1. 20 Oct, 2010 1 commit
  2. 18 Aug, 2010 1 commit
    • Joerg Roedel's avatar
      x86-32: Separate 1:1 pagetables from swapper_pg_dir · fd89a137
      Joerg Roedel authored
      This patch fixes machine crashes which occur when heavily exercising the
      CPU hotplug codepaths on a 32-bit kernel. These crashes are caused by
      AMD Erratum 383 and result in a fatal machine check exception. Here's
      the scenario:
      1. On 32-bit, the swapper_pg_dir page table is used as the initial page
      table for booting a secondary CPU.
      2. To make this work, swapper_pg_dir needs a direct mapping of physical
      memory in it (the low mappings). By adding those low, large page (2M)
      mappings (PAE kernel), we create the necessary conditions for Erratum
      383 to occur.
      3. Other CPUs which do not participate in the off- and onlining game may
      use swapper_pg_dir while the low mappings are present (when leave_mm is
      called). For all steps below, the CPU referred to is a CPU that is using
      swapper_pg_dir, and not the CPU which is being onlined.
      4. The presence of the low mappings in swapper_pg_dir can result
      in TLB entries for addresses below __PAGE_OFFSET to be established
      speculatively. These TLB entries are marked global and large.
      5. When the CPU with such TLB entry switches to another page table, this
      TLB entry remains because it is global.
      6. The process then generates an access to an address covered by the
      above TLB entry but there is a permission mismatch - the TLB entry
      covers a large global page not accessible to userspace.
      7. Due to this permission mismatch a new 4kb, user TLB entry gets
      established. Further, Erratum 383 provides for a small window of time
      where both TLB entries are present. This results in an uncorrectable
      machine check exception signalling a TLB multimatch which panics the
      There are two ways to fix this issue:
              1. Always do a global TLB flush when a new cr3 is loaded and the
              old page table was swapper_pg_dir. I consider this a hack hard
              to understand and with performance implications
              2. Do not use swapper_pg_dir to boot secondary CPUs like 64-bit
      This patch implements solution 2. It introduces a trampoline_pg_dir
      which has the same layout as swapper_pg_dir with low_mappings. This page
      table is used as the initial page table of the booting CPU. Later in the
      bringup process, it switches to swapper_pg_dir and does a global TLB
      flush. This fixes the crashes in our test cases.
      -v2: switch to swapper_pg_dir right after entering start_secondary() so
      that we are able to access percpu data which might not be mapped in the
      trampoline page table.
      Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
      LKML-Reference: <20100816123833.GB28147@aftab>
      Signed-off-by: default avatarBorislav Petkov <borislav.petkov@amd.com>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
  3. 18 Jun, 2010 1 commit
    • Andres Salomon's avatar
      x86, olpc: Add support for calling into OpenFirmware · fd699c76
      Andres Salomon authored
      Add support for saving OFW's cif, and later calling into it to run OFW
      commands.  OFW remains resident in memory, living within virtual range
      0xff800000 - 0xffc00000.  A single page directory entry points to the
      pgdir that OFW actually uses, so rather than saving the entire page
      table, we grab and install that one entry permanently in the kernel's
      page table.
      This is currently only used by the OLPC XO.  Note that this particular
      calling convention breaks PAE and PAT, and so cannot be used on newer
      x86 hardware.
      Signed-off-by: default avatarAndres Salomon <dilinger@queued.net>
      LKML-Reference: <20100618174653.7755a39a@dev.queued.net>
      Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
  4. 16 Nov, 2009 1 commit
  5. 29 Oct, 2009 1 commit
  6. 20 Sep, 2009 2 commits
  7. 18 Sep, 2009 1 commit
    • Tim Abbott's avatar
      x86: convert to use __HEAD and HEAD_TEXT macros. · 4ae59b91
      Tim Abbott authored
      This has the consequence of changing the section name use for head
      code from ".text.head" to ".head.text".  It also eliminates the
      ".text.head" output section (instead placing head code at the start of
      the .text output section), which should be harmless.
      This patch only changes the sections in the actual kernel, not those
      in the compressed boot loader.
      Signed-off-by: default avatarTim Abbott <tabbott@ksplice.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Sam Ravnborg <sam@ravnborg.org>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
  8. 03 Sep, 2009 1 commit
    • Jeremy Fitzhardinge's avatar
      x86/i386: Make sure stack-protector segment base is cache aligned · 1ea0d14e
      Jeremy Fitzhardinge authored
      The Intel Optimization Reference Guide says:
      	In Intel Atom microarchitecture, the address generation unit
      	assumes that the segment base will be 0 by default. Non-zero
      	segment base will cause load and store operations to experience
      	a delay.
      		- If the segment base isn't aligned to a cache line
      		  boundary, the max throughput of memory operations is
      		  reduced to one [e]very 9 cycles.
      	Assembly/Compiler Coding Rule 15. (H impact, ML generality)
      	For Intel Atom processors, use segments with base set to 0
      	whenever possible; avoid non-zero segment base address that is
      	not aligned to cache line boundary at all cost.
      We can't avoid having a non-zero base for the stack-protector
      segment, but we can make it cache-aligned.
      Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
      Cc: <stable@kernel.org>
      LKML-Reference: <4AA01893.6000507@goop.org>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
  9. 31 Aug, 2009 1 commit
  10. 18 Aug, 2009 1 commit
    • Jan Beulich's avatar
      i386: Fix section mismatches for init code with !HOTPLUG_CPU · 78b89ecd
      Jan Beulich authored
      Commit 0e83815b
       changed the
      section the initial_code variable gets allocated in, in an
      attempt to address a section conflict warning. This, however
      created a new section conflict when building without
      HOTPLUG_CPU. The apparently only (reasonable) way to address
      this is to always use __REFDATA.
      Once at it, also fix a second section mismatch when not using
      Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
      Cc: Robert Richter <robert.richter@amd.com>
      LKML-Reference: <4A8AE7CD020000780001054B@vpn.id2.novell.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
  11. 27 Jul, 2009 1 commit
    • Robert Richter's avatar
      x86: fix section mismatch for i386 init code · 0e83815b
      Robert Richter authored
      Startup code for i386 in arch/x86/kernel/head_32.S is using the
      reference variable initial_code that is located in the .cpuinit.data
      section. If CONFIG_HOTPLUG_CPU is enabled, startup code is not in an
      init section and can be called later too. In this case the reference
      initial_code must be kept too. This patch fixes this. See below for
      the section mismatch warning.
       WARNING: vmlinux.o(.cpuinit.data+0x0): Section mismatch in reference
       from the variable initial_code to the function
       The variable __cpuinitdata initial_code references
       a function __init i386_start_kernel().
       If i386_start_kernel is only used by initial_code then
       annotate i386_start_kernel with a matching annotation.
      Signed-off-by: default avatarRobert Richter <robert.richter@amd.com>
      LKML-Reference: <1248716632-26844-1-git-send-email-robert.richter@amd.com>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
  12. 17 Jun, 2009 1 commit
  13. 29 Apr, 2009 1 commit
    • Sam Ravnborg's avatar
      x86, vmlinux.lds: unify .text output sections · dfc20895
      Sam Ravnborg authored
      32 bit x86 had a dedicated .text.head output section,
      whereas 64 bit had it all in a single output section.
      In the unified version the dedicated .text.head output section
      was kept to have full control over the head code.
      32 bit:
      - Moved definition of _stext to the linker script.
        The definition is located _after_ .text.page_aligned as this
        is what 32 bit did before.
      The ALIGN(8) was introduced so we hit the exact same address
      (on the tested config) before and after the move.
      I assume that it is a bug that _stext did not cover the
      .text.page_aligned section - if this is true it can be fixed
      in a follow-up patch (and the ugly ALIGN() can be dropped).
      [ Impact: 64-bit: cleanup, 32-bit: use the 64-bit linker script ]
      Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
      Cc: Tim Abbott <tabbott@MIT.EDU>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      LKML-Reference: <1240991249-27117-5-git-send-email-sam@ravnborg.org>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
  14. 17 Mar, 2009 3 commits
  15. 14 Mar, 2009 4 commits
  16. 13 Feb, 2009 1 commit
  17. 11 Feb, 2009 1 commit
    • Tejun Heo's avatar
      x86: fix x86_32 stack protector bugs · 5c79d2a5
      Tejun Heo authored
      Impact: fix x86_32 stack protector
      Brian Gerst found out that %gs was being initialized to stack_canary
      instead of stack_canary - 20, which basically gave the same canary
      value for all threads.  Fixing this also exposed the following bugs.
      * cpu_idle() didn't call boot_init_stack_canary()
      * stack canary switching in switch_to() was being done too late making
        the initial run of a new thread use the old stack canary value.
      Fix all of them and while at it update comment in cpu_idle() about
      calling boot_init_stack_canary().
      Reported-by: default avatarBrian Gerst <brgerst@gmail.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
  18. 09 Feb, 2009 1 commit
    • Tejun Heo's avatar
      x86: implement x86_32 stack protector · 60a5317f
      Tejun Heo authored
      Impact: stack protector for x86_32
      Implement stack protector for x86_32.  GDT entry 28 is used for it.
      It's set to point to stack_canary-20 and have the length of 24 bytes.
      CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs
      to the stack canary segment on entry.  As %gs is otherwise unused by
      the kernel, the canary can be anywhere.  It's defined as a percpu
      x86_32 exception handlers take register frame on stack directly as
      struct pt_regs.  With -fstack-protector turned on, gcc copies the
      whole structure after the stack canary and (of course) doesn't copy
      back on return thus losing all changed.  For now, -fno-stack-protector
      is added to all files which contain those functions.  We definitely
      need something better.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
  19. 26 Jan, 2009 2 commits
  20. 21 Jan, 2009 1 commit
  21. 10 Oct, 2008 1 commit
  22. 27 Jul, 2008 1 commit
  23. 08 Jul, 2008 2 commits
  24. 12 Jun, 2008 1 commit
    • Joe Korty's avatar
      x86: fix asm warning in head_32.S · 86b2b70e
      Joe Korty authored
      On Mon, May 19, 2008 at 04:10:02PM -0700, Linus Torvalds wrote:
      > It also causes these warnings on 32-bit PAE:
      > 	  AS      arch/x86/kernel/head_32.o
      > 	arch/x86/kernel/head_32.S: Assembler messages:
      > 	arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
      > 	arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed
      > and I do not see why (the end result seems to be identical).
      Fix head_32.S gcc bignum warnings when CONFIG_PAE=y.
          arch/x86/kernel/head_32.S: Assembler messages:
          arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
          arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed
      The assembler was stumbling over the 64-bit constant 0x100000000 in the
      KPMDS #define.
      Testing: a cmp(1) on head_32.o before and after shows the binary is unchanged.
      Signed-off-by: Joe Korty <joe.korty@ccur.com
      Cc: Hugh Dickins <hugh@veritas.com>
      Cc: Theodore Tso <tytso@mit.edu>
      Cc: Gabriel C <nix.or.die@googlemail.com>
      Cc: Keith Packard <keithp@keithp.com>
      Cc: "Pallipadi Venkatesh" <venkatesh.pallipadi@intel.com>
      Cc: Eric Anholt <eric@anholt.net>
      Cc: "Siddha Suresh B" <suresh.b.siddha@intel.com>
      Cc: bugme-daemon@bugzilla.kernel.org
      Cc: airlied@linux.ie
      Cc: "Barnes Jesse" <jesse.barnes@intel.com>
      Cc: Jeremy Fitzhardinge <jeremy@goop.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
  25. 03 Jun, 2008 1 commit
  26. 31 May, 2008 1 commit
  27. 30 Apr, 2008 1 commit
  28. 19 Apr, 2008 1 commit
  29. 17 Apr, 2008 1 commit
  30. 21 Mar, 2008 1 commit
  31. 26 Feb, 2008 1 commit
  32. 19 Feb, 2008 1 commit