2018 3 次提交