[Qemu-devel] [Bug 1095857] [NEW] incorrect handling of [r32] address (long mode)

[Stefan Fanslow]

Public bug reported:

while executing in Long Mode (x86-64) instructions such as

mov eax,[r15d]

end up executing as

mov eax,[r15]

according to x86 programmer manuals the behavior of using the Address-
Size override (in long mode) is supposed to ignore the high 32bits of
the register. I use this fact in my operating system to reduce register
usage (the high 32 bits of r15 holds other data). consequently a general
protection exception occurs since the memory address isn't "canonical".
this error doesn't always appear since the high 32 bits might not be
zero in those conditions.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1095857

Title:
  incorrect handling of [r32] address (long mode)

Status in QEMU:
  New

Bug description:
  while executing in Long Mode (x86-64) instructions such as

  mov eax,[r15d]

  end up executing as

  mov eax,[r15]

  according to x86 programmer manuals the behavior of using the Address-
  Size override (in long mode) is supposed to ignore the high 32bits of
  the register. I use this fact in my operating system to reduce
  register usage (the high 32 bits of r15 holds other data).
  consequently a general protection exception occurs since the memory
  address isn't "canonical". this error doesn't always appear since the
  high 32 bits might not be zero in those conditions.

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