// SPDX-License-Identifier: GPL-2.0-only
/*
* genelf_debug.c
* Copyright (C) 2015, Google, Inc
*
* Contributed by:
* Stephane Eranian <[email protected]>
*
* based on GPLv2 source code from Oprofile
* @remark Copyright 2007 OProfile authors
* @author Philippe Elie
*/
#include <linux/compiler.h>
#include <linux/zalloc.h>
#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 "genelf.h"
#include "../util/jitdump.h"
#define BUFFER_EXT_DFL_SIZE (4 * 1024)
typedef uint32_t uword;
typedef uint16_t uhalf;
typedef int32_t sword;
typedef int16_t shalf;
typedef uint8_t ubyte;
typedef int8_t sbyte;
struct buffer_ext {
size_t cur_pos;
size_t max_sz;
void *data;
};
static void
buffer_ext_dump(struct buffer_ext *be, const char *msg)
{
size_t i;
warnx("DUMP for %s", msg);
for (i = 0 ; i < be->cur_pos; i++)
warnx("%4zu 0x%02x", i, (((char *)be->data)[i]) & 0xff);
}
static inline int
buffer_ext_add(struct buffer_ext *be, void *addr, size_t sz)
{
void *tmp;
size_t be_sz = be->max_sz;
retry:
if ((be->cur_pos + sz) < be_sz) {
memcpy(be->data + be->cur_pos, addr, sz);
be->cur_pos += sz;
return 0;
}
if (!be_sz)
be_sz = BUFFER_EXT_DFL_SIZE;
else
be_sz <<= 1;
tmp = realloc(be->data, be_sz);
if (!tmp)
return -1;
be->data = tmp;
be->max_sz = be_sz;
goto retry;
}
static void
buffer_ext_init(struct buffer_ext *be)
{
be->data = NULL;
be->cur_pos = 0;
be->max_sz = 0;
}
static void
buffer_ext_exit(struct buffer_ext *be)
{
zfree(&be->data);
}
static inline size_t
buffer_ext_size(struct buffer_ext *be)
{
return be->cur_pos;
}
static inline void *
buffer_ext_addr(struct buffer_ext *be)
{
return be->data;
}
struct debug_line_header {
// Not counting this field
uword total_length;
// version number (2 currently)
uhalf version;
// relative offset from next field to
// program statement
uword prolog_length;
ubyte minimum_instruction_length;
ubyte default_is_stmt;
// line_base - see DWARF 2 specs
sbyte line_base;
// line_range - see DWARF 2 specs
ubyte line_range;
// number of opcode + 1
ubyte opcode_base;
/* follow the array of opcode args nr: ubytes [nr_opcode_base] */
/* follow the search directories index, zero terminated string
* terminated by an empty string.
*/
/* follow an array of { filename, LEB128, LEB128, LEB128 }, first is
* the directory index entry, 0 means current directory, then mtime
* and filesize, last entry is followed by en empty string.
*/
/* follow the first program statement */
} __packed;
/* DWARF 2 spec talk only about one possible compilation unit header while
* binutils can handle two flavours of dwarf 2, 32 and 64 bits, this is not
* related to the used arch, an ELF 32 can hold more than 4 Go of debug
* information. For now we handle only DWARF 2 32 bits comp unit. It'll only
* become a problem if we generate more than 4GB of debug information.
*/
struct compilation_unit_header {
uword total_length;
uhalf version;
uword debug_abbrev_offset;
ubyte pointer_size;
} __packed;
#define DW_LNS_num_opcode (DW_LNS_set_isa + 1)
/* field filled at run time are marked with -1 */
static struct debug_line_header const default_debug_line_header = {
.total_length = -1,
.version = 2,
.prolog_length = -1,
.minimum_instruction_length = 1, /* could be better when min instruction size != 1 */
.default_is_stmt = 1, /* we don't take care about basic block */
.line_base = -5, /* sensible value for line base ... */
.line_range = -14, /* ... and line range are guessed statically */
.opcode_base = DW_LNS_num_opcode
};
static ubyte standard_opcode_length[] =
{
0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1
};
#if 0
{
[DW_LNS_advance_pc] = 1,
[DW_LNS_advance_line] = 1,
[DW_LNS_set_file] = 1,
[DW_LNS_set_column] = 1,
[DW_LNS_fixed_advance_pc] = 1,
[DW_LNS_set_isa] = 1,
};
#endif
/* field filled at run time are marked with -1 */
static struct compilation_unit_header default_comp_unit_header = {
.total_length = -1,
.version = 2,
.debug_abbrev_offset = 0, /* we reuse the same abbrev entries for all comp unit */
.pointer_size = sizeof(void *)
};
static void emit_uword(struct buffer_ext *be, uword data)
{
buffer_ext_add(be, &data, sizeof(uword));
}
static void emit_string(struct buffer_ext *be, const char *s)
{
buffer_ext_add(be, (void *)s, strlen(s) + 1);
}
static void emit_unsigned_LEB128(struct buffer_ext *be,
unsigned long data)
{
do {
ubyte cur = data & 0x7F;
data >>= 7;
if (data)
cur |= 0x80;
buffer_ext_add(be, &cur, 1);
} while (data);
}
static void emit_signed_LEB128(struct buffer_ext *be, long data)
{
int more = 1;
int negative = data < 0;
int size = sizeof(long) * CHAR_BIT;
while (more) {
ubyte cur = data & 0x7F;
data >>= 7;
if (negative)
data |= - (1 << (size - 7));
if ((data == 0 && !(cur & 0x40)) ||
(data == -1l && (cur & 0x40)))
more = 0;
else
cur |= 0x80;
buffer_ext_add(be, &cur, 1);
}
}
static void emit_extended_opcode(struct buffer_ext *be, ubyte opcode,
void *data, size_t data_len)
{
buffer_ext_add(be, (char *)"", 1);
emit_unsigned_LEB128(be, data_len + 1);
buffer_ext_add(be, &opcode, 1);
buffer_ext_add(be, data, data_len);
}
static void emit_opcode(struct buffer_ext *be, ubyte opcode)
{
buffer_ext_add(be, &opcode, 1);
}
static void emit_opcode_signed(struct buffer_ext *be,
ubyte opcode, long data)
{
buffer_ext_add(be, &opcode, 1);
emit_signed_LEB128(be, data);
}
static void emit_opcode_unsigned(struct buffer_ext *be, ubyte opcode,
unsigned long data)
{
buffer_ext_add(be, &opcode, 1);
emit_unsigned_LEB128(be, data);
}
static void emit_advance_pc(struct buffer_ext *be, unsigned long delta_pc)
{
emit_opcode_unsigned(be, DW_LNS_advance_pc, delta_pc);
}
static void emit_advance_lineno(struct buffer_ext *be, long delta_lineno)
{
emit_opcode_signed(be, DW_LNS_advance_line, delta_lineno);
}
static void emit_lne_end_of_sequence(struct buffer_ext *be)
{
emit_extended_opcode(be, DW_LNE_end_sequence, NULL, 0);
}
static void emit_set_file(struct buffer_ext *be, unsigned long idx)
{
emit_opcode_unsigned(be, DW_LNS_set_file, idx);
}
static void emit_lne_define_filename(struct buffer_ext *be,
const char *filename)
{
buffer_ext_add(be, (void *)"", 1);
/* LNE field, strlen(filename) + zero termination, 3 bytes for: the dir entry, timestamp, filesize */
emit_unsigned_LEB128(be, strlen(filename) + 5);
emit_opcode(be, DW_LNE_define_file);
emit_string(be, filename);
/* directory index 0=do not know */
emit_unsigned_LEB128(be, 0);
/* last modification date on file 0=do not know */
emit_unsigned_LEB128(be, 0);
/* filesize 0=do not know */
emit_unsigned_LEB128(be, 0);
}
static void emit_lne_set_address(struct buffer_ext *be,
void *address)
{
emit_extended_opcode(be, DW_LNE_set_address, &address, sizeof(unsigned long));
}
static ubyte get_special_opcode(struct debug_entry *ent,
unsigned int last_line,
unsigned long last_vma)
{
unsigned int temp;
unsigned long delta_addr;
/*
* delta from line_base
*/
temp = (ent->lineno - last_line) - default_debug_line_header.line_base;
if (temp >= default_debug_line_header.line_range)
return 0;
/*
* delta of addresses
*/
delta_addr = (ent->addr - last_vma) / default_debug_line_header.minimum_instruction_length;
/* This is not sufficient to ensure opcode will be in [0-256] but
* sufficient to ensure when summing with the delta lineno we will
* not overflow the unsigned long opcode */
if (delta_addr <= 256 / default_debug_line_header.line_range) {
unsigned long opcode = temp +
(delta_addr * default_debug_line_header.line_range) +
default_debug_line_header.opcode_base;
return opcode <= 255 ? opcode : 0;
}
return 0;
}
static void emit_lineno_info(struct buffer_ext *be,
struct debug_entry *ent, size_t nr_entry,
unsigned long code_addr)
{
size_t i;
/* as described in the jitdump format */
const char repeated_name_marker[] = {'\xff', '\0'};
/*
* Machine state at start of a statement program
* address = 0
* file = 1
* line = 1
* column = 0
* is_stmt = default_is_stmt as given in the debug_line_header
* basic block = 0
* end sequence = 0
*/
/* start state of the state machine we take care of */
unsigned long last_vma = 0;
char const *cur_filename = NULL;
unsigned long cur_file_idx = 0;
int last_line = 1;
emit_lne_set_address(be, (void *)code_addr);
for (i = 0; i < nr_entry; i++, ent = debug_entry_next(ent)) {
int need_copy = 0;
ubyte special_opcode;
/*
* check if filename changed, if so add it
*/
if ((!cur_filename || strcmp(cur_filename, ent->name)) &&
strcmp(repeated_name_marker, ent->name)) {
emit_lne_define_filename(be, ent->name);
cur_filename = ent->name;
emit_set_file(be, ++cur_file_idx);
need_copy = 1;
}
special_opcode = get_special_opcode(ent, last_line, last_vma);
if (special_opcode != 0) {
last_line = ent->lineno;
last_vma = ent->addr;
emit_opcode(be, special_opcode);
} else {
/*
* lines differ, emit line delta
*/
if (last_line != ent->lineno) {
emit_advance_lineno(be, ent->lineno - last_line);
last_line = ent->lineno;
need_copy = 1;
}
/*
* addresses differ, emit address delta
*/
if (last_vma != ent->addr) {
emit_advance_pc(be, ent->addr - last_vma);
last_vma = ent->addr;
need_copy = 1;
}
/*
* add new row to matrix
*/
if (need_copy)
emit_opcode(be, DW_LNS_copy);
}
}
}
static void add_debug_line(struct buffer_ext *be,
struct debug_entry *ent, size_t nr_entry,
unsigned long code_addr)
{
struct debug_line_header * dbg_header;
size_t old_size;
old_size = buffer_ext_size(be);
buffer_ext_add(be, (void *)&default_debug_line_header,
sizeof(default_debug_line_header));
buffer_ext_add(be, &standard_opcode_length, sizeof(standard_opcode_length));
// empty directory entry
buffer_ext_add(be, (void *)"", 1);
// empty filename directory
buffer_ext_add(be, (void *)"", 1);
dbg_header = buffer_ext_addr(be) + old_size;
dbg_header->prolog_length = (buffer_ext_size(be) - old_size) -
offsetof(struct debug_line_header, minimum_instruction_length);
emit_lineno_info(be, ent, nr_entry, code_addr);
emit_lne_end_of_sequence(be);
dbg_header = buffer_ext_addr(be) + old_size;
dbg_header->total_length = (buffer_ext_size(be) - old_size) -
offsetof(struct debug_line_header, version);
}
static void
add_debug_abbrev(struct buffer_ext *be)
{
emit_unsigned_LEB128(be, 1);
emit_unsigned_LEB128(be, DW_TAG_compile_unit);
emit_unsigned_LEB128(be, DW_CHILDREN_yes);
emit_unsigned_LEB128(be, DW_AT_stmt_list);
emit_unsigned_LEB128(be, DW_FORM_data4);
emit_unsigned_LEB128(be, 0);
emit_unsigned_LEB128(be, 0);
emit_unsigned_LEB128(be, 0);
}
static void
add_compilation_unit(struct buffer_ext *be,
size_t offset_debug_line)
{
struct compilation_unit_header *comp_unit_header;
size_t old_size = buffer_ext_size(be);
buffer_ext_add(be, &default_comp_unit_header,
sizeof(default_comp_unit_header));
emit_unsigned_LEB128(be, 1);
emit_uword(be, offset_debug_line);
comp_unit_header = buffer_ext_addr(be) + old_size;
comp_unit_header->total_length = (buffer_ext_size(be) - old_size) -
offsetof(struct compilation_unit_header, version);
}
static int
jit_process_debug_info(uint64_t code_addr,
void *debug, int nr_debug_entries,
struct buffer_ext *dl,
struct buffer_ext *da,
struct buffer_ext *di)
{
struct debug_entry *ent = debug;
int i;
for (i = 0; i < nr_debug_entries; i++) {
ent->addr = ent->addr - code_addr;
ent = debug_entry_next(ent);
}
add_compilation_unit(di, buffer_ext_size(dl));
add_debug_line(dl, debug, nr_debug_entries, GEN_ELF_TEXT_OFFSET);
add_debug_abbrev(da);
if (0) buffer_ext_dump(da, "abbrev");
return 0;
}
int
jit_add_debug_info(Elf *e, uint64_t code_addr, void *debug, int nr_debug_entries)
{
Elf_Data *d;
Elf_Scn *scn;
Elf_Shdr *shdr;
struct buffer_ext dl, di, da;
int ret = -1;
buffer_ext_init(&dl);
buffer_ext_init(&di);
buffer_ext_init(&da);
if (jit_process_debug_info(code_addr, debug, nr_debug_entries, &dl, &da, &di))
goto out;
/*
* setup .debug_line section
*/
scn = elf_newscn(e);
if (!scn) {
warnx("cannot create section");
goto out;
}
d = elf_newdata(scn);
if (!d) {
warnx("cannot get new data");
goto out;
}
d->d_align = 1;
d->d_off = 0LL;
d->d_buf = buffer_ext_addr(&dl);
d->d_type = ELF_T_BYTE;
d->d_size = buffer_ext_size(&dl);
d->d_version = EV_CURRENT;
shdr = elf_getshdr(scn);
if (!shdr) {
warnx("cannot get section header");
goto out;
}
shdr->sh_name = 52; /* .debug_line */
shdr->sh_type = SHT_PROGBITS;
shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
shdr->sh_flags = 0;
shdr->sh_entsize = 0;
/*
* setup .debug_info section
*/
scn = elf_newscn(e);
if (!scn) {
warnx("cannot create section");
goto out;
}
d = elf_newdata(scn);
if (!d) {
warnx("cannot get new data");
goto out;
}
d->d_align = 1;
d->d_off = 0LL;
d->d_buf = buffer_ext_addr(&di);
d->d_type = ELF_T_BYTE;
d->d_size = buffer_ext_size(&di);
d->d_version = EV_CURRENT;
shdr = elf_getshdr(scn);
if (!shdr) {
warnx("cannot get section header");
goto out;
}
shdr->sh_name = 64; /* .debug_info */
shdr->sh_type = SHT_PROGBITS;
shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
shdr->sh_flags = 0;
shdr->sh_entsize = 0;
/*
* setup .debug_abbrev section
*/
scn = elf_newscn(e);
if (!scn) {
warnx("cannot create section");
goto out;
}
d = elf_newdata(scn);
if (!d) {
warnx("cannot get new data");
goto out;
}
d->d_align = 1;
d->d_off = 0LL;
d->d_buf = buffer_ext_addr(&da);
d->d_type = ELF_T_BYTE;
d->d_size = buffer_ext_size(&da);
d->d_version = EV_CURRENT;
shdr = elf_getshdr(scn);
if (!shdr) {
warnx("cannot get section header");
goto out;
}
shdr->sh_name = 76; /* .debug_info */
shdr->sh_type = SHT_PROGBITS;
shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */
shdr->sh_flags = 0;
shdr->sh_entsize = 0;
/*
* now we update the ELF image with all the sections
*/
if (elf_update(e, ELF_C_WRITE) < 0)
warnx("elf_update debug failed");
else
ret = 0;
out:
buffer_ext_exit(&dl);
buffer_ext_exit(&di);
buffer_ext_exit(&da);
return ret;
}
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