xref: /openbmc/linux/arch/x86/entry/vdso/vdso32/note.S (revision 4f6cce39)
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. */
12ELFNOTE_START(Linux, 0, "a")
13	.long LINUX_VERSION_CODE
14ELFNOTE_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
38ELFNOTE_START(GNU, 2, "a")
39	.long 1			/* ncaps */
40VDSO32_NOTE_MASK:		/* Symbol used by arch/x86/xen/setup.c */
41	.long 0			/* mask */
42	.byte VDSO_NOTE_NONEGSEG_BIT; .asciz "nosegneg"	/* bit, name */
43ELFNOTE_END
44#endif
45