1. 19 Dec, 2018 1 commit
  2. 04 Oct, 2018 1 commit
    • Nadav Amit's avatar
      x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs · 77f48ec2
      Nadav Amit authored
      As described in:
      
        77b0bf55
      
      : ("kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs")
      
      GCC's inlining heuristics are broken with common asm() patterns used in
      kernel code, resulting in the effective disabling of inlining.
      
      The workaround is to set an assembly macro and call it from the inline
      assembly block - i.e. to macrify the affected block.
      
      As a result GCC considers the inline assembly block as a single instruction.
      
      This patch handles the LOCK prefix, allowing more aggresive inlining:
      
            text     data     bss      dec     hex  filename
        18140140 10225284 2957312 31322736 1ddf270  ./vmlinux before
        18146889 10225380 2957312 31329581 1de0d2d  ./vmlinux after (+6845)
      
      This is the reduction in non-inlined functions:
      
        Before: 40286
        After:  40218 (-68)
      Tested-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarNadav Amit <namit@vmware.com>
      Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/20181003213100.189959-6-namit@vmware.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      77f48ec2
  3. 27 Mar, 2018 1 commit
  4. 05 Jan, 2018 1 commit
  5. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      
      How this work was done:
      
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      
      Further patches will be generated in subsequent months to fix up cases
      where non-standard...
      b2441318
  6. 09 Oct, 2017 1 commit
  7. 23 Sep, 2017 1 commit
    • Josh Poimboeuf's avatar
      x86/asm: Fix inline asm call constraints for Clang · f5caf621
      Josh Poimboeuf authored
      
      For inline asm statements which have a CALL instruction, we list the
      stack pointer as a constraint to convince GCC to ensure the frame
      pointer is set up first:
      
        static inline void foo()
        {
      	register void *__sp asm(_ASM_SP);
      	asm("call bar" : "+r" (__sp))
        }
      
      Unfortunately, that pattern causes Clang to corrupt the stack pointer.
      
      The fix is easy: convert the stack pointer register variable to a global
      variable.
      
      It should be noted that the end result is different based on the GCC
      version.  With GCC 6.4, this patch has exactly the same result as
      before:
      
      	defconfig	defconfig-nofp	distro		distro-nofp
       before	9820389		9491555		8816046		8516940
       after	9820389		9491555		8816046		8516940
      
      With GCC 7.2, however, GCC's behavior has changed.  It now changes its
      behavior based on the conversion of the register variable to a global.
      That somehow convinces it to *always* set up the frame pointer before
      inserting *any* inline asm.  (Therefore, listing the variable as an
      output constraint is a no-op and is no longer necessary.)  It's a bit
      overkill, but the performance impact should be negligible.  And in fact,
      there's a nice improvement with frame pointers disabled:
      
      	defconfig	defconfig-nofp	distro		distro-nofp
       before	9796316		9468236		9076191		8790305
       after	9796957		9464267		9076381		8785949
      
      So in summary, while listing the stack pointer as an output constraint
      is no longer necessary for newer versions of GCC, it's still needed for
      older versions.
      Suggested-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
      Reported-by: default avatarMatthias Kaehlcke <mka@chromium.org>
      Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Dmitriy Vyukov <dvyukov@google.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/3db862e970c432ae823cf515c52b54fec8270e0e.1505942196.git.jpoimboe@redhat.com
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      f5caf621
  8. 24 Sep, 2016 1 commit
  9. 29 Apr, 2016 2 commits
  10. 30 Jan, 2016 1 commit
  11. 19 May, 2015 1 commit
    • Ingo Molnar's avatar
      x86/alternatives, x86/fpu: Add 'alternatives_patched' debug flag and use it in xsave_state() · 5e907bb0
      Ingo Molnar authored
      
      We'd like to use xsave_state() earlier, but its SYSTEM_BOOTING check
      is too imprecise.
      
      The real condition that xsave_state() would like to check is whether
      alternative XSAVE instructions were patched into the kernel image
      already.
      
      Add such a (read-mostly) debug flag and use it in xsave_state().
      
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      5e907bb0
  12. 04 Apr, 2015 1 commit
    • Borislav Petkov's avatar
      x86/alternatives: Fix ALTERNATIVE_2 padding generation properly · dbe4058a
      Borislav Petkov authored
      
      Quentin caught a corner case with the generation of instruction
      padding in the ALTERNATIVE_2 macro: if len(orig_insn) <
      len(alt1) < len(alt2), then not enough padding gets added and
      that is not good(tm) as we could overwrite the beginning of the
      next instruction.
      
      Luckily, at the time of this writing, we don't have
      ALTERNATIVE_2() invocations which have that problem and even if
      we did, a simple fix would be to prepend the instructions with
      enough prefixes so that that corner case doesn't happen.
      
      However, best it would be if we fixed it properly. See below for
      a simple, abstracted example of what we're doing.
      
      So what we ended up doing is, we compute the
      
      	max(len(alt1), len(alt2)) - len(orig_insn)
      
      and feed that value to the .skip gas directive. The max() cannot
      have conditionals due to gas limitations, thus the fancy integer
      math.
      
      With this patch, all ALTERNATIVE_2 sites get padded correctly;
      generating obscure test cases pass too:
      
        #define alt_max_short(a, b)    ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
      
        #define gen_skip(orig, alt1, alt2, marker)	\
        	.skip -((alt_max_short(alt1, alt2) - (orig)) > 0) * \
        		(alt_max_short(alt1, alt2) - (orig)),marker
      
        	.pushsection .text, "ax"
        .globl main
        main:
        	gen_skip(1, 2, 4, 0x09)
        	gen_skip(4, 1, 2, 0x10)
        	...
        	.popsection
      
      Thanks to Quentin for catching it and double-checking the fix!
      Reported-by: default avatarQuentin Casasnovas <quentin.casasnovas@oracle.com>
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/20150404133443.GE21152@pd.tnic
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      dbe4058a
  13. 23 Feb, 2015 1 commit
    • Borislav Petkov's avatar
      x86/alternatives: Add instruction padding · 4332195c
      Borislav Petkov authored
      
      Up until now we have always paid attention to make sure the length of
      the new instruction replacing the old one is at least less or equal to
      the length of the old instruction. If the new instruction is longer, at
      the time it replaces the old instruction it will overwrite the beginning
      of the next instruction in the kernel image and cause your pants to
      catch fire.
      
      So instead of having to pay attention, teach the alternatives framework
      to pad shorter old instructions with NOPs at buildtime - but only in the
      case when
      
        len(old instruction(s)) < len(new instruction(s))
      
      and add nothing in the >= case. (In that case we do add_nops() when
      patching).
      
      This way the alternatives user shouldn't have to care about instruction
      sizes and simply use the macros.
      
      Add asm ALTERNATIVE* flavor macros too, while at it.
      
      Also, we need to save the pad length in a separate struct alt_instr
      member for NOP optimization and the way to do that reliably is to carry
      the pad length instead of trying to detect whether we're looking at
      single-byte NOPs or at pathological instruction offsets like e9 90 90 90
      90, for example, which is a valid instruction.
      
      Thanks to Michael Matz for the great help with toolchain questions.
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      4332195c
  14. 29 May, 2014 1 commit
  15. 23 Jul, 2013 1 commit
    • Jiri Kosina's avatar
      kprobes/x86: Call out into INT3 handler directly instead of using notifier · 17f41571
      Jiri Kosina authored
      In fd4363ff
      
       ("x86: Introduce int3 (breakpoint)-based
      instruction patching"), the mechanism that was introduced for
      notifying alternatives code from int3 exception handler that and
      exception occured was die_notifier.
      
      This is however problematic, as early code might be using jump
      labels even before the notifier registration has been performed,
      which will then lead to an oops due to unhandled exception. One
      of such occurences has been encountered by Fengguang:
      
       int3: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
       Modules linked in:
       CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.11.0-rc1-01429-g04bf576 #8
       task: ffff88000da1b040 ti: ffff88000da1c000 task.ti: ffff88000da1c000
       RIP: 0010:[<ffffffff811098cc>]  [<ffffffff811098cc>] ttwu_do_wakeup+0x28/0x225
       RSP: 0000:ffff88000dd03f10  EFLAGS: 00000006
       RAX: 0000000000000000 RBX: ffff88000dd12940 RCX: ffffffff81769c40
       RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000001
       RBP: ffff88000dd03f28 R08: ffffffff8176a8c0 R09: 0000000000000002
       R10: ffffffff810ff484 R11: ffff88000dd129e8 R12: ffff88000dbc90c0
       R13: ffff88000dbc90c0 R14: ffff88000da1dfd8 R15: ffff88000da1dfd8
       FS:  0000000000000000(0000) GS:ffff88000dd00000(0000) knlGS:0000000000000000
       CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
       CR2: 00000000ffffffff CR3: 0000000001c88000 CR4: 00000000000006e0
       Stack:
        ffff88000dd12940 ffff88000dbc90c0 ffff88000da1dfd8 ffff88000dd03f48
        ffffffff81109e2b ffff88000dd12940 0000000000000000 ffff88000dd03f68
        ffffffff81109e9e 0000000000000000 0000000000012940 ffff88000dd03f98
       Call Trace:
        <IRQ>
        [<ffffffff81109e2b>] ttwu_do_activate.constprop.56+0x6d/0x79
        [<ffffffff81109e9e>] sched_ttwu_pending+0x67/0x84
        [<ffffffff8110c845>] scheduler_ipi+0x15a/0x2b0
        [<ffffffff8104dfb4>] smp_reschedule_interrupt+0x38/0x41
        [<ffffffff8173bf5d>] reschedule_interrupt+0x6d/0x80
        <EOI>
        [<ffffffff810ff484>] ? __atomic_notifier_call_chain+0x5/0xc1
        [<ffffffff8105cc30>] ? native_safe_halt+0xd/0x16
        [<ffffffff81015f10>] default_idle+0x147/0x282
        [<ffffffff81017026>] arch_cpu_idle+0x3d/0x5d
        [<ffffffff81127d6a>] cpu_idle_loop+0x46d/0x5db
        [<ffffffff81127f5c>] cpu_startup_entry+0x84/0x84
        [<ffffffff8104f4f8>] start_secondary+0x3c8/0x3d5
        [...]
      
      Fix this by directly calling poke_int3_handler() from the int3
      exception handler (analogically to what ftrace has been doing
      already), instead of relying on notifier, registration of which
      might not have yet been finalized by the time of the first trap.
      Reported-and-tested-by: default avatarFengguang Wu <fengguang.wu@intel.com>
      Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
      Acked-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
      Cc: H. Peter Anvin <hpa@linux.intel.com>
      Cc: Fengguang Wu <fengguang.wu@intel.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1307231007490.14024@pobox.suse.cz
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      17f41571
  16. 19 Jul, 2013 1 commit
  17. 17 Jul, 2013 1 commit
  18. 21 Sep, 2012 1 commit
  19. 23 Aug, 2012 1 commit
    • Rusty Russell's avatar
      x86/smp: Don't ever patch back to UP if we unplug cpus · 816afe4f
      Rusty Russell authored
      
      We still patch SMP instructions to UP variants if we boot with a
      single CPU, but not at any other time.  In particular, not if we
      unplug CPUs to return to a single cpu.
      
      Paul McKenney points out:
      
       mean offline overhead is 6251/48=130.2 milliseconds.
      
       If I remove the alternatives_smp_switch() from the offline
       path [...] the mean offline overhead is 550/42=13.1 milliseconds
      
      Basically, we're never going to get those 120ms back, and the
      code is pretty messy.
      
      We get rid of:
      
       1) The "smp-alt-once" boot option. It's actually "smp-alt-boot", the
          documentation is wrong. It's now the default.
      
       2) The skip_smp_alternatives flag used by suspend.
      
       3) arch_disable_nonboot_cpus_begin() and arch_disable_nonboot_cpus_end()
          which were only used to set this one flag.
      Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      Cc: Paul McKenney <paul.mckenney@us.ibm.com>
      Cc: Suresh Siddha <suresh.b.siddha@intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Link: http://lkml.kernel.org/r/87vcgwwive.fsf@rustcorp.com.au
      
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      816afe4f
  20. 29 Jun, 2012 1 commit
  21. 21 Jan, 2012 1 commit
    • Jan Beulich's avatar
      x86: Adjust asm constraints in atomic64 wrappers · 819165fb
      Jan Beulich authored
      
      Eric pointed out overly restrictive constraints in atomic64_set(), but
      there are issues throughout the file. In the cited case, %ebx and %ecx
      are inputs only (don't get changed by either of the two low level
      implementations). This was also the case elsewhere.
      
      Further in many cases early-clobber indicators were missing.
      
      Finally, the previous implementation rolled a custom alternative
      instruction macro from scratch, rather than using alternative_call()
      (which was introduced with the commit that the description of the
      change in question actually refers to). Adjusting has the benefit of
      not hiding referenced symbols from the compiler, which however requires
      them to be declared not just in the exporting source file (which, as a
      desirable side effect, in turn allows that exporting file to become a
      real 5-line stub).
      
      This patch does not eliminate the overly restrictive memory clobbers,
      however: Doing so would occasionally make the compiler set up a second
      register for accessing the memory object (to satisfy the added "m"
      constraint), and it's not clear which of the two non-optimal
      alternatives is better.
      
      v2: Re-do the declaration and exporting of the internal symbols.
      Reported-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: default avatarJan Beulich <jbeulich@suse.com>
      Link: http://lkml.kernel.org/r/4F19A2A5020000780006E0D9@nat28.tlf.novell.com
      
      
      Cc: Luca Barbieri <luca@luca-barbieri.com>
      Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
      819165fb
  22. 15 Sep, 2011 1 commit
    • Linus Torvalds's avatar
      asm alternatives: remove incorrect alignment notes · a7f934d4
      Linus Torvalds authored
      On x86-64, they were just wasteful: with the explicitly added (now
      unnecessary) padding, the size of the alternatives structure was 16
      bytes, and an alignment of 8 bytes didn't hurt much.
      
      However, it was still silly, since the natural size and alignment for
      the structure is actually just 12 bytes, 4-byte aligned since commit
      59e97e4d
      
       ("x86: Make alternative instruction pointers relative").
      So removing the padding, and removing the extra alignment is just a good
      idea.
      
      On x86-32, the alignment of 4 bytes was correct, but was incorrectly
      hardcoded as 8 bytes in <asm/alternative-asm.h>.  That header file had
      used to be an x86-64 only header file, but various unification efforts
      have made it be used for x86-32 too (ie the unification of rwlock and
      rwsem).
      
      That in turn caused x86-32 boot failures, because the extra alignment
      would result in random zero-filled words in the altinstructions section,
      causing oopses early at boot when doing alternative instruction
      replacement.
      
      So just remove all the alignment noise entirely.  It's wrong, and it's
      unnecessary.  The section itself is already properly aligned by the
      linker scripts, and all additions to the section had better be of the
      proper 12-byte format, keeping it aligned.  So if the align directive
      were to ever make a difference, that would be an indication of a serious
      bug to begin with.
      Reported-by: default avatarWerner Landgraf <w.landgraf@ru.r>
      Acked-by: default avatarAndrew Lutomirski <luto@mit.edu>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a7f934d4
  23. 13 Jul, 2011 1 commit
  24. 18 Apr, 2011 1 commit
  25. 04 Apr, 2011 1 commit
    • Jason Baron's avatar
      jump label: Introduce static_branch() interface · d430d3d7
      Jason Baron authored
      
      Introduce:
      
      static __always_inline bool static_branch(struct jump_label_key *key);
      
      instead of the old JUMP_LABEL(key, label) macro.
      
      In this way, jump labels become really easy to use:
      
      Define:
      
              struct jump_label_key jump_key;
      
      Can be used as:
      
              if (static_branch(&jump_key))
                      do unlikely code
      
      enable/disale via:
      
              jump_label_inc(&jump_key);
              jump_label_dec(&jump_key);
      
      that's it!
      
      For the jump labels disabled case, the static_branch() becomes an
      atomic_read(), and jump_label_inc()/dec() are simply atomic_inc(),
      atomic_dec() operations. We show testing results for this change below.
      
      Thanks to H. Peter Anvin for suggesting the 'static_branch()' construct.
      
      Since we now require a 'struct jump_label_key *key', we can store a pointer into
      the jump table addresses. In this way, we can enable/disable jump labels, in
      basically constant time. This change allows us to completely remove the previous
      hashtable scheme. Thanks to Peter Zijlstra for this re-write.
      
      Testing:
      
      I ran a series of 'tbench 20' runs 5 times (with reboots) for 3
      configurations, where tracepoints were disabled.
      
      jump label configured in
      avg: 815.6
      
      jump label *not* configured in (using atomic reads)
      avg: 800.1
      
      jump label *not* configured in (regular reads)
      avg: 803.4
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      LKML-Reference: <20110316212947.GA8792@redhat.com>
      Signed-off-by: default avatarJason Baron <jbaron@redhat.com>
      Suggested-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
      Tested-by: default avatarDavid Daney <ddaney@caviumnetworks.com>
      Acked-by: default avatarRalf Baechle <ralf@linux-mips.org>
      Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
      Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      d430d3d7
  26. 14 Dec, 2010 1 commit
  27. 06 Dec, 2010 1 commit
    • Masami Hiramatsu's avatar
      x86: Introduce text_poke_smp_batch() for batch-code modifying · 7deb18dc
      Masami Hiramatsu authored
      
      Introduce text_poke_smp_batch(). This function modifies several
      text areas with one stop_machine() on SMP. Because calling
      stop_machine() is heavy task, it is better to aggregate
      text_poke requests.
      
      ( Note: I've talked with Rusty about this interface, and
        he would not like to expand stop_machine() interface, since
        it is not for generic use. )
      Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
      Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
      Cc: Jason Baron <jbaron@redhat.com>
      Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Cc: Jan Beulich <jbeulich@novell.com>
      Cc: 2nddept-manager@sdl.hitachi.co.jp
      LKML-Reference: <20101203095422.2961.51217.stgit@ltc236.sdl.hitachi.co.jp>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      7deb18dc
  28. 22 Sep, 2010 1 commit
    • Jason Baron's avatar
      jump label: Base patch for jump label · bf5438fc
      Jason Baron authored
      
      base patch to implement 'jump labeling'. Based on a new 'asm goto' inline
      assembly gcc mechanism, we can now branch to labels from an 'asm goto'
      statment. This allows us to create a 'no-op' fastpath, which can subsequently
      be patched with a jump to the slowpath code. This is useful for code which
      might be rarely used, but which we'd like to be able to call, if needed.
      Tracepoints are the current usecase that these are being implemented for.
      Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarJason Baron <jbaron@redhat.com>
      LKML-Reference: <ee8b3595967989fdaf84e698dc7447d315ce972a.1284733808.git.jbaron@redhat.com>
      
      [ cleaned up some formating ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      bf5438fc
  29. 20 Sep, 2010 2 commits
  30. 07 Jul, 2010 1 commit
    • H. Peter Anvin's avatar
      x86, alternatives: Use 16-bit numbers for cpufeature index · 83a7a2ad
      H. Peter Anvin authored
      
      We already have cpufeature indicies above 255, so use a 16-bit number
      for the alternatives index.  This consumes a padding field and so
      doesn't add any size, but it means that abusing the padding field to
      create assembly errors on overflow no longer works.  We can retain the
      test simply by redirecting it to the .discard section, however.
      
      [ v3: updated to include open-coded locations ]
      Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
      LKML-Reference: <tip-f88731e3068f9d1392ba71cc9f50f035d26a0d4f@git.kernel.org>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      83a7a2ad
  31. 29 Apr, 2010 2 commits
  32. 06 Apr, 2010 1 commit
    • Borislav Petkov's avatar
      x86: Add optimized popcnt variants · d61931d8
      Borislav Petkov authored
      
      Add support for the hardware version of the Hamming weight function,
      popcnt, present in CPUs which advertize it under CPUID, Function
      0x0000_0001_ECX[23]. On CPUs which don't support it, we fallback to the
      default lib/hweight.c sw versions.
      
      A synthetic benchmark comparing popcnt with __sw_hweight64 showed almost
      a 3x speedup on a F10h machine.
      Signed-off-by: default avatarBorislav Petkov <borislav.petkov@amd.com>
      LKML-Reference: <20100318112015.GC11152@aftab>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      d61931d8
  33. 26 Feb, 2010 1 commit
    • Luca Barbieri's avatar
      x86: Add support for lock prefix in alternatives · b3ac891b
      Luca Barbieri authored
      
      The current lock prefix UP/SMP alternative code doesn't allow
      LOCK_PREFIX to be used in alternatives code.
      
      This patch solves the problem by adding a new LOCK_PREFIX_ALTERNATIVE_PATCH
      macro that only records the lock prefix location but does not emit
      the prefix.
      
      The user of this macro can then start any alternative sequence with
      "lock" and have it UP/SMP patched.
      
      To make this work, the UP/SMP alternative code is changed to do the
      lock/DS prefix switching only if the byte actually contains a lock or
      DS prefix.
      
      Thus, if an alternative without the "lock" is selected, it will now do
      nothing instead of clobbering the code.
      
      Changes in v2:
      - Naming change
      - Change label to not conflict with alternatives
      Signed-off-by: default avatarLuca Barbieri <luca@luca-barbieri.com>
      LKML-Reference: <1267005265-27958-2-git-send-email-luca@luca-barbieri.com>
      Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      b3ac891b
  34. 25 Feb, 2010 1 commit
    • Masami Hiramatsu's avatar
      x86: Add text_poke_smp for SMP cross modifying code · 3d55cc8a
      Masami Hiramatsu authored
      
      Add generic text_poke_smp for SMP which uses stop_machine()
      to synchronize modifying code.
      This stop_machine() method is officially described at "7.1.3
      Handling Self- and Cross-Modifying Code" on the intel's
      software developer's manual 3A.
      
      Since stop_machine() can't protect code against NMI/MCE, this
      function can not modify those handlers. And also, this function
      is basically for modifying multibyte-single-instruction. For
      modifying multibyte-multi-instructions, we need another special
      trap & detour code.
      
      This code originaly comes from immediate values with
      stop_machine() version. Thanks Jason and Mathieu!
      Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
      Cc: systemtap <systemtap@sources.redhat.com>
      Cc: DLE <dle-develop@lists.sourceforge.net>
      Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
      Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
      Cc: Jim Keniston <jkenisto@us.ibm.com>
      Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Anders Kaseorg <andersk@ksplice.com>
      Cc: Tim Abbott <tabbott@ksplice.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Jason Baron <jbaron@redhat.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
      LKML-Reference: <20100225133438.6725.80273.stgit@localhost6.localdomain6>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      3d55cc8a
  35. 04 Feb, 2010 1 commit
    • Masami Hiramatsu's avatar
      ftrace/alternatives: Introducing *_text_reserved functions · 2cfa1978
      Masami Hiramatsu authored
      
      Introducing *_text_reserved functions for checking the text
      address range is partially reserved or not. This patch provides
      checking routines for x86 smp alternatives and dynamic ftrace.
      Since both functions modify fixed pieces of kernel text, they
      should reserve and protect those from other dynamic text
      modifier, like kprobes.
      
      This will also be extended when introducing other subsystems
      which modify fixed pieces of kernel text. Dynamic text modifiers
      should avoid those.
      Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
      Cc: systemtap <systemtap@sources.redhat.com>
      Cc: DLE <dle-develop@lists.sourceforge.net>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: przemyslaw@pawelczyk.it
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
      Cc: Jim Keniston <jkenisto@us.ibm.com>
      Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
      Cc: Jason Baron <jbaron@redhat.com>
      LKML-Reference: <20100202214911.4694.16587.stgit@dhcp-100-2-132.bos.redhat.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      2cfa1978
  36. 30 Dec, 2009 1 commit
    • Jan Beulich's avatar
      x86-64: Modify copy_user_generic() alternatives mechanism · 1b1d9258
      Jan Beulich authored
      
      In order to avoid unnecessary chains of branches, rather than
      implementing copy_user_generic() as a function consisting of
      just a single (possibly patched) branch, instead properly deal
      with patching call instructions in the alternative instructions
      framework, and move the patching into the callers.
      
      As a follow-on, one could also introduce something like
      __EXPORT_SYMBOL_ALT() to avoid patching call sites in modules.
      Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      LKML-Reference: <4B2BB8180200007800026AE7@vpn.id2.novell.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      1b1d9258
  37. 02 Dec, 2009 1 commit
    • Jan Beulich's avatar
      x86/alternatives: Check replacementlen <= instrlen at build time · 01be50a3
      Jan Beulich authored
      
      Having run into the run-(boot-)time check a couple of times lately,
      I finally took time to find a build-time check so that one doesn't
      need to analyze the register/stack dump and resolve this (through
      manual lookup in vmlinux) to the offending construct.
      
      The assembler will emit a message like "Error: value of <num> too
      large for field of 1 bytes at <offset>", which while not pointing
      out the source location still makes analysis quite a bit easier.
      Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
      LKML-Reference: <4B0FF8AA0200007800022703@vpn.id2.novell.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      01be50a3