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Variables defined in shared libraries are copied into an executable's .bss section when code in the executable is non-PIC and thus would require dynamic text relocations to access the variable directly in the shared library. Recent x86 toolchains also copy variables into the executable to gain a small speed improvement. The problem is that if the variable was originally read-only, the copy in .bss is writable, potentially opening a security hole. This patch cures that problem by putting the copy in a section that becomes read-only after ld.so relocation, provided -z relro is in force. The patch also fixes a microblaze linker segfault on attempting to use dynamic bss variables. bfd/ PR ld/20995 * elf-bfd.h (struct elf_link_hash_table): Add sdynrelro and sreldynrelro. (struct elf_backend_data): Add want_dynrelro. * elfxx-target.h (elf_backend_want_dynrelro): Define. (elfNN_bed): Update initializer. * elflink.c (_bfd_elf_create_dynamic_sections): Create sdynrelro and sreldynrelro sections. * elf32-arm.c (elf32_arm_adjust_dynamic_symbol): Place variables copied into the executable from read-only sections into sdynrelro. (elf32_arm_size_dynamic_sections): Handle sdynrelro. (elf32_arm_finish_dynamic_symbol): Select sreldynrelro for dynamic relocs in sdynrelro. (elf_backend_want_dynrelro): Define. * elf32-hppa.c (elf32_hppa_adjust_dynamic_symbol) (elf32_hppa_size_dynamic_sections, elf32_hppa_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf32-i386.c (elf_i386_adjust_dynamic_symbol) (elf_i386_size_dynamic_sections, elf_i386_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf32-metag.c (elf_metag_adjust_dynamic_symbol) (elf_metag_size_dynamic_sections, elf_metag_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol) (microblaze_elf_size_dynamic_sections) (microblaze_elf_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf32-nios2.c (nios2_elf32_finish_dynamic_symbol) (nios2_elf32_adjust_dynamic_symbol) (nios2_elf32_size_dynamic_sections) (elf_backend_want_dynrelro): As above. * elf32-or1k.c (or1k_elf_finish_dynamic_symbol) (or1k_elf_adjust_dynamic_symbol, or1k_elf_size_dynamic_sections) (elf_backend_want_dynrelro): As above. * elf32-ppc.c (ppc_elf_adjust_dynamic_symbol) (ppc_elf_size_dynamic_sections, ppc_elf_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf32-s390.c (elf_s390_adjust_dynamic_symbol) (elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf32-tic6x.c (elf32_tic6x_adjust_dynamic_symbol) (elf32_tic6x_size_dynamic_sections) (elf32_tic6x_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf32-tilepro.c (tilepro_elf_adjust_dynamic_symbol) (tilepro_elf_size_dynamic_sections) (tilepro_elf_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol) (ppc64_elf_size_dynamic_sections, ppc64_elf_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf64-s390.c (elf_s390_adjust_dynamic_symbol) (elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elf64-x86-64.c (elf_x86_64_adjust_dynamic_symbol) (elf_x86_64_size_dynamic_sections) (elf_x86_64_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elfnn-aarch64.c (elfNN_aarch64_adjust_dynamic_symbol) (elfNN_aarch64_size_dynamic_sections) (elfNN_aarch64_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elfnn-riscv.c (riscv_elf_adjust_dynamic_symbol) (riscv_elf_size_dynamic_sections, riscv_elf_finish_dynamic_symbol) (elf_backend_want_dynrelro): As above. * elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol) (_bfd_mips_elf_size_dynamic_sections) (_bfd_mips_vxworks_finish_dynamic_symbol): As above. * elfxx-sparc.c (_bfd_sparc_elf_adjust_dynamic_symbol) (_bfd_sparc_elf_size_dynamic_sections) (_bfd_sparc_elf_finish_dynamic_symbol): As above. * elfxx-tilegx.c (tilegx_elf_adjust_dynamic_symbol) (tilegx_elf_size_dynamic_sections) (tilegx_elf_finish_dynamic_symbol): As above. * elf32-mips.c (elf_backend_want_dynrelro): Define. * elf64-mips.c (elf_backend_want_dynrelro): Define. * elf32-sparc.c (elf_backend_want_dynrelro): Define. * elf64-sparc.c (elf_backend_want_dynrelro): Define. * elf32-tilegx.c (elf_backend_want_dynrelro): Define. * elf64-tilegx.c (elf_backend_want_dynrelro): Define. * elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol): Tidy. (microblaze_elf_size_dynamic_sections): Handle sdynbss. * elf32-nios2.c (nios2_elf32_size_dynamic_sections): Make use of linker shortcuts to dynamic sections rather than comparing names. Correctly set "got" flag. ld/ PR ld/20995 * testsuite/ld-arm/farcall-mixed-app-v5.d: Update to suit changed stub hash table traversal caused by section id increment. Accept the previous output too. * testsuite/ld-arm/farcall-mixed-app.d: Likewise. * testsuite/ld-arm/farcall-mixed-lib-v4t.d: Likewise. * testsuite/ld-arm/farcall-mixed-lib.d: Likewise. * testsuite/ld-elf/pr20995a.s, * testsuite/ld-elf/pr20995b.s, * testsuite/ld-elf/pr20995.r: New test. * testsuite/ld-elf/elf.exp: Run it.
90 lines
2.6 KiB
Makefile
90 lines
2.6 KiB
Makefile
tmpdir/farcall-mixed-lib.so: file format elf32-(little|big)arm
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architecture: arm.*, flags 0x00000150:
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HAS_SYMS, DYNAMIC, D_PAGED
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start address 0x.*
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Disassembly of section .plt:
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.* <.plt>:
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.*: e52de004 push {lr} ; \(str lr, \[sp, #-4\]!\)
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.*: e59fe004 ldr lr, \[pc, #4\] ; .* <.*>
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.*: e08fe00e add lr, pc, lr
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.*: e5bef008 ldr pc, \[lr, #8\]!
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.*: .*
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.* <app_func@plt>:
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.*: e28fc6.* add ip, pc, #.*
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.*: e28cca.* add ip, ip, #.* ; 0x.*
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.*: e5bcf.* ldr pc, \[ip, #.*\]!.*
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.* <app_func_weak@plt>:
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.*: e28fc6.* add ip, pc, #.*
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.*: e28cca.* add ip, ip, #.* ; 0x.*
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.*: e5bcf.* ldr pc, \[ip, #.*\]!.*
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.* <lib_func3@plt>:
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.*: e28fc6.* add ip, pc, #.*
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.*: e28cca.* add ip, ip, #.* ; 0x.*
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.*: e5bcf.* ldr pc, \[ip, #.*\]!.*
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.* <lib_func4@plt>:
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.*: e28fc6.* add ip, pc, #.*
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.*: e28cca.* add ip, ip, #.* ; 0x.*
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.*: e5bcf.* ldr pc, \[ip, #.*\]!.*
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Disassembly of section .text:
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.* <lib_func1>:
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.*: e1a0c00d mov ip, sp
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.*: e92dd800 push {fp, ip, lr, pc}
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.*: ebffff.. bl .* <app_func@plt>
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.*: ebffff.. bl .* <app_func_weak@plt>
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.*: ebfffff. bl .* <lib_func3@plt>
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.*: ebfffff. bl .* <lib_func4@plt>
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.*: e89d6800 ldm sp, {fp, sp, lr}
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.*: e12fff1e bx lr
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...
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.* <lib_func2>:
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.*: f000 e8.. blx .* <__app_func_from_thumb>
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.*: f000 e8.. blx .* <__app_func_weak_from_thumb>
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.*: f000 e8.. blx .* <__lib_func3_from_thumb>
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.*: f000 e8.. blx .* <__lib_func4_from_thumb>
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.*: 4770 bx lr
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.*: 46c0 nop.*
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#...
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.* <__lib_func3_from_thumb>:
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.*: e59fc000 ldr ip, \[pc\] ; .* <__lib_func3_from_thumb\+0x8>
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.*: e08ff00c add pc, pc, ip
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.*: feffff.. .word 0xfeffff..
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.* <__app_func_weak_from_thumb>:
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.*: e59fc000 ldr ip, \[pc\] ; .* <__app_func_weak_from_thumb\+0x8>
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.*: e08ff00c add pc, pc, ip
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.*: feffff.. .word 0xfeffff..
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.* <__lib_func4_from_thumb>:
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.*: e59fc000 ldr ip, \[pc\] ; .* <__lib_func4_from_thumb\+0x8>
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.*: e08ff00c add pc, pc, ip
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.*: feffff.. .word 0xfeffff..
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.* <__app_func_from_thumb>:
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.*: e59fc000 ldr ip, \[pc\] ; .* <__app_func_from_thumb\+0x8>
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.*: e08ff00c add pc, pc, ip
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.*: feffff.. .word 0xfeffff..
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...
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.* <lib_func3>:
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.*: f000 e80(c|6) blx .* <__app_func_from_thumb>
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.*: f000 e80(4|a) blx .* <__app_func_weak_from_thumb>
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.*: 4770 bx lr
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#...
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.* <__app_func(_weak)?_from_thumb>:
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.*: e59fc000 ldr ip, \[pc\] ; 2000378 <__app_func(_weak)?_from_thumb\+0x8>
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.*: e08ff00c add pc, pc, ip
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.*: fdffff(34|28) .word 0xfdffff(34|28)
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.* <__app_func(_weak)?_from_thumb>:
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.*: e59fc000 ldr ip, \[pc\] ; 2000384 <__app_func(_weak)?_from_thumb\+0x8>
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.*: e08ff00c add pc, pc, ip
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.*: fdffff(1c|28) .word 0xfdffff(1c|28)
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...
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