<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - data32 ljmp in .code16 should select FARJMP32i instead of FARJMP16i"
href="https://bugs.llvm.org/show_bug.cgi?id=47632">47632</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>data32 ljmp in .code16 should select FARJMP32i instead of FARJMP16i
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>i@maskray.me
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
</td>
</tr></table>
<p>
<div>
<pre>This may be the last problem blocking assembling kexec-tools with the
integrated assembler (I reported another issue in <a class="bz_bug_link
bz_status_NEW "
title="NEW - data32 prefix in .code16 block is not respected"
href="show_bug.cgi?id=46942">bug 46942</a>)
git clone git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
cd kexec-tools
./bootstrap
./configure CC=clang
make -j10
There is a red-herring "relocation R_386_16 out of range" issue. The problem
(according to -debug-only=asm-matcher) is that the wrong FARJMP16i is selected.
% cat a.s
.code16
.space 0x104, 0x90
data32 ljmp $(0x10000)>>4, $2f-0x10000
2:
movw %cs,%ax
% as --32 a.s -o a.o && llvm-mc -filetype=obj -triple=i386 a.s -o b.o
% diff -u =(objdump -mi386 -Maddr16,data16 -wdrz a.o) =(objdump -mi386
-Maddr16,data16 -wdrz b.o)
--- /tmp/zshZyzVFz 2020-09-23 18:30:43.748829551 -0700
+++ /tmp/zshLrHrMy 2020-09-23 18:30:43.756829581 -0700
@@ -1,5 +1,5 @@
-a.o: file format elf32-i386
+b.o: file format elf32-i386
Disassembly of section .text:
@@ -265,5 +265,4 @@
101: 90 nop
102: 90 nop
103: 90 nop
- 104: 66 ea 0c 01 ff ff 00 10 ljmpl $0x1000,$0xffff010c 106:
R_386_32 .text
- 10c: 8c c8 mov %cs,%ax
+ 104: 66 ea 0a 01 00 10 8c c8 ljmpl $0xc88c,$0x1000010a 106:
R_386_16 .text
% llvm-mc -triple=i386 a.s -debug-only=asm-matcher
...
Trying to match opcode FARJMP32i
Matching formal operand class MCK_Imm against actual operand at index 1
(Imm:4096): match success using generic matcher
Matching formal operand class MCK_Imm against actual operand at index 2 ():
match success using generic matcher
Matching formal operand class InvalidMatchClass against actual operand at
index 3: actual operand index out of range Missing target features: 1
Trying to match opcode FARJMP16i
Matching formal operand class MCK_Imm against actual operand at index 1
(Imm:4096): match success using generic matcher
Matching formal operand class MCK_Imm against actual operand at index 2 ():
match success using generic matcher
Matching formal operand class InvalidMatchClass against actual operand at
index 3: actual operand index out of range Opcode result: complete match,
selecting this opcode
ljmpw $4096, $.Ltmp0-65536 # imm = 0x1000</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>