arch/i386/kernel/vsyscall-note.S

   1 /*
   2  * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text.
   3  * Here we can supply some information useful to userland.
   4  */
   5
   6 #include <linux/version.h>
   7 #include <linux/elfnote.h>
   8
   9 /* Ideally this would use UTS_NAME, but using a quoted string here
  10    doesn't work. Remember to change this when changing the
  11    kernel's name. */
  12 ELFNOTE_START(Linux, 0, "a")
  13         .long LINUX_VERSION_CODE
  14 ELFNOTE_END
  15
  16 #ifdef CONFIG_XEN
  17 /*
  18  * Add a special note telling glibc's dynamic linker a fake hardware
  19  * flavor that it will use to choose the search path for libraries in the
  20  * same way it uses real hardware capabilities like "mmx".
  21  * We supply "nosegneg" as the fake capability, to indicate that we
  22  * do not like negative offsets in instructions using segment overrides,
  23  * since we implement those inefficiently.  This makes it possible to
  24  * install libraries optimized to avoid those access patterns in someplace
  25  * like /lib/i686/tls/nosegneg.  Note that an /etc/ld.so.conf.d/file
  26  * corresponding to the bits here is needed to make ldconfig work right.
  27  * It should contain:
  28  *      hwcap 1 nosegneg
  29  * to match the mapping of bit to name that we give here.
  30  *
  31  * At runtime, the fake hardware feature will be considered to be present
  32  * if its bit is set in the mask word.  So, we start with the mask 0, and
  33  * at boot time we set VDSO_NOTE_NONEGSEG_BIT if running under Xen.
  34  */
  35
  36 #include "../xen/vdso.h"        /* Defines VDSO_NOTE_NONEGSEG_BIT.  */
  37
  38         .globl VDSO_NOTE_MASK
  39 ELFNOTE_START(GNU, 2, "a")
  40         .long 1                 /* ncaps */
  41 VDSO_NOTE_MASK:
  42         .long 0                 /* mask */
  43         .byte VDSO_NOTE_NONEGSEG_BIT; .asciz "nosegneg" /* bit, name */
  44 ELFNOTE_END
  45 #endif