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 GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
   8 {
   9         int found_load = 0;
  10         unsigned long load_size = -1;  /* Work around bogus warning */
  11         unsigned long data_size;
  12         Elf_Ehdr *hdr = (Elf_Ehdr *)addr;
  13         int i;
  14         unsigned long j;
  15         Elf_Shdr *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
  16                 *alt_sec = NULL;
  17         Elf_Dyn *dyn = 0, *dyn_end = 0;
  18         const char *secstrings;
  19         uint64_t syms[NSYMS] = {};
  20
  21         Elf_Phdr *pt = (Elf_Phdr *)(addr + GET_LE(&hdr->e_phoff));
  22
  23         /* Walk the segment table. */
  24         for (i = 0; i < GET_LE(&hdr->e_phnum); i++) {
  25                 if (GET_LE(&pt[i].p_type) == PT_LOAD) {
  26                         if (found_load)
  27                                 fail("multiple PT_LOAD segs\n");
  28
  29                         if (GET_LE(&pt[i].p_offset) != 0 ||
  30                             GET_LE(&pt[i].p_vaddr) != 0)
  31                                 fail("PT_LOAD in wrong place\n");
  32
  33                         if (GET_LE(&pt[i].p_memsz) != GET_LE(&pt[i].p_filesz))
  34                                 fail("cannot handle memsz != filesz\n");
  35
  36                         load_size = GET_LE(&pt[i].p_memsz);
  37                         found_load = 1;
  38                 } else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) {
  39                         dyn = addr + GET_LE(&pt[i].p_offset);
  40                         dyn_end = addr + GET_LE(&pt[i].p_offset) +
  41                                 GET_LE(&pt[i].p_memsz);
  42                 }
  43         }
  44         if (!found_load)
  45                 fail("no PT_LOAD seg\n");
  46         data_size = (load_size + 4095) / 4096 * 4096;
  47
  48         /* Walk the dynamic table */
  49         for (i = 0; dyn + i < dyn_end &&
  50                      GET_LE(&dyn[i].d_tag) != DT_NULL; i++) {
  51                 typeof(dyn[i].d_tag) tag = GET_LE(&dyn[i].d_tag);
  52                 if (tag == DT_REL || tag == DT_RELSZ ||
  53                     tag == DT_RELENT || tag == DT_TEXTREL)
  54                         fail("vdso image contains dynamic relocations\n");
  55         }
  56
  57         /* Walk the section table */
  58         secstrings_hdr = addr + GET_LE(&hdr->e_shoff) +
  59                 GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx);
  60         secstrings = addr + GET_LE(&secstrings_hdr->sh_offset);
  61         for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
  62                 Elf_Shdr *sh = addr + GET_LE(&hdr->e_shoff) +
  63                         GET_LE(&hdr->e_shentsize) * i;
  64                 if (GET_LE(&sh->sh_type) == SHT_SYMTAB)
  65                         symtab_hdr = sh;
  66
  67                 if (!strcmp(secstrings + GET_LE(&sh->sh_name),
  68                             ".altinstructions"))
  69                         alt_sec = sh;
  70         }
  71
  72         if (!symtab_hdr)
  73                 fail("no symbol table\n");
  74
  75         strtab_hdr = addr + GET_LE(&hdr->e_shoff) +
  76                 GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link);
  77
  78         /* Walk the symbol table */
  79         for (i = 0;
  80              i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
  81              i++) {
  82                 int k;
  83                 Elf_Sym *sym = addr + GET_LE(&symtab_hdr->sh_offset) +
  84                         GET_LE(&symtab_hdr->sh_entsize) * i;
  85                 const char *name = addr + GET_LE(&strtab_hdr->sh_offset) +
  86                         GET_LE(&sym->st_name);
  87                 for (k = 0; k < NSYMS; k++) {
  88                         if (!strcmp(name, required_syms[k])) {
  89                                 if (syms[k]) {
  90                                         fail("duplicate symbol %s\n",
  91                                              required_syms[k]);
  92                                 }
  93                                 syms[k] = GET_LE(&sym->st_value);
  94                         }
  95                 }
  96         }
  97
  98         /* Validate mapping addresses. */
  99         for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
 100                 if (!syms[i])
 101                         continue;  /* The mapping isn't used; ignore it. */
 102
 103                 if (syms[i] % 4096)
 104                         fail("%s must be a multiple of 4096\n",
 105                              required_syms[i]);
 106                 if (syms[i] < data_size)
 107                         fail("%s must be after the text mapping\n",
 108                              required_syms[i]);
 109                 if (syms[sym_end_mapping] < syms[i] + 4096)
 110                         fail("%s overruns end_mapping\n", required_syms[i]);
 111         }
 112         if (syms[sym_end_mapping] % 4096)
 113                 fail("end_mapping must be a multiple of 4096\n");
 114
 115         /* Remove sections. */
 116         hdr->e_shoff = 0;
 117         hdr->e_shentsize = 0;
 118         hdr->e_shnum = 0;
 119         hdr->e_shstrndx = SHN_UNDEF; /* SHN_UNDEF == 0 */
 120
 121         if (!name) {
 122                 fwrite(addr, load_size, 1, outfile);
 123                 return;
 124         }
 125
 126         fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n");
 127         fprintf(outfile, "#include <linux/linkage.h>\n");
 128         fprintf(outfile, "#include <asm/page_types.h>\n");
 129         fprintf(outfile, "#include <asm/vdso.h>\n");
 130         fprintf(outfile, "\n");
 131         fprintf(outfile,
 132                 "static unsigned char raw_data[%lu] __page_aligned_data = {",
 133                 data_size);
 134         for (j = 0; j < load_size; j++) {
 135                 if (j % 10 == 0)
 136                         fprintf(outfile, "\n\t");
 137                 fprintf(outfile, "0x%02X, ", (int)((unsigned char *)addr)[j]);
 138         }
 139         fprintf(outfile, "\n};\n\n");
 140
 141         fprintf(outfile, "static struct page *pages[%lu];\n\n",
 142                 data_size / 4096);
 143
 144         fprintf(outfile, "const struct vdso_image %s = {\n", name);
 145         fprintf(outfile, "\t.data = raw_data,\n");
 146         fprintf(outfile, "\t.size = %lu,\n", data_size);
 147         fprintf(outfile, "\t.text_mapping = {\n");
 148         fprintf(outfile, "\t\t.name = \"[vdso]\",\n");
 149         fprintf(outfile, "\t\t.pages = pages,\n");
 150         fprintf(outfile, "\t},\n");
 151         if (alt_sec) {
 152                 fprintf(outfile, "\t.alt = %lu,\n",
 153                         (unsigned long)GET_LE(&alt_sec->sh_offset));
 154                 fprintf(outfile, "\t.alt_len = %lu,\n",
 155                         (unsigned long)GET_LE(&alt_sec->sh_size));
 156         }
 157         for (i = 0; i < NSYMS; i++) {
 158                 if (syms[i])
 159                         fprintf(outfile, "\t.sym_%s = 0x%" PRIx64 ",\n",
 160                                 required_syms[i], syms[i]);
 161         }
 162         fprintf(outfile, "};\n");
 163 }