1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * This file is included twice from vdso2c.c. It generates code for 32-bit 4 * and 64-bit vDSOs. We need both for 64-bit builds, since 32-bit vDSOs 5 * are built for 32-bit userspace. 6 */ 7 8 static void BITSFUNC(go)(void *raw_addr, size_t raw_len, 9 void *stripped_addr, size_t stripped_len, 10 FILE *outfile, const char *image_name) 11 { 12 int found_load = 0; 13 unsigned long load_size = -1; /* Work around bogus warning */ 14 unsigned long mapping_size; 15 ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr; 16 int i; 17 unsigned long j; 18 ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr, 19 *alt_sec = NULL; 20 ELF(Dyn) *dyn = 0, *dyn_end = 0; 21 const char *secstrings; 22 INT_BITS syms[NSYMS] = {}; 23 24 ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_LE(&hdr->e_phoff)); 25 26 if (GET_LE(&hdr->e_type) != ET_DYN) 27 fail("input is not a shared object\n"); 28 29 /* Walk the segment table. */ 30 for (i = 0; i < GET_LE(&hdr->e_phnum); i++) { 31 if (GET_LE(&pt[i].p_type) == PT_LOAD) { 32 if (found_load) 33 fail("multiple PT_LOAD segs\n"); 34 35 if (GET_LE(&pt[i].p_offset) != 0 || 36 GET_LE(&pt[i].p_vaddr) != 0) 37 fail("PT_LOAD in wrong place\n"); 38 39 if (GET_LE(&pt[i].p_memsz) != GET_LE(&pt[i].p_filesz)) 40 fail("cannot handle memsz != filesz\n"); 41 42 load_size = GET_LE(&pt[i].p_memsz); 43 found_load = 1; 44 } else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) { 45 dyn = raw_addr + GET_LE(&pt[i].p_offset); 46 dyn_end = raw_addr + GET_LE(&pt[i].p_offset) + 47 GET_LE(&pt[i].p_memsz); 48 } 49 } 50 if (!found_load) 51 fail("no PT_LOAD seg\n"); 52 53 if (stripped_len < load_size) 54 fail("stripped input is too short\n"); 55 56 if (!dyn) 57 fail("input has no PT_DYNAMIC section -- your toolchain is buggy\n"); 58 59 /* Walk the dynamic table */ 60 for (i = 0; dyn + i < dyn_end && 61 GET_LE(&dyn[i].d_tag) != DT_NULL; i++) { 62 typeof(dyn[i].d_tag) tag = GET_LE(&dyn[i].d_tag); 63 if (tag == DT_REL || tag == DT_RELSZ || tag == DT_RELA || 64 tag == DT_RELENT || tag == DT_TEXTREL) 65 fail("vdso image contains dynamic relocations\n"); 66 } 67 68 /* Walk the section table */ 69 secstrings_hdr = raw_addr + GET_LE(&hdr->e_shoff) + 70 GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx); 71 secstrings = raw_addr + GET_LE(&secstrings_hdr->sh_offset); 72 for (i = 0; i < GET_LE(&hdr->e_shnum); i++) { 73 ELF(Shdr) *sh = raw_addr + GET_LE(&hdr->e_shoff) + 74 GET_LE(&hdr->e_shentsize) * i; 75 if (GET_LE(&sh->sh_type) == SHT_SYMTAB) 76 symtab_hdr = sh; 77 78 if (!strcmp(secstrings + GET_LE(&sh->sh_name), 79 ".altinstructions")) 80 alt_sec = sh; 81 } 82 83 if (!symtab_hdr) 84 fail("no symbol table\n"); 85 86 strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) + 87 GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link); 88 89 /* Walk the symbol table */ 90 for (i = 0; 91 i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize); 92 i++) { 93 int k; 94 ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) + 95 GET_LE(&symtab_hdr->sh_entsize) * i; 96 const char *sym_name = raw_addr + 97 GET_LE(&strtab_hdr->sh_offset) + 98 GET_LE(&sym->st_name); 99 100 for (k = 0; k < NSYMS; k++) { 101 if (!strcmp(sym_name, required_syms[k].name)) { 102 if (syms[k]) { 103 fail("duplicate symbol %s\n", 104 required_syms[k].name); 105 } 106 107 /* 108 * Careful: we use negative addresses, but 109 * st_value is unsigned, so we rely 110 * on syms[k] being a signed type of the 111 * correct width. 112 */ 113 syms[k] = GET_LE(&sym->st_value); 114 } 115 } 116 } 117 118 /* Validate mapping addresses. */ 119 for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) { 120 INT_BITS symval = syms[special_pages[i]]; 121 122 if (!symval) 123 continue; /* The mapping isn't used; ignore it. */ 124 125 if (symval % 4096) 126 fail("%s must be a multiple of 4096\n", 127 required_syms[i].name); 128 if (symval + 4096 < syms[sym_vvar_start]) 129 fail("%s underruns vvar_start\n", 130 required_syms[i].name); 131 if (symval + 4096 > 0) 132 fail("%s is on the wrong side of the vdso text\n", 133 required_syms[i].name); 134 } 135 if (syms[sym_vvar_start] % 4096) 136 fail("vvar_begin must be a multiple of 4096\n"); 137 138 if (!image_name) { 139 fwrite(stripped_addr, stripped_len, 1, outfile); 140 return; 141 } 142 143 mapping_size = (stripped_len + 4095) / 4096 * 4096; 144 145 fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n"); 146 fprintf(outfile, "#include <linux/linkage.h>\n"); 147 fprintf(outfile, "#include <asm/page_types.h>\n"); 148 fprintf(outfile, "#include <asm/vdso.h>\n"); 149 fprintf(outfile, "\n"); 150 fprintf(outfile, 151 "static unsigned char raw_data[%lu] __ro_after_init __aligned(PAGE_SIZE) = {", 152 mapping_size); 153 for (j = 0; j < stripped_len; j++) { 154 if (j % 10 == 0) 155 fprintf(outfile, "\n\t"); 156 fprintf(outfile, "0x%02X, ", 157 (int)((unsigned char *)stripped_addr)[j]); 158 } 159 fprintf(outfile, "\n};\n\n"); 160 161 fprintf(outfile, "const struct vdso_image %s = {\n", image_name); 162 fprintf(outfile, "\t.data = raw_data,\n"); 163 fprintf(outfile, "\t.size = %lu,\n", mapping_size); 164 if (alt_sec) { 165 fprintf(outfile, "\t.alt = %lu,\n", 166 (unsigned long)GET_LE(&alt_sec->sh_offset)); 167 fprintf(outfile, "\t.alt_len = %lu,\n", 168 (unsigned long)GET_LE(&alt_sec->sh_size)); 169 } 170 for (i = 0; i < NSYMS; i++) { 171 if (required_syms[i].export && syms[i]) 172 fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n", 173 required_syms[i].name, (int64_t)syms[i]); 174 } 175 fprintf(outfile, "};\n"); 176 } 177