static const char *_stp_kallsyms_lookup(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset,
const char **modname,
/* char ** secname? */
struct task_struct *task)
{
struct _stp_module *m = NULL;
struct _stp_section *sec = NULL;
struct _stp_symbol *s = NULL;
unsigned end, begin = 0;
unsigned long rel_addr = 0;
if (addr == 0)
return NULL;
if (task)
{
unsigned long vm_start = 0;
unsigned long vm_end = 0;
#ifdef CONFIG_COMPAT
/* Handle 32bit signed values in 64bit longs, chop off top bits.
_stp_umod_lookup does the same, but we need it here for the
binary search on addr below. */
if (test_tsk_thread_flag(task, TIF_32BIT))
addr &= ((compat_ulong_t) ~0);
#endif
m = _stp_umod_lookup(addr, task, modname, &vm_start, &vm_end);
if (m)
{
sec = &m->sections[0];
/* XXX .absolute sections really shouldn't be here... */
if (strcmp(".dynamic", m->sections[0].name) == 0)
rel_addr = addr - vm_start;
else
rel_addr = addr;
}
if (modname && *modname)
{
/* In case no symbol is found, fill in based on module. */
if (offset)
*offset = addr - vm_start;
if (symbolsize)
*symbolsize = vm_end - vm_start;
}
}
else
{
m = _stp_kmod_sec_lookup(addr, &sec);
if (m)
{
rel_addr = addr - sec->static_addr;
if (modname)
*modname = m->name;
}
}
if (unlikely (m == NULL || sec == NULL))
return NULL;
/* NB: relativize the address to the section. */
addr = rel_addr;
end = sec->num_symbols;
/* binary search for symbols within the module */
do {
unsigned mid = (begin + end) / 2;
if (addr < sec->symbols[mid].addr)
end = mid;
else
begin = mid;
} while (begin + 1 < end);
/* result index in $begin */
s = & sec->symbols[begin];
if (likely(addr >= s->addr)) {
if (offset)
*offset = addr - s->addr;
/* We could also pass sec->name here. */
if (symbolsize) {
if ((begin + 1) < sec->num_symbols)
*symbolsize = sec->symbols[begin + 1].addr - s->addr;
else
*symbolsize = 0;
// NB: This is only a heuristic. Sometimes there are large
// gaps between text areas of modules.
}
return s->symbol;
}
return NULL;
}
unsigned long _stp_linenumber_lookup(unsigned long addr, struct task_struct *task, char ** filename, int need_filename)
{
struct _stp_module *m;
struct _stp_section *sec;
const char *modname = NULL;
uint8_t *linep, *enddatap;
int compat_task = _stp_is_compat_task();
int user = (task ? 1 : 0);
// the portion below is encased in this conditional because some of the functions
// and constants needed are encased in a similar condition
#ifdef STP_NEED_LINE_DATA
if (addr == 0)
return 0;
if (task)
{
unsigned long vm_start = 0;
unsigned long vm_end = 0;
#ifdef CONFIG_COMPAT
/* Handle 32bit signed values in 64bit longs, chop off top bits. */
if (test_tsk_thread_flag(task, TIF_32BIT))
addr &= ((compat_ulong_t) ~0);
#endif
m = _stp_umod_lookup(addr, task, &modname, &vm_start, &vm_end);
}
else
m = _stp_kmod_sec_lookup(addr, &sec);
if (m == NULL || m->debug_line == NULL)
return 0;
// if addr is a kernel address, it will need to be adjusted
if (!task)
{
int i;
unsigned long offset = 0;
// have to factor in the load_offset of (specifically) the .text section
for (i=0; i<m->num_sections; i++)
if (!strcmp(m->sections[i].name, ".text"))
{
offset = (m->sections[i].static_addr - m->sections[i].sec_load_offset);
break;
}
if (addr < offset)
return 0;
addr = addr - offset;
}
linep = m->debug_line;
enddatap = m->debug_line + m->debug_line_len;
while (linep < enddatap)
{
// similar to print_debug_line_section() in elfutils
unsigned int length = 4, curr_file_idx = 1, prev_file_idx = 1;
unsigned int skip_to_seq_end = 0, op_index = 0;
uint64_t unit_length, hdr_length, curr_addr = 0;
uint8_t *endunitp, *endhdrp, *dirsecp, *stdopcode_lens_secp;
uint16_t version;
uint8_t opcode_base, line_range, min_instr_len = 0, max_ops = 1;
unsigned long curr_linenum = 1;
int8_t line_base;
long cumm_line_adv = 0;
unit_length = (uint64_t) read_pointer ((const uint8_t **) &linep, enddatap, DW_EH_PE_data4, user, compat_task);
if (unit_length == 0xffffffff)
{
if (unlikely (linep + 8 > enddatap))
return 0;
unit_length = (uint64_t) read_pointer ((const uint8_t **) &linep, enddatap, DW_EH_PE_data8, user, compat_task);
length = 8;
}
if (unit_length < (length + 2) || (linep + unit_length) > enddatap)
return 0;
endunitp = linep + unit_length;
version = read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_data2, user, compat_task);
if (length == 4)
hdr_length = (uint64_t) read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_data4, user, compat_task);
else
hdr_length = (uint64_t) read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_data8, user, compat_task);
if ((linep + hdr_length) > endunitp || hdr_length < (version >= 4 ? 6 : 5))
return 0;
endhdrp = linep + hdr_length;
// minimum instruction length
min_instr_len = *linep++;
// max operations per instruction
if (version >= 4)
{
max_ops = *linep++;
if (max_ops == 0)
return 0; // max operations per instruction is supposed to > 0;
}
// default value of the is_stmt register
++linep;
// line base. this is a signed value.
line_base = *linep++;
// line range
line_range = *linep++;
if (line_range == 0)
return 0;
// opcode base
opcode_base = *linep++;
// opcodes
stdopcode_lens_secp = linep - 1;
// need this check if the header length check covers this region?
if ((linep + opcode_base - 1) >= endhdrp)
return 0;
linep += opcode_base - 1;
// at the directory table. don't need an other information from the header
// in order to find the desired line number, so we will save a pointer to
// this point and skip ahead to the end of the header. this portion of the
// header will be visited again after a line number has been found if a
// filename is needed.
dirsecp = linep;
linep = endhdrp;
// iterating through the opcodes. will deal with three defined types of
// opcode: special, extended and standard. there is also a portion at
// the end of this loop that will deal with unknown (standard) opcodes.
while (linep < endunitp)
{
uint8_t opcode = *linep++;
long addr_adv = 0;
if (opcode >= opcode_base) // special opcode
{
// line range was checked before this point. this variable is not altered after it is initialized.
cumm_line_adv += (line_base + ((opcode - opcode_base) % line_range));
addr_adv = ((opcode - opcode_base) / line_range);
}
else if (opcode == 0) // extended opcode
{
int len;
uint8_t subopcode;
if (linep + 1 > endunitp)
return 0;
len = *linep++;
if (linep + len > endunitp || len < 1)
return 0;
subopcode = *linep++; // the sub opcode
switch (subopcode)
{
case DW_LNE_end_sequence:
// reset the line and address.
cumm_line_adv = 1 - curr_linenum;
addr_adv = 0 - curr_addr;
skip_to_seq_end = 0;
op_index = 0;
break;
case DW_LNE_set_address:
if ((len - 1) == 4) // account for the opcode (the -1)
curr_addr = (uint64_t) read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_data4, user, compat_task);
else if ((len - 1) == 8)
curr_addr = (uint64_t) read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_data8, user, compat_task);
else
return 0;
// if the set address is past the address we want, iterate
// to the end of the sequence without doing more address
// and linenumber calcs than necessary
if (curr_addr > addr)
skip_to_seq_end = 1;
op_index = 0;
break;
default: // advance the ptr by the specified amount
linep += len-1;
break;
}
}
else if (opcode <= DW_LNS_set_isa) // known standard opcode
{
uint8_t *linep_before = linep;
switch (opcode)
{
case DW_LNS_advance_pc:
addr_adv = read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_leb128, user, compat_task);
break;
case DW_LNS_fixed_advance_pc:
addr_adv = read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_data2, user, compat_task);
if (linep_before == linep) // the read failed
return 0;
op_index = 0;
break;
case DW_LNS_advance_line:
cumm_line_adv += read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_leb128+DW_EH_PE_signed, user, compat_task);
break;
case DW_LNS_set_file:
curr_file_idx = read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_leb128, user, compat_task);
break;
case DW_LNS_set_column:
read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_leb128, user, compat_task);
break;
case DW_LNS_const_add_pc:
addr_adv = ((255 - opcode_base) / line_range);
break;
case DW_LNS_set_isa:
read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_leb128, user, compat_task);
break;
}
if (linep > endunitp) // reading in the leb128 failed
return 0;
}
else
{
int i;
for (i=stdopcode_lens_secp[opcode]; i>0; --i)
{
read_pointer ((const uint8_t **) &linep, endunitp, DW_EH_PE_leb128, user, compat_task);
if (linep > endunitp)
return 0;
}
}
// don't worry about doing line/address advances since we are waiting
// till we hit the end of the sequence or the end of the unit at which
// point the address and linenumber will be reset
if (skip_to_seq_end == 1)
continue;
// calculate actual address advance
if (opcode != 0 && opcode != DW_LNS_fixed_advance_pc)
{
addr_adv = min_instr_len * (op_index + addr_adv) / max_ops;
op_index = (op_index + addr_adv) % max_ops;
}
// found an address that at least sort of matches the address we
// were looking for
if ((curr_addr <= addr && addr < (curr_addr + addr_adv))
|| (curr_addr == addr && addr_adv != 0))
{
if (need_filename)
_stp_filename_lookup(m, filename, dirsecp, endhdrp,
prev_file_idx, user, compat_task);
return curr_linenum;
}
// update the linenumber and file index if the curr_addr is to be updated
if (addr_adv != 0)
{
prev_file_idx = curr_file_idx;
}
if (prev_file_idx == curr_file_idx)
{
curr_linenum += cumm_line_adv;
cumm_line_adv = 0;
}
curr_addr += addr_adv;
}
}
#endif /* STP_NEED_LINE_DATA */
// no linenumber was found otherwise this function would have returned before this point
return 0;
}
