1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _LINUX_ELFNOTE_H
 3#define _LINUX_ELFNOTE_H
 4/*
 5 * Helper macros to generate ELF Note structures, which are put into a
 6 * PT_NOTE segment of the final vmlinux image.  These are useful for
 7 * including name-value pairs of metadata into the kernel binary (or
 8 * modules?) for use by external programs.
 9 *
10 * Each note has three parts: a name, a type and a desc.  The name is
11 * intended to distinguish the note's originator, so it would be a
12 * company, project, subsystem, etc; it must be in a suitable form for
13 * use in a section name.  The type is an integer which is used to tag
14 * the data, and is considered to be within the "name" namespace (so
15 * "FooCo"'s type 42 is distinct from "BarProj"'s type 42).  The
16 * "desc" field is the actual data.  There are no constraints on the
17 * desc field's contents, though typically they're fairly small.
18 *
19 * All notes from a given NAME are put into a section named
20 * .note.NAME.  When the kernel image is finally linked, all the notes
21 * are packed into a single .notes section, which is mapped into the
22 * PT_NOTE segment.  Because notes for a given name are grouped into
23 * the same section, they'll all be adjacent the output file.
24 *
25 * This file defines macros for both C and assembler use.  Their
26 * syntax is slightly different, but they're semantically similar.
27 *
28 * See the ELF specification for more detail about ELF notes.
29 */
30
31#ifdef __ASSEMBLER__
32/*
33 * Generate a structure with the same shape as Elf{32,64}_Nhdr (which
34 * turn out to be the same size and shape), followed by the name and
35 * desc data with appropriate padding.  The 'desctype' argument is the
36 * assembler pseudo op defining the type of the data e.g. .asciz while
37 * 'descdata' is the data itself e.g.  "hello, world".
38 *
39 * e.g. ELFNOTE(XYZCo, 42, .asciz, "forty-two")
40 *      ELFNOTE(XYZCo, 12, .long, 0xdeadbeef)
41 */
42#define ELFNOTE_START(name, type, flags)	\
43.pushsection .note.name, flags,@note	;	\
44  .balign 4				;	\
45  .long 2f - 1f		/* namesz */	;	\
46  .long 4484f - 3f	/* descsz */	;	\
47  .long type				;	\
481:.asciz #name				;	\
492:.balign 4				;	\
503:
51
52#define ELFNOTE_END				\
534484:.balign 4				;	\
54.popsection				;
55
56#define ELFNOTE(name, type, desc)		\
57	ELFNOTE_START(name, type, "a")		\
58		desc			;	\
59	ELFNOTE_END
60
61#else	/* !__ASSEMBLER__ */
62#include <uapi/linux/elf.h>
63/*
64 * Use an anonymous structure which matches the shape of
65 * Elf{32,64}_Nhdr, but includes the name and desc data.  The size and
66 * type of name and desc depend on the macro arguments.  "name" must
67 * be a literal string, and "desc" must be passed by value.  You may
68 * only define one note per line, since __LINE__ is used to generate
69 * unique symbols.
70 */
71#define _ELFNOTE_PASTE(a,b)	a##b
72#define _ELFNOTE(size, name, unique, type, desc)			\
73	static const struct {						\
74		struct elf##size##_note _nhdr;				\
75		unsigned char _name[sizeof(name)]			\
76		__attribute__((aligned(sizeof(Elf##size##_Word))));	\
77		typeof(desc) _desc					\
78			     __attribute__((aligned(sizeof(Elf##size##_Word)))); \
79	} _ELFNOTE_PASTE(_note_, unique)				\
80		__used							\
81		__attribute__((section(".note." name),			\
82			       aligned(sizeof(Elf##size##_Word)),	\
83			       unused)) = {				\
84		{							\
85			sizeof(name),					\
86			sizeof(desc),					\
87			type,						\
88		},							\
89		name,							\
90		desc							\
91	}
92#define ELFNOTE(size, name, type, desc)		\
93	_ELFNOTE(size, name, __LINE__, type, desc)
94
95#define ELFNOTE32(name, type, desc) ELFNOTE(32, name, type, desc)
96#define ELFNOTE64(name, type, desc) ELFNOTE(64, name, type, desc)
97#endif	/* __ASSEMBLER__ */
98
99#endif /* _LINUX_ELFNOTE_H */

 
 1#ifndef _LINUX_ELFNOTE_H
 2#define _LINUX_ELFNOTE_H
 3/*
 4 * Helper macros to generate ELF Note structures, which are put into a
 5 * PT_NOTE segment of the final vmlinux image.  These are useful for
 6 * including name-value pairs of metadata into the kernel binary (or
 7 * modules?) for use by external programs.
 8 *
 9 * Each note has three parts: a name, a type and a desc.  The name is
10 * intended to distinguish the note's originator, so it would be a
11 * company, project, subsystem, etc; it must be in a suitable form for
12 * use in a section name.  The type is an integer which is used to tag
13 * the data, and is considered to be within the "name" namespace (so
14 * "FooCo"'s type 42 is distinct from "BarProj"'s type 42).  The
15 * "desc" field is the actual data.  There are no constraints on the
16 * desc field's contents, though typically they're fairly small.
17 *
18 * All notes from a given NAME are put into a section named
19 * .note.NAME.  When the kernel image is finally linked, all the notes
20 * are packed into a single .notes section, which is mapped into the
21 * PT_NOTE segment.  Because notes for a given name are grouped into
22 * the same section, they'll all be adjacent the output file.
23 *
24 * This file defines macros for both C and assembler use.  Their
25 * syntax is slightly different, but they're semantically similar.
26 *
27 * See the ELF specification for more detail about ELF notes.
28 */
29
30#ifdef __ASSEMBLER__
31/*
32 * Generate a structure with the same shape as Elf{32,64}_Nhdr (which
33 * turn out to be the same size and shape), followed by the name and
34 * desc data with appropriate padding.  The 'desctype' argument is the
35 * assembler pseudo op defining the type of the data e.g. .asciz while
36 * 'descdata' is the data itself e.g.  "hello, world".
37 *
38 * e.g. ELFNOTE(XYZCo, 42, .asciz, "forty-two")
39 *      ELFNOTE(XYZCo, 12, .long, 0xdeadbeef)
40 */
41#define ELFNOTE_START(name, type, flags)	\
42.pushsection .note.name, flags,@note	;	\
43  .balign 4				;	\
44  .long 2f - 1f		/* namesz */	;	\
45  .long 4484f - 3f	/* descsz */	;	\
46  .long type				;	\
471:.asciz #name				;	\
482:.balign 4				;	\
493:
50
51#define ELFNOTE_END				\
524484:.balign 4				;	\
53.popsection				;
54
55#define ELFNOTE(name, type, desc)		\
56	ELFNOTE_START(name, type, "")		\
57		desc			;	\
58	ELFNOTE_END
59
60#else	/* !__ASSEMBLER__ */
61#include <linux/elf.h>
62/*
63 * Use an anonymous structure which matches the shape of
64 * Elf{32,64}_Nhdr, but includes the name and desc data.  The size and
65 * type of name and desc depend on the macro arguments.  "name" must
66 * be a literal string, and "desc" must be passed by value.  You may
67 * only define one note per line, since __LINE__ is used to generate
68 * unique symbols.
69 */
70#define _ELFNOTE_PASTE(a,b)	a##b
71#define _ELFNOTE(size, name, unique, type, desc)			\
72	static const struct {						\
73		struct elf##size##_note _nhdr;				\
74		unsigned char _name[sizeof(name)]			\
75		__attribute__((aligned(sizeof(Elf##size##_Word))));	\
76		typeof(desc) _desc					\
77			     __attribute__((aligned(sizeof(Elf##size##_Word)))); \
78	} _ELFNOTE_PASTE(_note_, unique)				\
79		__used							\
80		__attribute__((section(".note." name),			\
81			       aligned(sizeof(Elf##size##_Word)),	\
82			       unused)) = {				\
83		{							\
84			sizeof(name),					\
85			sizeof(desc),					\
86			type,						\
87		},							\
88		name,							\
89		desc							\
90	}
91#define ELFNOTE(size, name, type, desc)		\
92	_ELFNOTE(size, name, __LINE__, type, desc)
93
94#define ELFNOTE32(name, type, desc) ELFNOTE(32, name, type, desc)
95#define ELFNOTE64(name, type, desc) ELFNOTE(64, name, type, desc)
96#endif	/* __ASSEMBLER__ */
97
98#endif /* _LINUX_ELFNOTE_H */