kernel/arch/x86/vdso/vdso2c.h

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