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x86: Do not dump DS/CS segment overrides for branch hints

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The previous change

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

to ignore segment override prefixes in 64-bit mode lead to dumping
branch hints as excessive prefixes:

  ffffffff8109d5a0 <vmx_get_rflags>:
  ...
  ffffffff8109d601:       3e 77 0a                ds ja,pt ffffffff8109d60e <vmx_get_rflags+0x6e>
  						^^^^^

In this particular case, those prefixes are not excessive but are used
to provide branch hints - taken/not-taken - to the CPU.

Assign active_seg_prefix in that particular case to consume them.

gas/

2002-11-29  Borislav Petkov  <bp@suse.de>

        * testsuite/gas/i386/branch.d: Add new branch insns test.
        * testsuite/gas/i386/branch.s: Likewise.
        * testsuite/gas/i386/i386.exp: Insert the new branch test.
        * testsuite/gas/i386/x86-64-branch.d: Test for branch hints insns.
        * testsuite/gas/i386/x86-64-branch.s: Likewise.
        * testsuite/gas/i386/ilp32/x86-64-branch.d: Likewise.

opcodes/

2020-11-28 Borislav Petkov  <bp@suse.de>

        * i386-dis.c (print_insn): Set active_seg_prefix for branch hint insns
        to not dump branch hint prefixes 0x2E and 0x3E as unused prefixes.
This commit is contained in:
Borislav Petkov
2020-11-28 14:20:06 +01:00
committed by H.J. Lu
parent 568cbddc71
commit 632ee6fd82
9 changed files with 50 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
gas/ChangeLog
View File

@@ -1,3 +1,12 @@
2002-11-29 Borislav Petkov <bp@suse.de>
* testsuite/gas/i386/branch.d: Add new branch insns test.
* testsuite/gas/i386/branch.s: Likewise.
* testsuite/gas/i386/i386.exp: Insert the new branch test.
* testsuite/gas/i386/x86-64-branch.d: Test for branch hints insns.
* testsuite/gas/i386/x86-64-branch.s: Likewise.
* testsuite/gas/i386/ilp32/x86-64-branch.d: Likewise.
2020-11-27 Jozef Lawrynowicz <jozef.l@mittosystems.com>
* testsuite/gas/elf/elf.exp: Run new tests.

12
gas/testsuite/gas/i386/branch.d Normal file
View File

@@ -0,0 +1,12 @@
#as: -J
#objdump: -dw
#name: i386 branch
.*: +file format .*
Disassembly of section .text:
0+ <.text>:
[ ]*[a-f0-9]+: 3e 74 03[ ]+je,pt +0x[0-9a-f]+
[ ]*[a-f0-9]+: 2e 74 00[ ]+je,pn +0x[0-9a-f]+
#pass

4
gas/testsuite/gas/i386/branch.s Normal file
View File

@@ -0,0 +1,4 @@
.text
jz,pt .Llabel
jz,pn .Llabel
.Llabel:

1
gas/testsuite/gas/i386/i386.exp
View File

@@ -565,6 +565,7 @@ if [gas_32_check] then {
run_dump_test "lfence-ret-c"
run_dump_test "lfence-ret-d"
run_dump_test "lfence-byte"
run_dump_test "branch"
# These tests require support for 8 and 16 bit relocs,
# so we only run them for ELF and COFF targets.

2
gas/testsuite/gas/i386/ilp32/x86-64-branch.d
View File

@@ -25,6 +25,8 @@ Disassembly of section .text:
[ ]*[a-f0-9]+: 66 0f 82 00 00 00 00 data16 jb 0x37 33: R_X86_64_PLT32 foo-0x4
[ ]*[a-f0-9]+: 66 c3 data16 ret *
[ ]*[a-f0-9]+: 66 c2 08 00 data16 ret \$0x8
[ ]*[a-f0-9]+: 3e 74 03[ ]+je,pt +0x[0-9a-f]+
[ ]*[a-f0-9]+: 2e 74 00[ ]+je,pn +0x[0-9a-f]+
[ ]*[a-f0-9]+: ff d0 call \*%rax
[ ]*[a-f0-9]+: ff d0 call \*%rax
[ ]*[a-f0-9]+: 66 ff d0 data16 call \*%rax

2
gas/testsuite/gas/i386/x86-64-branch.d
View File

@@ -24,6 +24,8 @@ Disassembly of section .text:
[ ]*[a-f0-9]+: 66 0f 82 00 00 00 00 data16 jb (0x37|37 <.text\+0x37>)
[ ]*[a-f0-9]+: 66 c3 data16 ret *
[ ]*[a-f0-9]+: 66 c2 08 00 data16 ret \$0x8
[ ]*[a-f0-9]+: 3e 74 03[ ]+je,pt +0x[0-9a-f]+
[ ]*[a-f0-9]+: 2e 74 00[ ]+je,pn +0x[0-9a-f]+
[ ]*[a-f0-9]+: ff d0 call \*%rax
[ ]*[a-f0-9]+: ff d0 call \*%rax
[ ]*[a-f0-9]+: 66 ff d0 data16 call \*%rax

4
gas/testsuite/gas/i386/x86-64-branch.s
View File

@@ -22,6 +22,10 @@
retw
retw $8
jz,pt .Llabel
jz,pn .Llabel
.Llabel:
.intel_syntax noprefix
call rax
callq rax

5
opcodes/ChangeLog
View File

@@ -1,3 +1,8 @@
2020-11-28 Borislav Petkov <bp@suse.de>
* i386-dis.c (print_insn): Set active_seg_prefix for branch hint insns
to not dump branch hint prefixes 0x2E and 0x3E as unused prefixes.
2020-11-16 Przemyslaw Wirkus <przemyslaw.wirkus@arm.com>
* aarch64-tbl.h (FLAGM): Handle for FLAGM feature.

13
opcodes/i386-dis.c
View File

@@ -10910,10 +10910,19 @@ putop (const char *in_template, int sizeflag)
used_prefixes |= prefixes & (PREFIX_CS | PREFIX_DS);
*obufp++ = ',';
*obufp++ = 'p';
/* Set active_seg_prefix even if not set in 64-bit mode
because here it is a valid branch hint. */
if (prefixes & PREFIX_DS)
*obufp++ = 't';
{
active_seg_prefix = PREFIX_DS;
*obufp++ = 't';
}
else
*obufp++ = 'n';
{
active_seg_prefix = PREFIX_CS;
*obufp++ = 'n';
}
}
break;
case 'K':