x86: Ignore CS/DS/ES/SS segment-override prefixes in 64-bit mode

x86: Ignore CS/DS/ES/SS segment-override prefixes in 64-bit mode

"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.