[Bug binutils/25279] New: vmload/vmrun/vmsave: objdump -d should print the operand %rax

[i at maskray dot me]

https://sourceware.org/bugzilla/show_bug.cgi?id=25279

            Bug ID: 25279
           Summary: vmload/vmrun/vmsave: objdump -d should print the
                    operand %rax
           Product: binutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: i at maskray dot me
  Target Milestone: ---

% cat a.s
vmload %rax
vmrun %rax
vmsave %rax
% as a.s -o a.o
% objdump -d a.o

a.o:     file format elf64-x86-64


Disassembly of section .text:

0000000000000000 <.text>:
   0:   0f 01 da                vmload 
   3:   0f 01 d8                vmrun  
   6:   0f 01 db                vmsave


In AMD64 Architecture. Programmer's Manual. Volume 2: System Programming
(https://www.amd.com/system/files/TechDocs/24593.pdf), rAX is specified as a
required operand.

> Instruction Encoding
> Mnemonic        Opcode      Description
> VMSAVE rAX      0F 01 DB    Save additional guest state to VMCB.

While gas may accept vmload/vmrun/vmsave with an implicit %rax (currently
https://patchwork.kernel.org/patch/10822711/ makes use of this abbreviation),
objdump -d should probably decode them with an explicit %rax.

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