The original discussion was here,
https://github.com/riscv/riscv-elf-psabi-doc/issues/184
After discussing with Kito Cheng, I think the addends of %pcrel_hi
and %pcrel_lo are both allowed in GNU toolchain. However, both of
the them mean the offset of symbols, rather than the pc address.
But the addends of %got_pcrel_hi and it's %pcrel_lo do not look
reasonable. I believe gcc won't generate the got patterns with
addends, so linker should report dangerous relocation errors,
in case the assembly code use them.
Another issue was here,
https://sourceware.org/pipermail/binutils/2021-June/116983.html
At the beginnig, I suppose %pcrel_hi and %pcrel_lo are valid only
when they are in the same input section. But Jim Wilson points out
that gcc may generate %hi and %lo in the different input sections,
when -freorder-blocks-and-partition option is used. So that a memory
references for a loop may have the %hi outside the loop, but the %lo
remain in the loop. However, it is hard to create the testcases,
to see if %pcrel_hi and %pcrel_lo have the same behavior.
Unfortunately, I notice that the current pcrel resolver cannot
work for the above case. For now we build a hash table for pcrel
at the start of riscv_elf_relocate_section, and then free the hash
at the end. But riscv_elf_relocate_section only handles an input
section at a time, so that means we can only resolve the %pcrel_hi
and %pcrel_lo which are in the same input section. Otherwise, like
the above case, we will report "%pcrel_lo missing matching %pcrel_hi"
for them. I have no plan to improve this in the short-term, so maybe
we can wait until someone meets the problem before we deal with it.
bfd/
* elfnn-riscv.c (riscv_pcrel_hi_reloc): Added field to store
the original relocation type, in case the type is converted to
R_RISCV_HI20.
(riscv_pcrel_lo_reloc): Removed unused name field.
(riscv_pcrel_relocs): Added comments.
(riscv_zero_pcrel_hi_reloc): Removed unused input_bfd.
(riscv_record_pcrel_hi_reloc): Updated.
(riscv_record_pcrel_lo_reloc): Likewise.
(riscv_resolve_pcrel_lo_relocs): Likewise. Check the original
type of auipc, to make sure the %pcrel_lo without any addends.
Otherwise, report dangerous relocation error.
(riscv_elf_relocate_section): Updated above functions are changed.
For R_RISCV_GOT_HI20, report dangerous relocation error when addend
isn't zero.
ld/
* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated.
* testsuite/ld-riscv-elf/pcrel-lo-addend-3a.d: New testcase.
* testsuite/ld-riscv-elf/pcrel-lo-addend-3a.s: Likewise.
* testsuite/ld-riscv-elf/pcrel-lo-addend-3b.d: New testcase.
Should report error since the %pcrel_lo with addend refers to
%got_pcrel_hi.
* testsuite/ld-riscv-elf/pcrel-lo-addend-3b.s: Likewise.
* testsuite/ld-riscv-elf/pcrel-lo-addend-3c.d: New testcase.
Should report error since the %got_pcrel_hi with addend.
* testsuite/ld-riscv-elf/pcrel-lo-addend-3c.s: Likewise.
* testsuite/ld-riscv-elf/pcrel-lo-addend-3.ld: Likewise.
Since GOTOFF relocations against IFUNC symbols must go through PLT,
set PLT reference count to 1 for GOTOFF relocation.
bfd/
PR ld/27998
* elfxx-x86.c (elf_x86_allocate_dynrelocs): Count PLT for GOTOFF
relocation against IFUNC symbols.
(_bfd_x86_elf_adjust_dynamic_symbol): Likewise.
ld/
PR ld/27998
* testsuite/ld-i386/i386.exp: Run PR ld/27998 tests.
* testsuite/ld-i386/pr27998a.d: New file.
* testsuite/ld-i386/pr27998a.s: Likewise.
* testsuite/ld-i386/pr27998b.d: Likewise.
* testsuite/ld-i386/pr27998b.s: Likewise.
Change
ld: warning: creating DT_TEXTREL in a PIE
to
ld: warning: creating DT_TEXTREL in a PDE
on PDE.
bfd/
* elflink.c (bfd_elf_final_link): Correct DT_TEXTREL warning in
PDE.
ld/
* testsuite/ld-x86-64/textrel-1.err: New file.
* testsuite/ld-x86-64/textrel-1a.s: Likewise.
* testsuite/ld-x86-64/textrel-1b.s: Likewise.
* testsuite/ld-x86-64/x86-64.exp: Run textrel-1 tests.
Implement GNU_PROPERTY_UINT32_AND_XXX/GNU_PROPERTY_UINT32_OR_XXX:
https://sourceware.org/pipermail/gnu-gabi/2021q1/000467.html
1. GNU_PROPERTY_UINT32_AND_LO..GNU_PROPERTY_UINT32_AND_HI
#define GNU_PROPERTY_UINT32_AND_LO 0xb0000000
#define GNU_PROPERTY_UINT32_AND_HI 0xb0007fff
A bit in the output pr_data field is set only if it is set in all
relocatable input pr_data fields. If all bits in the the output
pr_data field are zero, this property should be removed from output.
If the bit is 1, all input relocatables have the feature. If the
bit is 0 or the property is missing, the info is unknown.
2. GNU_PROPERTY_UINT32_OR_LO..GNU_PROPERTY_UINT32_OR_HI
#define GNU_PROPERTY_UINT32_OR_LO 0xb0008000
#define GNU_PROPERTY_UINT32_OR_HI 0xb000ffff
A bit in the output pr_data field is set if it is set in any
relocatable input pr_data fields. If all bits in the the output
pr_data field are zero, this property should be removed from output.
If the bit is 1, some input relocatables have the feature. If the
bit is 0 or the property is missing, the info is unknown.
bfd/
* elf-properties.c (_bfd_elf_parse_gnu_properties): Handle
GNU_PROPERTY_UINT32_AND_LO, GNU_PROPERTY_UINT32_AND_HI,
GNU_PROPERTY_UINT32_OR_LO and GNU_PROPERTY_UINT32_OR_HI.
(elf_merge_gnu_properties): Likewise.
binutils/
* readelf.c (print_gnu_property_note): Handle
GNU_PROPERTY_UINT32_AND_LO, GNU_PROPERTY_UINT32_AND_HI,
GNU_PROPERTY_UINT32_OR_LO and GNU_PROPERTY_UINT32_OR_HI.
include/
* elf/common.h (GNU_PROPERTY_UINT32_AND_LO): New.
(GNU_PROPERTY_UINT32_AND_HI): Likewise.
(GNU_PROPERTY_UINT32_OR_LO): Likewise.
(GNU_PROPERTY_UINT32_OR_HI): Likewise.
ld/
* testsuite/ld-elf/property-and-1.d: New file.
* testsuite/ld-elf/property-and-1.s: Likewise.
* testsuite/ld-elf/property-and-2.d: Likewise.
* testsuite/ld-elf/property-and-2.s: Likewise.
* testsuite/ld-elf/property-and-3.d: Likewise.
* testsuite/ld-elf/property-and-3.s: Likewise.
* testsuite/ld-elf/property-and-4.d: Likewise.
* testsuite/ld-elf/property-and-empty.s: Likewise.
* testsuite/ld-elf/property-or-1.d: Likewise.
* testsuite/ld-elf/property-or-1.s: Likewise.
* testsuite/ld-elf/property-or-2.d: Likewise.
* testsuite/ld-elf/property-or-2.s: Likewise.
* testsuite/ld-elf/property-or-3.d: Likewise.
* testsuite/ld-elf/property-or-3.s: Likewise.
* testsuite/ld-elf/property-or-4.d: Likewise.
* testsuite/ld-elf/property-or-empty.s: Likewise.
This patch adds a new elf_tdata flag, is_pie, set during the linker's
open_input_bfds processing. The flag is then used to reject attempts
to link a PIE as if it were a shared library.
bfd/
PR 27952
* elf-bfd.h (struct elf_obj_tdata): Add is_pie.
* elflink.c (elf_link_add_object_symbols): Set is_pie.
ld/
PR 27952
* ldelf.c (ldelf_after_open): Error on input PIEs too.
PR 27666
bfd * config.bfd: Do not add the sparc_elf32_vec or sparc_elf64_vec
vectors to Sparc Solaris2 targets.
ld * testsuite/ld-sparc/sparc.exp: Do not run the sparctests or
sparc64tests for Solaris2 targets.
Without this we unconditionally try to slurp in secondary
relocs for each input section, leading to quadratic behaviour
even for strip(1). On write-out we already used a flag to avoid
this.
So track existence of secondary relocs on read-in as well and
only slurp in when needed. This still doesn't implement a proper
list of secondary reloc sections, and still would exhibit quadratic
behaviour if most input sections have a secondary reloc section.
But at least on normal input this avoids any slowdown from trying
to handle secondary relocation sections.
bfd/
* elf.c (bfd_section_from_shdr): Set has_secondary_relocs flag.
(_bfd_elf_slurp_secondary_reloc_section): Use it for early-out.
Older gcc reports:
.../bfd/dwarf2.c: In function 'read_ranges':
.../bfd/dwarf2.c:3107: error: comparison between signed and unsigned
.../bfd/dwarf2.c: In function 'read_rnglists':
.../bfd/dwarf2.c:3189: error: comparison between signed and unsigned
Similarly for binutils/dwarf.c. Arrange for the left sides of the > to
also be unsigned quantities.
2021-05-31 Nelson Chu <nelson.chu@sifive.com>
Lifang Xia <lifang_xia@c-sky.com>
The data segment phase exp_seg_relro_adjust means we are still adjusting the
relro segments, so we will get the symbol values which havn't consider the
relro. It is dangerous and we shouldn't do the relaxations at this stage.
Otherwise, we may get the truncated fails when the relax range crossing the
data segment.
One of the solution is that, we use a pointer to monitor the data segment
phase while relaxing, to know whether the relro has been handled or not.
Once we check the phase is exp_seg_relro_adjust, we should skip this round
of relaxations, since the incorrect symbol values will affect the correctness
of relaxations. I think we probably need to record more information about
data segment or alignments in the future, to make sure it is safe to doing
relaxations.
For the two new testcases, relro-relax-lui and relro-relax-pcrel, we get
the following truncated errors when using toolchains, which enable relro:
(.text+0x0): relocation truncated to fit: R_RISCV_GPREL_I against symbol `SymbolRodata' defined in .rodata section in test1.o
After applying this patch, the truncated errors should be resolved.
However, only linux toolchains support -z relro, so we only test these
two testcases when supporting shared library.
bfd/
PR 27566
* elfnn-riscv.c (struct riscv_elf_link_hash_table): New integer pointer
to monitor the data segment phase.
(bfd_elfNN_riscv_set_data_segment_info): New function called by
after_allocation, to set the data_segment_phase from expld.dataseg.
(_bfd_riscv_relax_section): Don't relax when data_segment_phase is
exp_seg_relro_adjust (0x4).
* elfxx-riscv.h (bfd_elf32_riscv_set_data_segment_info): New extern.
(bfd_elf64_riscv_set_data_segment_info): Likewise.
ld/
PR 27566
* emultempl/riscvelf.em (after_allocation): Call
riscv_set_data_segment_info to set data segment phase before relaxing.
* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated.
* testsuite/ld-riscv-elf/relro-relax-lui.d: New testcase.
* testsuite/ld-riscv-elf/relro-relax-lui.s: Likewise.
* testsuite/ld-riscv-elf/relro-relax-pcrel.d: Likewise.
* testsuite/ld-riscv-elf/relro-relax-pcrel.s: Likewise.
commit a7664973b2
Author: Jan Beulich <jbeulich@suse.com>
Date: Mon Apr 26 10:41:35 2021 +0200
x86: correct overflow checking for 16-bit PC-relative relocs
caused linker failure when building 16-bit program in a 32-bit ELF
container. Update GNU_PROPERTY_X86_FEATURE_2_USED with
#define GNU_PROPERTY_X86_FEATURE_2_CODE16 (1U << 12)
to indicate that 16-bit mode instructions are used in the input object:
https://groups.google.com/g/x86-64-abi/c/UvvXWeHIGMA
to indicate that 16-bit mode instructions are used in the object to
allow linker to properly perform relocation overflow check for 16-bit
PC-relative relocations in 16-bit mode instructions.
1. Update x86 assembler to always generate the GNU property note with
GNU_PROPERTY_X86_FEATURE_2_CODE16 for .code16 in ELF object.
2. Update i386 and x86-64 linkers to use 16-bit PC16 relocations if
input object is marked with GNU_PROPERTY_X86_FEATURE_2_CODE16.
bfd/
PR ld/27905
* elf32-i386.c: Include "libiberty.h".
(elf_howto_table): Add 16-bit R_386_PC16 entry.
(elf_i386_rtype_to_howto): Add a BFD argument. Use 16-bit
R_386_PC16 if input has 16-bit mode instructions.
(elf_i386_info_to_howto_rel): Update elf_i386_rtype_to_howto
call.
(elf_i386_tls_transition): Likewise.
(elf_i386_relocate_section): Likewise.
* elf64-x86-64.c (x86_64_elf_howto_table): Add 16-bit
R_X86_64_PC16 entry.
(elf_x86_64_rtype_to_howto): Use 16-bit R_X86_64_PC16 if input
has 16-bit mode instructions.
* elfxx-x86.c (_bfd_x86_elf_parse_gnu_properties): Set
elf_x86_has_code16 if relocatable input is marked with
GNU_PROPERTY_X86_FEATURE_2_CODE16.
* elfxx-x86.h (elf_x86_obj_tdata): Add has_code16.
(elf_x86_has_code16): New.
binutils/
PR ld/27905
* readelf.c (decode_x86_feature_2): Support
GNU_PROPERTY_X86_FEATURE_2_CODE16.
gas/
PR ld/27905
* config/tc-i386.c (set_code_flag): Update x86_feature_2_used
with GNU_PROPERTY_X86_FEATURE_2_CODE16 for .code16 in ELF
object.
(set_16bit_gcc_code_flag): Likewise.
(x86_cleanup): Always generate the GNU property note if
x86_feature_2_used isn't 0.
* testsuite/gas/i386/code16-2.d: New file.
* testsuite/gas/i386/code16-2.s: Likewise.
* testsuite/gas/i386/x86-64-code16-2.d: Likewise.
* testsuite/gas/i386/i386.exp: Run code16-2 and x86-64-code16-2.
include/
PR ld/27905
* elf/common.h (GNU_PROPERTY_X86_FEATURE_2_CODE16): New.
ld/
PR ld/27905
* testsuite/ld-i386/code16.d: New file.
* testsuite/ld-i386/code16.t: Likewise.
* testsuite/ld-x86-64/code16.d: Likewise.
* testsuite/ld-x86-64/code16.t: Likewise.
* testsuite/ld-i386/i386.exp: Run code16.
* testsuite/ld-x86-64/x86-64.exp: Likewise.
Since the policies of GNU and llvm toolchain are different for now,
current binutils mainline cannot accept any draft extensions, including
rvv, zfh, .... The Clang/LLVM allows these draft stuff on mainline,
but the GNU ld might be used with them, so this causes the link time
problems.
The patch allows ld to link the objects with unknown prefixed extensions,
which are probably generated by LLVM or customized toolchains.
bfd/
* elfxx-riscv.h (check_unknown_prefixed_ext): New bool.
* elfxx-riscv.c (riscv_parse_prefixed_ext): Do not check the
prefixed extension name if check_unknown_prefixed_ext is false.
* elfnn-riscv.c (riscv_merge_arch_attr_info): Set
check_unknown_prefixed_ext to false for linker.
gas/
* config/tc-riscv.c (riscv_set_arch): Set
check_unknown_prefixed_ext to true for assembler.
I exposed a problem with the change in commit 574ec1084d to the outer
loop of _bfd_elf_parse_attributes. "p_end - p >= 4" is better than
"p < p_end - 4" as far as pointer UB is concerned if the size of the
attritbute section is say, 3 bytes. However you do need to ensure p
never exceeds p_end, and that length remaining is kept consistent with
the pointer.
* elf-attrs.c (elf_attr_strdup): New function.
(_bfd_elf_attr_strdup): Use it here.
(elf_add_obj_attr_string): New function, extracted from..
(bfd_elf_add_obj_attr_string): ..here.
(elf_add_obj_attr_int_string): New function, extracted from..
(bfd_elf_add_obj_attr_int_string): ..here.
(_bfd_elf_parse_attributes): Don't allocate an extra byte for a
string terminator. Instead ensure parsing doesn't go past
end of sub-section. Use size_t variables for lengths.
