note.S 1.7 KB

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  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. #include <linux/build-salt.h>
  7. #include <linux/version.h>
  8. #include <linux/elfnote.h>
  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. BUILD_SALT
  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. #include "../../xen/vdso.h" /* Defines VDSO_NOTE_NONEGSEG_BIT. */
  36. ELFNOTE_START(GNU, 2, "a")
  37. .long 1 /* ncaps */
  38. VDSO32_NOTE_MASK: /* Symbol used by arch/x86/xen/setup.c */
  39. .long 0 /* mask */
  40. .byte VDSO_NOTE_NONEGSEG_BIT; .asciz "nosegneg" /* bit, name */
  41. ELFNOTE_END
  42. #endif