[Bug 1847467] [NEW] qemu-x86_64 segment prefixes error

[Bug 1847467] [NEW] qemu-x86_64 segment prefixes error

[Yves Lhuillier]

Public bug reported:

qemu-x86_64 version 4.1.0 (qemu-x86_64 version 4.0.0 also have the
issue)

In 64-bit mode (x86_64) the DS, ES, SS or CS segment prefixes should be
ignored; qemu-x86_64 does not ignore them.

example: an x86_64 instructions preceded by FS DS (0x64 0x26) segment
prefixes have the linear address of its memory reference flat-mapped (as
if DS was in action) whereas it should be FS-mapped (offset by FS_base,
because the DS, ES, SS or CS are just ignored).


I attach a small C++ program that shows this discrepancy.

$ ./sample
I'm not in QEMU

$ qemu-x86_64 ./sample
I'm in QEMU

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: amd64

** Attachment added: "small C++ program to reproduce the bug"
   https://bugs.launchpad.net/bugs/1847467/+attachment/5295831/+files/sample.cc

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Title:
  qemu-x86_64 segment prefixes error

Status in QEMU:
  New

Bug description:
  qemu-x86_64 version 4.1.0 (qemu-x86_64 version 4.0.0 also have the
  issue)

  In 64-bit mode (x86_64) the DS, ES, SS or CS segment prefixes should
  be ignored; qemu-x86_64 does not ignore them.

  example: an x86_64 instructions preceded by FS DS (0x64 0x26) segment
  prefixes have the linear address of its memory reference flat-mapped
  (as if DS was in action) whereas it should be FS-mapped (offset by
  FS_base, because the DS, ES, SS or CS are just ignored).

  
  I attach a small C++ program that shows this discrepancy.

  $ ./sample
  I'm not in QEMU

  $ qemu-x86_64 ./sample
  I'm in QEMU

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[Bug 1847467] Re: qemu-x86_64 segment prefixes error

[Thomas Huth]

The QEMU project is currently considering to move its bug tracking to
another system. For this we need to know which bugs are still valid
and which could be closed already. Thus we are setting older bugs to
"Incomplete" now.

If you still think this bug report here is valid, then please switch
the state back to "New" within the next 60 days, otherwise this report
will be marked as "Expired". Or please mark it as "Fix Released" if
the problem has been solved with a newer version of QEMU already.

Thank you and sorry for the inconvenience.


** Changed in: qemu
       Status: New => Incomplete

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Title:
  qemu-x86_64 segment prefixes error

Status in QEMU:
  Incomplete

Bug description:
  qemu-x86_64 version 4.1.0 (qemu-x86_64 version 4.0.0 also have the
  issue)

  In 64-bit mode (x86_64) the DS, ES, SS or CS segment prefixes should
  be ignored; qemu-x86_64 does not ignore them.

  example: an x86_64 instructions preceded by FS DS (0x64 0x26) segment
  prefixes have the linear address of its memory reference flat-mapped
  (as if DS was in action) whereas it should be FS-mapped (offset by
  FS_base, because the DS, ES, SS or CS are just ignored).

  
  I attach a small C++ program that shows this discrepancy.

  $ ./sample
  I'm not in QEMU

  $ qemu-x86_64 ./sample
  I'm in QEMU

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[Bug 1847467] Re: qemu-x86_64 segment prefixes error

[Peter Maydell]

Repro case in comment #1 still demonstrates bug.


** Changed in: qemu
       Status: Incomplete => Confirmed

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Title:
  qemu-x86_64 segment prefixes error

Status in QEMU:
  Confirmed

Bug description:
  qemu-x86_64 version 4.1.0 (qemu-x86_64 version 4.0.0 also have the
  issue)

  In 64-bit mode (x86_64) the DS, ES, SS or CS segment prefixes should
  be ignored; qemu-x86_64 does not ignore them.

  example: an x86_64 instructions preceded by FS DS (0x64 0x26) segment
  prefixes have the linear address of its memory reference flat-mapped
  (as if DS was in action) whereas it should be FS-mapped (offset by
  FS_base, because the DS, ES, SS or CS are just ignored).

  
  I attach a small C++ program that shows this discrepancy.

  $ ./sample
  I'm not in QEMU

  $ qemu-x86_64 ./sample
  I'm in QEMU

To manage notifications about this bug go to:
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[Bug 1847467] Re: qemu-x86_64 segment prefixes error

[Thomas Huth]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/267


** Changed in: qemu
       Status: Confirmed => Expired

** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #267
   https://gitlab.com/qemu-project/qemu/-/issues/267

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Title:
  qemu-x86_64 segment prefixes error

Status in QEMU:
  Expired

Bug description:
  qemu-x86_64 version 4.1.0 (qemu-x86_64 version 4.0.0 also have the
  issue)

  In 64-bit mode (x86_64) the DS, ES, SS or CS segment prefixes should
  be ignored; qemu-x86_64 does not ignore them.

  example: an x86_64 instructions preceded by FS DS (0x64 0x26) segment
  prefixes have the linear address of its memory reference flat-mapped
  (as if DS was in action) whereas it should be FS-mapped (offset by
  FS_base, because the DS, ES, SS or CS are just ignored).

  
  I attach a small C++ program that shows this discrepancy.

  $ ./sample
  I'm not in QEMU

  $ qemu-x86_64 ./sample
  I'm in QEMU

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1847467/+subscriptions