dwarfdump man page

dwarfdump — dumps DWARF debug information of an ELF object

Synopsis

dwarfdump [options] objectfilename

Description

The dwarfdump command prints or checks DWARF sections as requested by specific options. With no options (but with the required objectfilename ) all sections print (but some sections cannot be printed independently safely, so those are only printed at offsets where the .debug_info section refers to those sections).

All options are available in the traditional (single-letter) form and in a long-options form with meaningful names.

With no options dwarfdump prints a basic set of DWARF section information.  If any option is given on the command line the basic set is ignored and one must tell dwarfdump what to print or check (for example by adding the -a option).

As of June 2011 the printing options and the checking options are mutually exclusive (if checking options are selected the section details are not printed). When errors are encountered dwarfdump does attempt to print sufficient context so that one can understand exactly where the error is in the DWARF. This change makes checking really large object files much easier.

The format is intended to be human readable. If a script is to parse the output, the --format-dense (-d) option is useful.

Not all sections actually exist in any given object file.

The format may change from release to release, so it is unwise to depend too heavily on the format.

Frame information (.debug_frame and .eh_frame) is heavily dependent on the ABI/ISA of the object file.  By default we use a generic set of register names handling up to 100 registers named r0-r99.

The --format-registers (-R) option uses a built-in generic register name set handling up to 1200 registers named r0-r1199.

The -file-abi=<abi> (-x abi=<abi>) description below shows how to name an abi and use that to guide the --print-frame (-f) or --print-eh-frame (-F) processing.

Unless one of --print-frame (-f) or --print-eh-frame (-F) or --print-all (-a) is used any abi reference is ignored because no frame data will be printed.

Unless the cpu for the object file being dumped has many registers, do not use --format-registers or -file-abi=<abi> as those can be needlessly  slow dumping frame sections. Instead, use the correct abi (if it exists in dwarfdump.conf) or a generic such as --file-abi=abi=generic100 or --file-abi=abi=generic500
.

The most useful abi choices are likely mips or x86 or x86_64 or ppc or arm
. Without --format-registers (-R) or -file-abi=<abi> (-x abi=<abi>) dwarfdump ignores the dwarfdump.conf file and uses compiled-in generic set of register names. If no --file-name=<path> (-x name=<path>) is given, dwarfdump looks for "./dwarfdump.conf",  "$HOME/.dwarfdump.conf",  "<install-prefix>/lib/dwarfdump.conf"  and takes the first it finds. If one or more --file-name=<path> (-x name=<path>) is given the last of these is used and all other such files are ignored.

Some checking ( -k) options  (See "Check DWARF Integrity" in the help output) print so-called harmless errors. These are compiler errors that do not cause any known problem and are only detected inside libdwarf itself. These are difficult to properly report in dwarfdump and any error strings may not appear close to the time the error was encountered.

If zlib compression was used on the DWARF sections in the object file being read the real section names such as .zdebug_info etc will be reported by dwarfdump.   When dwarfdump says something is at offset 55  of .zdebug_info (or the like) keep in mind that  the offset applies to the uncompressed section (in memory),  not the .zdebug_ compressed section in objectfilename.

URI Style Input Strings

The <objectfilename> and all the options taking name strings look for URIs and translate the URI strings to characters by default. So any single % character is treated as if the following two characters are hex digits representing the underlying true character. Various characters are meaningful to shells (such as bash or sh)  and to getopt (such as the space character)  If the URI translation does anything it prints the before and after of the URI translation on standard output, so inspection of the first lines of output will show if URI did anything. The actual options themselves are assumed to be non-URI. So in the option --format-producer=S&T (-cS&T) the & character might cause input issues so --format-producer=S%26T should be used instead. To actually input a single % character (in a name, for example),  double it to %% on the command line (or simply use %25).

Options --format-suppress-uri (-U) (turning off URI interpretation) and --format-suppress-uri-msg (-q) (making finding URI sequences silent) give finer control of URI interpretation. PP As an example, to get a string'a b' make the string 'a%20b' (here the quote (') is for exposition not part of the string, though quote is certainly problematic in a name). Instead of escaping " quotes in the string, type %25, as in
'a "b' should be typed 'a%20%25b' Any characters can be typed in URI style, not just characters which are problematic to the shell or getopt. We strongly suggest you not type URI-style characters where such are not needed or use the % character itself in command line strings unless you must.

Printing Options

--print-all (-a)

Print each section as independently as possible. Sections that can safely be printed independently (like .debug_abbrev) have relevant info printed in the report (sometimes dependent on -v).

--print-abbrev (-b)

Print the .debug_abbrev section. Because the DWARF specifications do not rule out garbage data areas in .debug_abbrev (if they are not referenced from .debug_info) any garbage bytes can result in this print failing.

--print-loc (-c)

Print locations lists.

--elf (-E)

prints, for Elf objects, object file details. See the "Print ELF sections header" section of the help file for additional choices on elf printing. If libdwarf or dwarfdump is built without libelf this option is unavailable.

--print-frame (-f)

Print the .debug_frame section.

--print-eh-frame (-F)

Print the GNU .eh_frame section.

--print-info (-i)

Print the .debug_info section.

--print-fission (-I)

Print any .gdb_index, .debug_cu_index, and .debug_tu_index sections that exist in the object.

--print-gnu-debuglinkIfthe.gnu_debuglinksection

is present its content is printed. If the .note.gnu.build-id section is present its content is printed. If a DWARF containing file named by the content of the .gnu_debuglink section exists the name will be printed.

--print-lines (-l)

Print the .debug_info section and  the associated line section data.

--print-lines-short (-ls)

Print the .debug_info section and  the associated line section data, but omit the <pc> address.  Useful when a comparison of line sections from objects with slight differences is required.

--print-macinfo (-m)

Print the .debug_macinfo (DWARF 2,3,4) and .debug_macro (DWARF5) sections.

--print-ranges (-N)

Print .debug_ranges section.  Because the DWARF specifications do not rule out garbage data areas in .debug_ranges (if they are not referenced from .debug_info) any garbage bytes can result in this print failing.

--print-pubnames (-p)

Print the .debug_pubnames section.

--print-str-offsets

Print the .debug_str_offsets section.

--print-aranges (-r)

Print the .debug_aranges section.

--print-strings (-s)

Print .debug_string section.

--print-static (-ta)

Print the IRIX only sections .debug_static_funcs and .debug_static_vars.

--print-type (-y)

Print the .debug_pubtypes section (and .debug_typenames, an SGI IRIX-only section).

Having dwarfdump print relocations may help establish whether dwarfdump understands any relocations that might exist. Other tools may be more useful than dwarfdump for printing object-file details. See "Print Relocations Info" in the help output for additional relocation printing choices.

--reloc (-o)

Print all relocation records as well as we can manage. If libdwarf or dwarfdump were built without libelf this option is unavailable.

--version (-V)

Print a dwarfdump date/version string and stop.

Checking Options

--check-all (-ka)

Turns on all checking options except --check-frame-extended (-kxe) (which might be slow enough one  might not want to use it routinely.)

--check-abbrev (-kb)

Checks for certain abbreviations section errors when reading DIEs.

--check-constants (-kc)

Checks for errors in constants in debug_info.

-check-show (-kd)

Turns on full reporting of error totals per producer. (the default shows less detail).

--check-silent-ks

Turns off some verbose checking detection.

--check-attr-dup (-kD)

Turns on reporting of duplicated attributes. Duplicated attributes on a single DW_TAG are improper DWARF, but at least one compiler emitted such.

--check-pubnames (-ke)

Turns on reading pubnames and checking for fde errors.

--check-attr-encodings (-kE)

Checks the integer encoding representation in debug_info, computing whether these integer values could fit in fewer bytes if represented in LEB128.

--check-frame-info (-kf)

Turns on checking for FDE errors (.debug_frame  and .eh_frame).

--check-files-lines (-kF)

Turns on checking for line table errors.

--check-gaps (-kg)

Turns on checking for unused gaps in .debug_info (these gaps are not an error, just a waste of space).

--check-unique (-kG)

Print only unique errors. Error lines are simpified (hex numbers removed, for example) and when a given message string would otherwise appear  again it is suppressed.

--check-summary (-ki)

Causes a summary of checking results per compiler (producer) to be printed at the end.

--check-loc (-kl)

Turns on locations list checking.

--check-ranges (-km)

Turns on checking of ranges.

--check-aranges (-kM)

Turns on checking of aranges.

--check-tag-attr (-kr)

Turns on DIE tag-attr combinations checking, looking for surprising attributes for DIE tags.

--check-forward-refs (-kR)

Turns on reading DIEs and checking for forward declarations from DW_AT_specification attributes. (which are not an error but can be a source of inefficiency for debuggers).

--check-self-refs (-kS)

Turns on checking DIE references for circular references.

--check-tag-tag (-kt)

Turns on tag-tag combinations checking, looking for surprising parent-child DIE relationships.

--check-usage (-ku)

Print tag-tree and tag-attribute usage (basic format).

--check-usage-extended (-kuf)

Print tag-tree and tag-attribute usage (full format).  For standard TAGs and ATtributes this presents an overview of how they were used.

--check-frame-basic (-kx)

Turns on basic frames checking for .debug_frame and .eh_frame).

--check-frame-extended (-kxe)

Turns off basic check_frames and  turns on extended frame checking for .debug_frame and .eh_frame. This option can be slow.

--check-type (-ky)

Turns on type_offset checking (ensuring local attribute  offsets refer to what they should) and that DW_AT_decl_file and some other offsets refer to appropriate locations.

Option Modifiers

--format-extensions (-C)

Normally when checking for tag-tag  or tag-attribute combinations both the standard combinations and  some common extensions are allowed. With -C the extensions are taken out of the allowed class of combinations.

--format-dense (-d)

When printing DIEs, put all the  attributes for each DIE on the same (long) line as the TAG. This makes searching for DIE information (as with grep) much simpler as the entire DIE is on one line.

--format-supress-offsets (-D)

Turns off the display of section offsets and attribute values in printed output. So the .debug_info output is just TAGs and Attributes. For pubnames (and the like) it removes offsets from the output. For locations lists it removes offsets from the output, but that is useless since the attribute values don't show so neither does the location data.

--format-ellipsis (-e)

Turns on truncation of attribute and tag names. For example DW_TAG_foo becomes foo. Not compatible with checking, only useful for printing DIEs.

--format-global-offsets (-G)

When printing, add global offsets to the offsets printed.

--format-limit=<num> (-H number)

When printing or checking .debug_info, this terminates the search after 'number' compilation units. When printing frame information this terminates the FDE reporting  after 'number' FDEs and the CIE reporting (which occurs if one adds -v) after 'number' CIEs. Example '--format-limit=1'

--format-attr-name (-M)

When printing, show the FORM for each attribute. If a -v is added (or more than one) then details of any form indirection are also shown.

--format-suppress-lookup (-n)

When printing frames, this turns off the search for function names. In a really large object the search can take more time than one wants to wait, so this avoids the search.

--file-output=<path> (-Ofile=<path>)

The <path> will be used as the file name for output instead  of writing to stdout (stdout is the default).

-format-suppress-data (-Q)

Suppresses section data printing (set automatically with a checking option).

--format-registers (-R)

When printing frames for ABIs with lots of registers, this allows up to 1200 registers to be named (like R999) without choosing an ABI with, for example '-x abi=ppc'

--version (-v)

Increases the detail shown when printing. In some sections, using more -v options will increase the detail (one to three are useful) or may change the report to show, for example, the actual line-data-commands instead of the resultant line-table.

Selective Entry Printing

These --search (-S) options stand alone and  basic print information about the compilation unit and DIE where the string(s) appear. At most one of each of the following is effective (so for example one can only have one 'match', but one can  have a 'match', an 'any', and a 'regex'). Any --search (-S) causes the .debug_info section to be inspected. No checking options or printing options should be supplied  with --search(-S) options. The strings should use URI-style to avoid any conflicts with the command-line parser applicable (bash, sh, ...) or getopt().

These are particularly useful when the amount of DWARF information is really large.

If v is added to the -S option, the number of occurrences is printed. (see below for an example).

--search-match=<string> (-Smatch=string)
--search-match-count=<string> (-Svmatch=string)

When printing DIEs for each tag value or attribute name that matches 'string' exactly print the compilation unit information and its section offset. Any CU with no match is not printed. The 'string' is read as a URI string. The count (Sv) form reports the count of occurrences.

--search-any=<string> (-Sany=string)
--search-any-count=<string> (-Svany=string)

When printing DIEs for each tag value or attribute name that contains 'string' somewhere in the tag or attribute (case insensitive) print the compilation unit information and its section offset. Any CU with no match is not printed. The 'string' is read as a URI string. The count (Sv) form reports the count of occurrences.

--search-regex=string (-Sregex=string)
--search-regex-count=string (-Svregex=string)

When printing DIEs for each tag value or attribute name where the 'string' reqular expression matches print the compilation unit information and its section offset. Any CU with no match is not printed. The 'string' is read as a URI string. The count (Sv) form reports the count of occurrences.

The string cannot have spaces or other characters which are meaningful to getopt(3) and the shell will strip off quotes and other characters. So the string is assumed to be in URI style and is translated. In other words, to match 'a b' make the -S string 'a%20b' Instead of escaping " quotes in the string, type %25, as in
'a "b' should be typed 'a%20%25b' (the ' are for exposition here, not part of the strings). Any characters can be typed in URI style, not just characters which are problematic to the shell or getopt.

The --search-any (-Sany) and --regex-any (-Sregex) options are only usable if regular-expression library functions required are found at configure time.

The --search-print (-W) option is a modifier to the -S option, and increases the amount of output -S prints. An example v modifier to the -S option is shown below. And we show the -W in context with a -S option.

--search-match-count=string1 (-S vmatch=string1)

Prints information about the DIEs that -S matches and prints the count of occurrences.

-S match=string1 -W
--search-match=string1 --search-print-tree

Prints the parent tree and the children tree for the DIEs that -S matches.

-S match=string2 -Wp
--search-match=string2 --search-print-parent

Prints the parent tree for the DIEs that -S matches.

-S match=string3 -Wc
--search-match=string3 --search-print-children

Prints the children tree for the DIEs that -S matches.

--format-gcc (-cg)

Restricts printing/checking to compilers whose producer string starts with 'GNU' and turns off -cs.

--format-snc (-cs)

Restricts printing/checking to compilers whose producer string starts with 'SN' and turns off -cg.

--format-producer=<name> (-c<name>)

Restricts printing/checking to compilers whose producer string contains 'name' (not case sensitive). The 'name' is read as a URI string.

Other Options

-x name=<path>
--file-name=/p/a/t/h.conf (-xname=/p/a/t/h.conf)

The file path given is the name of a file assumed to be a dwarfdump.conf-like file. The file path is read as a URI string.

-x abi=ppc
--file-abi=ppc

Selects the abi (from a dwarfdump.conf file) to be used in printing frame information (here using ppc as an example). The abi is read as a URI string.

--format-group=<n> (-x groupnumber=<n>)

For an object file with both DWARF5 split  dwarf (.debug_info.dwo for example)  and ordinary DWARF sections (.debug_info for example) in the single object file one must use --format-group=2 to print the dwo sections. Adding --file-tied=<path> naming the same object file ties in the non-dwo sections.

-x tied=/t/i/depath
--file-tied=/t/i/depath

Used when opening a main object that is a .dwo or .dwp file. The tied file path names the executable which has the .debug_addr section that may be referred to from the main object. See Split Objects (aka Debug Fission).

-x line5=s2l
--file-line5=s2l

Normally used only to test libdwarf interfaces. There are 4 different interface function sets and to ensure they all work this option lets us choose which to use.  The options are 's2l' (default, Allows standard and two-level line tables using the latest interface functions), 'std' (Allows standard single level line tables using the latest interface functions), 'orig' (allows DWARF2,3,4 original line tables using an older interface function set), 'orig2l' (allows original line tables and some two-level line tables using an older interface set).

--print-producers

-P When checking this adds the list of compilation-unit names seen for each producer-compiler to the printed checking results.

-q
--format-suppress-uri-msg

When a URI is found and translated while reading the command line, be quiet about the URI translation. That is, don't print the original and translated option strings.

-u cuname
--format-file=<file>

Turns on selective printing of DIEs (printing like -i). Only the DIEs for a compilation unit that match the name provided are printed. If the compilation unit is ./a/b/c.c the 'cuname' you provide should be c.c as the characters through the final path-separating / are ignored. If 'cuname' begins with a / then the entire name string of a compilation unit must match 'cuname'. The 'file' is read as a URI string.

-U
--format-suppress-uri

Turn off the URI interpretation of the command line strings entirely. Must be be on the command line before any URI strings encountered to be fully effective. Likely something no one needs to do.

-h
--help

Show this man page.

Files

dwarfdump

./dwarfdump.conf

$(HOME)/.dwarfdump.conf

$(HOME)/dwarfdump.conf

<install-prefix>/lib/dwarfdump.conf

Notes

In some cases compilers use DW_FORM_data1 (for example) and in such cases the signedness of the value must be taken from context. Rather than attempt to determine the context, dwarfdump prints the value with both signednesses whenever there is ambiguity about the correct interpretation. For example,  "DW_AT_const_value           176(as signed = -80)". For normal DWARF consumers that correctly and fully evaluate all attributes there is no ambiguity of signedness: the ambiguity for dwarfdump is due to dwarfdump evaluating DIEs in a simple order and not keeping track of much context.

Bugs

Support for DWARF5 is being completed but may not be complete.