1. 27 6月, 2006 3 次提交
  2. 20 4月, 2006 1 次提交
    • A
      [PATCH] i386/x86-64: Fix x87 information leak between processes · 18bd057b
      Andi Kleen 提交于
      AMD K7/K8 CPUs only save/restore the FOP/FIP/FDP x87 registers in FXSAVE
      when an exception is pending.  This means the value leak through
      context switches and allow processes to observe some x87 instruction
      state of other processes.
      
      This was actually documented by AMD, but nobody recognized it as
      being different from Intel before.
      
      The fix first adds an optimization: instead of unconditionally
      calling FNCLEX after each FXSAVE test if ES is pending and skip
      it when not needed. Then do a x87 load from a kernel variable to
      clear FOP/FIP/FDP.
      
      This means other processes always will only see a constant value
      defined by the kernel in their FP state.
      
      I took some pain to make sure to chose a variable that's already
      in L1 during context switch to make the overhead of this low.
      
      Also alternative() is used to patch away the new code on CPUs
      who don't need it.
      
      Patch for both i386/x86-64.
      
      The problem was discovered originally by Jan Beulich. Richard
      Brunner provided the basic code for the workarounds, with contribution
      from Jan.
      
      This is CVE-2006-1056
      
      Cc: richard.brunner@amd.com
      Cc: jbeulich@novell.com
      Signed-off-by: NAndi Kleen <ak@suse.de>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      18bd057b
  3. 10 4月, 2006 1 次提交
    • J
      [PATCH] x86_64: Plug GS leak in arch_prctl() · 97c2803c
      John Blackwood 提交于
      In linux-2.6.16, we have noticed a problem where the gs base value
      returned from an arch_prtcl(ARCH_GET_GS, ...) call will be incorrect if:
      
         - the current/calling task has NOT set its own gs base yet to a
           non-zero value,
      
         - some other task that ran on the same processor previously set their
           own gs base to a non-zero value.
      
      In this situation, the ARCH_GET_GS code will read and return the
      MSR_KERNEL_GS_BASE msr register.
      
      However, since the __switch_to() code does NOT load/zero the
      MSR_KERNEL_GS_BASE register when the task that is switched IN has a zero
      next->gs value, the caller of arch_prctl(ARCH_GET_GS, ...) will get back
      the value of some previous tasks's gs base value instead of 0.
      
          Change the arch_prctl() ARCH_GET_GS code to only read and return
          the MSR_KERNEL_GS_BASE msr register if the 'gs' register of the calling
          task is non-zero.
      
          Side note: Since in addition to using arch_prctl(ARCH_SET_GS, ...),
          a task can also setup a gs base value by using modify_ldt() and write
          an index value into 'gs' from user space, the patch below reads
          'gs' instead of using thread.gs, since in the modify_ldt() case,
          the thread.gs value will be 0, and incorrect value would be returned
          (the task->thread.gs value).
      
          When the user has not set its own gs base value and the 'gs'
          register is zero, then the MSR_KERNEL_GS_BASE register will not be
          read and a value of zero will be returned by reading and returning
          'task->thread.gs'.
      
          The first patch shown below is an attempt at implementing this
          approach.
      Signed-off-by: NAndi Kleen <ak@suse.de>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      97c2803c
  4. 28 3月, 2006 1 次提交
    • A
      [PATCH] Notifier chain update: API changes · e041c683
      Alan Stern 提交于
      The kernel's implementation of notifier chains is unsafe.  There is no
      protection against entries being added to or removed from a chain while the
      chain is in use.  The issues were discussed in this thread:
      
          http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
      
      We noticed that notifier chains in the kernel fall into two basic usage
      classes:
      
      	"Blocking" chains are always called from a process context
      	and the callout routines are allowed to sleep;
      
      	"Atomic" chains can be called from an atomic context and
      	the callout routines are not allowed to sleep.
      
      We decided to codify this distinction and make it part of the API.  Therefore
      this set of patches introduces three new, parallel APIs: one for blocking
      notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
      really just the old API under a new name).  New kinds of data structures are
      used for the heads of the chains, and new routines are defined for
      registration, unregistration, and calling a chain.  The three APIs are
      explained in include/linux/notifier.h and their implementation is in
      kernel/sys.c.
      
      With atomic and blocking chains, the implementation guarantees that the chain
      links will not be corrupted and that chain callers will not get messed up by
      entries being added or removed.  For raw chains the implementation provides no
      guarantees at all; users of this API must provide their own protections.  (The
      idea was that situations may come up where the assumptions of the atomic and
      blocking APIs are not appropriate, so it should be possible for users to
      handle these things in their own way.)
      
      There are some limitations, which should not be too hard to live with.  For
      atomic/blocking chains, registration and unregistration must always be done in
      a process context since the chain is protected by a mutex/rwsem.  Also, a
      callout routine for a non-raw chain must not try to register or unregister
      entries on its own chain.  (This did happen in a couple of places and the code
      had to be changed to avoid it.)
      
      Since atomic chains may be called from within an NMI handler, they cannot use
      spinlocks for synchronization.  Instead we use RCU.  The overhead falls almost
      entirely in the unregister routine, which is okay since unregistration is much
      less frequent that calling a chain.
      
      Here is the list of chains that we adjusted and their classifications.  None
      of them use the raw API, so for the moment it is only a placeholder.
      
        ATOMIC CHAINS
        -------------
      arch/i386/kernel/traps.c:		i386die_chain
      arch/ia64/kernel/traps.c:		ia64die_chain
      arch/powerpc/kernel/traps.c:		powerpc_die_chain
      arch/sparc64/kernel/traps.c:		sparc64die_chain
      arch/x86_64/kernel/traps.c:		die_chain
      drivers/char/ipmi/ipmi_si_intf.c:	xaction_notifier_list
      kernel/panic.c:				panic_notifier_list
      kernel/profile.c:			task_free_notifier
      net/bluetooth/hci_core.c:		hci_notifier
      net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_chain
      net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_expect_chain
      net/ipv6/addrconf.c:			inet6addr_chain
      net/netfilter/nf_conntrack_core.c:	nf_conntrack_chain
      net/netfilter/nf_conntrack_core.c:	nf_conntrack_expect_chain
      net/netlink/af_netlink.c:		netlink_chain
      
        BLOCKING CHAINS
        ---------------
      arch/powerpc/platforms/pseries/reconfig.c:	pSeries_reconfig_chain
      arch/s390/kernel/process.c:		idle_chain
      arch/x86_64/kernel/process.c		idle_notifier
      drivers/base/memory.c:			memory_chain
      drivers/cpufreq/cpufreq.c		cpufreq_policy_notifier_list
      drivers/cpufreq/cpufreq.c		cpufreq_transition_notifier_list
      drivers/macintosh/adb.c:		adb_client_list
      drivers/macintosh/via-pmu.c		sleep_notifier_list
      drivers/macintosh/via-pmu68k.c		sleep_notifier_list
      drivers/macintosh/windfarm_core.c	wf_client_list
      drivers/usb/core/notify.c		usb_notifier_list
      drivers/video/fbmem.c			fb_notifier_list
      kernel/cpu.c				cpu_chain
      kernel/module.c				module_notify_list
      kernel/profile.c			munmap_notifier
      kernel/profile.c			task_exit_notifier
      kernel/sys.c				reboot_notifier_list
      net/core/dev.c				netdev_chain
      net/decnet/dn_dev.c:			dnaddr_chain
      net/ipv4/devinet.c:			inetaddr_chain
      
      It's possible that some of these classifications are wrong.  If they are,
      please let us know or submit a patch to fix them.  Note that any chain that
      gets called very frequently should be atomic, because the rwsem read-locking
      used for blocking chains is very likely to incur cache misses on SMP systems.
      (However, if the chain's callout routines may sleep then the chain cannot be
      atomic.)
      
      The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
      material written by Keith Owens and suggestions from Paul McKenney and Andrew
      Morton.
      
      [jes@sgi.com: restructure the notifier chain initialization macros]
      Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
      Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
      Signed-off-by: NJes Sorensen <jes@sgi.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      e041c683
  5. 27 3月, 2006 1 次提交
    • B
      [PATCH] kretprobe instance recycled by parent process · c6fd91f0
      bibo mao 提交于
      When kretprobe probes the schedule() function, if the probed process exits
      then schedule() will never return, so some kretprobe instances will never
      be recycled.
      
      In this patch the parent process will recycle retprobe instances of the
      probed function and there will be no memory leak of kretprobe instances.
      Signed-off-by: Nbibo mao <bibo.mao@intel.com>
      Cc: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
      Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
      Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
      Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      c6fd91f0
  6. 26 3月, 2006 2 次提交
  7. 24 3月, 2006 1 次提交
  8. 05 2月, 2006 1 次提交
  9. 13 1月, 2006 3 次提交
  10. 12 1月, 2006 2 次提交
    • A
      [PATCH] x86_64: Add idle notifiers · 95833c83
      Andi Kleen 提交于
      This adds a new notifier chain that is called with IDLE_START
      when a CPU goes idle and IDLE_END when it goes out of idle.
      The context can be idle thread or interrupt context.
      
      Since we cannot rely on MONITOR/MWAIT existing the idle
      end check currently has to be done in all interrupt
      handlers.
      
      They were originally inspired by the similar s390 implementation.
      
      They have a variety of applications:
      - They will be needed for CONFIG_NO_IDLE_HZ
      - They can be used for oprofile to fix up the missing time
      in idle when performance counters don't tick.
      - They can be used for better C state management in ACPI
      - They could be used for microstate accounting.
      
      This is just infrastructure so far, no users.
      Signed-off-by: NAndi Kleen <ak@suse.de>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      95833c83
    • A
      [PATCH] x86_64: Remove enable/disable_hlt · 2d52ede9
      Andi Kleen 提交于
      Was only used by the floppy driver to work around some ancient
      hardware bug that should never occur on any 64bit system.
      Signed-off-by: NAndi Kleen <ak@suse.de>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      2d52ede9
  11. 07 1月, 2006 1 次提交
  12. 24 11月, 2005 1 次提交
    • J
      [PATCH] kprobes: Fix return probes on sys_execve · 8bf1101b
      Jim Keniston 提交于
      Fix a bug in kprobes that can cause an Oops or even a crash when a return
      probe is installed on one of the following functions: sys_execve,
      do_execve, load_*_binary, flush_old_exec, or flush_thread.  The fix is to
      remove the call to kprobe_flush_task() in flush_thread().  This fix has
      been tested on all architectures for which the return-probes feature has
      been implemented (i386, x86_64, ppc64, ia64).  Please apply.
      
      BACKGROUND
      
      Up to now, we have called kprobe_flush_task() under two situations: when a
      task exits, and when it execs.  Flushing kretprobe_instances on exit is
      correct because (a) do_exit() doesn't return, and (b) one or more
      return-probed functions may be active when a task calls do_exit().  Neither
      is the case for sys_execve() and its callees.
      
      Initially, the mistaken call to kprobe_flush_task() on exec was harmless
      because we put the "real" return address of each active probed function
      back in the stack, just to be safe, when we recycled its
      kretprobe_instance.  When support for ppc64 and ia64 was added, this safety
      measure couldn't be employed, and was eventually dropped even for i386 and
      x86_64.  sys_execve() and its callees were informally blacklisted for
      return probes until this fix was developed.
      Acked-by: NPrasanna S Panchamukhi <prasanna@in.ibm.com>
      Signed-off-by: NJim Keniston <jkenisto@us.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      8bf1101b
  13. 15 11月, 2005 1 次提交
  14. 09 11月, 2005 2 次提交
    • N
      [PATCH] sched: resched and cpu_idle rework · 64c7c8f8
      Nick Piggin 提交于
      Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce
      confusion, and make their semantics rigid.  Improves efficiency of
      resched_task and some cpu_idle routines.
      
      * In resched_task:
      - TIF_NEED_RESCHED is only cleared with the task's runqueue lock held,
        and as we hold it during resched_task, then there is no need for an
        atomic test and set there. The only other time this should be set is
        when the task's quantum expires, in the timer interrupt - this is
        protected against because the rq lock is irq-safe.
      
      - If TIF_NEED_RESCHED is set, then we don't need to do anything. It
        won't get unset until the task get's schedule()d off.
      
      - If we are running on the same CPU as the task we resched, then set
        TIF_NEED_RESCHED and no further action is required.
      
      - If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set
        after TIF_NEED_RESCHED has been set, then we need to send an IPI.
      
      Using these rules, we are able to remove the test and set operation in
      resched_task, and make clear the previously vague semantics of
      POLLING_NRFLAG.
      
      * In idle routines:
      - Enter cpu_idle with preempt disabled. When the need_resched() condition
        becomes true, explicitly call schedule(). This makes things a bit clearer
        (IMO), but haven't updated all architectures yet.
      
      - Many do a test and clear of TIF_NEED_RESCHED for some reason. According
        to the resched_task rules, this isn't needed (and actually breaks the
        assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock
        held). So remove that. Generally one less locked memory op when switching
        to the idle thread.
      
      - Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner
        most polling idle loops. The above resched_task semantics allow it to be
        set until before the last time need_resched() is checked before going into
        a halt requiring interrupt wakeup.
      
        Many idle routines simply never enter such a halt, and so POLLING_NRFLAG
        can be always left set, completely eliminating resched IPIs when rescheduling
        the idle task.
      
        POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs.
      Signed-off-by: NNick Piggin <npiggin@suse.de>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Con Kolivas <kernel@kolivas.org>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      64c7c8f8
    • N
      [PATCH] sched: disable preempt in idle tasks · 5bfb5d69
      Nick Piggin 提交于
      Run idle threads with preempt disabled.
      
      Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()).
      How did it ever work before?
      
      Might fix the CPU hotplugging hang which Nigel Cunningham noted.
      
      We think the bug hits if the idle thread is preempted after checking
      need_resched() and before going to sleep, then the CPU offlined.
      
      After calling stop_machine_run, the CPU eventually returns from preemption and
      into the idle thread and goes to sleep.  The CPU will continue executing
      previous idle and have no chance to call play_dead.
      
      By disabling preemption until we are ready to explicitly schedule, this bug is
      fixed and the idle threads generally become more robust.
      
      From: alexs <ashepard@u.washington.edu>
      
        PPC build fix
      
      From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>
      
        MIPS build fix
      Signed-off-by: NNick Piggin <npiggin@suse.de>
      Signed-off-by: NYoichi Yuasa <yuasa@hh.iij4u.or.jp>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      5bfb5d69
  15. 13 9月, 2005 4 次提交
  16. 08 9月, 2005 1 次提交
  17. 28 6月, 2005 1 次提交
    • A
      [PATCH] seccomp: tsc disable · ffaa8bd6
      Andrea Arcangeli 提交于
      I believe at least for seccomp it's worth to turn off the tsc, not just for
      HT but for the L2 cache too.  So it's up to you, either you turn it off
      completely (which isn't very nice IMHO) or I recommend to apply this below
      patch.
      
      This has been tested successfully on x86-64 against current cogito
      repository (i686 compiles so I didn't bother testing ;).  People selling
      the cpu through cpushare may appreciate this bit for a peace of mind.
      
      There's no way to get any timing info anymore with this applied
      (gettimeofday is forbidden of course).  The seccomp environment is
      completely deterministic so it can't be allowed to get timing info, it has
      to be deterministic so in the future I can enable a computing mode that
      does a parallel computing for each task with server side transparent
      checkpointing and verification that the output is the same from all the 2/3
      seller computers for each task, without the buyer even noticing (for now
      the verification is left to the buyer client side and there's no
      checkpointing, since that would require more kernel changes to track the
      dirty bits but it'll be easy to extend once the basic mode is finished).
      
      Eliminating a cold-cache read of the cr4 global variable will save one
      cacheline during the tlb flush while making the code per-cpu-safe at the
      same time.  Thanks to Mikael Pettersson for noticing the tlb flush wasn't
      per-cpu-safe.
      
      The global tlb flush can run from irq (IPI calling do_flush_tlb_all) but
      it'll be transparent to the switch_to code since the IPI won't make any
      change to the cr4 contents from the point of view of the interrupted code
      and since it's now all per-cpu stuff, it will not race.  So no need to
      disable irqs in switch_to slow path.
      Signed-off-by: NAndrea Arcangeli <andrea@cpushare.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      ffaa8bd6
  18. 26 6月, 2005 2 次提交
  19. 24 6月, 2005 1 次提交
    • R
      [PATCH] x86_64 specific function return probes · 73649dab
      Rusty Lynch 提交于
      The following patch adds the x86_64 architecture specific implementation
      for function return probes.
      
      Function return probes is a mechanism built on top of kprobes that allows
      a caller to register a handler to be called when a given function exits.
      For example, to instrument the return path of sys_mkdir:
      
      static int sys_mkdir_exit(struct kretprobe_instance *i, struct pt_regs *regs)
      {
      	printk("sys_mkdir exited\n");
      	return 0;
      }
      static struct kretprobe return_probe = {
      	.handler = sys_mkdir_exit,
      };
      
      <inside setup function>
      
      return_probe.kp.addr = (kprobe_opcode_t *) kallsyms_lookup_name("sys_mkdir");
      if (register_kretprobe(&return_probe)) {
      	printk(KERN_DEBUG "Unable to register return probe!\n");
      	/* do error path */
      }
      
      <inside cleanup function>
      unregister_kretprobe(&return_probe);
      
      The way this works is that:
      
      * At system initialization time, kernel/kprobes.c installs a kprobe
        on a function called kretprobe_trampoline() that is implemented in
        the arch/x86_64/kernel/kprobes.c  (More on this later)
      
      * When a return probe is registered using register_kretprobe(),
        kernel/kprobes.c will install a kprobe on the first instruction of the
        targeted function with the pre handler set to arch_prepare_kretprobe()
        which is implemented in arch/x86_64/kernel/kprobes.c.
      
      * arch_prepare_kretprobe() will prepare a kretprobe instance that stores:
        - nodes for hanging this instance in an empty or free list
        - a pointer to the return probe
        - the original return address
        - a pointer to the stack address
      
        With all this stowed away, arch_prepare_kretprobe() then sets the return
        address for the targeted function to a special trampoline function called
        kretprobe_trampoline() implemented in arch/x86_64/kernel/kprobes.c
      
      * The kprobe completes as normal, with control passing back to the target
        function that executes as normal, and eventually returns to our trampoline
        function.
      
      * Since a kprobe was installed on kretprobe_trampoline() during system
        initialization, control passes back to kprobes via the architecture
        specific function trampoline_probe_handler() which will lookup the
        instance in an hlist maintained by kernel/kprobes.c, and then call
        the handler function.
      
      * When trampoline_probe_handler() is done, the kprobes infrastructure
        single steps the original instruction (in this case just a top), and
        then calls trampoline_post_handler().  trampoline_post_handler() then
        looks up the instance again, puts the instance back on the free list,
        and then makes a long jump back to the original return instruction.
      
      So to recap, to instrument the exit path of a function this implementation
      will cause four interruptions:
      
        - A breakpoint at the very beginning of the function allowing us to
          switch out the return address
        - A single step interruption to execute the original instruction that
          we replaced with the break instruction (normal kprobe flow)
        - A breakpoint in the trampoline function where our instrumented function
          returned to
        - A single step interruption to execute the original instruction that
          we replaced with the break instruction (normal kprobe flow)
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      73649dab
  20. 22 6月, 2005 1 次提交
    • S
      [PATCH] x86_64: TASK_SIZE fixes for compatibility mode processes · 84929801
      Suresh Siddha 提交于
      Appended patch will setup compatibility mode TASK_SIZE properly.  This will
      fix atleast three known bugs that can be encountered while running
      compatibility mode apps.
      
      a) A malicious 32bit app can have an elf section at 0xffffe000.  During
         exec of this app, we will have a memory leak as insert_vm_struct() is
         not checking for return value in syscall32_setup_pages() and thus not
         freeing the vma allocated for the vsyscall page.  And instead of exec
         failing (as it has addresses > TASK_SIZE), we were allowing it to
         succeed previously.
      
      b) With a 32bit app, hugetlb_get_unmapped_area/arch_get_unmapped_area
         may return addresses beyond 32bits, ultimately causing corruption
         because of wrap-around and resulting in SEGFAULT, instead of returning
         ENOMEM.
      
      c) 32bit app doing this below mmap will now fail.
      
        mmap((void *)(0xFFFFE000UL), 0x10000UL, PROT_READ|PROT_WRITE,
      	MAP_FIXED|MAP_PRIVATE|MAP_ANON, 0, 0);
      Signed-off-by: NZou Nan hai <nanhai.zou@intel.com>
      Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
      Cc: Andi Kleen <ak@muc.de>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      84929801
  21. 01 5月, 2005 1 次提交
    • H
      [PATCH] i386/x86_64 segment register access update · fd51f666
      H. J. Lu 提交于
      The new i386/x86_64 assemblers no longer accept instructions for moving
      between a segment register and a 32bit memory location, i.e.,
      
              movl (%eax),%ds
              movl %ds,(%eax)
      
      To generate instructions for moving between a segment register and a
      16bit memory location without the 16bit operand size prefix, 0x66,
      
              mov (%eax),%ds
              mov %ds,(%eax)
      
      should be used. It will work with both new and old assemblers. The
      assembler starting from 2.16.90.0.1 will also support
      
              movw (%eax),%ds
              movw %ds,(%eax)
      
      without the 0x66 prefix. I am enclosing patches for 2.4 and 2.6 kernels
      here. The resulting kernel binaries should be unchanged as before, with
      old and new assemblers, if gcc never generates memory access for
      
                     unsigned gsindex;
                     asm volatile("movl %%gs,%0" : "=g" (gsindex));
      
      If gcc does generate memory access for the code above, the upper bits
      in gsindex are undefined and the new assembler doesn't allow it.
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      fd51f666
  22. 17 4月, 2005 1 次提交
    • L
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds 提交于
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4