| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef _LINUX_ELFNOTE_H |
| #define _LINUX_ELFNOTE_H |
| /* |
| * Helper macros to generate ELF Note structures, which are put into a |
| * PT_NOTE segment of the final vmlinux image. These are useful for |
| * including name-value pairs of metadata into the kernel binary (or |
| * modules?) for use by external programs. |
| * |
| * Each note has three parts: a name, a type and a desc. The name is |
| * intended to distinguish the note's originator, so it would be a |
| * company, project, subsystem, etc; it must be in a suitable form for |
| * use in a section name. The type is an integer which is used to tag |
| * the data, and is considered to be within the "name" namespace (so |
| * "FooCo"'s type 42 is distinct from "BarProj"'s type 42). The |
| * "desc" field is the actual data. There are no constraints on the |
| * desc field's contents, though typically they're fairly small. |
| * |
| * All notes from a given NAME are put into a section named |
| * .note.NAME. When the kernel image is finally linked, all the notes |
| * are packed into a single .notes section, which is mapped into the |
| * PT_NOTE segment. Because notes for a given name are grouped into |
| * the same section, they'll all be adjacent the output file. |
| * |
| * This file defines macros for both C and assembler use. Their |
| * syntax is slightly different, but they're semantically similar. |
| * |
| * See the ELF specification for more detail about ELF notes. |
| */ |
| |
| #ifdef __ASSEMBLER__ |
| /* |
| * Generate a structure with the same shape as Elf{32,64}_Nhdr (which |
| * turn out to be the same size and shape), followed by the name and |
| * desc data with appropriate padding. The 'desctype' argument is the |
| * assembler pseudo op defining the type of the data e.g. .asciz while |
| * 'descdata' is the data itself e.g. "hello, world". |
| * |
| * e.g. ELFNOTE(XYZCo, 42, .asciz, "forty-two") |
| * ELFNOTE(XYZCo, 12, .long, 0xdeadbeef) |
| */ |
| #define ELFNOTE_START(name, type, flags) \ |
| .pushsection .note.name, flags,@note ; \ |
| .balign 4 ; \ |
| .long 2f - 1f /* namesz */ ; \ |
| .long 4484f - 3f /* descsz */ ; \ |
| .long type ; \ |
| 1:.asciz #name ; \ |
| 2:.balign 4 ; \ |
| 3: |
| |
| #define ELFNOTE_END \ |
| 4484:.balign 4 ; \ |
| .popsection ; |
| |
| #define ELFNOTE(name, type, desc) \ |
| ELFNOTE_START(name, type, "a") \ |
| desc ; \ |
| ELFNOTE_END |
| |
| #else /* !__ASSEMBLER__ */ |
| #include <uapi/linux/elf.h> |
| /* |
| * Use an anonymous structure which matches the shape of |
| * Elf{32,64}_Nhdr, but includes the name and desc data. The size and |
| * type of name and desc depend on the macro arguments. "name" must |
| * be a literal string, and "desc" must be passed by value. You may |
| * only define one note per line, since __LINE__ is used to generate |
| * unique symbols. |
| */ |
| #define _ELFNOTE_PASTE(a,b) a##b |
| #define _ELFNOTE(size, name, unique, type, desc) \ |
| static const struct { \ |
| struct elf##size##_note _nhdr; \ |
| unsigned char _name[sizeof(name)] \ |
| __attribute__((aligned(sizeof(Elf##size##_Word)))); \ |
| typeof(desc) _desc \ |
| __attribute__((aligned(sizeof(Elf##size##_Word)))); \ |
| } _ELFNOTE_PASTE(_note_, unique) \ |
| __used \ |
| __attribute__((section(".note." name), \ |
| aligned(sizeof(Elf##size##_Word)), \ |
| unused)) = { \ |
| { \ |
| sizeof(name), \ |
| sizeof(desc), \ |
| type, \ |
| }, \ |
| name, \ |
| desc \ |
| } |
| #define ELFNOTE(size, name, type, desc) \ |
| _ELFNOTE(size, name, __LINE__, type, desc) |
| |
| #define ELFNOTE32(name, type, desc) ELFNOTE(32, name, type, desc) |
| #define ELFNOTE64(name, type, desc) ELFNOTE(64, name, type, desc) |
| #endif /* __ASSEMBLER__ */ |
| |
| #endif /* _LINUX_ELFNOTE_H */ |