linux-next/scripts/sortextable.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * sortextable.h
 *
 * Copyright 2011 - 2012 Cavium, Inc.
 *
 * Some of this code was taken out of recordmcount.h written by:
 *
 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
 */

#undef extable_ent_size
#undef compare_extable
#undef do_sort
#undef Elf_Addr
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
#undef Elf_Rela
#undef Elf_Sym
#undef ELF_R_SYM
#undef Elf_r_sym
#undef ELF_R_INFO
#undef Elf_r_info
#undef ELF_ST_BIND
#undef ELF_ST_TYPE
#undef fn_ELF_R_SYM
#undef fn_ELF_R_INFO
#undef uint_t
#undef _r
#undef _w

#ifdef SORTEXTABLE_64
# define extable_ent_size	16
# define compare_extable	compare_extable_64
# define do_sort		do_sort_64
# define Elf_Addr		Elf64_Addr
# define Elf_Ehdr		Elf64_Ehdr
# define Elf_Shdr		Elf64_Shdr
# define Elf_Rel		Elf64_Rel
# define Elf_Rela		Elf64_Rela
# define Elf_Sym		Elf64_Sym
# define ELF_R_SYM		ELF64_R_SYM
# define Elf_r_sym		Elf64_r_sym
# define ELF_R_INFO		ELF64_R_INFO
# define Elf_r_info		Elf64_r_info
# define ELF_ST_BIND		ELF64_ST_BIND
# define ELF_ST_TYPE		ELF64_ST_TYPE
# define fn_ELF_R_SYM		fn_ELF64_R_SYM
# define fn_ELF_R_INFO		fn_ELF64_R_INFO
# define uint_t			uint64_t
# define _r			r8
# define _w			w8
#else
# define extable_ent_size	8
# define compare_extable	compare_extable_32
# define do_sort		do_sort_32
# define Elf_Addr		Elf32_Addr
# define Elf_Ehdr		Elf32_Ehdr
# define Elf_Shdr		Elf32_Shdr
# define Elf_Rel		Elf32_Rel
# define Elf_Rela		Elf32_Rela
# define Elf_Sym		Elf32_Sym
# define ELF_R_SYM		ELF32_R_SYM
# define Elf_r_sym		Elf32_r_sym
# define ELF_R_INFO		ELF32_R_INFO
# define Elf_r_info		Elf32_r_info
# define ELF_ST_BIND		ELF32_ST_BIND
# define ELF_ST_TYPE		ELF32_ST_TYPE
# define fn_ELF_R_SYM		fn_ELF32_R_SYM
# define fn_ELF_R_INFO		fn_ELF32_R_INFO
# define uint_t			uint32_t
# define _r			r
# define _w			w
#endif

static int compare_extable(const void *a, const void *b)
{
	Elf_Addr av = _r(a);
	Elf_Addr bv = _r(b);

	if (av < bv)
		return -1;
	if (av > bv)
		return 1;
	return 0;
}

static int do_sort(Elf_Ehdr *ehdr,
		   char const *const fname,
		   table_sort_t custom_sort)
{
	Elf_Shdr *s, *shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
	Elf_Shdr *strtab_sec = NULL;
	Elf_Shdr *symtab_sec = NULL;
	Elf_Shdr *extab_sec = NULL;
	Elf_Sym *sym;
	const Elf_Sym *symtab;
	Elf32_Word *symtab_shndx = NULL;
	Elf_Sym *sort_needed_sym = NULL;
	Elf_Shdr *sort_needed_sec;
	Elf_Rel *relocs = NULL;
	int relocs_size = 0;
	uint32_t *sort_needed_loc;
	const char *secstrings;
	const char *strtab;
	char *extab_image;
	int extab_index = 0;
	int i;
	int idx;
	unsigned int shnum;
	unsigned int shstrndx;

	shstrndx = r2(&ehdr->e_shstrndx);
	if (shstrndx == SHN_XINDEX)
		shstrndx = r(&shdr[0].sh_link);
	secstrings = (const char *)ehdr + _r(&shdr[shstrndx].sh_offset);

	shnum = r2(&ehdr->e_shnum);
	if (shnum == SHN_UNDEF)
		shnum = _r(&shdr[0].sh_size);

	for (i = 0, s = shdr; s < shdr + shnum; i++, s++) {
		idx = r(&s->sh_name);
		if (!strcmp(secstrings + idx, "__ex_table")) {
			extab_sec = s;
			extab_index = i;
		}
		if (!strcmp(secstrings + idx, ".symtab"))
			symtab_sec = s;
		if (!strcmp(secstrings + idx, ".strtab"))
			strtab_sec = s;

		if ((r(&s->sh_type) == SHT_REL ||
		     r(&s->sh_type) == SHT_RELA) &&
		    r(&s->sh_info) == extab_index) {
			relocs = (void *)ehdr + _r(&s->sh_offset);
			relocs_size = _r(&s->sh_size);
		}
		if (r(&s->sh_type) == SHT_SYMTAB_SHNDX)
			symtab_shndx = (Elf32_Word *)((const char *)ehdr +
						      _r(&s->sh_offset));
	}

	if (!extab_sec) {
		fprintf(stderr,	"no __ex_table in file: %s\n", fname);
		return -1;
	}

	if (!symtab_sec) {
		fprintf(stderr,	"no .symtab in file: %s\n", fname);
		return -1;
	}

	if (!strtab_sec) {
		fprintf(stderr,	"no .strtab in file: %s\n", fname);
		return -1;
	}

	extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
	strtab = (const char *)ehdr + _r(&strtab_sec->sh_offset);
	symtab = (const Elf_Sym *)((const char *)ehdr +
						  _r(&symtab_sec->sh_offset));

	if (custom_sort) {
		custom_sort(extab_image, _r(&extab_sec->sh_size));
	} else {
		int num_entries = _r(&extab_sec->sh_size) / extable_ent_size;
		qsort(extab_image, num_entries,
		      extable_ent_size, compare_extable);
	}

	/* If there were relocations, we no longer need them. */
	if (relocs)
		memset(relocs, 0, relocs_size);

	/* find the flag main_extable_sort_needed */
	for (sym = (void *)ehdr + _r(&symtab_sec->sh_offset);
	     sym < sym + _r(&symtab_sec->sh_size) / sizeof(Elf_Sym);
	     sym++) {
		if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
			continue;
		if (!strcmp(strtab + r(&sym->st_name),
			    "main_extable_sort_needed")) {
			sort_needed_sym = sym;
			break;
		}
	}

	if (!sort_needed_sym) {
		fprintf(stderr,
			"no main_extable_sort_needed symbol in file: %s\n",
			fname);
		return -1;
	}

	sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
					     sort_needed_sym - symtab,
					     symtab_shndx)];
	sort_needed_loc = (void *)ehdr +
		_r(&sort_needed_sec->sh_offset) +
		_r(&sort_needed_sym->st_value) -
		_r(&sort_needed_sec->sh_addr);

	/* extable has been sorted, clear the flag */
	w(0, sort_needed_loc);

	return 0;
}