dwarf_get_fde_info_for_reg3 —
retrieve register rule
DWARF Access Library (libdwarf, -ldwarf)
#include
<libdwarf.h>
int
dwarf_get_fde_info_for_reg3(
Dwarf_Fde
fde,
Dwarf_Half table_column,
Dwarf_Addr pc,
Dwarf_Small *type,
Dwarf_Signed *offset_relevant,
Dwarf_Signed *register_num,
Dwarf_Signed *offset_or_block_len,
Dwarf_Ptr *block_ptr,
Dwarf_Addr *row_pc,
Dwarf_Error *error);
Function
dwarf_get_fde_info_for_reg3() retrieves a
register rule from the register rule table associated with a given FDE
descriptor, given a program counter address and rule column number.
Argument
fde should reference a valid DWARF FDE
descriptor.
Arugment
table_column should hold the column
number of the register rule desired.
Argument
pc should hold the program counter
address to be used to locate the desired register rule row.
On successful execution,
dwarf_get_fde_info_for_reg3() stores information
about the register rule found into the locations pointed to by the arguments
type,
offset_relevant,
register_num,
offset_or_block_len,
block_ptr and
row_pc.
Argument
type should point to a location which
will hold the type code of the register rule found. The returned value is one
of the
DW_EXPR_*
contants defined in the
header file
<libdwarf.h>.
If there is an offset value associated with the register rule, the location
pointed to by argument
offset_relevant will
be set to 1.
Argument
register_num should point to a
location which will hold the register number associated with the register
rule.
If the register rule is of type
DW_EXPR_OFFSET
or
DW_EXPR_VAL_OFFSET
, the location pointed to
by argument
offset_or_block_len will be set
to the offset value associated with the register rule, or to 0 if the register
rule does not have an offset value. If the type code is
DW_EXPR_EXPRESSION
or
DW_EXPR_VAL_EXPRESSION
, the location
pointed to by argument
offset_or_block_len
will be set to the length in bytes of the DWARF expression block associated
with the register rule.
Argument
block_ptr should point to a location
which will be set to a pointer to the content of the DWARF expression block
associated with the register rule.
Argument
row_pc should point to a location
which will be set to the lowest program counter address associated with the
register rule found.
If argument
err is not NULL, it will be used to
return an error descriptor in case of an error.
Function
dwarf_get_fde_info_for_reg3() returns
DW_DLV_OK
when it succeeds. In case of an
error, it returns
DW_DLV_ERROR
and sets the
argument
err.
To retrieve the register rules at column 3 from a rule table associated with a
FDE descriptor:
Dwarf_Fde fde;
Dwarf_Off fde_offset, cie_offset;
Dwarf_Unsigned func_len, fde_length;
Dwarf_Signed cie_index, offset_relevant, register_num;
Dwarf_Signed offset_or_block_len;
Dwarf_Addr low_pc, row_pc;
Dwarf_Ptr fde_addr, block_ptr;
Dwarf_Small type;
Dwarf_Error de;
/* ... assuming `fde` references a valid FDE descriptor... */
if (dwarf_get_fde_range(fde, &low_pc, &func_len, &fde_addr,
&fde_length, &cie_offset, &cie_index, &fde_offset,
&de) != DW_DLV_OK)
errx(EXIT_FAILURE, "dwarf_get_fde_range failed: %s",
dwarf_errmsg(de));
/* Iterate all the table rows. */
for (pc = low_pc; pc < low_pc + func_len; pc++) {
if (dwarf_get_fde_info_for_reg3(fde, 3, pc, &type,
&offset_relevant, ®ister_num, &offset_or_block_len,
&block_ptr, &row_pc, &de) != DW_DLV_OK) {
warnx("dwarf_get_fde_info_for_reg3 failed: %s",
dwarf_errmsg(de));
continue;
}
/* ... use the retrieved register rule ... */
}
Function
dwarf_get_fde_info_for_reg3() can fail
with:
-
-
- [
DW_DLE_ARGUMENT
]
- One of the arguments
block_ptr,
fde,
offset_or_block_len,
offset_relevant,
register_num,
row_pc, or
type was NULL.
-
-
- [
DW_DLE_FRAME_TABLE_COL_BAD
]
- The column number provided in argument
table_column was too large.
-
-
- [
DW_DLE_PC_NOT_IN_FDE_RANGE
]
- The program counter value provided in argument
pc did not fall in the range covered by
argument fde.
dwarf(3),
dwarf_get_fde_at_pc(3),
dwarf_get_fde_info_for_all_regs(3),
dwarf_get_fde_info_for_all_regs3(3),
dwarf_get_fde_info_for_cfa_reg3(3),
dwarf_get_fde_info_for_reg(3),
dwarf_get_fde_n(3),
dwarf_set_frame_cfa_value(3),
dwarf_set_frame_rule_initial_value(3),
dwarf_set_frame_rule_table_size(3),
dwarf_set_frame_same_value(3),
dwarf_set_frame_undefined_value(3)