arch/x86/entry/vdso/vdso2c.h - linux - Git at Google

 /* 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");
 }
	/* 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");
	}