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