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