lkml.org 
[lkml]   [2004]   [Jul]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subjectserious performance regression due to NX patch
    The "No eXecute patch for x86" causes a serious exec() performance
    degradation on ia64 since it ends up incorrectly turning on the
    execute protection on all segments (since most ia64 binaries don't
    have a gnu_stack program-header).

    The patch below fixes the problem by turning on VM_EXEC and VM_MAYEXEC
    only if VM_DATA_DEFAULT_FLAGS mentions them. Note that on ia64, the
    value of VM_DATA_DEFAULT_FLAGS depends on the personality (to support
    x86 binaries) and hence I had to move the setting of "def_flags" down
    a bit to a point after SET_PERSONALITY() has been done.

    Please apply.

    --david

    ===== fs/binfmt_elf.c 1.78 vs edited =====
    --- 1.78/fs/binfmt_elf.c 2004-06-29 07:43:10 -07:00
    +++ edited/fs/binfmt_elf.c 2004-07-09 21:53:05 -07:00
    @@ -493,8 +493,8 @@
    char passed_fileno[6];
    struct files_struct *files;
    int executable_stack = EXSTACK_DEFAULT;
    - unsigned long def_flags = 0;
    -
    + unsigned long no_gnu_stack, def_flags = 0;
    +
    /* Get the exec-header */
    elf_ex = *((struct elfhdr *) bprm->buf);

    @@ -627,8 +627,7 @@
    executable_stack = EXSTACK_DISABLE_X;
    break;
    }
    - if (i == elf_ex.e_phnum)
    - def_flags |= VM_EXEC | VM_MAYEXEC;
    + no_gnu_stack = (i == elf_ex.e_phnum);

    /* Some simple consistency checks for the interpreter */
    if (elf_interpreter) {
    @@ -662,6 +661,10 @@
    /* Executables without an interpreter also need a personality */
    SET_PERSONALITY(elf_ex, ibcs2_interpreter);
    }
    +
    + /* Now that personality is set, we can use VM_DATA_DEFAULT_FLAGS. */
    + if (no_gnu_stack)
    + def_flags |= VM_DATA_DEFAULT_FLAGS & (VM_EXEC | VM_MAYEXEC);

    /* OK, we are done with that, now set up the arg stuff,
    and then start this sucker up */
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/
    \
     
     \ /
      Last update: 2005-03-22 14:04    [W:0.022 / U:0.388 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site