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This is the original discussion, https://github.com/riscv/riscv-elf-psabi-doc/pull/190 And here is the glibc part, https://sourceware.org/pipermail/libc-alpha/2021-August/129931.html For binutils part, we need to support a new direcitve: .variant_cc. The function symbol marked by .variant_cc means it need to be resolved directly without resolver for dynamic linker. We also add a new dynamic entry, STO_RISCV_VARIANT_CC, to indicate there are symbols with the special attribute in the dynamic symbol table of the object. I heard that llvm already have supported this in their mainline, so I think it's time to commit this. bfd/ * elfnn-riscv.c (riscv_elf_link_hash_table): Added variant_cc flag. It is used to check if relocations for variant CC symbols may be present. (allocate_dynrelocs): If the symbol has STO_RISCV_VARIANT_CC flag, then raise the variant_cc flag of riscv_elf_link_hash_table. (riscv_elf_size_dynamic_sections): Added dynamic entry for variant_cc. (riscv_elf_merge_symbol_attribute): New function, used to merge non-visibility st_other attributes, including STO_RISCV_VARIANT_CC. binutils/ * readelf.c (get_riscv_dynamic_type): New function. (get_dynamic_type): Called get_riscv_dynamic_type for riscv targets. (get_riscv_symbol_other): New function. (get_symbol_other): Called get_riscv_symbol_other for riscv targets. gas/ * config/tc-riscv.c (s_variant_cc): Marked symbol that it follows a variant CC convention. (riscv_elf_copy_symbol_attributes): Same as elf_copy_symbol_attributes, but without copying st_other. If a function symbol has special st_other value set via directives, then attaching an IFUNC resolver to that symbol should not override the st_other setting. (riscv_pseudo_table): Support variant_cc diretive. * config/tc-riscv.h (OBJ_COPY_SYMBOL_ATTRIBUTES): Defined. * testsuite/gas/riscv/variant_cc-set.d: New testcase. * testsuite/gas/riscv/variant_cc-set.s: Likewise. * testsuite/gas/riscv/variant_cc.d: Likewise. * testsuite/gas/riscv/variant_cc.s: Likewise. include/ * elf/riscv.h (DT_RISCV_VARIANT_CC): Defined to (DT_LOPROC + 1). (STO_RISCV_VARIANT_CC): Defined to 0x80. ld/ * testsuite/ld-riscv-elf/variant_cc-1.s: New testcase. * testsuite/ld-riscv-elf/variant_cc-2.s: Likewise. * testsuite/ld-riscv-elf/variant_cc-now.d: Likewise. * testsuite/ld-riscv-elf/variant_cc-r.d: Likewise. * testsuite/ld-riscv-elf/variant_cc-shared.d: Likewise. * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated. |
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| config.in | ||
| configure | ||
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| ld.h | ||
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| TODO | ||
README for LD
This is the GNU linker. It is distributed with other "binary
utilities" which should be in ../binutils. See ../binutils/README for
more general notes, including where to send bug reports.
There are many features of the linker:
* The linker uses a Binary File Descriptor library (../bfd)
that it uses to read and write object files. This helps
insulate the linker itself from the format of object files.
* The linker supports a number of different object file
formats. It can even handle multiple formats at once:
Read two input formats and write a third.
* The linker can be configured for cross-linking.
* The linker supports a control language.
* There is a user manual (ld.texi), as well as the
beginnings of an internals manual (ldint.texi).
Installation
============
See ../binutils/README.
If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.
To build just the linker, make the target all-ld from the top level
directory (one directory above this one).
Porting to a new target
=======================
See the ldint.texi manual.
Reporting bugs etc
===========================
See ../binutils/README.
Known problems
==============
The Solaris linker normally exports all dynamic symbols from an
executable. The GNU linker does not do this by default. This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets). This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl. You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.
HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly. The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages. There are various
workarounds to this:
* Build and install bash, and build with "make SHELL=bash".
* Update to a version of HP/UX with a working shell (e.g., 9.05).
* Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
emulparams script used exports any shell variables it sets.
Copyright (C) 2012-2021 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.