1/* SPDX-License-Identifier: GPL-2.0-or-later */
  2/*
  3 * Copyright (C) 2015 Imagination Technologies
  4 * Author: Alex Smith <alex.smith@imgtec.com>
  5 */
  6
  7static inline bool FUNC(patch_vdso)(const char *path, void *vdso)
  8{
  9	const ELF(Ehdr) *ehdr = vdso;
 10	void *shdrs;
 11	ELF(Shdr) *shdr;
 12	char *shstrtab, *name;
 13	uint16_t sh_count, sh_entsize, i;
 14
 15	shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff);
 16	sh_count = swap_uint16(ehdr->e_shnum);
 17	sh_entsize = swap_uint16(ehdr->e_shentsize);
 18
 19	shdr = shdrs + (sh_entsize * swap_uint16(ehdr->e_shstrndx));
 20	shstrtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
 21
 22	for (i = 0; i < sh_count; i++) {
 23		shdr = shdrs + (i * sh_entsize);
 24		name = shstrtab + swap_uint32(shdr->sh_name);
 25
 26		/*
 27		 * Ensure there are no relocation sections - ld.so does not
 28		 * relocate the VDSO so if there are relocations things will
 29		 * break.
 30		 */
 31		switch (swap_uint32(shdr->sh_type)) {
 32		case SHT_REL:
 33		case SHT_RELA:
 34			fprintf(stderr,
 35				"%s: '%s' contains relocation sections\n",
 36				program_name, path);
 37			return false;
 38		}
 39
 40		/* Check for existing sections. */
 41		if (strcmp(name, ".MIPS.abiflags") == 0) {
 42			fprintf(stderr,
 43				"%s: '%s' already contains a '.MIPS.abiflags' section\n",
 44				program_name, path);
 45			return false;
 46		}
 47
 48		if (strcmp(name, ".mips_abiflags") == 0) {
 49			strcpy(name, ".MIPS.abiflags");
 50			shdr->sh_type = swap_uint32(SHT_MIPS_ABIFLAGS);
 51			shdr->sh_entsize = shdr->sh_size;
 52		}
 53	}
 54
 55	return true;
 56}
 57
 58static inline bool FUNC(get_symbols)(const char *path, void *vdso)
 59{
 60	const ELF(Ehdr) *ehdr = vdso;
 61	void *shdrs, *symtab;
 62	ELF(Shdr) *shdr;
 63	const ELF(Sym) *sym;
 64	char *strtab, *name;
 65	uint16_t sh_count, sh_entsize, st_count, st_entsize, i, j;
 66	uint64_t offset;
 67	uint32_t flags;
 68
 69	shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff);
 70	sh_count = swap_uint16(ehdr->e_shnum);
 71	sh_entsize = swap_uint16(ehdr->e_shentsize);
 72
 73	for (i = 0; i < sh_count; i++) {
 74		shdr = shdrs + (i * sh_entsize);
 75
 76		if (swap_uint32(shdr->sh_type) == SHT_SYMTAB)
 77			break;
 78	}
 79
 80	if (i == sh_count) {
 81		fprintf(stderr, "%s: '%s' has no symbol table\n", program_name,
 82			path);
 83		return false;
 84	}
 85
 86	/* Get flags */
 87	flags = swap_uint32(ehdr->e_flags);
 88	if (elf_class == ELFCLASS64)
 89		elf_abi = ABI_N64;
 90	else if (flags & EF_MIPS_ABI2)
 91		elf_abi = ABI_N32;
 92	else
 93		elf_abi = ABI_O32;
 94
 95	/* Get symbol table. */
 96	symtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
 97	st_entsize = FUNC(swap_uint)(shdr->sh_entsize);
 98	st_count = FUNC(swap_uint)(shdr->sh_size) / st_entsize;
 99
100	/* Get string table. */
101	shdr = shdrs + (swap_uint32(shdr->sh_link) * sh_entsize);
102	strtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
103
104	/* Write offsets for symbols needed by the kernel. */
105	for (i = 0; vdso_symbols[i].name; i++) {
106		if (!(vdso_symbols[i].abis & elf_abi))
107			continue;
108
109		for (j = 0; j < st_count; j++) {
110			sym = symtab + (j * st_entsize);
111			name = strtab + swap_uint32(sym->st_name);
112
113			if (!strcmp(name, vdso_symbols[i].name)) {
114				offset = FUNC(swap_uint)(sym->st_value);
115
116				fprintf(out_file,
117					"\t.%s = 0x%" PRIx64 ",\n",
118					vdso_symbols[i].offset_name, offset);
119				break;
120			}
121		}
122
123		if (j == st_count) {
124			fprintf(stderr,
125				"%s: '%s' is missing required symbol '%s'\n",
126				program_name, path, vdso_symbols[i].name);
127			return false;
128		}
129	}
130
131	return true;
132}