To find SFrame stack trace information from an FDE of type
SFRAME_FDE_TYPE_PCMASK, sframe_find_fre () was doing an operation
like,
(start_ip_offset & 0xff) >= (pc & 0xff), etc.
This is buggy and needs correction. The mask 0xff should be 0xf (to
work for a pltN entry of size say, 16 bytes).
At this time, the size of the pltN entry is implicitly assumed to be 16
bytes by libsframe. In next version of the SFrame format, we can encode
this information explicitly in the SFrame FDE.
For now, we should fix the code to at least behave correctly for the
generated code and the generated SFrame stack trace information for the
pltN entries on x86_64.
libsframe/
* sframe.c (sframe_find_fre): Correct the bitmask used for
SFrame FDEs of type SFRAME_FDE_TYPE_PCMASK.
sframe_decoder_get_funcdesc_at_index () is the function to access SFrame
FDEs in the SFrame decoder context. Use it consistently.
Avoid unnecessary type cast and include minor enhancements as the code
is moved around.
libsframe/
* sframe.c (sframe_decoder_get_funcdesc_at_index): Move some
checks here. Move the static function definition before the new
use.
(sframe_decoder_get_funcdesc): Use
sframe_decoder_get_funcdesc_at_index instead.
include/
* sframe-api.h (sframe_decoder_get_num_fidx): Use extern.
libsframe/
* sframe-dump.c (dump_sframe_func_with_fres): Fix line length.
* sframe.c (sframe_frame_row_entry_copy): Likewise.
(sframe_decode_fre_start_address): Use the intended type uint32_t.
Change the data type of some of the members of the sframe_decoder_ctx
and sframe_encoder_ctx data structures to use the applicable data types
explicitly. Current implementation in libsframe does type casts, which
seem unnecessary.
libsframe/
* libsframe/sframe-impl.h (struct sframe_decoder_ctx): Use
applicable data type explicitly.
(struct sframe_encoder_ctx): Likewise. Use same style of
comments consistently.
* libsframe/sframe.c (struct sf_fde_tbl): Define without
typedef.
(struct sf_fre_tbl): Likewise.
(sframe_decode): Remove unnecessary type casts.
(sframe_encoder_get_funcdesc_at_index): Likewise.
(sframe_encoder_add_fre): Likewise.
(sframe_encoder_add_funcdesc): Likewise.
(sframe_sort_funcdesc): Likewise.
(sframe_encoder_write_sframe): Likewise.
Define a new constant for the maximum number of stack offsets handled in
libsframe, and use it. Note that the SFrame format does not define such
a constant (limit). This is an implmentation-defined constant in
libsframe.
include/
* sframe-api.h (MAX_NUM_STACK_OFFSETS): New definition.
libsframe/
* sframe.c (sframe_fre_sanity_check_p): Use it.
Inspite of implementing a rather simple functionality, this function was
relatively difficult to follow, and maintain. Some changes are done now
to address that - refactor the function and use better names to make it
more readable.
The changes to the implementation do not cause any change in the
contract of the API.
libsframe/
* sframe.c (sframe_fre_get_end_ip_offset): to here...
(sframe_find_fre): Refactor some bits from...
libsframe/
* sframe.c (sframe_decoder_get_header): Use consistent function
arg names.
(sframe_decoder_free): Likewise.
(sframe_encode): Use more appropriate var name.
An earlier commit 3f107464 defined the SFRAME_FRE_TYPE_*_LIMIT
constants. These constants are used (by gas and libsframe) to pick an
SFrame FRE type based on the function size. Those constants, however,
were buggy, causing the generated SFrame sections to be bloated as
SFRAME_FRE_TYPE_ADDR2/SFRAME_FRE_TYPE_ADDR4 got chosen more often than
necessary.
gas/
* sframe-opt.c (sframe_estimate_size_before_relax): Use
typecast.
(sframe_convert_frag): Likewise.
libsframe/
* sframe.c (sframe_calc_fre_type): Use a more appropriate type
for argument. Adjust the check for SFRAME_FRE_TYPE_ADDR4_LIMIT
to keep it warning-free but meaningful.
include/
* sframe-api.h (sframe_calc_fre_type): Use a more appropriate
type for the argument.
* sframe.h (SFRAME_FRE_TYPE_ADDR1_LIMIT): Correct the constant.
(SFRAME_FRE_TYPE_ADDR2_LIMIT): Likewise.
(SFRAME_FRE_TYPE_ADDR4_LIMIT): Likewise.
When sframe_encoder_write needs to flip the buffer containing the SFrame
section before writing, it is not necessary that the SFrame FDES are in
the order of their sfde_func_start_fre_off. On the contrary, SFrame
FDEs will be sorted in the order of their start address. So, remove
this incorrect assumption which is basically assuming that the last
sfde_func_start_fre_off seen will help determine the end of the flipped
buffer.
The function now keeps track of the bytes_flipped and then compares it with
the expected value. Also, added two more checks at appropriate places:
- check that the SFrame FDE read is within bounds
- check that the SFrame FRE read is within bounds
libsframe/
* sframe.c (flip_sframe): Adjust an incorrect check.
Add other checks to ensure reads are within the buffer size.
The newer update-copyright.py fixes file encoding too, removing cr/lf
on binutils/bfdtest2.c and ld/testsuite/ld-cygwin/exe-export.exp, and
embedded cr in binutils/testsuite/binutils-all/ar.exp string match.
The following test was failing on ppc64 and s390x:
"FAIL: encode-1: Encode buffer match"
The offending stub was how we memcpy the FRE start address to the buffer
(on-disk format). When the host is big-endian, the address of the
source buffer for the memcpy needs to point to the uint8_t/uint16_t sized
value of the FRE start addr, not uint32_t sized value; we intend to copy
out only the fre_start_addr_sz number of bytes.
ChangeLog:
* libsframe/sframe.c (sframe_encoder_write_fre_start_addr): New
function.
(sframe_encoder_write_fre): Use it instead of memcpy.
sframe_decode () needs to malloc a temporary buffer of the same size as
the input buffer (containing the SFrame section bytes) when endian
flipping is needed. The decoder keeps the endian flipped contents in
this buffer for its usage. This code is necessary when the target
endianneess is not the same as host endianness.
The malloc'd buffer needs to be kept track of, so that it can freed up in
sframe_decoder_free () later.
ChangeLog:
* libsframe/sframe-impl.h (struct sframe_decoder_ctx): Add new
member to keep track of the internally malloc'd buffer.
* libsframe/sframe.c (sframe_decoder_free): Free it up.
(sframe_decode): Update the reference to the buffer.
There are two places where unaligned loads were seen on aarch64:
- #1. access to the SFrame FRE stack offsets in the in-memory
representation/abstraction provided by libsframe.
- #2. access to the SFrame FRE start address in the on-disk representation
of the frame row entry.
For #1, we can fix this by reordering the struct members of
sframe_frame_row_entry in libsframe/sframe-api.h.
For #2, we need to default to using memcpy instead, and copy out the bytes
to a location for output.
SFrame format is an unaligned on-disk format. As such, there are other blobs
of memory in the on-disk SFrame FRE that are on not on their natural
boundaries. But that does not pose further problems yet, because the users
are provided access to the on-disk SFrame FRE data via libsframe's
sframe_frame_row_entry, the latter has its' struct members aligned on their
respective natural boundaries (and initialized using memcpy).
PR 29856 libsframe asan: load misaligned at sframe.c:516
ChangeLog:
PR libsframe/29856
* bfd/elf64-x86-64.c: Adjust as the struct members have been
reordered.
* libsframe/sframe.c (sframe_decode_fre_start_address): Use
memcpy to perform 16-bit/32-bit reads.
* libsframe/testsuite/libsframe.encode/encode-1.c: Adjust as the
struct members have been reordered.
include/ChangeLog:
PR libsframe/29856
* sframe-api.h: Reorder fre_offsets for natural alignment.
The new name better reflects the purpose of the function.
ChangeLog:
* bfd/elfxx-x86.c (_bfd_x86_elf_create_sframe_plt): Use new
name.
* libsframe/sframe.c (sframe_fde_create_func_info): Rename
sframe_fde_func_info to this.
* libsframe/testsuite/libsframe.encode/encode-1.c: Use new name.
include/ChangeLog:
* sframe-api.h (sframe_fde_create_func_info): Rename
sframe_fde_func_info to this.
Define constants in sframe.h for the various limits associated with the
range of offsets that can be encoded in the start address of an SFrame
FRE. E.g., sframe_frame_row_entry_addr1 is used when start address
offset can be encoded as 1-byte unsigned value.
Update the code in gas to use these defined constants as it checks for
these limits, and remove the usage of magic numbers.
ChangeLog:
* gas/sframe-opt.c (sframe_estimate_size_before_relax):
(sframe_convert_frag): Do not use magic numbers.
* libsframe/sframe.c (sframe_calc_fre_type): Likewise.
include/ChangeLog:
* sframe.h (SFRAME_FRE_TYPE_ADDR1_LIMIT): New constant.
(SFRAME_FRE_TYPE_ADDR2_LIMIT): Likewise.
(SFRAME_FRE_TYPE_ADDR4_LIMIT): Likewise.
The linker merges all the input .sframe sections. When merging, the
linker verifies that all the input .sframe sections have the same
abi/arch.
The linker uses libsframe library to perform key actions on the
.sframe sections - decode, read, and create output data. This
implies buildsystem changes to make and install libsframe before
libbfd.
The linker places the output .sframe section in a new segment of its
own: PT_GNU_SFRAME. A new segment is not added, however, if the
generated .sframe section is empty.
When a section is discarded from the final link, the corresponding
entries in the .sframe section for those functions are also deleted.
The linker sorts the SFrame FDEs on start address by default and sets
the SFRAME_F_FDE_SORTED flag in the .sframe section.
This patch also adds support for generation of SFrame unwind
information for the .plt* sections on x86_64. SFrame unwind info is
generated for IBT enabled PLT, lazy/non-lazy PLT.
The existing linker option --no-ld-generated-unwind-info has been
adapted to include the control of whether .sframe unwind information
will be generated for the linker generated sections like PLT.
Changes to the linker script have been made as necessary.
ChangeLog:
* Makefile.def: Add install dependency on libsframe for libbfd.
* Makefile.in: Regenerated.
* bfd/Makefile.am: Add elf-sframe.c
* bfd/Makefile.in: Regenerated.
* bfd/bfd-in2.h (SEC_INFO_TYPE_SFRAME): Regenerated.
* bfd/configure: Regenerate.
* bfd/configure.ac: Add elf-sframe.lo.
* bfd/elf-bfd.h (struct sframe_func_bfdinfo): New struct.
(struct sframe_dec_info): Likewise.
(struct sframe_enc_info): Likewise.
(struct elf_link_hash_table): New member for encoded .sframe
object.
(struct output_elf_obj_tdata): New member.
(elf_sframe): New access macro.
(_bfd_elf_set_section_sframe): New declaration.
* bfd/elf.c (get_segment_type): Handle new segment
PT_GNU_SFRAME.
(bfd_section_from_phdr): Likewise.
(get_program_header_size): Likewise.
(_bfd_elf_map_sections_to_segments): Likewise.
* bfd/elf64-x86-64.c (elf_x86_64_link_setup_gnu_properties): Add
contents to the .sframe sections or .plt* entries.
* bfd/elflink.c (elf_section_ignore_discarded_relocs): Handle
SEC_INFO_TYPE_SFRAME.
(_bfd_elf_default_action_discarded): Handle .sframe section.
(elf_link_input_bfd): Merge .sframe section.
(bfd_elf_final_link): Write the output .sframe section.
(bfd_elf_discard_info): Handle discarding .sframe section.
* bfd/elfxx-x86.c (_bfd_x86_elf_size_dynamic_sections): Create
.sframe section for .plt and .plt.sec.
(_bfd_x86_elf_finish_dynamic_sections): Handle .sframe from
.plt* sections.
* bfd/elfxx-x86.h (PLT_SFRAME_FDE_START_OFFSET): New
definition.
(SFRAME_PLT0_MAX_NUM_FRES): Likewise.
(SFRAME_PLTN_MAX_NUM_FRES): Likewise.
(struct elf_x86_sframe_plt): New structure.
(struct elf_x86_link_hash_table): New member.
(struct elf_x86_init_table): New members for .sframe
creation.
* bfd/section.c: Add new definition SEC_INFO_TYPE_SFRAME.
* binutils/readelf.c (get_segment_type): Handle new segment
PT_GNU_SFRAME.
* ld/ld.texi: Update documentation for
--no-ld-generated-unwind-info.
* ld/scripttempl/elf.sc: Support .sframe sections.
* ld/Makefile.am (TESTSFRAMELIB): Use it.
(check-DEJAGNU): Likewise.
* ld/Makefile.in: Regenerated.
* ld/configure.ac (TESTSFRAMELIB): Set to the .so or .a like TESTBFDLIB.
* ld/configure: Regenerated.
* bfd/elf-sframe.c: New file.
include/ChangeLog:
* elf/common.h (PT_GNU_SFRAME): New definition.
* elf/internal.h (struct elf_segment_map): Handle new segment
type PT_GNU_SFRAME.
ld/testsuite/ChangeLog:
* ld/testsuite/ld-bootstrap/bootstrap.exp: Add SFRAMELIB.
* ld/testsuite/ld-aarch64/aarch64-elf.exp: Add new test
sframe-simple-1.
* ld/testsuite/ld-aarch64/sframe-bar.s: New file.
* ld/testsuite/ld-aarch64/sframe-foo.s: Likewise.
* ld/testsuite/ld-aarch64/sframe-simple-1.d: Likewise.
* ld/testsuite/ld-sframe/sframe-empty.d: New test.
* ld/testsuite/ld-sframe/sframe-empty.s: New file.
* ld/testsuite/ld-sframe/sframe.exp: New testsuite.
* ld/testsuite/ld-x86-64/sframe-bar.s: New file.
* ld/testsuite/ld-x86-64/sframe-foo.s: Likewise.
* ld/testsuite/ld-x86-64/sframe-simple-1.d: Likewise.
* ld/testsuite/ld-x86-64/sframe-plt-1.d: Likewise.
* ld/testsuite/ld-x86-64/sframe-simple-1.d: Likewise.
* ld/testsuite/ld-x86-64/x86-64.exp: Add new tests -
sframe-simple-1, sframe-plt-1.
* ld/testsuite/lib/ld-lib.exp: Add new proc to check if
assembler supports SFrame section.
* ld/testsuite/ld-sframe/discard.d: New file.
* ld/testsuite/ld-sframe/discard.ld: Likewise.
* ld/testsuite/ld-sframe/discard.s: Likewise.
libsframe is a library that allows you to:
- decode a .sframe section
- probe and inspect a .sframe section
- encode (and eventually write) a .sframe section.
This library is currently being used by the linker, readelf, objdump.
This library will also be used by the SFrame unwinder which is still
to be upstream'd.
The file include/sframe-api.h defines the user-facing APIs for decoding,
encoding and probing .sframe sections. A set of error codes together
with their error message strings are also defined.
Endian flipping is performed automatically at read and write time, if
cross-endianness is detected.
ChangeLog:
* Makefile.def: Add libsframe as new module with its
dependencies.
* Makefile.in: Regenerated.
* binutils/Makefile.am: Add libsframe.
* binutils/Makefile.in: Regenerated.
* configure: Regenerated
* configure.ac: Add libsframe to host_libs.
* libsframe/Makefile.am: New file.
* libsframe/Makefile.in: New file.
* libsframe/aclocal.m4: New file.
* libsframe/config.h.in: New file.
* libsframe/configure: New file.
* libsframe/configure.ac: New file.
* libsframe/sframe-error.c: New file.
* libsframe/sframe-impl.h: New file.
* libsframe/sframe.c: New file.
include/ChangeLog:
* sframe-api.h: New file.
testsuite/ChangeLog:
* libsframe/testsuite/Makefile.am: New file.
* libsframe/testsuite/Makefile.in: Regenerated.
* libsframe/testsuite/libsframe.decode/Makefile.am: New
file.
* libsframe/testsuite/libsframe.decode/Makefile.in:
Regenerated.
* libsframe/testsuite/libsframe.decode/decode.exp: New file.
* libsframe/testsuite/libsframe.encode/Makefile.am:
Likewise.
* libsframe/testsuite/libsframe.encode/Makefile.in:
Regenerated.
* libsframe/testsuite/libsframe.encode/encode.exp: New file.
* libsframe/testsuite/libsframe.encode/encode-1.c: Likewise.
* libsframe/testsuite/libsframe.decode/be-flipping.c: Likewise.
* libsframe/testsuite/libsframe.decode/frecnt-1.c: Likewise.
* libsframe/testsuite/libsframe.decode/frecnt-2.c: Likewise.
* libsframe/testsuite/libsframe.decode/DATA-BE: New file.
* libsframe/testsuite/libsframe.decode/DATA1: Likewise.
* libsframe/testsuite/libsframe.decode/DATA2: Likewise.
