/* 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");
}