[linux-2.6-block.git] / tools / perf / util / genelf.c

/*
 * genelf.c
 * Copyright (C) 2014, Google, Inc
 *
 * Contributed by:
 * 	Stephane Eranian <eranian@gmail.com>
 *
 * Released under the GPL v2. (and only v2, not any later version)
 */

#include <sys/types.h>
#include <stdio.h>
#include <getopt.h>
#include <stddef.h>
#include <libelf.h>
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include <limits.h>
#include <fcntl.h>
#include <err.h>
#include <dwarf.h>

#include "perf.h"
#include "genelf.h"
#include "../util/jitdump.h"

#define JVMTI

#define BUILD_ID_URANDOM /* different uuid for each run */

#ifdef HAVE_LIBCRYPTO

#define BUILD_ID_MD5
#undef BUILD_ID_SHA	/* does not seem to work well when linked with Java */
#undef BUILD_ID_URANDOM /* different uuid for each run */

#ifdef BUILD_ID_SHA
#include <openssl/sha.h>
#endif

#ifdef BUILD_ID_MD5
#include <openssl/md5.h>
#endif
#endif


typedef struct {
  unsigned int namesz;  /* Size of entry's owner string */
  unsigned int descsz;  /* Size of the note descriptor */
  unsigned int type;    /* Interpretation of the descriptor */
  char         name[0]; /* Start of the name+desc data */
} Elf_Note;

struct options {
	char *output;
	int fd;
};

static char shd_string_table[] = {
	0,
	'.', 't', 'e', 'x', 't', 0,			/*  1 */
	'.', 's', 'h', 's', 't', 'r', 't', 'a', 'b', 0, /*  7 */
	'.', 's', 'y', 'm', 't', 'a', 'b', 0,		/* 17 */
	'.', 's', 't', 'r', 't', 'a', 'b', 0,		/* 25 */
	'.', 'n', 'o', 't', 'e', '.', 'g', 'n', 'u', '.', 'b', 'u', 'i', 'l', 'd', '-', 'i', 'd', 0, /* 33 */
	'.', 'd', 'e', 'b', 'u', 'g', '_', 'l', 'i', 'n', 'e', 0, /* 52 */
	'.', 'd', 'e', 'b', 'u', 'g', '_', 'i', 'n', 'f', 'o', 0, /* 64 */
	'.', 'd', 'e', 'b', 'u', 'g', '_', 'a', 'b', 'b', 'r', 'e', 'v', 0, /* 76 */
};

static struct buildid_note {
	Elf_Note desc;		/* descsz: size of build-id, must be multiple of 4 */
	char	 name[4];	/* GNU\0 */
	char	 build_id[20];
} bnote;

static Elf_Sym symtab[]={
	/* symbol 0 MUST be the undefined symbol */
	{ .st_name  = 0, /* index in sym_string table */
	  .st_info  = ELF_ST_TYPE(STT_NOTYPE),
	  .st_shndx = 0, /* for now */
	  .st_value = 0x0,
	  .st_other = ELF_ST_VIS(STV_DEFAULT),
	  .st_size  = 0,
	},
	{ .st_name  = 1, /* index in sym_string table */
	  .st_info  = ELF_ST_BIND(STB_LOCAL) | ELF_ST_TYPE(STT_FUNC),
	  .st_shndx = 1,
	  .st_value = 0, /* for now */
	  .st_other = ELF_ST_VIS(STV_DEFAULT),
	  .st_size  = 0, /* for now */
	}
};

#ifdef BUILD_ID_URANDOM
static void
gen_build_id(struct buildid_note *note,
	     unsigned long load_addr __maybe_unused,
	     const void *code __maybe_unused,
	     size_t csize __maybe_unused)
{
	int fd;
	size_t sz = sizeof(note->build_id);
	ssize_t sret;

	fd = open("/dev/urandom", O_RDONLY);
	if (fd == -1)
		err(1, "cannot access /dev/urandom for builid");

	sret = read(fd, note->build_id, sz);

	close(fd);

	if (sret != (ssize_t)sz)
		memset(note->build_id, 0, sz);
}
#endif

#ifdef BUILD_ID_SHA
static void
gen_build_id(struct buildid_note *note,
	     unsigned long load_addr __maybe_unused,
	     const void *code,
	     size_t csize)
{
	if (sizeof(note->build_id) < SHA_DIGEST_LENGTH)
		errx(1, "build_id too small for SHA1");

	SHA1(code, csize, (unsigned char *)note->build_id);
}
#endif

#ifdef BUILD_ID_MD5
static void
gen_build_id(struct buildid_note *note, unsigned long load_addr, const void *code, size_t csize)
{
	MD5_CTX context;

	if (sizeof(note->build_id) < 16)
		errx(1, "build_id too small for MD5");

	MD5_Init(&context);
	MD5_Update(&context, &load_addr, sizeof(load_addr));
	MD5_Update(&context, code, csize);
	MD5_Final((unsigned char *)note->build_id, &context);
}
#endif

/*
 * fd: file descriptor open for writing for the output file
 * load_addr: code load address (could be zero, just used for buildid)
 * sym: function name (for native code - used as the symbol)
 * code: the native code
 * csize: the code size in bytes
 */
int
jit_write_elf(int fd, uint64_t load_addr, const char *sym,
	      const void *code, int csize,
	      void *debug, int nr_debug_entries)
{
	Elf *e;
	Elf_Data *d;
	Elf_Scn *scn;
	Elf_Ehdr *ehdr;
	Elf_Shdr *shdr;
	char *strsym = NULL;
	int symlen;
	int retval = -1;

	if (elf_version(EV_CURRENT) == EV_NONE) {
		warnx("ELF initialization failed");
		return -1;
	}

	e = elf_begin(fd, ELF_C_WRITE, NULL);
	if (!e) {
		warnx("elf_begin failed");
		goto error;
	}

	/*
	 * setup ELF header
	 */
	ehdr = elf_newehdr(e);
	if (!ehdr) {
		warnx("cannot get ehdr");
		goto error;
	}

	ehdr->e_ident[EI_DATA] = GEN_ELF_ENDIAN;
	ehdr->e_ident[EI_CLASS] = GEN_ELF_CLASS;
	ehdr->e_machine = GEN_ELF_ARCH;
	ehdr->e_type = ET_DYN;
	ehdr->e_entry = GEN_ELF_TEXT_OFFSET;
	ehdr->e_version = EV_CURRENT;
	ehdr->e_shstrndx= 2; /* shdr index for section name */

	/*
	 * setup text section
	 */
	scn = elf_newscn(e);
	if (!scn) {
		warnx("cannot create section");
		goto error;
	}

	d = elf_newdata(scn);
	if (!d) {
		warnx("cannot get new data");
		goto error;
	}

	d->d_align = 16;
	d->d_off = 0LL;
	d->d_buf = (void *)code;
	d->d_type = ELF_T_BYTE;
	d->d_size = csize;
	d->d_version = EV_CURRENT;

	shdr = elf_getshdr(scn);
	if (!shdr) {
		warnx("cannot get section header");
		goto error;
	}

	shdr->sh_name = 1;
	shdr->sh_type = SHT_PROGBITS;
	shdr->sh_addr = GEN_ELF_TEXT_OFFSET;
	shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
	shdr->sh_entsize = 0;

	/*
	 * setup section headers string table
	 */
	scn = elf_newscn(e);
	if (!scn) {
		warnx("cannot create section");
		goto error;
	}

	d = elf_newdata(scn);
	if (!d) {
		warnx("cannot get new data");
		goto error;
	}

	d->d_align = 1;
	d->d_off = 0LL;
	d->d_buf = shd_string_table;
	d->d_type = ELF_T_BYTE;
	d->d_size = sizeof(shd_string_table);
	d->d_version = EV_CURRENT;

	shdr = elf_getshdr(scn);
	if (!shdr) {
		warnx("cannot get section header");
		goto error;
	}

	shdr->sh_name = 7; /* offset of '.shstrtab' in shd_string_table */
	shdr->sh_type = SHT_STRTAB;
	shdr->sh_flags = 0;
	shdr->sh_entsize = 0;

	/*
	 * setup symtab section
	 */
	symtab[1].st_size  = csize;
	symtab[1].st_value = GEN_ELF_TEXT_OFFSET;

	scn = elf_newscn(e);
	if (!scn) {
		warnx("cannot create section");
		goto error;
	}

	d = elf_newdata(scn);
	if (!d) {
		warnx("cannot get new data");
		goto error;
	}

	d->d_align = 8;
	d->d_off = 0LL;
	d->d_buf = symtab;
	d->d_type = ELF_T_SYM;
	d->d_size = sizeof(symtab);
	d->d_version = EV_CURRENT;

	shdr = elf_getshdr(scn);
	if (!shdr) {
		warnx("cannot get section header");
		goto error;
	}

	shdr->sh_name = 17; /* offset of '.symtab' in shd_string_table */
	shdr->sh_type = SHT_SYMTAB;
	shdr->sh_flags = 0;
	shdr->sh_entsize = sizeof(Elf_Sym);
	shdr->sh_link = 4; /* index of .strtab section */

	/*
	 * setup symbols string table
	 * 2 = 1 for 0 in 1st entry, 1 for the 0 at end of symbol for 2nd entry
	 */
	symlen = 2 + strlen(sym);
	strsym = calloc(1, symlen);
	if (!strsym) {
		warnx("cannot allocate strsym");
		goto error;
	}
	strcpy(strsym + 1, sym);

	scn = elf_newscn(e);
	if (!scn) {
		warnx("cannot create section");
		goto error;
	}

	d = elf_newdata(scn);
	if (!d) {
		warnx("cannot get new data");
		goto error;
	}

	d->d_align = 1;
	d->d_off = 0LL;
	d->d_buf = strsym;
	d->d_type = ELF_T_BYTE;
	d->d_size = symlen;
	d->d_version = EV_CURRENT;

	shdr = elf_getshdr(scn);
	if (!shdr) {
		warnx("cannot get section header");
		goto error;
	}

	shdr->sh_name = 25; /* offset in shd_string_table */
	shdr->sh_type = SHT_STRTAB;
	shdr->sh_flags = 0;
	shdr->sh_entsize = 0;

	/*
	 * setup build-id section
	 */
	scn = elf_newscn(e);
	if (!scn) {
		warnx("cannot create section");
		goto error;
	}

	d = elf_newdata(scn);
	if (!d) {
		warnx("cannot get new data");
		goto error;
	}

	/*
	 * build-id generation
	 */
	gen_build_id(&bnote, load_addr, code, csize);
	bnote.desc.namesz = sizeof(bnote.name); /* must include 0 termination */
	bnote.desc.descsz = sizeof(bnote.build_id);
	bnote.desc.type   = NT_GNU_BUILD_ID;
	strcpy(bnote.name, "GNU");

	d->d_align = 4;
	d->d_off = 0LL;
	d->d_buf = &bnote;
	d->d_type = ELF_T_BYTE;
	d->d_size = sizeof(bnote);
	d->d_version = EV_CURRENT;

	shdr = elf_getshdr(scn);
	if (!shdr) {
		warnx("cannot get section header");
		goto error;
	}

	shdr->sh_name = 33; /* offset in shd_string_table */
	shdr->sh_type = SHT_NOTE;
	shdr->sh_addr = 0x0;
	shdr->sh_flags = SHF_ALLOC;
	shdr->sh_size = sizeof(bnote);
	shdr->sh_entsize = 0;

	if (debug && nr_debug_entries) {
		retval = jit_add_debug_info(e, load_addr, debug, nr_debug_entries);
		if (retval)
			goto error;
	} else {
		if (elf_update(e, ELF_C_WRITE) < 0) {
			warnx("elf_update 4 failed");
			goto error;
		}
	}

	retval = 0;
error:
	(void)elf_end(e);

	free(strsym);


	return retval;
}

#ifndef JVMTI

static unsigned char x86_code[] = {
    0xBB, 0x2A, 0x00, 0x00, 0x00, /* movl $42, %ebx */
    0xB8, 0x01, 0x00, 0x00, 0x00, /* movl $1, %eax */
    0xCD, 0x80            /* int $0x80 */
};

static struct options options;

int main(int argc, char **argv)
{
	int c, fd, ret;

	while ((c = getopt(argc, argv, "o:h")) != -1) {
		switch (c) {
		case 'o':
			options.output = optarg;
			break;
		case 'h':
			printf("Usage: genelf -o output_file [-h]\n");
			return 0;
		default:
			errx(1, "unknown option");
		}
	}

	fd = open(options.output, O_CREAT|O_TRUNC|O_RDWR, 0666);
	if (fd == -1)
		err(1, "cannot create file %s", options.output);

	ret = jit_write_elf(fd, "main", x86_code, sizeof(x86_code));
	close(fd);

	if (ret != 0)
		unlink(options.output);

	return ret;
}
#endif
Commit	Line	Data
9b07e27f SE	1	/*
	2	* genelf.c
	3	* Copyright (C) 2014, Google, Inc
	4	*
	5	* Contributed by:
	6	* Stephane Eranian <eranian@gmail.com>
	7	*
	8	* Released under the GPL v2. (and only v2, not any later version)
	9	*/
	10
	11	#include <sys/types.h>
	12	#include <stdio.h>
	13	#include <getopt.h>
	14	#include <stddef.h>
	15	#include <libelf.h>
	16	#include <string.h>
	17	#include <stdlib.h>
	18	#include <inttypes.h>
	19	#include <limits.h>
	20	#include <fcntl.h>
	21	#include <err.h>
	22	#include <dwarf.h>
	23
	24	#include "perf.h"
	25	#include "genelf.h"
	26	#include "../util/jitdump.h"
	27
	28	#define JVMTI
	29
	30	#define BUILD_ID_URANDOM /* different uuid for each run */
	31
	32	#ifdef HAVE_LIBCRYPTO
	33
	34	#define BUILD_ID_MD5
	35	#undef BUILD_ID_SHA /* does not seem to work well when linked with Java */
	36	#undef BUILD_ID_URANDOM /* different uuid for each run */
	37
	38	#ifdef BUILD_ID_SHA
	39	#include <openssl/sha.h>
	40	#endif
	41
	42	#ifdef BUILD_ID_MD5
	43	#include <openssl/md5.h>
	44	#endif
	45	#endif
	46
	47
	48	typedef struct {
	49	unsigned int namesz; /* Size of entry's owner string */
	50	unsigned int descsz; /* Size of the note descriptor */
	51	unsigned int type; /* Interpretation of the descriptor */
	52	char name[0]; /* Start of the name+desc data */
	53	} Elf_Note;
	54
	55	struct options {
	56	char *output;
	57	int fd;
	58	};
	59
	60	static char shd_string_table[] = {
	61	0,
	62	'.', 't', 'e', 'x', 't', 0, /* 1 */
	63	'.', 's', 'h', 's', 't', 'r', 't', 'a', 'b', 0, /* 7 */
	64	'.', 's', 'y', 'm', 't', 'a', 'b', 0, /* 17 */
65	'.', 's', 't', 'r', 't', 'a', 'b', 0, /* 25 */
66	'.', 'n', 'o', 't', 'e', '.', 'g', 'n', 'u', '.', 'b', 'u', 'i', 'l', 'd', '-', 'i', 'd', 0, /* 33 */
67	'.', 'd', 'e', 'b', 'u', 'g', '_', 'l', 'i', 'n', 'e', 0, /* 52 */
68	'.', 'd', 'e', 'b', 'u', 'g', '_', 'i', 'n', 'f', 'o', 0, /* 64 */
69	'.', 'd', 'e', 'b', 'u', 'g', '_', 'a', 'b', 'b', 'r', 'e', 'v', 0, /* 76 */
70	};
71
72	static struct buildid_note {
73	Elf_Note desc; /* descsz: size of build-id, must be multiple of 4 */
74	char name[4]; /* GNU\0 */
75	char build_id[20];
76	} bnote;
77
78	static Elf_Sym symtab[]={
79	/* symbol 0 MUST be the undefined symbol */
80	{ .st_name = 0, /* index in sym_string table */
81	.st_info = ELF_ST_TYPE(STT_NOTYPE),
82	.st_shndx = 0, /* for now */
83	.st_value = 0x0,
84	.st_other = ELF_ST_VIS(STV_DEFAULT),
85	.st_size = 0,
86	},
87	{ .st_name = 1, /* index in sym_string table */
88	.st_info = ELF_ST_BIND(STB_LOCAL) \| ELF_ST_TYPE(STT_FUNC),
89	.st_shndx = 1,
90	.st_value = 0, /* for now */
91	.st_other = ELF_ST_VIS(STV_DEFAULT),
92	.st_size = 0, /* for now */
93	}
94	};
95
96	#ifdef BUILD_ID_URANDOM
97	static void
98	gen_build_id(struct buildid_note *note,
99	unsigned long load_addr __maybe_unused,
100	const void *code __maybe_unused,
101	size_t csize __maybe_unused)
102	{
103	int fd;
104	size_t sz = sizeof(note->build_id);
105	ssize_t sret;
106
107	fd = open("/dev/urandom", O_RDONLY);
108	if (fd == -1)
109	err(1, "cannot access /dev/urandom for builid");
110
111	sret = read(fd, note->build_id, sz);
112
113	close(fd);
114
115	if (sret != (ssize_t)sz)
116	memset(note->build_id, 0, sz);
117	}
118	#endif
119
120	#ifdef BUILD_ID_SHA
121	static void
122	gen_build_id(struct buildid_note *note,
123	unsigned long load_addr __maybe_unused,
124	const void *code,
125	size_t csize)
126	{
127	if (sizeof(note->build_id) < SHA_DIGEST_LENGTH)
128	errx(1, "build_id too small for SHA1");
129
130	SHA1(code, csize, (unsigned char *)note->build_id);
131	}
132	#endif
133
134	#ifdef BUILD_ID_MD5
135	static void
136	gen_build_id(struct buildid_note note, unsigned long load_addr, const void code, size_t csize)
137	{
138	MD5_CTX context;
139
140	if (sizeof(note->build_id) < 16)
141	errx(1, "build_id too small for MD5");
142
143	MD5_Init(&context);
144	MD5_Update(&context, &load_addr, sizeof(load_addr));
145	MD5_Update(&context, code, csize);
146	MD5_Final((unsigned char *)note->build_id, &context);
147	}
148	#endif
149
150	/*
151	* fd: file descriptor open for writing for the output file
152	* load_addr: code load address (could be zero, just used for buildid)
153	* sym: function name (for native code - used as the symbol)
154	* code: the native code
155	* csize: the code size in bytes
156	*/
157	int
158	jit_write_elf(int fd, uint64_t load_addr, const char *sym,
598b7c69 SE	159	const void *code, int csize,
598b7c69 SE	160	void *debug, int nr_debug_entries)
9b07e27f SE	161	{
	162	Elf *e;
	163	Elf_Data *d;
	164	Elf_Scn *scn;
	165	Elf_Ehdr *ehdr;
	166	Elf_Shdr *shdr;
	167	char *strsym = NULL;
	168	int symlen;
	169	int retval = -1;
	170
	171	if (elf_version(EV_CURRENT) == EV_NONE) {
	172	warnx("ELF initialization failed");
	173	return -1;
	174	}
	175
	176	e = elf_begin(fd, ELF_C_WRITE, NULL);
	177	if (!e) {
	178	warnx("elf_begin failed");
	179	goto error;
	180	}
	181
	182	/*
	183	* setup ELF header
	184	*/
	185	ehdr = elf_newehdr(e);
	186	if (!ehdr) {
	187	warnx("cannot get ehdr");
	188	goto error;
	189	}
	190
	191	ehdr->e_ident[EI_DATA] = GEN_ELF_ENDIAN;
	192	ehdr->e_ident[EI_CLASS] = GEN_ELF_CLASS;
	193	ehdr->e_machine = GEN_ELF_ARCH;
	194	ehdr->e_type = ET_DYN;
	195	ehdr->e_entry = GEN_ELF_TEXT_OFFSET;
	196	ehdr->e_version = EV_CURRENT;
	197	ehdr->e_shstrndx= 2; /* shdr index for section name */
	198
	199	/*
	200	* setup text section
	201	*/
	202	scn = elf_newscn(e);
	203	if (!scn) {
	204	warnx("cannot create section");
	205	goto error;
	206	}
	207
	208	d = elf_newdata(scn);
	209	if (!d) {
	210	warnx("cannot get new data");
	211	goto error;
	212	}
	213
	214	d->d_align = 16;
	215	d->d_off = 0LL;
	216	d->d_buf = (void *)code;
	217	d->d_type = ELF_T_BYTE;
	218	d->d_size = csize;
	219	d->d_version = EV_CURRENT;
	220
	221	shdr = elf_getshdr(scn);
	222	if (!shdr) {
	223	warnx("cannot get section header");
	224	goto error;
225	}
226
227	shdr->sh_name = 1;
228	shdr->sh_type = SHT_PROGBITS;
229	shdr->sh_addr = GEN_ELF_TEXT_OFFSET;
230	shdr->sh_flags = SHF_EXECINSTR \| SHF_ALLOC;
231	shdr->sh_entsize = 0;
232
233	/*
234	* setup section headers string table
235	*/
236	scn = elf_newscn(e);
237	if (!scn) {
238	warnx("cannot create section");
239	goto error;
240	}
241
242	d = elf_newdata(scn);
243	if (!d) {
244	warnx("cannot get new data");
245	goto error;
246	}
247
248	d->d_align = 1;
249	d->d_off = 0LL;
250	d->d_buf = shd_string_table;
251	d->d_type = ELF_T_BYTE;
252	d->d_size = sizeof(shd_string_table);
253	d->d_version = EV_CURRENT;
254
255	shdr = elf_getshdr(scn);
256	if (!shdr) {
257	warnx("cannot get section header");
258	goto error;
259	}
260
261	shdr->sh_name = 7; /* offset of '.shstrtab' in shd_string_table */
262	shdr->sh_type = SHT_STRTAB;
263	shdr->sh_flags = 0;
264	shdr->sh_entsize = 0;
265
266	/*
267	* setup symtab section
268	*/
269	symtab[1].st_size = csize;
270	symtab[1].st_value = GEN_ELF_TEXT_OFFSET;
271
272	scn = elf_newscn(e);
273	if (!scn) {
274	warnx("cannot create section");
275	goto error;
276	}
277
278	d = elf_newdata(scn);
279	if (!d) {
280	warnx("cannot get new data");
281	goto error;
282	}
283
284	d->d_align = 8;
285	d->d_off = 0LL;
286	d->d_buf = symtab;
287	d->d_type = ELF_T_SYM;
288	d->d_size = sizeof(symtab);
289	d->d_version = EV_CURRENT;
290
291	shdr = elf_getshdr(scn);
292	if (!shdr) {
293	warnx("cannot get section header");
294	goto error;
295	}
296
297	shdr->sh_name = 17; /* offset of '.symtab' in shd_string_table */
298	shdr->sh_type = SHT_SYMTAB;
299	shdr->sh_flags = 0;
300	shdr->sh_entsize = sizeof(Elf_Sym);
301	shdr->sh_link = 4; /* index of .strtab section */
302
303	/*
304	* setup symbols string table
305	* 2 = 1 for 0 in 1st entry, 1 for the 0 at end of symbol for 2nd entry
306	*/
307	symlen = 2 + strlen(sym);
308	strsym = calloc(1, symlen);
309	if (!strsym) {
310	warnx("cannot allocate strsym");
311	goto error;
312	}
313	strcpy(strsym + 1, sym);
314
315	scn = elf_newscn(e);
316	if (!scn) {
317	warnx("cannot create section");
318	goto error;
319	}
320
321	d = elf_newdata(scn);
322	if (!d) {
323	warnx("cannot get new data");
324	goto error;
325	}
326
327	d->d_align = 1;
328	d->d_off = 0LL;
329	d->d_buf = strsym;
330	d->d_type = ELF_T_BYTE;
331	d->d_size = symlen;
332	d->d_version = EV_CURRENT;
333
334	shdr = elf_getshdr(scn);
335	if (!shdr) {
336	warnx("cannot get section header");
337	goto error;
338	}
339
340	shdr->sh_name = 25; /* offset in shd_string_table */
341	shdr->sh_type = SHT_STRTAB;
342	shdr->sh_flags = 0;
343	shdr->sh_entsize = 0;
344
345	/*
346	* setup build-id section
347	*/
348	scn = elf_newscn(e);
349	if (!scn) {
350	warnx("cannot create section");
351	goto error;
352	}
353
354	d = elf_newdata(scn);
355	if (!d) {
356	warnx("cannot get new data");
357	goto error;
358	}
359
360	/*
361	* build-id generation
362	*/
363	gen_build_id(&bnote, load_addr, code, csize);
364	bnote.desc.namesz = sizeof(bnote.name); /* must include 0 termination */
365	bnote.desc.descsz = sizeof(bnote.build_id);
366	bnote.desc.type = NT_GNU_BUILD_ID;
367	strcpy(bnote.name, "GNU");
368
369	d->d_align = 4;
370	d->d_off = 0LL;
371	d->d_buf = &bnote;
372	d->d_type = ELF_T_BYTE;
373	d->d_size = sizeof(bnote);
374	d->d_version = EV_CURRENT;
375
376	shdr = elf_getshdr(scn);
377	if (!shdr) {
378	warnx("cannot get section header");
379	goto error;
380	}
381
382	shdr->sh_name = 33; /* offset in shd_string_table */
383	shdr->sh_type = SHT_NOTE;
384	shdr->sh_addr = 0x0;
385	shdr->sh_flags = SHF_ALLOC;
386	shdr->sh_size = sizeof(bnote);
387	shdr->sh_entsize = 0;
388
598b7c69 SE	389	if (debug && nr_debug_entries) {
	390	retval = jit_add_debug_info(e, load_addr, debug, nr_debug_entries);
	391	if (retval)
	392	goto error;
	393	} else {
	394	if (elf_update(e, ELF_C_WRITE) < 0) {
	395	warnx("elf_update 4 failed");
	396	goto error;
	397	}
9b07e27f SE	398	}
	399
	400	retval = 0;
	401	error:
	402	(void)elf_end(e);
	403
	404	free(strsym);
	405
	406
	407	return retval;
	408	}
	409
	410	#ifndef JVMTI
	411
	412	static unsigned char x86_code[] = {
	413	0xBB, 0x2A, 0x00, 0x00, 0x00, /* movl $42, %ebx */
	414	0xB8, 0x01, 0x00, 0x00, 0x00, /* movl $1, %eax */
	415	0xCD, 0x80 /* int $0x80 */
	416	};
	417
	418	static struct options options;
	419
	420	int main(int argc, char **argv)
	421	{
	422	int c, fd, ret;
	423
	424	while ((c = getopt(argc, argv, "o:h")) != -1) {
	425	switch (c) {
	426	case 'o':
	427	options.output = optarg;
	428	break;
	429	case 'h':
	430	printf("Usage: genelf -o output_file [-h]\n");
	431	return 0;
	432	default:
	433	errx(1, "unknown option");
	434	}
	435	}
	436
	437	fd = open(options.output, O_CREAT\|O_TRUNC\|O_RDWR, 0666);
	438	if (fd == -1)
	439	err(1, "cannot create file %s", options.output);
	440
	441	ret = jit_write_elf(fd, "main", x86_code, sizeof(x86_code));
	442	close(fd);
	443
	444	if (ret != 0)
	445	unlink(options.output);
	446
	447	return ret;
	448	}
	449	#endif