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