/*
 * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
 */

/*
 * This file is included up to twice from vdso2c.c.  It generates code for
 * 32-bit and 64-bit vDSOs.  We will eventually need both for 64-bit builds,
 * since 32-bit vDSOs will then be built for 32-bit userspace.
 */

static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
                         void *stripped_addr, size_t stripped_len,
                         FILE *outfile, const char *name)
{
        int found_load = 0;
        unsigned long load_size = -1;  /* Work around bogus warning */
        unsigned long mapping_size;
        int i;
        unsigned long j;
        ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr;
        ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
        ELF(Dyn) *dyn = 0, *dyn_end = 0;
        INT_BITS syms[NSYMS] = {};

        ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_BE(&hdr->e_phoff));

        /* Walk the segment table. */
        for (i = 0; i < GET_BE(&hdr->e_phnum); i++) {
                if (GET_BE(&pt[i].p_type) == PT_LOAD) {
                        if (found_load)
                                fail("multiple PT_LOAD segs\n");

                        if (GET_BE(&pt[i].p_offset) != 0 ||
                            GET_BE(&pt[i].p_vaddr) != 0)
                                fail("PT_LOAD in wrong place\n");

                        if (GET_BE(&pt[i].p_memsz) != GET_BE(&pt[i].p_filesz))
                                fail("cannot handle memsz != filesz\n");

                        load_size = GET_BE(&pt[i].p_memsz);
                        found_load = 1;
                } else if (GET_BE(&pt[i].p_type) == PT_DYNAMIC) {
                        dyn = raw_addr + GET_BE(&pt[i].p_offset);
                        dyn_end = raw_addr + GET_BE(&pt[i].p_offset) +
                                GET_BE(&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");

        /* Walk the dynamic table */
        for (i = 0; dyn + i < dyn_end &&
                     GET_BE(&dyn[i].d_tag) != DT_NULL; i++) {
                typeof(dyn[i].d_tag) tag = GET_BE(&dyn[i].d_tag);
                typeof(dyn[i].d_un.d_val) val = GET_BE(&dyn[i].d_un.d_val);

                if ((tag == DT_RELSZ || tag == DT_RELASZ) && (val != 0))
                        fail("vdso image contains dynamic relocations\n");
        }

        /* Walk the section table */
        for (i = 0; i < GET_BE(&hdr->e_shnum); i++) {
                ELF(Shdr) *sh = raw_addr + GET_BE(&hdr->e_shoff) +
                        GET_BE(&hdr->e_shentsize) * i;
                if (GET_BE(&sh->sh_type) == SHT_SYMTAB)
                        symtab_hdr = sh;
        }

        if (!symtab_hdr)
                fail("no symbol table\n");

        strtab_hdr = raw_addr + GET_BE(&hdr->e_shoff) +
                GET_BE(&hdr->e_shentsize) * GET_BE(&symtab_hdr->sh_link);

        /* Walk the symbol table */
        for (i = 0;
             i < GET_BE(&symtab_hdr->sh_size) / GET_BE(&symtab_hdr->sh_entsize);
             i++) {
                int k;

                ELF(Sym) *sym = raw_addr + GET_BE(&symtab_hdr->sh_offset) +
                        GET_BE(&symtab_hdr->sh_entsize) * i;
                const char *name = raw_addr + GET_BE(&strtab_hdr->sh_offset) +
                        GET_BE(&sym->st_name);

                for (k = 0; k < NSYMS; k++) {
                        if (!strcmp(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_BE(&sym->st_value);
                        }
                }
        }

        /* Validate mapping addresses. */
        if (syms[sym_vvar_start] % 8192)
                fail("vvar_begin must be a multiple of 8192\n");

        if (!name) {
                fwrite(stripped_addr, stripped_len, 1, outfile);
                return;
        }

        mapping_size = (stripped_len + 8191) / 8192 * 8192;

        fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n");
        fprintf(outfile, "#include <linux/cache.h>\n");
        fprintf(outfile, "#include <asm/vdso.h>\n");
        fprintf(outfile, "\n");
        fprintf(outfile,
                "static unsigned char raw_data[%lu] __ro_after_init __aligned(8192)= {",
                mapping_size);
        for (j = 0; j < stripped_len; j++) {
                if (j % 10 == 0)
                        fprintf(outfile, "\n\t");
                fprintf(outfile, "0x%02X, ",
                        (int)((unsigned char *)stripped_addr)[j]);
        }
        fprintf(outfile, "\n};\n\n");

        fprintf(outfile, "const struct vdso_image %s_builtin = {\n", name);
        fprintf(outfile, "\t.data = raw_data,\n");
        fprintf(outfile, "\t.size = %lu,\n", mapping_size);
        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");
}