NEWS - pub/scm/devel/pahole/pahole - Git at Google

 v1.12

 Thu Aug 16 2018

 1ca2e351dfa1 README.btf: Add section on validating the .BTF section via the kernel
 9eda5e8163ce README.btf: No need to use 'llvm.opts = -mattr=dwarfris' with elfutils >= 0.173
 7818af53f64a dwarves: Add a README.btf file with steps to test the BTF encoder
 f727c22191d0 dwarf_loader: Initial support for DW_TAG_partial_unit
 e975ff247aa8 dwarves_fprintf: Print cacheline boundaries in multiple union members
 68645f7facc2 btf: Add BTF support
 81466af0d4f8 pahole: Show the file where a struct was used
 2dd87be78bb2 dwarves_fprintf: Show offsets at union members
 66cf3983e1ac README.DEBUG: Add an extra step to make the instructions cut'n'exec
 2a092d61453c dwarves: Fix cus__load_files() success return value
 02a456f5f54c pahole: Search and use running kernel vmlinux when no file is passed
 5f057919a0c0 man-pages: Add entry for --hex
 [acme@jouet pahole]$

 v1.11

 Wed Jun 2017

 5a57eb074170 man-pages: Update URL to the dwarves paper
 b52386d041fa dwarves_fprintf: Find holes when expanding types
 103e89bb257d dwarves_fprintf: Find holes on structs embedded in other structs
 ab97c07a7ebe dwarves_fprintf: Fixup cacheline boundary printing on expanded structs
 046ad67af383 dwarves_fprintf: Shorten class__fprintf() sig
 44130bf70e1c dwarves: Update e-mail address
 327757975b94 dwarf_loader: Add URL for template tags description
 f4d5e21fd1b2 dwarf_loader: Tidy up template tags usage
 e12bf9999944 dwarf_loader: Do not hash unsupported tags
 3afcfbec9e08 dwarf_loader: Add DW_TAG_GNU_formal_parameter_pack stub in process_function
 55d9b20dbaf6 dwarf_loader: Ignore DW_TAG_dwarf_procedure when processing functions
 45618c7ec122 dwarf_loader: Initial support for DW_TAG_unspecified_type
 658a238b9890 dwarf_loader: Stop emitting warnings about DW_TAG_call_site
 0fbb39291d59 dwarf_loader: Add support for DW_TAG_restrict_type
 9df42c68265d dwarves: Initial support for rvalue_reference_type
 8af5ccd86d21 dwarves: Use cus__fprintf_load_files_err() in the remaining tools
 10515a7c4db7 dwarves: Introduce cus__fprintf_load_files_err()
 0e6463635082 pahole: Show more informative message when errno is properly set on error
 2566cc2c8715 pdwtags: Show proper error messages for files it can't handle
 9f3f67e78679 dwarves: Fix cus__load_files() error return
 ae3a2720c3d3 dutil: Add ____ilog2_NaN declaration to silence compiler warning
 0b81b5ad4743 Update version in CMakeLists.txt
 79536f4f9587 cmake: Use INTERFACE_LINK_LIBRARIES
 1decb1bc4a41 dwarf_loader: Check cu__find_type_by_ref result
 956343d05a41 Add instructions on how to build with debug info
 e71353c3fa0a dwarf_loader: Ignore DW_TAG_dwarf_procedure
 189695907242 dwarves_fprintf: Add the missing GNU_ suffix to DWARF_TAG_ created by the GNU project
 d973b1d5daf0 dwarf_fprintf: Handle DW_TAG_GNU_call_site{_parameter}
 c23eab4b1253 dwarf_loader: Print unknown tags as an hex number
 943a0de0679a dwarves_fprintf: DW_TAG_mutable_type doesn't exist.
 a8e562a15767 dwarf_loader: Use obstack_zalloc when allocating tag
 fd3838ae9aa3 dwarves: Stop using 'self'
 5ecf1aab9e10 dwarf_loader: Support DW_FORM_data{4,8} for reading class member offsets
 c4ccdd5ae63b dwarves_reorganize: Fix member type fixup
 e31fda3063e3 dwarves_reorganize: Fixup calculation of bytes needed for bitfield
 1e461ec7e0e8 dwarves_fprintf: Fix printf types on 64bit linux
 222f0067a9c3 dwarves_fprintf: Don't ignore virtual data members
 e512e3f9b36b dwarves: Update git url
 8c6378fd8834 dwarves: Support static class data members
 a54515fa6ee4 dwarves: Stop using 'self'
 6035b0d91f19 rpm: Add missing BuildRequires: zlib-devel
 be7b691756ff dwarf_loader: Don't stop processing after finding unsupported tag

 v1.10

 Wed May 30 2012

 . Initial DWARF4 support, by Tom Tromey

 . Add stubs for some new GNU Tags

 . Fix build on older systems

 . Fix a crash when pahole is called with -R -S, from Tal Kelrich

 v1.9:

 Ignore DW_TAG_template_{type,value}_parameter, fixing a bug reported at:

 https://bugzilla.redhat.com/show_bug.cgi?id=654471

 More work is needed to properly support these tags.

 -----------------------------------------

 After a long time without a new release because I was trying to get the CTF
 support completed, and due to the very strong gravity force in the Linux kernel
 perf tools, here it is 1.8, with lots of performance improvements, bug fixes
 and changes to better use these tools in scripts.

 For full details please take a look at the git changesets, repo available at:

 http://git.kernel.org/cgit/devel/pahole/pahole.git

 - Arnaldo

 pahole:

 . Allow list of structs to be passed to pahole.

 	E.g.: 'pahole -C str_node,strings'

   Suggested by Zack Weinberg <zweinberg@mozilla.com>, for scripting.

 . Introduce --hex to print offsets and sizes in hexadecimal

 codiff:

 . Improve detection of removal and addition of members in structs

 . Detect changes in padding and the number of holes/bit_holes

 pfunct:

 . --no_parm_names

     Because CTF doesn't encodes the names of the parameters and I want to
     test the upcoming CTF function section code in ctftwdiff.

 . pfunct --addr

     Using an rbtree to find in which function the given addr is.

 libdwarves:

 . Greatly reduce the data structures footprint and lookup by recoding
   the IDs as short integers, that was done to facilitate support for CTF
   but benefited the core libraries greatly.

 . Handle GCC support for vector instructions

     So now it recognizes, as printed by pdwtags:

     908 typedef int __m64 __attribute__ ((__vector_size__ (8))); size: 8
     909 int         array __attribute__ ((__vector_size__ (8))); size: 8
     910 int         array __attribute__ ((__vector_size__ (4))); size: 4
     911 short int   array __attribute__ ((__vector_size__ (2))); size: 2
     912 char        array __attribute__ ((__vector_size__ (1))); size: 1

 . Destructors were added so that no leaks are left if this library is to
   be used in other tools that don't end the program when done using this lib.

 . Allow the tools to pass a callback that is used after loading each object
   file (CU/Compile Unit), so that we can more quickly find tags and stop
   the processing sooner, or at least delete the CU if it doesn't have anything
   needed by the tool. This _greatly_ speeded up most of the tools.

 . Tools now can pass a debug format "path", specifying the order it wants to
   try, so that if a file have both DWARF and CTF, specifying 'ctf,dwarf' will
   use the CTF info.

 . Now the formatting routines are in a separate file, dwarves_fprintf.c. This
   was done for organizational purposes but also to pave the way for multiple
   formatting backends, so that we can print, for instance, in CSV the structs,
   for easier scripting like done by several folks out there.

 . Handle volatile typedef bitfields, like:

     struct _GClosure {
             volatile guint ref_count:15;    /* 0:17  4 */
             volatile guint meta_marshal:1;  /* 0:16  4 */
             volatile guint n_guards:1;      /* 0:15  4 */

 . Load java 'interfaces' as a struct/class.

 . Fix buffer expansion bug, detected thanks to boost that provided things like:

         virtual int undefine(class
     grammar_helper<boost::spirit::grammar<boost::detail::graph::dot_skipper,
     boost::spirit::parser_context<boost::spirit::nil, class
     grammar<boost::detail::graph::dot_skipper,
     boost::spirit::parser_context<boost::spirit::nil_t> > *); /*
     linkage=_ZN5boost6spirit4impl14grammar_helperINS0_7grammarINS_6detail5graph11dot_skipperENS0_14parser_contextINS0_5nil_tEEEEES6_NS0_7scannerINS0_10multi_passISt16istream_i
     */

 . Allow optional addr information loading, speeding up some apps that don't
   use such addresses (or in modes where addrs aren't used) such as pahole.

 . Use a obstacks, speeding up apps as measured with the perf tools.

 . Support zero sized arrays in the middle of a struct.

 . Fix padding calculation in the reorganize routines.

 . Fix bitfield demotion in the reorganize routines.

 . Support "using" pointing to data members (C++).

 . Properly support pointers to const, reported by Jan Engelhardt <jengelh@medozas.de>:

 . Support more compact DW_AT_data_member_location form, pointed out by Mark
   Wielaard <mjw@redhat.com> and reported by Mike Snitzer <snitzer@redhat.com>

 Experimental CTF support:

 libdwarves was reorganized so that it can support multiple debugging formats,
 with the first one being supported being the Compact C Type Format that comes
 from the OpenSolaris world.

 David S. Miller contributed an initial CTF decoder and from there I wrote an
 encoder.

 To test this a regression testing harness (regtest in the sources) that will
 take files with DWARF info and from there encode its contents in CTF in another
 ELF section in the same file (.SUN_ctf).  Then it will decode both the DWARF
 and CTF sections and compare the results for pahole running with some new
 flags that cope with some subtleties in the way CTF encodes things.

   --flat_arrays

 	We have just one dimension in CTF, with the total number of entries,
 	in DWARF we can express this, but not in CTF:

 	__u8            addr[0][6];    /*   4  0 */

 	So --flat_arrays will show it as:

 	__u8            addr[0];       /*   4  0 */

   --show_private_classes
   --fixup_silly_bitfields

 	To cope with things like 'char foo:8' that since CTF has only the
 	number of bits, can't be expressed as we don't know if it is a
 	bitfield or just a char without the ':8' suffix.

   --first_obj_only

 	Look only at the first object file in a file with multiple object
 	files, like vmlinux. This is because the CTF support is not complete yet,
 	needing the merging of types in multiple object files to be done.

   --classes_as_structs

 	CTF has only a type for structs, not for classes like DWARF (DW_TAG_class_type
 	is not present in CTF), so print them all as 'struct'.

 Running with the above limitations produce just a few mismatches, related to
 packed structs and enumerations and bitfields.
	v1.12

	Thu Aug 16 2018

	1ca2e351dfa1 README.btf: Add section on validating the .BTF section via the kernel
	9eda5e8163ce README.btf: No need to use 'llvm.opts = -mattr=dwarfris' with elfutils >= 0.173
	7818af53f64a dwarves: Add a README.btf file with steps to test the BTF encoder
	f727c22191d0 dwarf_loader: Initial support for DW_TAG_partial_unit
	e975ff247aa8 dwarves_fprintf: Print cacheline boundaries in multiple union members
	68645f7facc2 btf: Add BTF support
	81466af0d4f8 pahole: Show the file where a struct was used
	2dd87be78bb2 dwarves_fprintf: Show offsets at union members
	66cf3983e1ac README.DEBUG: Add an extra step to make the instructions cut'n'exec
	2a092d61453c dwarves: Fix cus__load_files() success return value
	02a456f5f54c pahole: Search and use running kernel vmlinux when no file is passed
	5f057919a0c0 man-pages: Add entry for --hex
	[acme@jouet pahole]$

	v1.11

	Wed Jun 2017

	5a57eb074170 man-pages: Update URL to the dwarves paper
	b52386d041fa dwarves_fprintf: Find holes when expanding types
	103e89bb257d dwarves_fprintf: Find holes on structs embedded in other structs
	ab97c07a7ebe dwarves_fprintf: Fixup cacheline boundary printing on expanded structs
	046ad67af383 dwarves_fprintf: Shorten class__fprintf() sig
	44130bf70e1c dwarves: Update e-mail address
	327757975b94 dwarf_loader: Add URL for template tags description
	f4d5e21fd1b2 dwarf_loader: Tidy up template tags usage
	e12bf9999944 dwarf_loader: Do not hash unsupported tags
	3afcfbec9e08 dwarf_loader: Add DW_TAG_GNU_formal_parameter_pack stub in process_function
	55d9b20dbaf6 dwarf_loader: Ignore DW_TAG_dwarf_procedure when processing functions
	45618c7ec122 dwarf_loader: Initial support for DW_TAG_unspecified_type
	658a238b9890 dwarf_loader: Stop emitting warnings about DW_TAG_call_site
	0fbb39291d59 dwarf_loader: Add support for DW_TAG_restrict_type
	9df42c68265d dwarves: Initial support for rvalue_reference_type
	8af5ccd86d21 dwarves: Use cus__fprintf_load_files_err() in the remaining tools
	10515a7c4db7 dwarves: Introduce cus__fprintf_load_files_err()
	0e6463635082 pahole: Show more informative message when errno is properly set on error
	2566cc2c8715 pdwtags: Show proper error messages for files it can't handle
	9f3f67e78679 dwarves: Fix cus__load_files() error return
	ae3a2720c3d3 dutil: Add ____ilog2_NaN declaration to silence compiler warning
	0b81b5ad4743 Update version in CMakeLists.txt
	79536f4f9587 cmake: Use INTERFACE_LINK_LIBRARIES
	1decb1bc4a41 dwarf_loader: Check cu__find_type_by_ref result
	956343d05a41 Add instructions on how to build with debug info
	e71353c3fa0a dwarf_loader: Ignore DW_TAG_dwarf_procedure
	189695907242 dwarves_fprintf: Add the missing GNU_ suffix to DWARF_TAG_ created by the GNU project
	d973b1d5daf0 dwarf_fprintf: Handle DW_TAG_GNU_call_site{_parameter}
	c23eab4b1253 dwarf_loader: Print unknown tags as an hex number
	943a0de0679a dwarves_fprintf: DW_TAG_mutable_type doesn't exist.
	a8e562a15767 dwarf_loader: Use obstack_zalloc when allocating tag
	fd3838ae9aa3 dwarves: Stop using 'self'
	5ecf1aab9e10 dwarf_loader: Support DW_FORM_data{4,8} for reading class member offsets
	c4ccdd5ae63b dwarves_reorganize: Fix member type fixup
	e31fda3063e3 dwarves_reorganize: Fixup calculation of bytes needed for bitfield
	1e461ec7e0e8 dwarves_fprintf: Fix printf types on 64bit linux
	222f0067a9c3 dwarves_fprintf: Don't ignore virtual data members
	e512e3f9b36b dwarves: Update git url
	8c6378fd8834 dwarves: Support static class data members
	a54515fa6ee4 dwarves: Stop using 'self'
	6035b0d91f19 rpm: Add missing BuildRequires: zlib-devel
	be7b691756ff dwarf_loader: Don't stop processing after finding unsupported tag

	v1.10

	Wed May 30 2012

	. Initial DWARF4 support, by Tom Tromey

	. Add stubs for some new GNU Tags

	. Fix build on older systems

	. Fix a crash when pahole is called with -R -S, from Tal Kelrich

	v1.9:

	Ignore DW_TAG_template_{type,value}_parameter, fixing a bug reported at:

	https://bugzilla.redhat.com/show_bug.cgi?id=654471

	More work is needed to properly support these tags.

	-----------------------------------------

	After a long time without a new release because I was trying to get the CTF
	support completed, and due to the very strong gravity force in the Linux kernel
	perf tools, here it is 1.8, with lots of performance improvements, bug fixes
	and changes to better use these tools in scripts.

	For full details please take a look at the git changesets, repo available at:

	http://git.kernel.org/cgit/devel/pahole/pahole.git

	- Arnaldo

	pahole:

	. Allow list of structs to be passed to pahole.

	E.g.: 'pahole -C str_node,strings'

	Suggested by Zack Weinberg <zweinberg@mozilla.com>, for scripting.

	. Introduce --hex to print offsets and sizes in hexadecimal

	codiff:

	. Improve detection of removal and addition of members in structs

	. Detect changes in padding and the number of holes/bit_holes

	pfunct:

	. --no_parm_names

	Because CTF doesn't encodes the names of the parameters and I want to
	test the upcoming CTF function section code in ctftwdiff.

	. pfunct --addr

	Using an rbtree to find in which function the given addr is.

	libdwarves:

	. Greatly reduce the data structures footprint and lookup by recoding
	the IDs as short integers, that was done to facilitate support for CTF
	but benefited the core libraries greatly.

	. Handle GCC support for vector instructions

	So now it recognizes, as printed by pdwtags:

	908 typedef int __m64 __attribute__ ((__vector_size__ (8))); size: 8
	909 int array __attribute__ ((__vector_size__ (8))); size: 8
	910 int array __attribute__ ((__vector_size__ (4))); size: 4
	911 short int array __attribute__ ((__vector_size__ (2))); size: 2
	912 char array __attribute__ ((__vector_size__ (1))); size: 1

	. Destructors were added so that no leaks are left if this library is to
	be used in other tools that don't end the program when done using this lib.

	. Allow the tools to pass a callback that is used after loading each object
	file (CU/Compile Unit), so that we can more quickly find tags and stop
	the processing sooner, or at least delete the CU if it doesn't have anything
	needed by the tool. This _greatly_ speeded up most of the tools.

	. Tools now can pass a debug format "path", specifying the order it wants to
	try, so that if a file have both DWARF and CTF, specifying 'ctf,dwarf' will
	use the CTF info.

	. Now the formatting routines are in a separate file, dwarves_fprintf.c. This
	was done for organizational purposes but also to pave the way for multiple
	formatting backends, so that we can print, for instance, in CSV the structs,
	for easier scripting like done by several folks out there.

	. Handle volatile typedef bitfields, like:

	struct _GClosure {
	volatile guint ref_count:15; /* 0:17 4 */
	volatile guint meta_marshal:1; /* 0:16 4 */
	volatile guint n_guards:1; /* 0:15 4 */

	. Load java 'interfaces' as a struct/class.

	. Fix buffer expansion bug, detected thanks to boost that provided things like:

	virtual int undefine(class
	grammar_helper<boost::spirit::grammar<boost::detail::graph::dot_skipper,
	boost::spirit::parser_context<boost::spirit::nil, class
	grammar<boost::detail::graph::dot_skipper,
	boost::spirit::parser_context<boost::spirit::nil_t> > ); /
	linkage=_ZN5boost6spirit4impl14grammar_helperINS0_7grammarINS_6detail5graph11dot_skipperENS0_14parser_contextINS0_5nil_tEEEEES6_NS0_7scannerINS0_10multi_passISt16istream_i
	*/

	. Allow optional addr information loading, speeding up some apps that don't
	use such addresses (or in modes where addrs aren't used) such as pahole.

	. Use a obstacks, speeding up apps as measured with the perf tools.

	. Support zero sized arrays in the middle of a struct.

	. Fix padding calculation in the reorganize routines.

	. Fix bitfield demotion in the reorganize routines.

	. Support "using" pointing to data members (C++).

	. Properly support pointers to const, reported by Jan Engelhardt <jengelh@medozas.de>:

	. Support more compact DW_AT_data_member_location form, pointed out by Mark
	Wielaard <mjw@redhat.com> and reported by Mike Snitzer <snitzer@redhat.com>

	Experimental CTF support:

	libdwarves was reorganized so that it can support multiple debugging formats,
	with the first one being supported being the Compact C Type Format that comes
	from the OpenSolaris world.

	David S. Miller contributed an initial CTF decoder and from there I wrote an
	encoder.

	To test this a regression testing harness (regtest in the sources) that will
	take files with DWARF info and from there encode its contents in CTF in another
	ELF section in the same file (.SUN_ctf). Then it will decode both the DWARF
	and CTF sections and compare the results for pahole running with some new
	flags that cope with some subtleties in the way CTF encodes things.

	--flat_arrays

	We have just one dimension in CTF, with the total number of entries,
	in DWARF we can express this, but not in CTF:

	__u8 addr[0][6]; /* 4 0 */

	So --flat_arrays will show it as:

	__u8 addr[0]; /* 4 0 */

	--show_private_classes
	--fixup_silly_bitfields

	To cope with things like 'char foo:8' that since CTF has only the
	number of bits, can't be expressed as we don't know if it is a
	bitfield or just a char without the ':8' suffix.

	--first_obj_only

	Look only at the first object file in a file with multiple object
	files, like vmlinux. This is because the CTF support is not complete yet,
	needing the merging of types in multiple object files to be done.

	--classes_as_structs

	CTF has only a type for structs, not for classes like DWARF (DW_TAG_class_type
	is not present in CTF), so print them all as 'struct'.

	Running with the above limitations produce just a few mismatches, related to
	packed structs and enumerations and bitfields.