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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. |
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README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.