1 files changed, 293 insertions, 0 deletions
diff --git a/efi/wrapper.c b/efi/wrapper.c
new file mode 100644
index 0000000..1988124
--- /dev/null
+++ b/efi/wrapper.c
@@ -0,0 +1,293 @@
+/*
+ * Copyright (C) 2011 Intel Corporation; author Matt Fleming
+ *
+ * Wrap the ELF shared library in a PE32 (32bit) or PE32+ (64bit) suit.
+ *
+ * Syslinux plays some games with the ELF sections that are not easily
+ * converted to a PE32 executable. For instance, Syslinux requires
+ * that a symbol hash table be present (GNU hash or SysV) so that
+ * symbols in ELF modules can be resolved at runtime but the EFI
+ * firmware loader doesn't like that and refuses to load the file.
+ *
+ * We pretend that we have an EFI executable with a single .text
+ * section so that the EFI loader will load it and jump to the entry
+ * point. Once the Syslinux ELF shared object has control we can do
+ * whatever we want.
+ */
+#include <linux/elf.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "wrapper.h"
+
+#if __SIZEOF_POINTER__ == 4
+typedef Elf32_Ehdr Elf_Ehdr;
+typedef Elf32_Addr Elf_Addr;
+#elif __SIZEOF_POINTER__ == 8
+typedef Elf64_Ehdr Elf_Ehdr;
+typedef Elf64_Addr Elf_Addr;
+#else
+#error "unsupported architecture"
+#endif
+
+/*
+ * 'so_memsz' is the size of the ELF shared object once loaded.
+ * 'data_size' is the size of initialised data in the shared object.
+ *  'class' dictates how the header is written
+ * 	For 32bit machines (class == ELFCLASS32), the optional
+ * 	header includes PE32 header fields
+ * 	For 64bit machines (class == ELFCLASS64), the optional
+ * 	header includes PE32+header fields
+ */
+static void write_header(FILE *f, __uint32_t entry, size_t data_size,
+			 __uint32_t so_memsz, __uint8_t class)
+{
+	struct optional_hdr o_hdr;
+	struct optional_hdr_pe32p o_hdr_pe32p;
+	struct section t_sec;
+	struct extra_hdr e_hdr;
+	struct extra_hdr_pe32p e_hdr_pe32p;
+	struct coff_hdr c_hdr;
+	struct header hdr;
+	__uint32_t total_sz = data_size;
+	__uint32_t hdr_sz;
+	__uint32_t reloc_start, reloc_end;
+
+	/*
+	 * The header size have to be a multiple of file_align, which currently
+	 * is 512
+	 */
+	hdr_sz = 512;
+	total_sz += hdr_sz;
+	entry += hdr_sz;
+
+	memset(&hdr, 0, sizeof(hdr));
+	hdr.msdos_signature = MSDOS_SIGNATURE;
+
+	/*
+	 * The relocs table pointer needs to be >= 0x40 for PE files. It
+	 * informs things like file(1) that we are not an MS-DOS
+	 * executable.
+	 */
+	hdr.relocs_ptr = 0x40;
+
+	hdr.pe_hdr = OFFSETOF(struct header, pe_signature);
+	hdr.pe_signature = PE_SIGNATURE;
+	fwrite(&hdr, sizeof(hdr), 1, f);
+
+	memset(&c_hdr, 0, sizeof(c_hdr));
+	c_hdr.nr_sections = 1;
+	c_hdr.nr_syms = 1;
+	if (class == ELFCLASS32) {
+		c_hdr.arch = IMAGE_FILE_MACHINE_I386;
+		c_hdr.characteristics = IMAGE_FILE_32BIT_MACHINE |
+			IMAGE_FILE_DEBUG_STRIPPED | IMAGE_FILE_EXECUTABLE_IMAGE |
+			IMAGE_FILE_LINE_NUMBERS_STRIPPED;
+		c_hdr.optional_hdr_sz = sizeof(o_hdr) + sizeof(e_hdr);
+		fwrite(&c_hdr, sizeof(c_hdr), 1, f);
+		memset(&o_hdr, 0, sizeof(o_hdr));
+		o_hdr.format = PE32_FORMAT;
+		o_hdr.major_linker_version = 0x02;
+		o_hdr.minor_linker_version = 0x14;
+		o_hdr.code_sz = data_size;
+		o_hdr.entry_point = entry;
+		o_hdr.initialized_data_sz = data_size;
+		fwrite(&o_hdr, sizeof(o_hdr), 1, f);
+		memset(&e_hdr, 0, sizeof(e_hdr));
+		e_hdr.section_align = 4096;
+		e_hdr.file_align = 512;
+		e_hdr.image_sz = hdr_sz + so_memsz;
+		e_hdr.headers_sz = hdr_sz;
+		e_hdr.subsystem = IMAGE_SUBSYSTEM_EFI_APPLICATION;
+		e_hdr.rva_and_sizes_nr = sizeof(e_hdr.data_directory) / sizeof(__uint64_t);
+		fwrite(&e_hdr, sizeof(e_hdr), 1, f);
+	}
+	else if (class == ELFCLASS64) {
+		c_hdr.arch = IMAGE_FILE_MACHINE_X86_64;
+		c_hdr.characteristics = IMAGE_FILE_DEBUG_STRIPPED | IMAGE_FILE_EXECUTABLE_IMAGE |
+			IMAGE_FILE_LINE_NUMBERS_STRIPPED;
+		c_hdr.optional_hdr_sz = sizeof(o_hdr_pe32p) + sizeof(e_hdr_pe32p);
+		fwrite(&c_hdr, sizeof(c_hdr), 1, f);
+		memset(&o_hdr_pe32p, 0, sizeof(o_hdr_pe32p));
+		o_hdr_pe32p.format = PE32P_FORMAT;
+		o_hdr_pe32p.major_linker_version = 0x02;
+		o_hdr_pe32p.minor_linker_version = 0x14;
+		o_hdr_pe32p.code_sz = data_size;
+		o_hdr_pe32p.entry_point = entry;
+		o_hdr.initialized_data_sz = data_size;
+		fwrite(&o_hdr_pe32p, sizeof(o_hdr_pe32p), 1, f);
+		memset(&e_hdr_pe32p, 0, sizeof(e_hdr_pe32p));
+		e_hdr_pe32p.section_align = 4096;
+		e_hdr_pe32p.file_align = 512;
+		e_hdr_pe32p.image_sz = hdr_sz + so_memsz;
+		e_hdr_pe32p.headers_sz = hdr_sz;
+		e_hdr_pe32p.subsystem = IMAGE_SUBSYSTEM_EFI_APPLICATION;
+		e_hdr_pe32p.rva_and_sizes_nr = sizeof(e_hdr_pe32p.data_directory) / sizeof(__uint64_t);
+		fwrite(&e_hdr_pe32p, sizeof(e_hdr_pe32p), 1, f);
+	}
+
+	memset(&t_sec, 0, sizeof(t_sec));
+	strcpy((char *)t_sec.name, ".text");
+	t_sec.virtual_sz = data_size;
+	t_sec.virtual_address = hdr_sz;
+	t_sec.raw_data_sz = t_sec.virtual_sz;
+	t_sec.raw_data = t_sec.virtual_address;
+	t_sec.characteristics = IMAGE_SCN_CNT_CODE |
+		IMAGE_SCN_ALIGN_16BYTES | IMAGE_SCN_MEM_EXECUTE |
+		IMAGE_SCN_MEM_READ;
+	fwrite(&t_sec, sizeof(t_sec), 1, f);
+
+	/*
+	 * Add some padding to align the ELF as needed
+	 */
+	if (ftell(f) > t_sec.virtual_address) {
+		/* Don't rewind! hdr_sz need to be increased. */
+		fprintf(stderr, "PE32+ headers are too large.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	fseek(f, t_sec.virtual_address, SEEK_SET);
+}
+
+static void usage(char *progname)
+{
+	fprintf(stderr,	"usage: %s <ELF shared object> <output file>\n",
+		progname);
+}
+
+int main(int argc, char **argv)
+{
+	Elf32_Ehdr e32_hdr;
+	Elf64_Ehdr e64_hdr;
+	__uint32_t entry;
+	__uint8_t class;
+	__uint64_t phoff = 0;
+	__uint16_t phnum = 0, phentsize = 0;
+	unsigned char *id;
+	FILE *f_in, *f_out;
+	void *buf;
+	size_t datasz, memsz, rv;
+
+	if (argc < 3) {
+		usage(argv[0]);
+		exit(0);
+	}
+
+	f_in = fopen(argv[1], "r");
+	if (!f_in) {
+		perror("fopen");
+		exit(EXIT_FAILURE);
+	}
+
+	f_out = fopen(argv[2], "w");
+	if (!f_out) {
+		perror("fopen");
+		exit(EXIT_FAILURE);
+	}
+
+	/*
+	 * Parse the ELF header and find the entry point.
+	 */
+	fread((void *)&e32_hdr, sizeof(e32_hdr), 1, f_in);
+	if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS32) {
+		id = e32_hdr.e_ident;
+		class = ELFCLASS32;
+		entry = e32_hdr.e_entry;
+		phoff = e32_hdr.e_phoff;
+		phnum = e32_hdr.e_phnum;
+		phentsize = e32_hdr.e_phentsize;
+	}
+	else if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS64) {
+		/* read the header again for x86_64 
+		 * note that the elf header entry point is 64bit whereas
+		 * the entry point in PE/COFF format is 32bit!*/
+		class = ELFCLASS64;
+		rewind(f_in);
+		fread((void *)&e64_hdr, sizeof(e64_hdr), 1, f_in);
+		id = e64_hdr.e_ident;
+		entry = e64_hdr.e_entry;
+		phoff = e64_hdr.e_phoff;
+		phnum = e64_hdr.e_phnum;
+		phentsize = e64_hdr.e_phentsize;
+	} else {
+		fprintf(stderr, "Unsupported architecture\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (id[EI_MAG0] != ELFMAG0 ||
+	    id[EI_MAG1] != ELFMAG1 ||
+	    id[EI_MAG2] != ELFMAG2 ||
+	    id[EI_MAG3] != ELFMAG3) {
+		fprintf(stderr, "Input file not ELF shared object\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (!phoff || !phnum) {
+		fprintf(stderr, "Cannot find segment table\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/*
+	 * Find the LOAD program header. Everything in this segment
+	 * is copied verbatim to the output file.
+	 * Although there may be several LOAD program headers, only
+	 * one is currently copied.
+	 */
+	if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS32) {
+		Elf32_Phdr phdr;
+		int i;
+
+		/* Find the first LOAD program header */
+		for (i = 0; i < phnum; i++) {
+			fseek(f_in, phoff + i * phentsize, SEEK_SET);
+			fread(&phdr, sizeof(phdr), 1, f_in);
+
+			if (phdr.p_type == PT_LOAD)
+				break;
+		}
+
+		datasz = phdr.p_filesz;
+		memsz = phdr.p_memsz;
+	} else if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS64) {
+		Elf64_Phdr phdr;
+		int i;
+
+		/* Find the first LOAD program header */
+		for (i = 0; i < phnum; i++) {
+			fseek(f_in, phoff + i * phentsize, SEEK_SET);
+			fread(&phdr, sizeof(phdr), 1, f_in);
+
+			if (phdr.p_type == PT_LOAD)
+				break;
+		}
+
+		datasz = phdr.p_filesz;
+		memsz = phdr.p_memsz;
+	}
+
+	buf = malloc(datasz);
+	if (!buf) {
+		perror("malloc");
+		exit(EXIT_FAILURE);
+	}
+
+	write_header(f_out, entry, datasz, memsz, class);
+
+	/* Write out the entire ELF shared object */
+	rewind(f_in);
+	rv = fread(buf, datasz, 1, f_in);
+	if (!rv && ferror(f_in)) {
+		fprintf(stderr, "Failed to read all bytes from input\n");
+		exit(EXIT_FAILURE);
+	}
+
+	fwrite(buf, datasz, rv, f_out);
+	free(buf);
+	fclose(f_out);
+	fclose(f_in);
+	return 0;
+}