229 lines
6.9 KiB
C
229 lines
6.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* This file is included twice from vdso2c.c. It generates code for 32-bit
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* and 64-bit vDSOs. We need both for 64-bit builds, since 32-bit vDSOs
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* are built for 32-bit userspace.
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*/
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static void BITSFUNC(copy)(FILE *outfile, const unsigned char *data, size_t len)
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{
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size_t i;
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for (i = 0; i < len; i++) {
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if (i % 10 == 0)
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fprintf(outfile, "\n\t");
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fprintf(outfile, "0x%02X, ", (int)(data)[i]);
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}
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}
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/*
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* Extract a section from the input data into a standalone blob. Used to
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* capture kernel-only data that needs to persist indefinitely, e.g. the
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* exception fixup tables, but only in the kernel, i.e. the section can
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* be stripped from the final vDSO image.
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*/
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static void BITSFUNC(extract)(const unsigned char *data, size_t data_len,
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FILE *outfile, ELF(Shdr) *sec, const char *name)
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{
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unsigned long offset;
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size_t len;
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offset = (unsigned long)GET_LE(&sec->sh_offset);
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len = (size_t)GET_LE(&sec->sh_size);
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if (offset + len > data_len)
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fail("section to extract overruns input data");
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fprintf(outfile, "static const unsigned char %s[%zu] = {", name, len);
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BITSFUNC(copy)(outfile, data + offset, len);
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fprintf(outfile, "\n};\n\n");
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}
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static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
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void *stripped_addr, size_t stripped_len,
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FILE *outfile, const char *image_name)
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{
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int found_load = 0;
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unsigned long load_size = -1; /* Work around bogus warning */
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unsigned long mapping_size;
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ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
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unsigned long i, syms_nr;
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ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
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*alt_sec = NULL, *extable_sec = NULL;
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ELF(Dyn) *dyn = 0, *dyn_end = 0;
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const char *secstrings;
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INT_BITS syms[NSYMS] = {};
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ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_LE(&hdr->e_phoff));
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if (GET_LE(&hdr->e_type) != ET_DYN)
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fail("input is not a shared object\n");
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/* Walk the segment table. */
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for (i = 0; i < GET_LE(&hdr->e_phnum); i++) {
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if (GET_LE(&pt[i].p_type) == PT_LOAD) {
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if (found_load)
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fail("multiple PT_LOAD segs\n");
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if (GET_LE(&pt[i].p_offset) != 0 ||
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GET_LE(&pt[i].p_vaddr) != 0)
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fail("PT_LOAD in wrong place\n");
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if (GET_LE(&pt[i].p_memsz) != GET_LE(&pt[i].p_filesz))
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fail("cannot handle memsz != filesz\n");
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load_size = GET_LE(&pt[i].p_memsz);
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found_load = 1;
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} else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) {
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dyn = raw_addr + GET_LE(&pt[i].p_offset);
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dyn_end = raw_addr + GET_LE(&pt[i].p_offset) +
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GET_LE(&pt[i].p_memsz);
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}
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}
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if (!found_load)
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fail("no PT_LOAD seg\n");
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if (stripped_len < load_size)
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fail("stripped input is too short\n");
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if (!dyn)
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fail("input has no PT_DYNAMIC section -- your toolchain is buggy\n");
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/* Walk the dynamic table */
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for (i = 0; dyn + i < dyn_end &&
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GET_LE(&dyn[i].d_tag) != DT_NULL; i++) {
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typeof(dyn[i].d_tag) tag = GET_LE(&dyn[i].d_tag);
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if (tag == DT_REL || tag == DT_RELSZ || tag == DT_RELA ||
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tag == DT_RELENT || tag == DT_TEXTREL)
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fail("vdso image contains dynamic relocations\n");
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}
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/* Walk the section table */
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secstrings_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
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GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx);
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secstrings = raw_addr + GET_LE(&secstrings_hdr->sh_offset);
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for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
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ELF(Shdr) *sh = raw_addr + GET_LE(&hdr->e_shoff) +
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GET_LE(&hdr->e_shentsize) * i;
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if (GET_LE(&sh->sh_type) == SHT_SYMTAB)
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symtab_hdr = sh;
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if (!strcmp(secstrings + GET_LE(&sh->sh_name),
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".altinstructions"))
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alt_sec = sh;
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if (!strcmp(secstrings + GET_LE(&sh->sh_name), "__ex_table"))
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extable_sec = sh;
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}
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if (!symtab_hdr)
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fail("no symbol table\n");
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strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
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GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link);
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syms_nr = GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
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/* Walk the symbol table */
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for (i = 0; i < syms_nr; i++) {
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unsigned int k;
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ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) +
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GET_LE(&symtab_hdr->sh_entsize) * i;
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const char *sym_name = raw_addr +
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GET_LE(&strtab_hdr->sh_offset) +
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GET_LE(&sym->st_name);
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for (k = 0; k < NSYMS; k++) {
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if (!strcmp(sym_name, required_syms[k].name)) {
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if (syms[k]) {
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fail("duplicate symbol %s\n",
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required_syms[k].name);
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}
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/*
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* Careful: we use negative addresses, but
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* st_value is unsigned, so we rely
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* on syms[k] being a signed type of the
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* correct width.
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*/
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syms[k] = GET_LE(&sym->st_value);
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}
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}
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}
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/* Validate mapping addresses. */
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for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
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INT_BITS symval = syms[special_pages[i]];
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if (!symval)
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continue; /* The mapping isn't used; ignore it. */
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if (symval % 4096)
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fail("%s must be a multiple of 4096\n",
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required_syms[i].name);
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if (symval + 4096 < syms[sym_vvar_start])
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fail("%s underruns vvar_start\n",
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required_syms[i].name);
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if (symval + 4096 > 0)
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fail("%s is on the wrong side of the vdso text\n",
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required_syms[i].name);
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}
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if (syms[sym_vvar_start] % 4096)
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fail("vvar_begin must be a multiple of 4096\n");
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if (!image_name) {
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fwrite(stripped_addr, stripped_len, 1, outfile);
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return;
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}
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mapping_size = (stripped_len + 4095) / 4096 * 4096;
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fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n");
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fprintf(outfile, "#include <linux/linkage.h>\n");
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fprintf(outfile, "#include <linux/init.h>\n");
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fprintf(outfile, "#include <asm/page_types.h>\n");
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fprintf(outfile, "#include <asm/vdso.h>\n");
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fprintf(outfile, "\n");
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fprintf(outfile,
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"static unsigned char raw_data[%lu] __ro_after_init __aligned(PAGE_SIZE) = {",
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mapping_size);
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for (i = 0; i < stripped_len; i++) {
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if (i % 10 == 0)
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fprintf(outfile, "\n\t");
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fprintf(outfile, "0x%02X, ",
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(int)((unsigned char *)stripped_addr)[i]);
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}
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fprintf(outfile, "\n};\n\n");
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if (extable_sec)
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BITSFUNC(extract)(raw_addr, raw_len, outfile,
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extable_sec, "extable");
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fprintf(outfile, "const struct vdso_image %s = {\n", image_name);
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fprintf(outfile, "\t.data = raw_data,\n");
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fprintf(outfile, "\t.size = %lu,\n", mapping_size);
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if (alt_sec) {
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fprintf(outfile, "\t.alt = %lu,\n",
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(unsigned long)GET_LE(&alt_sec->sh_offset));
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fprintf(outfile, "\t.alt_len = %lu,\n",
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(unsigned long)GET_LE(&alt_sec->sh_size));
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}
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if (extable_sec) {
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fprintf(outfile, "\t.extable_base = %lu,\n",
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(unsigned long)GET_LE(&extable_sec->sh_offset));
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fprintf(outfile, "\t.extable_len = %lu,\n",
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(unsigned long)GET_LE(&extable_sec->sh_size));
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fprintf(outfile, "\t.extable = extable,\n");
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}
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for (i = 0; i < NSYMS; i++) {
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if (required_syms[i].export && syms[i])
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fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
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required_syms[i].name, (int64_t)syms[i]);
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}
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fprintf(outfile, "};\n\n");
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fprintf(outfile, "static __init int init_%s(void) {\n", image_name);
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fprintf(outfile, "\treturn init_vdso_image(&%s);\n", image_name);
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fprintf(outfile, "};\n");
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fprintf(outfile, "subsys_initcall(init_%s);\n", image_name);
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}
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