cvs commit: src/sys/kern imgact_aout.c imgact_elf.c imgact_gzip.c src/sys/vm vm_extern.h vm_glue.c

Alan Cox alc at
Thu Mar 16 00:25:33 UTC 2006

alc         2006-03-16 00:25:32 UTC

  FreeBSD src repository

  Modified files:        (Branch: RELENG_6)
    sys/kern             imgact_aout.c imgact_elf.c imgact_gzip.c 
    sys/vm               vm_extern.h vm_glue.c 
    File                  Revisions
    kern/imgact_aout.c    1.100
    kern/imgact_elf.c     1.167-1.172, 1.175
    kern/imgact_gzip.c    1.55
    vm/vm_extern.h        1.77
    vm/vm_glue.c          1.214
    Use sf_buf_alloc() instead of vm_map_find() on exec_map to create
    the ephemeral mappings that are used as the source for three copy
    operations from kernel space to user space.  There are two reasons
    for making this change: (1) Under heavy load exec_map can fill up
    causing vm_map_find() to fail.  When it fails, the nascent process
    is aborted (SIGABRT).  Whereas, this reimplementation using
    sf_buf_alloc() sleeps.  (2) Although it is possible to sleep on
    vm_map_find()'s failure until address space becomes available (see
    kmem_alloc_wait()), using sf_buf_alloc() is faster.  Furthermore,
    the reimplementation uses a CPU private mapping, avoiding a TLB
    shootdown on multiprocessors.
    The second argument to vm_map_find() should be NULL instead of 0.
    Correct a long-standing problem in elfN_map_insert(): In order to
    copy a page to user space, the user space mapping must allow write
    Eliminate an unneeded (vm_prot_t) parameter from two functions.
    Eliminate unnecessary uses of a local variable.
    Maintain the vnode lock throughout elfN_load_file() rather than
    releasing it and reacquiring it in vrele().  Consequently, there is
    no reason to increase the reference count on the vm object caching
    the file's pages.
    Eliminate unused parameters to elfN_load_file().
    Maintain the lock on the vnode for most of exec_elfN_imgact().
    Specifically, it is required for the I/O that may be performed by
    Avoid an obscure deadlock in the a.out, elf, and gzip image
    activators.  Add a comment describing why the deadlock does not
    occur in the common case and how it might occur in less usual
    Eliminate an unused variable from exec_aout_imgact().
    Avoid a vm object reference leak in a rarely used code path.
    An executable contains at most one PT_INTERP program header.
    Therefore, the loop that searches for it can terminate after it is
    found rather than iterating over the entire set of program headers.
    Eliminate an unneeded initialization.
  Approved by: re (mux)
  Revision   Changes    Path   +13 -2     src/sys/kern/imgact_aout.c  +97 -144   src/sys/kern/imgact_elf.c   +13 -0     src/sys/kern/imgact_gzip.c   +2 -0      src/sys/vm/vm_extern.h  +72 -0     src/sys/vm/vm_glue.c

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