We are used to generate these kinds of relocations by data directives.
Considering the following example,
.word (A + 3) - (B + 2)
The GAS will generate a pair of ADD/SUB for this,
R_RISCV_ADD, A + 1
R_RISCV_SUB, 0
The addend of R_RISCV_SUB will always be zero, and the summary of the
constants will be stored in the addend of R_RISCV_ADD/SET. Therefore,
we can always add the addend of these data relocations when doing relocations.
But unfortunately, I had heard that if we are using .reloc to generate
the data relocations will make the relocations failed. Refer to this,
.reloc offset, R_RISCV_ADD32, A + 3
.reloc offset, R_RISCV_SUB32, B + 2
.word 0
Then we can get the relocations as follows,
R_RISCV_ADD, A + 3
R_RISCV_SUB, B + 2
Then... Current LD does the relocation, B - A + 3 + 2, which is wrong
obviously...
So first of all, this patch fixes the wrong relocation behavior of
R_RISCV_SUB* relocations.
Afterwards, considering the uleb128 direcitve, we will get a pair of
SET_ULEB128/SUB_ULEB128 relocations for it for now,
.uleb128 (A + 3) - (B + 2)
R_RISCV_SET_ULEB128, A + 1
R_RISCV_SUB_ULEB128, B + 1
Which looks also wrong obviously, the summary of the constants should only
be stored into the addend of SET_ULEB128, and the addend of SUB_ULEB128 should
be zero like other SUB relocations. But the current LD will still get the right
relocation values since we only add the addend of SUB_ULEB128 by accident...
Anyway, this patch also fixes the behaviors above, to make sure that no matter
using .uleb128 or .reloc directives, we should always get the right values.
bfd/
* elfnn-riscv.c (perform_relocation): Clarify that SUB relocations
should substract the addend, rather than add.
(riscv_elf_relocate_section): Since SET_ULEB128 won't go into
perform_relocation, we should add it's addend here in advance.
gas/
* config/tc-riscv.c (riscv_insert_uleb128_fixes): Set the addend of
SUB_ULEB128 to zero since it should already be added into the addend
of SET_ULEB128.
Extends commit 6136093c0d to handle verdefs as well as verrefs.
PR 30886
* elf.c (_bfd_elf_slurp_version_tables): See free_contents for
verdefs too. Use free_contents rather than elf_tdata fields.
Sections without SEC_HAS_CONTENTS avoid the file size checks, and of
course it doesn't make sense to read such as the contents are all
zero.
* som.c (som_set_reloc_info): Don't read sections without contents.
This fixes some holes found by fuzzers, and removes aborts that can be
triggered by user input to objdump. Abort should only be used within
bfd to show programming errors in bfd.
* coff-alpha.c (alpha_ecoff_get_relocated_section_contents): Handle
NULL howto. Don't abort on stack errors or on unexpected relocs.
Show more bfd reloc status messages.
The as and ld use _bfd_error_handler to output error messages when
checking relocation alignment and relocation overflow. However, the
abfd value passed by as to the function is NULL, resulting in an
internal error. The ld passes a non-null value to the function,
so it can output an error message normally.
I noticed the regenerated BFD_RELOC_MICROBLAZE_32_NONE comment didn't
match that committed to bfd-in2.h, and was just going to regen
bfd-in2.h but then decided to do something about the silly formatting
of these comments in bfd-in2.h. eg. the BFD_RELOC_MICROBLAZE_32_NONE
comment:
-/* This is a 32 bit reloc that stores the 32 bit pc relative
-value in two words (with an imm instruction).No relocation is
-done here - only used for relaxing */
+ /* This is a 32 bit reloc that stores the 32 bit pc relative value in
+ two words (with an imm instruction). No relocation is done here -
+ only used for relaxing. */
BFD_RELOC_MICROBLAZE_32_NONE,
You'll notice how the second and third line of the original comment
aren't indented properly relative to the first line, and the whole
comment needs to be indented to match the code.
I've also edited reloc.c ENUMDOC paragraphs. Some of these had excess
indentation, presumably in an attempt to properly indent bfd-in2.h
comments but that fails due to chew.c removing leading whitespace
early by skip_white_and_stars. COMMENT was used in reloc.c to add
extra blank lines in bfd-in2.h. I've removed them too as I don't
think they add anything to readability of that file. (Perhaps more
usefully, they also add blank lines to libbfd.h separating relocs for
one target from others, but this isn't done consistently.)
* doc/chew.c (drop, idrop): Move earlier.
(strip_trailing_newlines): Check index before accessing array,
not after.
(wrap_comment): New function.
(main): Add "wrap_comment" intrinsic.
* doc/proto.str (ENUMDOC): Use wrap_comment.
(make_enum_header, ENDSENUM): Put start and end braces on
separate lines.
* reloc.c: Remove uses of COMMENT and edit ENUMDOC paragraphs.
* libbfd.h: Regenerate.
* bfd-in2.h: Regenerate.
This patch adds the R_MICROBLAZE_32_NONE relocation type.
This is a 32-bit reloc that stores the 32-bit pc relative
value in two words (with an imm instruction).
Add test case to gas test suite.
Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Michael J. Eager <eager@eagercon.com>
I get the following truncated errors recently when running riscv-gnu-toolchain
regressions,
/scratch/riscv-gnu-toolchain/regression/build/linux-rv32imafdc-ilp32d-medlow/build-glibc-linux-rv32imafdc-ilp32d/libc.a(libc-start.o): in function `elf_irela':
/scratch/riscv-gnu-toolchain/glibc/csu/../sysdeps/riscv/dl-irel.h:47:(.text+0x88): relocation truncated to fit: R_RISCV_GPREL_I against symbol `__ehdr_start' defined in .note.ABI-tag section in /scratch/riscv-gnu-toolchain/regression/build/linux-rv32imafdc-ilp32d-medlow/build-glibc-linux-rv32imafdc-ilp32d/elf/sln
The linker_def symbols like __ehdr_start that may be undefweak in early stages
of linking, including relax stage, but are guaranteed to be defined later.
Therefore, it seems like we shouldn't do the undefweak relaxations for these
kinds of symbols since they may be defined after relaxations.
bfd/
* elfnn-riscv.c (_bfd_riscv_relax_section): Don't do undefweak
relaxations for the linker_def symbols.
Before, readelf -d RELASZ is the sum of .rela.dyn size and .rela.plt size.
To consistent with LoongArch lld, RELASZ chang to only the size of .rela.dyn.
This fixes an ancient bug in commit a3a33af390 (which makes me think
this code has never been used).
* coff-alpha.c (alpha_ecoff_get_relocated_section_contents): Iterate
through reloc_vector using a temp.
Since RV32E *and* RV64E are ratified, RV64E is no longer invalid.
This commit removes a restriction that prevents making base ISA with
reduced GPRs with XLEN > 32.
bfd/ChangeLog:
* elfxx-riscv.c (riscv_parse_check_conflicts): Remove RV64E
conflict since the ratified 'E' base ISAs include RV64E.
gas/ChangeLog:
* testsuite/gas/riscv/march-fail-base-02.d: Removed.
* testsuite/gas/riscv/march-fail-base-02.l: Removed.
In GDB we have a problem with the BFD cache.
As GDB runs for a potentially extended period of time, if the BFD
cache holds a file descriptor for an open on-disk file, this can, on
some targets (e.g. Win32) prevent the OS writing to the file.
This might, for example, prevent a user from recompiling their
executable as GDB is (via the BFD cache) holding an open reference to
that file.
Another problem, relates to bfd_stat, for BFDs that are using the BFD
cache (i.e. they call cache_bstat to implement bfd_stat). The
cache_bstat function finds the BFD in the cache, opening the file if
needed, and then uses fstat on the open file descriptor.
What this means is that, if the on-disk file changes, but the cache
was holding an open reference to the file, the bfd_stat will return
the 'struct stat' for the old file, not the new file.
Now, for this second problem, we might be tempted to make use of an
actual stat call, instead of calling bfd_stat, however, this isn't
ideal as we have some BFDs that use a custom iovec, and implement the
various functions over GDB's remote protocol. By using bfd_stat we
can have a single call that should work for both local files, and for
remote files.
To solve both of these problems GDB has calls to bfd_cache_close_all
sprinkled around its code base. And in theory this should work fine.
However, I recently ran into a case where we had missed a
bfd_cache_close_all call, and as a result some BFDs were held open.
This caused a bfd_stat call to return an unexpected result (old file
vs new file).
What I'd like is some way within GDB that I can do:
gdb_assert ( /* Nothing is held open in the cache. */ );
As this would allow GDB to quickly identify when we've missed some
bfd_cache_close_all calls.
And so, to support this, I would like to add a new bfd_cache_size
function. This function returns an integer, which is the number of
open files in the cache. I can then start adding:
gdb_assert (bfd_cache_size() == 0);
to GDB in some strategic spots, and start fixing all of the missing
bfd_cache_close_all calls that crop up as a result.
Within bfd/cache.c change the type for max_open_files and open_files
variables from int to unsigned. As a consequence of this, the return
type for bfd_cache_max_open() is also changed from int to unsigned.
Within bfd_cache_max_open I've left the local 'max' variable as an
int, this should ensure that if the sysconf call fails, and returns
-1, then the computed max value will be less than 10, which means
max_open_files will be set to 10. If 'max' was changed to unsigned
then, should the sysconf call fail, we'd end up with max becoming a
very large positive number ... which is clearly not what we want.
And, while I was auditing how open_files is used, I added an assert
within bfd_cache_delete to ensure that we don't try to reduce
open_files below zero.
There should be no user visible change with this commit.
Guard against fuzzed files where .plt size isn't commensurate with
plt relocations.
* elf32-arm.c (elf32_arm_plt0_size): Add data_size param.
Return -1 if data_size is too small.
(elf32_arm_plt_size): Likewise. Delete temp var. Formatting.
(elf32_arm_get_synthetic_symtab): Adjust to suit.
With specially crafted compressed sections, it's possible to tickle a
problem when decompressing: If the compression headers says the
uncompressed size is zero, this will be seen as an error return from
bfd_compress_section_contents. On errors the caller should free any
malloc'd input buffers, but this isn't really an error and the section
contents have been updated to a bfd_alloc'd buffer which can't be
freed.
* compress.c (bfd_compress_section_contents): Return -1 as error
rather than 0.
(bfd_init_section_compress_status, bfd_compress_section): Adjust.
