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"In 64-bit mode, the CS, DS, ES, and SS segment-override prefixes have
no effect. These four prefixes are not treated as segment-override
prefixes for the purposes of multiple-prefix rules. Instead, they are
treated as null prefixes." (AMD APM v2).
However, objdump disassembles instructions containing those ignored
prefixes by still generating that segment override:
66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
00 00 00 00
Print those segment override prefixes as excessive ones:
66 66 2e 0f 1f 84 00 data16 cs nopw 0x0(%rax,%rax,1)
00 00 00 00
which is what they actually are - they have no effect and the decoding
hardware ignores them.
gas/
2020-11-14 Borislav Petkov <bp@suse.de>
* testsuite/gas/i386/x86-64-segovr.d: Adjust regexes.
* testsuite/gas/i386/x86-64-nops.d: Likewise.
* testsuite/gas/i386/x86-64-nops-1.d: Likewise.
* testsuite/gas/i386/x86-64-nops-1-g64.d: Likewise.
* testsuite/gas/i386/x86-64-nops-1-core2.d: Likewise.
* testsuite/gas/i386/x86-64-nops-1-k8.d: Likewise.
* testsuite/gas/i386/x86-64-nops-2.d: Likewise.
* testsuite/gas/i386/x86-64-nops-3.d: Likewise.
* testsuite/gas/i386/x86-64-nops-4.d: Likewise.
* testsuite/gas/i386/x86-64-nops-4-core2.d: Likewise.
* testsuite/gas/i386/x86-64-nops-4-k8.d: Likewise.
* testsuite/gas/i386/x86-64-nops-5.d: Likewise.
* testsuite/gas/i386/x86-64-nops-5-k8.d: Likewise.
* testsuite/gas/i386/x86-64-nops-7.d: Likewise.
* testsuite/gas/i386/x86-64-nop-1.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-1a.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-1b.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-1c.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-1d.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-1g.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-2c.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-6.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-7.d: Likewise.
* testsuite/gas/i386/x86-64-align-branch-8.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-1-core2.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-1-k8.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-1.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-2.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-3.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-4-core2.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-4-k8.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-4.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-5-k8.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops-5.d: Likewise.
* testsuite/gas/i386/ilp32/x86-64-nops.d:: Likewise.
ld/
2020-11-14 Borislav Petkov <bp@suse.de>
* testsuite/ld-x86-64/pe-x86-64-4.od: Adjust regexes.
* testsuite/ld-x86-64/tlsld3.dd: Likewise.
* testsuite/ld-x86-64/tlsld4.dd: Likewise.
opcodes/
2020-11-14 Borislav Petkov <bp@suse.de>
* i386-dis.c (ckprefix): Do not assign active_seg_prefix in
64-bit addressing mode.
(NOTRACK_Fixup): Test prefixes for PREFIX_DS, instead of
active_seg_prefix.
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We can generate x86-64 TLS code sequences for general and local dynamic
models without PLT, which uses indirect call via GOT:
call *__tls_get_addr@GOTPCREL(%rip)
instead of direct call:
call __tls_get_addr[@PLT]
Since direct call is 4-byte long and indirect call, is 5-byte long, the
extra one byte must be handled properly.
For general dynamic model, one 0x66 prefix before call instruction is
removed to make room for indirect call. For local dynamic model, we
simply use 5-byte indirect call.
TLS linker optimization is updated to recognize new instruction patterns.
For local dynamic model to local exec model transition, we generate
4 0x66 prefixes, instead of 3, before mov instruction in 64-bit and
generate a 5-byte nop, instead of 4-byte, before mov instruction in
32-bit. Since linker may convert
call *__tls_get_addr@GOTPCREL(%rip)
to
addr32 call __tls_get_addr
when producing static executable, both patterns are recognized.
bfd/
* elf64-x86-64.c (elf_x86_64_link_hash_entry): Add tls_get_addr.
(elf_x86_64_link_hash_newfunc): Initialize tls_get_addr to 2.
(elf_x86_64_check_tls_transition): Check indirect call and
direct call with the addr32 prefix for general and local dynamic
models. Set the tls_get_addr feild.
(elf_x86_64_convert_load_reloc): Always use addr32 prefix for
indirect __tls_get_addr call via GOT.
(elf_x86_64_relocate_section): Handle GD->LE, GD->IE and LD->LE
transitions with indirect call and direct call with the addr32
prefix.
ld/
* testsuite/ld-x86-64/pass.out: New file.
* testsuite/ld-x86-64/tls-def1.c: Likewise.
* testsuite/ld-x86-64/tls-gd1.S: Likewise.
* testsuite/ld-x86-64/tls-ld1.S: Likewise.
* testsuite/ld-x86-64/tls-main1.c: Likewise.
* testsuite/ld-x86-64/tls.exp: Likewise.
* testsuite/ld-x86-64/tlsbin2-nacl.rd: Likewise.
* testsuite/ld-x86-64/tlsbin2.dd: Likewise.
* testsuite/ld-x86-64/tlsbin2.rd: Likewise.
* testsuite/ld-x86-64/tlsbin2.sd: Likewise.
* testsuite/ld-x86-64/tlsbin2.td: Likewise.
* testsuite/ld-x86-64/tlsbinpic2.s: Likewise.
* testsuite/ld-x86-64/tlsgd10.dd: Likewise.
* testsuite/ld-x86-64/tlsgd10.s: Likewise.
* testsuite/ld-x86-64/tlsgd11.dd: Likewise.
* testsuite/ld-x86-64/tlsgd11.s: Likewise.
* testsuite/ld-x86-64/tlsgd12.d: Likewise.
* testsuite/ld-x86-64/tlsgd12.s: Likewise.
* testsuite/ld-x86-64/tlsgd13.d: Likewise.
* testsuite/ld-x86-64/tlsgd13.s: Likewise.
* testsuite/ld-x86-64/tlsgd14.dd: Likewise.
* testsuite/ld-x86-64/tlsgd14.s: Likewise.
* testsuite/ld-x86-64/tlsgd5c.s: Likewise.
* testsuite/ld-x86-64/tlsgd6c.s: Likewise.
* testsuite/ld-x86-64/tlsgd9.dd: Likewise.
* testsuite/ld-x86-64/tlsgd9.s: Likewise.
* testsuite/ld-x86-64/tlsld4.dd: Likewise.
* testsuite/ld-x86-64/tlsld4.s: Likewise.
* testsuite/ld-x86-64/tlsld5.dd: Likewise.
* testsuite/ld-x86-64/tlsld5.s: Likewise.
* testsuite/ld-x86-64/tlsld6.dd: Likewise.
* testsuite/ld-x86-64/tlsld6.s: Likewise.
* testsuite/ld-x86-64/tlspic2-nacl.rd: Likewise.
* testsuite/ld-x86-64/tlspic2.dd: Likewise.
* testsuite/ld-x86-64/tlspic2.rd: Likewise.
* testsuite/ld-x86-64/tlspic2.sd: Likewise.
* testsuite/ld-x86-64/tlspic2.td: Likewise.
* testsuite/ld-x86-64/tlspic3.s: Likewise.
* testsuite/ld-x86-64/tlspie2.s: Likewise.
* testsuite/ld-x86-64/tlspie2a.d: Likewise.
* testsuite/ld-x86-64/tlspie2b.d: Likewise.
* testsuite/ld-x86-64/tlspie2c.d: Likewise.
* testsuite/ld-x86-64/tlsgd5.dd: Updated.
* testsuite/ld-x86-64/tlsgd6.dd: Likewise.
* testsuite/ld-x86-64/x86-64.exp: Run libtlspic2.so, tlsbin2,
tlsgd5b, tlsgd6b, tlsld4, tlsld5, tlsld6, tlsgd9, tlsgd10,
tlsgd11, tlsgd14, tlsgd12, tlsgd13, tlspie2a, tlspie2b and
tlspie2c.
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