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611 lines
14 KiB
611 lines
14 KiB
/*
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* genelf_debug.c
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* Copyright (C) 2015, Google, Inc
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*
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* Contributed by:
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* Stephane Eranian <eranian@google.com>
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*
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* Released under the GPL v2.
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*
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* based on GPLv2 source code from Oprofile
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* @remark Copyright 2007 OProfile authors
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* @author Philippe Elie
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*/
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#include <linux/compiler.h>
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#include <sys/types.h>
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#include <stdio.h>
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#include <getopt.h>
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#include <stddef.h>
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#include <libelf.h>
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#include <string.h>
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#include <stdlib.h>
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#include <inttypes.h>
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#include <limits.h>
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#include <fcntl.h>
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#include <err.h>
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#include <dwarf.h>
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#include "perf.h"
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#include "genelf.h"
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#include "../util/jitdump.h"
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#define BUFFER_EXT_DFL_SIZE (4 * 1024)
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typedef uint32_t uword;
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typedef uint16_t uhalf;
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typedef int32_t sword;
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typedef int16_t shalf;
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typedef uint8_t ubyte;
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typedef int8_t sbyte;
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struct buffer_ext {
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size_t cur_pos;
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size_t max_sz;
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void *data;
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};
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static void
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buffer_ext_dump(struct buffer_ext *be, const char *msg)
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{
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size_t i;
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warnx("DUMP for %s", msg);
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for (i = 0 ; i < be->cur_pos; i++)
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warnx("%4zu 0x%02x", i, (((char *)be->data)[i]) & 0xff);
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}
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static inline int
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buffer_ext_add(struct buffer_ext *be, void *addr, size_t sz)
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{
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void *tmp;
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size_t be_sz = be->max_sz;
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retry:
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if ((be->cur_pos + sz) < be_sz) {
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memcpy(be->data + be->cur_pos, addr, sz);
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be->cur_pos += sz;
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return 0;
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}
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if (!be_sz)
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be_sz = BUFFER_EXT_DFL_SIZE;
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else
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be_sz <<= 1;
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tmp = realloc(be->data, be_sz);
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if (!tmp)
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return -1;
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be->data = tmp;
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be->max_sz = be_sz;
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goto retry;
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}
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static void
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buffer_ext_init(struct buffer_ext *be)
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{
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be->data = NULL;
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be->cur_pos = 0;
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be->max_sz = 0;
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}
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static inline size_t
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buffer_ext_size(struct buffer_ext *be)
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{
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return be->cur_pos;
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}
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static inline void *
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buffer_ext_addr(struct buffer_ext *be)
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{
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return be->data;
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}
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struct debug_line_header {
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// Not counting this field
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uword total_length;
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// version number (2 currently)
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uhalf version;
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// relative offset from next field to
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// program statement
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uword prolog_length;
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ubyte minimum_instruction_length;
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ubyte default_is_stmt;
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// line_base - see DWARF 2 specs
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sbyte line_base;
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// line_range - see DWARF 2 specs
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ubyte line_range;
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// number of opcode + 1
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ubyte opcode_base;
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/* follow the array of opcode args nr: ubytes [nr_opcode_base] */
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/* follow the search directories index, zero terminated string
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* terminated by an empty string.
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*/
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/* follow an array of { filename, LEB128, LEB128, LEB128 }, first is
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* the directory index entry, 0 means current directory, then mtime
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* and filesize, last entry is followed by en empty string.
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*/
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/* follow the first program statement */
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} __packed;
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/* DWARF 2 spec talk only about one possible compilation unit header while
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* binutils can handle two flavours of dwarf 2, 32 and 64 bits, this is not
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* related to the used arch, an ELF 32 can hold more than 4 Go of debug
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* information. For now we handle only DWARF 2 32 bits comp unit. It'll only
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* become a problem if we generate more than 4GB of debug information.
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*/
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struct compilation_unit_header {
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uword total_length;
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uhalf version;
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uword debug_abbrev_offset;
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ubyte pointer_size;
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} __packed;
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#define DW_LNS_num_opcode (DW_LNS_set_isa + 1)
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/* field filled at run time are marked with -1 */
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static struct debug_line_header const default_debug_line_header = {
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.total_length = -1,
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.version = 2,
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.prolog_length = -1,
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.minimum_instruction_length = 1, /* could be better when min instruction size != 1 */
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.default_is_stmt = 1, /* we don't take care about basic block */
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.line_base = -5, /* sensible value for line base ... */
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.line_range = -14, /* ... and line range are guessed statically */
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.opcode_base = DW_LNS_num_opcode
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};
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static ubyte standard_opcode_length[] =
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{
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0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1
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};
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#if 0
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{
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[DW_LNS_advance_pc] = 1,
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[DW_LNS_advance_line] = 1,
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[DW_LNS_set_file] = 1,
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[DW_LNS_set_column] = 1,
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[DW_LNS_fixed_advance_pc] = 1,
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[DW_LNS_set_isa] = 1,
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};
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#endif
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/* field filled at run time are marked with -1 */
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static struct compilation_unit_header default_comp_unit_header = {
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.total_length = -1,
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.version = 2,
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.debug_abbrev_offset = 0, /* we reuse the same abbrev entries for all comp unit */
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.pointer_size = sizeof(void *)
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};
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static void emit_uword(struct buffer_ext *be, uword data)
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{
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buffer_ext_add(be, &data, sizeof(uword));
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}
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static void emit_string(struct buffer_ext *be, const char *s)
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{
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buffer_ext_add(be, (void *)s, strlen(s) + 1);
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}
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static void emit_unsigned_LEB128(struct buffer_ext *be,
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unsigned long data)
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{
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do {
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ubyte cur = data & 0x7F;
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data >>= 7;
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if (data)
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cur |= 0x80;
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buffer_ext_add(be, &cur, 1);
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} while (data);
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}
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static void emit_signed_LEB128(struct buffer_ext *be, long data)
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{
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int more = 1;
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int negative = data < 0;
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int size = sizeof(long) * CHAR_BIT;
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while (more) {
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ubyte cur = data & 0x7F;
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data >>= 7;
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if (negative)
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data |= - (1 << (size - 7));
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if ((data == 0 && !(cur & 0x40)) ||
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(data == -1l && (cur & 0x40)))
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more = 0;
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else
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cur |= 0x80;
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buffer_ext_add(be, &cur, 1);
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}
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}
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static void emit_extended_opcode(struct buffer_ext *be, ubyte opcode,
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void *data, size_t data_len)
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{
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buffer_ext_add(be, (char *)"", 1);
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emit_unsigned_LEB128(be, data_len + 1);
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buffer_ext_add(be, &opcode, 1);
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buffer_ext_add(be, data, data_len);
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}
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static void emit_opcode(struct buffer_ext *be, ubyte opcode)
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{
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buffer_ext_add(be, &opcode, 1);
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}
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static void emit_opcode_signed(struct buffer_ext *be,
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ubyte opcode, long data)
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{
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buffer_ext_add(be, &opcode, 1);
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emit_signed_LEB128(be, data);
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}
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static void emit_opcode_unsigned(struct buffer_ext *be, ubyte opcode,
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unsigned long data)
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{
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buffer_ext_add(be, &opcode, 1);
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emit_unsigned_LEB128(be, data);
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}
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static void emit_advance_pc(struct buffer_ext *be, unsigned long delta_pc)
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{
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emit_opcode_unsigned(be, DW_LNS_advance_pc, delta_pc);
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}
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static void emit_advance_lineno(struct buffer_ext *be, long delta_lineno)
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{
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emit_opcode_signed(be, DW_LNS_advance_line, delta_lineno);
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}
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static void emit_lne_end_of_sequence(struct buffer_ext *be)
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{
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emit_extended_opcode(be, DW_LNE_end_sequence, NULL, 0);
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}
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static void emit_set_file(struct buffer_ext *be, unsigned long idx)
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{
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emit_opcode_unsigned(be, DW_LNS_set_file, idx);
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}
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static void emit_lne_define_filename(struct buffer_ext *be,
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const char *filename)
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{
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buffer_ext_add(be, (void *)"", 1);
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/* LNE field, strlen(filename) + zero termination, 3 bytes for: the dir entry, timestamp, filesize */
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emit_unsigned_LEB128(be, strlen(filename) + 5);
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emit_opcode(be, DW_LNE_define_file);
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emit_string(be, filename);
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/* directory index 0=do not know */
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emit_unsigned_LEB128(be, 0);
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/* last modification date on file 0=do not know */
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emit_unsigned_LEB128(be, 0);
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/* filesize 0=do not know */
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emit_unsigned_LEB128(be, 0);
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}
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static void emit_lne_set_address(struct buffer_ext *be,
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void *address)
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{
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emit_extended_opcode(be, DW_LNE_set_address, &address, sizeof(unsigned long));
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}
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static ubyte get_special_opcode(struct debug_entry *ent,
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unsigned int last_line,
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unsigned long last_vma)
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{
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unsigned int temp;
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unsigned long delta_addr;
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/*
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* delta from line_base
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*/
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temp = (ent->lineno - last_line) - default_debug_line_header.line_base;
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if (temp >= default_debug_line_header.line_range)
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return 0;
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/*
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* delta of addresses
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*/
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delta_addr = (ent->addr - last_vma) / default_debug_line_header.minimum_instruction_length;
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/* This is not sufficient to ensure opcode will be in [0-256] but
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* sufficient to ensure when summing with the delta lineno we will
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* not overflow the unsigned long opcode */
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if (delta_addr <= 256 / default_debug_line_header.line_range) {
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unsigned long opcode = temp +
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(delta_addr * default_debug_line_header.line_range) +
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default_debug_line_header.opcode_base;
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return opcode <= 255 ? opcode : 0;
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}
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return 0;
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}
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static void emit_lineno_info(struct buffer_ext *be,
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struct debug_entry *ent, size_t nr_entry,
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unsigned long code_addr)
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{
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size_t i;
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/*
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* Machine state at start of a statement program
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* address = 0
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* file = 1
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* line = 1
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* column = 0
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* is_stmt = default_is_stmt as given in the debug_line_header
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* basic block = 0
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* end sequence = 0
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*/
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/* start state of the state machine we take care of */
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unsigned long last_vma = code_addr;
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char const *cur_filename = NULL;
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unsigned long cur_file_idx = 0;
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int last_line = 1;
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emit_lne_set_address(be, (void *)code_addr);
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for (i = 0; i < nr_entry; i++, ent = debug_entry_next(ent)) {
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int need_copy = 0;
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ubyte special_opcode;
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/*
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* check if filename changed, if so add it
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*/
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if (!cur_filename || strcmp(cur_filename, ent->name)) {
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emit_lne_define_filename(be, ent->name);
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cur_filename = ent->name;
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emit_set_file(be, ++cur_file_idx);
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need_copy = 1;
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}
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special_opcode = get_special_opcode(ent, last_line, last_vma);
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if (special_opcode != 0) {
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last_line = ent->lineno;
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last_vma = ent->addr;
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emit_opcode(be, special_opcode);
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} else {
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/*
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* lines differ, emit line delta
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*/
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if (last_line != ent->lineno) {
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emit_advance_lineno(be, ent->lineno - last_line);
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last_line = ent->lineno;
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need_copy = 1;
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}
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/*
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* addresses differ, emit address delta
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*/
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if (last_vma != ent->addr) {
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emit_advance_pc(be, ent->addr - last_vma);
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last_vma = ent->addr;
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need_copy = 1;
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}
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/*
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* add new row to matrix
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*/
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if (need_copy)
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emit_opcode(be, DW_LNS_copy);
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}
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}
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}
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static void add_debug_line(struct buffer_ext *be,
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struct debug_entry *ent, size_t nr_entry,
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unsigned long code_addr)
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{
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struct debug_line_header * dbg_header;
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size_t old_size;
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old_size = buffer_ext_size(be);
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buffer_ext_add(be, (void *)&default_debug_line_header,
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sizeof(default_debug_line_header));
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buffer_ext_add(be, &standard_opcode_length, sizeof(standard_opcode_length));
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// empty directory entry
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buffer_ext_add(be, (void *)"", 1);
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// empty filename directory
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buffer_ext_add(be, (void *)"", 1);
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dbg_header = buffer_ext_addr(be) + old_size;
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dbg_header->prolog_length = (buffer_ext_size(be) - old_size) -
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offsetof(struct debug_line_header, minimum_instruction_length);
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emit_lineno_info(be, ent, nr_entry, code_addr);
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emit_lne_end_of_sequence(be);
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dbg_header = buffer_ext_addr(be) + old_size;
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dbg_header->total_length = (buffer_ext_size(be) - old_size) -
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offsetof(struct debug_line_header, version);
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}
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static void
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add_debug_abbrev(struct buffer_ext *be)
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{
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emit_unsigned_LEB128(be, 1);
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emit_unsigned_LEB128(be, DW_TAG_compile_unit);
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emit_unsigned_LEB128(be, DW_CHILDREN_yes);
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emit_unsigned_LEB128(be, DW_AT_stmt_list);
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emit_unsigned_LEB128(be, DW_FORM_data4);
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emit_unsigned_LEB128(be, 0);
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emit_unsigned_LEB128(be, 0);
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emit_unsigned_LEB128(be, 0);
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}
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static void
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add_compilation_unit(struct buffer_ext *be,
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size_t offset_debug_line)
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{
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struct compilation_unit_header *comp_unit_header;
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size_t old_size = buffer_ext_size(be);
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buffer_ext_add(be, &default_comp_unit_header,
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sizeof(default_comp_unit_header));
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emit_unsigned_LEB128(be, 1);
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emit_uword(be, offset_debug_line);
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comp_unit_header = buffer_ext_addr(be) + old_size;
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comp_unit_header->total_length = (buffer_ext_size(be) - old_size) -
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offsetof(struct compilation_unit_header, version);
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}
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static int
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jit_process_debug_info(uint64_t code_addr,
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void *debug, int nr_debug_entries,
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struct buffer_ext *dl,
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struct buffer_ext *da,
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struct buffer_ext *di)
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{
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struct debug_entry *ent = debug;
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int i;
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for (i = 0; i < nr_debug_entries; i++) {
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ent->addr = ent->addr - code_addr;
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ent = debug_entry_next(ent);
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}
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add_compilation_unit(di, buffer_ext_size(dl));
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add_debug_line(dl, debug, nr_debug_entries, 0);
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add_debug_abbrev(da);
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if (0) buffer_ext_dump(da, "abbrev");
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return 0;
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}
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int
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jit_add_debug_info(Elf *e, uint64_t code_addr, void *debug, int nr_debug_entries)
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{
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Elf_Data *d;
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Elf_Scn *scn;
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Elf_Shdr *shdr;
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struct buffer_ext dl, di, da;
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int ret;
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buffer_ext_init(&dl);
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buffer_ext_init(&di);
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buffer_ext_init(&da);
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ret = jit_process_debug_info(code_addr, debug, nr_debug_entries, &dl, &da, &di);
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if (ret)
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return -1;
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/*
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* setup .debug_line section
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*/
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scn = elf_newscn(e);
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if (!scn) {
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warnx("cannot create section");
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return -1;
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}
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d = elf_newdata(scn);
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if (!d) {
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warnx("cannot get new data");
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return -1;
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}
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d->d_align = 1;
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d->d_off = 0LL;
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d->d_buf = buffer_ext_addr(&dl);
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d->d_type = ELF_T_BYTE;
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d->d_size = buffer_ext_size(&dl);
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d->d_version = EV_CURRENT;
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shdr = elf_getshdr(scn);
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if (!shdr) {
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warnx("cannot get section header");
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return -1;
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}
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|
|
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");
|
|
return -1;
|
|
}
|
|
|
|
d = elf_newdata(scn);
|
|
if (!d) {
|
|
warnx("cannot get new data");
|
|
return -1;
|
|
}
|
|
|
|
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");
|
|
return -1;
|
|
}
|
|
|
|
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");
|
|
return -1;
|
|
}
|
|
|
|
d = elf_newdata(scn);
|
|
if (!d) {
|
|
warnx("cannot get new data");
|
|
return -1;
|
|
}
|
|
|
|
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");
|
|
return -1;
|
|
}
|
|
|
|
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");
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|