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Generally, glibc dynamic linker should have two ways to deal with ifunc - one is to handle the IRELATIVE relocations for the non-preemtive ifunc symbols, the other is to handle the R_RISCV_32/64 and R_RISCV_JUMP_SLOT relocations with the STT_IFUNC preemtive symbols. No matter which method is used, both of them should get the resolved ifunc symbols at runtime. Therefore, linker needs to generate the correct dynamic relocations for ifunc to make sure the the dynamic linker works well. For now, there are thirteen relocations are supported for ifunc in GNU ld, * R_RISCV_CALL and R_RISCV_CALL_PLT: The RISC-V compiler won't generate R_RISCV_JAL directly to jump to an ifunc. Besides, we disable the relaxations for the relocation referenced to ifunc, so just handling the R_RISCV_CALL and R_RISCV_CALL_PLT should be enough. Linker should generate a .plt entry and a .got.plt entry for it, and also needs to insert a dynamic IRELATIVE in the .got.plt enrty, or insert a R_RISCV_JUMP_SLOT when generating shared library. * R_RISCV_PCREL_HI20 and R_RISCV_PCREL_LO12_I/S: LA/LLA pattern with local fPIC ifunc symbol, or any non-PIC ifunc symbol. The PC-relative relocation. The current linker will deal with them in the same way as R_RISCV_CALL_PLT. * R_RISCV_GOT_HI20 and R_RISCV_PCREL_LO12_I/S: LA pattern with global PIC ifunc symbol. Linker should insert a dynamic IRELATIVE in the .got entry, or insert a R_RISCV_32/64 when generating shared library. * R_RISCV_32 and R_RISCV_64: Store the ifunc symbol into the data section. Linker should insert a dynamic IRELATIVE in the data section, or insert a R_RISCV_32/64 when generating shared library. * R_RISCV_HI20 and R_RISCV_LO12_I/S: The LUI + ADDI/LW/SW patterns. The absolute access relocation. The medlow model without the -fPIC compiler option should generate them. The ld ifunc testsuites "Build pr23169a" and "Build pr23169d" need the relocations, they are in the ld/testsuite/ld-ifunc/, and need compiler support. However, we also made some optimizations with reference to x86, * If GOT and PLT relocations refer to the same ifunc symbol when generating pie, then they can actually share a .got entry without creating two entries to store the same value and relocation. * If GOT, PLT and DATA relocations refer to the same ifunc symbol when generating position dependency executable, then linker will fill the address of .plt entry into the corresponding .got entry and data section, without insert any dynamic relocations for the GOT and DATA relocations. For the ifunc testcases, there are three types of them, 1. ifunc-reloc-*: Only check the single type of relocation refers to ifunc symbol. * ifunc-reloc-call: R_RISCV_CALL and R_RISCV_CALL_PLT. * ifunc-reloc-data: R_RISCV_32 and R_RISCV_64. * ifunc-reloc-got: R_RISCV_GOT_HI20 and R_RISCV_PCREL_LO_I/S. * ifunc-reloc-pcrel: R_RISCV_PCREL_HI20 and R_RISCV_PCREL_LO_I/S. 2. ifunc-[nonplt|plt]-*: If we don't have PLT relocs, then don't need to create the PLT and it's .plt entries. * ifunc-nonplt: Combine R_RISCV_GOT_HI20 and R_RISCV_32/64. * ifunc-plt: Combine all ifunc relocations. 3. ifunc-seperate-*: If we link the ifunc caller and resolver into the same module (link the objects), then the results are the same as the ifunc-reloc-* and ifunc-[noplt|plt]-* testcases. Consider the cases that the ifunc callers and resolver are in the different modules, that is, we compile the ifunc resolver to the shared library first, and then link it with the ifunc callers. The output of ifunc callers should be the same as the normal STT_FUNC cases, and the shared ifunc resolver should define the symbols as STT_IFUNC. The R_RISCV_PCREL_HI20 reloc is special. It should be linked and resolved locally, so if the ifunc resolver is defined in other modules (other shared libraries), then the R_RISCV_PCREL_HI20 is unresolvable, and linker should issue an unresolvable reloc error. bfd/ * elfnn-riscv.c: Include "objalloc.h" since we need objalloc_alloc. (riscv_elf_link_hash_table): Add loc_hash_table and loc_hash_memory for local STT_GNU_IFUNC symbols. (riscv_elf_got_plt_val): Removed. (riscv_elf_local_htab_hash, riscv_elf_local_htab_eq): New functions. Use to compare local hash entries. (riscv_elf_get_local_sym_hash): New function. Find a hash entry for local symbol, and create a new one if needed. (riscv_elf_link_hash_table_free): New function. Destroy an riscv elf linker hash table. (riscv_elf_link_hash_table_create): Create hash table for local ifunc. (riscv_elf_check_relocs): Create a fake global symbol to track the local ifunc symbol. Add support to check and handle the relocations reference to ifunc symbols. (allocate_dynrelocs): Let allocate_ifunc_dynrelocs and allocate_local_ifunc_dynrelocs to handle the ifunc symbols if they are defined and referenced in a non-shared object. (allocate_ifunc_dynrelocs): New function. Allocate space in .plt, .got and associated reloc sections for ifunc dynamic relocs. (allocate_local_ifunc_dynrelocs): Likewise, but for local ifunc dynamic relocs. (riscv_elf_relocate_section): Add support to handle the relocation referenced to ifunc symbols. (riscv_elf_size_dynamic_sections): Updated. (riscv_elf_adjust_dynamic_symbol): Updated. (riscv_elf_finish_dynamic_symbol): Finish up the ifunc handling, including fill the PLT and GOT entries for ifunc symbols. (riscv_elf_finish_local_dynamic_symbol): New function. Called by riscv_elf_finish_dynamic_symbol to handle the local ifunc symbols. (_bfd_riscv_relax_section): Don't do the relaxation for ifunc. * elfxx-riscv.c: Add R_RISCV_IRELATIVE. * configure.ac: Link elf-ifunc.lo to use the generic ifunc support. * configure: Regenerated. include/ * elf/riscv.h: Add R_RISCV_IRELATIVE to 58. ld/ * emulparams/elf32lriscv-defs.sh: Add IREL_IN_PLT. * testsuite/ld-ifunc/ifunc.exp: Enable ifunc tests for RISC-V. * testsuite/ld-riscv-elf/ld-riscv-elf.exp (run_dump_test_ifunc): New dump test for ifunc. There are two arguments, 'target` and `output`. The `target` is rv32 or rv64, and the `output` is used to choose which output you want to test (exe, pie or .so). * testsuite/ld-riscv-elf/ifunc-reloc-call-01.s: New testcase. * testsuite/ld-riscv-elf/ifunc-reloc-call-01.d: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-01-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-01-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-01-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-02.s: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-02.d: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-02-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-02-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-call-02-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-data.s: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-data.d: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-data-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-data-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-data-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-got.s: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-got.d: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-got-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-got-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-got-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-pcrel.s: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-pcrel.d: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-pcrel-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-pcrel-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-reloc-pcrel-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-nonplt.s: Likewise. * testsuite/ld-riscv-elf/ifunc-nonplt.d: Likewise. * testsuite/ld-riscv-elf/ifunc-nonplt-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-nonplt-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-nonplt-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-01.s: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-01.d: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-01-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-01-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-01-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-02.s: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-02.d: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-02-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-02-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-02-pie.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-resolver.s: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-caller.s: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-exe.d: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-pic.d: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-pie.d: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-caller-pcrel.s: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-pcrel-pic.d: Likewise. * testsuite/ld-riscv-elf/ifunc-seperate-pcrel-pie.d: Likewise.
15 lines
469 B
Makefile
15 lines
469 B
Makefile
#name: Link shared ifunc resolver with PLT caller (exe)
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#source: ifunc-seperate-caller-plt.s
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#as:
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#ld: -z nocombreloc tmpdir/ifunc-seperate-resolver.so
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#warning: .*
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#readelf: -rW
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Relocation section '.rela.got' at .*
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[ ]+Offset[ ]+Info[ ]+Type[ ]+.*
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[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_(32|64)[ ]+[0-9a-f]+[ ]+foo \+ 0
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#...
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Relocation section '.rela.plt' at .*
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[ ]+Offset[ ]+Info[ ]+Type[ ]+.*
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[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_JUMP_SLOT[ ]+[0-9a-f]+[ ]+foo \+ 0
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