arch/x86/entry/vdso/vdso32/note.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text.
   4  * Here we can supply some information useful to userland.
   5  */
   6
   7 #include <linux/version.h>
   8 #include <linux/elfnote.h>
   9
  10 /* Ideally this would use UTS_NAME, but using a quoted string here
  11    doesn't work. Remember to change this when changing the
  12    kernel's name. */
  13 ELFNOTE_START(Linux, 0, "a")
  14         .long LINUX_VERSION_CODE
  15 ELFNOTE_END
  16
  17 #ifdef CONFIG_XEN
  18 /*
  19  * Add a special note telling glibc's dynamic linker a fake hardware
  20  * flavor that it will use to choose the search path for libraries in the
  21  * same way it uses real hardware capabilities like "mmx".
  22  * We supply "nosegneg" as the fake capability, to indicate that we
  23  * do not like negative offsets in instructions using segment overrides,
  24  * since we implement those inefficiently.  This makes it possible to
  25  * install libraries optimized to avoid those access patterns in someplace
  26  * like /lib/i686/tls/nosegneg.  Note that an /etc/ld.so.conf.d/file
  27  * corresponding to the bits here is needed to make ldconfig work right.
  28  * It should contain:
  29  *      hwcap 1 nosegneg
  30  * to match the mapping of bit to name that we give here.
  31  *
  32  * At runtime, the fake hardware feature will be considered to be present
  33  * if its bit is set in the mask word.  So, we start with the mask 0, and
  34  * at boot time we set VDSO_NOTE_NONEGSEG_BIT if running under Xen.
  35  */
  36
  37 #include "../../xen/vdso.h"     /* Defines VDSO_NOTE_NONEGSEG_BIT.  */
  38
  39 ELFNOTE_START(GNU, 2, "a")
  40         .long 1                 /* ncaps */
  41 VDSO32_NOTE_MASK:               /* Symbol used by arch/x86/xen/setup.c */
  42         .long 0                 /* mask */
  43         .byte VDSO_NOTE_NONEGSEG_BIT; .asciz "nosegneg" /* bit, name */
  44 ELFNOTE_END
  45 #endif