1. 06 2月, 2008 3 次提交
    • J
      uml: kill processes instead of panicing kernel · 3e6f2ac4
      Jeff Dike 提交于
      UML was panicing in the case of failures of libc calls which shouldn't happen.
       This is an overreaction since a failure from libc doesn't normally mean that
      kernel data structures are in an unknown state.  Instead, the current process
      should just be killed if there is no way to recover.
      
      The case that prompted this was a failure of PTRACE_SETREGS restoring the same
      state that was read by PTRACE_GETREGS.  It appears that when a process tries
      to load a bogus value into a segment register, it segfaults (as expected) and
      the value is actually loaded and is seen by PTRACE_GETREGS (not expected).
      
      This case is fixed by forcing a fatal SIGSEGV on the process so that it
      immediately dies.  fatal_sigsegv was added for this purpose.  It was declared
      as noreturn, so in order to pursuade gcc that it actually does not return, I
      added a call to os_dump_core (and declared it noreturn) so that I get a core
      file if somehow the process survives.
      
      All other calls in arch/um/os-Linux/skas/process.c got the same treatment,
      with failures causing the process to die instead of a kernel panic, with some
      exceptions.
      
      userspace_tramp exits with status 1 if anything goes wrong there.  That will
      cause start_userspace to return an error.  copy_context_skas0 and
      map_stub_pages also now return errors instead of panicing.  Callers of thes
      functions were changed to check for errors and do something appropriate.
      Usually that's to return an error to their callers.
      check_skas3_ptrace_faultinfo just exits since that's too early to do anything
      else.
      
      save_registers, restore_registers, and init_registers now return status
      instead of panicing on failure, with their callers doing something
      appropriate.
      
      There were also duplicate declarations of save_registers and restore_registers
      in os.h - these are gone.
      
      I noticed and fixed up some whitespace damage.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3e6f2ac4
    • K
      uml: convert functions to void · 6b7e9674
      Karol Swietlicki 提交于
      This patch changes a few functions into returning void.  The return values
      were not used anyway, so I think it should not be a problem.  Also removed a
      little leftover bit from TT mode.
      Signed-off-by: NKarol Swietlicki <magotari@gmail.com>
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6b7e9674
    • W
      uml: code tidying under arch/um/os-Linux · c9a3072d
      WANG Cong 提交于
      This patch contains varied fixes and improvements for some files under
      arch/um/os-Linux/, such as a typo fix in a perror message, a missing
      argument fix for a printf, some constifying for pointers and so on.
      
      [ jdike - made sigprocmask failure return -errno instead of -1 ]
      Signed-off-by: NWANG Cong <xiyou.wangcong@gmail.com>
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c9a3072d
  2. 17 10月, 2007 7 次提交
    • J
      uml: userspace files should call libc directly · 512b6fb1
      Jeff Dike 提交于
      A number of files that were changed in the recent removal of tt mode
      are userspace files which call the os_* wrappers instead of calling
      libc directly.  A few other files were affected by this, through
      
      This patch makes these call glibc directly.
      
      There are also style fixes in the affected areas.
      
      os_print_error has no remaining callers, so it is deleted.
      
      There is a interface change to os_set_exec_close, eliminating a
      parameter which was always the same.  The callers are fixed as well.
      
      os_process_pc got its error path cleaned up.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      512b6fb1
    • J
      uml: replace clone with fork · 3cdaf455
      Jeff Dike 提交于
      Convert the boot-time host ptrace testing from clone to fork.  They were
      essentially doing fork anyway.  This cleans up the code a bit, and makes
      valgrind a bit happier about grinding it.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3cdaf455
    • J
      uml: style fixes pass 3 · ba180fd4
      Jeff Dike 提交于
      Formatting changes in the files which have been changed in the course
      of folding foo_skas functions into their callers.  These include:
      	copyright updates
      	header file trimming
      	style fixes
      	adding severity to printks
      
      These changes should be entirely non-functional.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ba180fd4
    • J
      uml: remove code made redundant by CHOOSE_MODE removal · 77bf4400
      Jeff Dike 提交于
      This patch makes a number of simplifications enabled by the removal of
      CHOOSE_MODE.  There were lots of functions that looked like
      
      	int foo(args){
      		foo_skas(args);
      	}
      
      The bodies of foo_skas are now folded into foo, and their declarations (and
      sometimes entire header files) are deleted.
      
      In addition, the union uml_pt_regs, which was a union between the tt and skas
      register formats, is now a struct, with the tt-mode arm of the union being
      removed.
      
      It turns out that usr2_handler was unused, so it is gone.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      77bf4400
    • J
      uml: throw out CHOOSE_MODE · 6aa802ce
      Jeff Dike 提交于
      The next stage after removing code which depends on CONFIG_MODE_TT is removing
      the CHOOSE_MODE abstraction, which provided both compile-time and run-time
      branching to either tt-mode or skas-mode code.
      
      This patch removes choose-mode.h and all inclusions of it, and replaces all
      CHOOSE_MODE invocations with the skas branch.  This leaves a number of trivial
      functions which will be dealt with in a later patch.
      
      There are some changes in the uaccess and tls support which go somewhat beyond
      this and eliminate some of the now-redundant functions.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6aa802ce
    • J
      uml: throw out CONFIG_MODE_TT · 42fda663
      Jeff Dike 提交于
      This patchset throws out tt mode, which has been non-functional for a while.
      
      This is done in phases, interspersed with code cleanups on the affected files.
      
      The removal is done as follows:
      	remove all code, config options, and files which depend on
      CONFIG_MODE_TT
      	get rid of the CHOOSE_MODE macro, which decided whether to
      call tt-mode or skas-mode code, and replace invocations with their
      skas portions
      	replace all now-trivial procedures with their skas equivalents
      
      There are now a bunch of now-redundant pieces of data structures, including
      mode-specific pieces of the thread structure, pt_regs, and mm_context.  These
      are all replaced with their skas-specific contents.
      
      As part of the ongoing style compliance project, I made a style pass over all
      files that were changed.  There are three such patches, one for each phase,
      covering the files affected by that phase but no later ones.
      
      I noticed that we weren't freeing the LDT state associated with a process when
      it exited, so that's fixed in one of the later patches.
      
      The last patch is a tidying patch which I've had for a while, but which caused
      inexplicable crashes under tt mode.  Since that is no longer a problem, this
      can now go in.
      
      This patch:
      
      Start getting rid of tt mode support.
      
      This patch throws out CONFIG_MODE_TT and all config options, code, and files
      which depend on it.
      
      CONFIG_MODE_SKAS is gone and everything that depends on it is included
      unconditionally.
      
      The few changed lines are in re-written Kconfig help, lines which needed
      something skas-related removed from them, and a few more which weren't
      strictly deletions.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      42fda663
    • J
      uml: stop using libc asm/page.h · 71f926f2
      Jeff Dike 提交于
      Remove includes of asm/page.h from libc code.  This header seems to be
      disappearing, and UML doesn't make much use of it anyway.
      
      The one use, PAGE_SHIFT in stub.h, is handled by copying the constant from the
      kernel side of the house in common_offsets.h.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      71f926f2
  3. 17 6月, 2007 1 次提交
  4. 24 5月, 2007 1 次提交
  5. 08 5月, 2007 4 次提交
  6. 12 2月, 2007 4 次提交
  7. 26 9月, 2006 1 次提交
    • J
      [PATCH] uml: stack usage reduction · 75e29b18
      Jeff Dike 提交于
      The KSTK_* macros used an inordinate amount of stack.  In order to overcome
      an impedance mismatch between their interface, which just returns a single
      register value, and the interface of get_thread_regs, which took a full
      pt_regs, the implementation created an on-stack pt_regs, filled it in, and
      returned one field.  do_task_stat calls KSTK_* twice, resulting in two
      local pt_regs, blowing out the stack.
      
      This patch changes the interface (and name) of get_thread_regs to just
      return a single register from a jmp_buf.
      
      The include of archsetjmp.h" in registers.h to get the definition of
      jmp_buf exposed a bogus include of <setjmp.h> in start_up.c.  <setjmp.h>
      shouldn't be used anywhere any more since UML uses the klibc
      setjmp/longjmp.
      Signed-off-by: NJeff Dike <jdike@addtoit.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      75e29b18
  8. 20 4月, 2006 1 次提交
  9. 01 4月, 2006 1 次提交
    • J
      [PATCH] UML: Hotplug memory, take 2 · 02dea087
      Jeff Dike 提交于
      Changes since first version
      	added check for MADV_REMOVE support on the host
      	fixed error return botch
      	shrunk sprintf array by one character
      
      This adds hotplug memory support to UML.  The mconsole syntax is
       	config mem=[+-]n[KMG]
      In other words, add or subtract some number of kilobytes, megabytes, or
      gigabytes.
      
      Unplugged pages are allocated and then madvise(MADV_TRUNCATE), which is a
      currently experimental madvise extension.  These pages are tracked so they
      can be plugged back in later if the admin decides to give them back.  The
      first page to be unplugged is used to keep track of about 4M of other
      pages.  A list_head is the first thing on this page.  The rest is filled
      with addresses of other unplugged pages.  This first page is not madvised,
      obviously.
      
      When this page is filled, the next page is used in a similar way and linked
      onto a list with the first page.  Etc.  This whole process reverses when
      pages are plugged back in.  When a tracking page no longer tracks any
      unplugged pages, then it is next in line for plugging, which is done by
      freeing pages back to the kernel.
      Signed-off-by: NJeff Dike <jdike@addtoit.com>
      Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      02dea087
  10. 28 3月, 2006 1 次提交
  11. 08 2月, 2006 1 次提交
  12. 19 1月, 2006 1 次提交
  13. 09 1月, 2006 1 次提交
  14. 30 12月, 2005 1 次提交
  15. 07 11月, 2005 2 次提交
  16. 10 10月, 2005 1 次提交
  17. 18 9月, 2005 1 次提交
  18. 05 9月, 2005 3 次提交
  19. 29 7月, 2005 1 次提交
  20. 28 7月, 2005 1 次提交
  21. 08 7月, 2005 1 次提交
    • J
      [PATCH] uml: skas0 - separate kernel address space on stock hosts · d67b569f
      Jeff Dike 提交于
      UML has had two modes of operation - an insecure, slow mode (tt mode) in
      which the kernel is mapped into every process address space which requires
      no host kernel modifications, and a secure, faster mode (skas mode) in
      which the UML kernel is in a separate host address space, which requires a
      patch to the host kernel.
      
      This patch implements something very close to skas mode for hosts which
      don't support skas - I'm calling this skas0.  It provides the security of
      the skas host patch, and some of the performance gains.
      
      The two main things that are provided by the skas patch, /proc/mm and
      PTRACE_FAULTINFO, are implemented in a way that require no host patch.
      
      For the remote address space changing stuff (mmap, munmap, and mprotect),
      we set aside two pages in the process above its stack, one of which
      contains a little bit of code which can call mmap et al.
      
      To update the address space, the system call information (system call
      number and arguments) are written to the stub page above the code.  The
      %esp is set to the beginning of the data, the %eip is set the the start of
      the stub, and it repeatedly pops the information into its registers and
      makes the system call until it sees a system call number of zero.  This is
      to amortize the cost of the context switch across multiple address space
      updates.
      
      When the updates are done, it SIGSTOPs itself, and the kernel process
      continues what it was doing.
      
      For a PTRACE_FAULTINFO replacement, we set up a SIGSEGV handler in the
      child, and let it handle segfaults rather than nullifying them.  The
      handler is in the same page as the mmap stub.  The second page is used as
      the stack.  The handler reads cr2 and err from the sigcontext, sticks them
      at the base of the stack in a faultinfo struct, and SIGSTOPs itself.  The
      kernel then reads the faultinfo and handles the fault.
      
      A complication on x86_64 is that this involves resetting the registers to
      the segfault values when the process is inside the kill system call.  This
      breaks on x86_64 because %rcx will contain %rip because you tell SYSRET
      where to return to by putting the value in %rcx.  So, this corrupts $rcx on
      return from the segfault.  To work around this, I added an
      arch_finish_segv, which on x86 does nothing, but which on x86_64 ptraces
      the child back through the sigreturn.  This causes %rcx to be restored by
      sigreturn and avoids the corruption.  Ultimately, I think I will replace
      this with the trick of having it send itself a blocked signal which will be
      unblocked by the sigreturn.  This will allow it to be stopped just after
      the sigreturn, and PTRACE_SYSCALLed without all the back-and-forth of
      PTRACE_SYSCALLing it through sigreturn.
      
      This runs on a stock host, so theoretically (and hopefully), tt mode isn't
      needed any more.  We need to make sure that this is better in every way
      than tt mode, though.  I'm concerned about the speed of address space
      updates and page fault handling, since they involve extra round-trips to
      the child.  We can amortize the round-trip cost for large address space
      updates by writing all of the operations to the data page and having the
      child execute them all at the same time.  This will help fork and exec, but
      not page faults, since they involve only one page.
      
      I can't think of any way to help page faults, except to add something like
      PTRACE_FAULTINFO to the host.  There is PTRACE_SIGINFO, but UML doesn't use
      siginfo for SIGSEGV (or anything else) because there isn't enough
      information in the siginfo struct to handle page faults (the faulting
      operation type is missing).  Adding that would make PTRACE_SIGINFO a usable
      equivalent to PTRACE_FAULTINFO.
      
      As for the code itself:
      
      - The system call stub is in arch/um/kernel/sys-$(SUBARCH)/stub.S.  It is
        put in its own section of the binary along with stub_segv_handler in
        arch/um/kernel/skas/process.c.  This is manipulated with run_syscall_stub
        in arch/um/kernel/skas/mem_user.c.  syscall_stub will execute any system
        call at all, but it's only used for mmap, munmap, and mprotect.
      
      - The x86_64 stub calls sigreturn by hand rather than allowing the normal
        sigreturn to happen, because the normal sigreturn is a SA_RESTORER in
        UML's address space provided by libc.  Needless to say, this is not
        available in the child's address space.  Also, it does a couple of odd
        pops before that which restore the stack to the state it was in at the
        time the signal handler was called.
      
      - There is a new field in the arch mmu_context, which is now a union.
        This is the pid to be manipulated rather than the /proc/mm file
        descriptor.  Code which deals with this now checks proc_mm to see whether
        it should use the usual skas code or the new code.
      
      - userspace_tramp is now used to create a new host process for every UML
        process, rather than one per UML processor.  It checks proc_mm and
        ptrace_faultinfo to decide whether to map in the pages above its stack.
      
      - start_userspace now makes CLONE_VM conditional on proc_mm since we need
        separate address spaces now.
      
      - switch_mm_skas now just sets userspace_pid[0] to the new pid rather
        than PTRACE_SWITCH_MM.  There is an addition to userspace which updates
        its idea of the pid being manipulated each time around the loop.  This is
        important on exec, when the pid will change underneath userspace().
      
      - The stub page has a pte, but it can't be mapped in using tlb_flush
        because it is part of tlb_flush.  This is why it's required for it to be
        mapped in by userspace_tramp.
      
      Other random things:
      
      - The stub section in uml.lds.S is page aligned.  This page is written
        out to the backing vm file in setup_physmem because it is mapped from
        there into user processes.
      
      - There's some confusion with TASK_SIZE now that there are a couple of
        extra pages that the process can't use.  TASK_SIZE is considered by the
        elf code to be the usable process memory, which is reasonable, so it is
        decreased by two pages.  This confuses the definition of
        USER_PGDS_IN_LAST_PML4, making it too small because of the rounding down
        of the uneven division.  So we round it to the nearest PGDIR_SIZE rather
        than the lower one.
      
      - I added a missing PT_SYSCALL_ARG6_OFFSET macro.
      
      - um_mmu.h was made into a userspace-usable file.
      
      - proc_mm and ptrace_faultinfo are globals which say whether the host
        supports these features.
      
      - There is a bad interaction between the mm.nr_ptes check at the end of
        exit_mmap, stack randomization, and skas0.  exit_mmap will stop freeing
        pages at the PGDIR_SIZE boundary after the last vma.  If the stack isn't
        on the last page table page, the last pte page won't be freed, as it
        should be since the stub ptes are there, and exit_mmap will BUG because
        there is an unfreed page.  To get around this, TASK_SIZE is set to the
        next lowest PGDIR_SIZE boundary and mm->nr_ptes is decremented after the
        calls to init_stub_pte.  This ensures that we know the process stack (and
        all other process mappings) will be below the top page table page, and
        thus we know that mm->nr_ptes will be one too many, and can be
        decremented.
      
      Things that need fixing:
      
      - We may need better assurrences that the stub code is PIC.
      
      - The stub pte is set up in init_new_context_skas.
      
      - alloc_pgdir is probably the right place.
      Signed-off-by: NJeff Dike <jdike@addtoit.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      d67b569f
  22. 14 6月, 2005 2 次提交