[Bug 1880722] [NEW] Changing executable page permissions with mmap causes user-mode failures

[Bug 1880722] [NEW] Changing executable page permissions with mmap causes user-mode failures

[Ahmed Karaman]

Public bug reported:

The discussion that led to this bug discovery can be found in this 
mailing list thread:
https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg05426.html

A workaround for this problem would be to check for page crossings for 
both the user and system modes in the use_goto_tb() function across 
targets. Some targets like "hppa" already implement this fix but others
don't.

To solve the root cause of this problem, the linux-user/mmap.c should 
be fixed to do all the invalidations required. By doing so, up to 6.93% 
performance improvements will be achieved.

** Affects: qemu
     Importance: Undecided
         Status: New

** Summary changed:

- Changing executable pages permissions with mmap causes user-mode failures
+ Changing executable page permissions with mmap causes user-mode failures

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https://bugs.launchpad.net/bugs/1880722

Title:
  Changing executable page permissions with mmap causes user-mode
  failures

Status in QEMU:
  New

Bug description:
  The discussion that led to this bug discovery can be found in this 
  mailing list thread:
  https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg05426.html

  A workaround for this problem would be to check for page crossings for 
  both the user and system modes in the use_goto_tb() function across 
  targets. Some targets like "hppa" already implement this fix but others
  don't.

  To solve the root cause of this problem, the linux-user/mmap.c should 
  be fixed to do all the invalidations required. By doing so, up to 6.93% 
  performance improvements will be achieved.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1880722/+subscriptions

[Bug 1880722] Re: Changing executable page permissions with mmap causes user-mode failures

[Ahmed Karaman]

** Tags added: linux-user

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https://bugs.launchpad.net/bugs/1880722

Title:
  Changing executable page permissions with mmap causes user-mode
  failures

Status in QEMU:
  New

Bug description:
  The discussion that led to this bug discovery can be found in this 
  mailing list thread:
  https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg05426.html

  A workaround for this problem would be to check for page crossings for 
  both the user and system modes in the use_goto_tb() function across 
  targets. Some targets like "hppa" already implement this fix but others
  don't.

  To solve the root cause of this problem, the linux-user/mmap.c should 
  be fixed to do all the invalidations required. By doing so, up to 6.93% 
  performance improvements will be achieved.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1880722/+subscriptions

[Bug 1880722] Re: Problems related to checking page crossing in use_goto_tb()

[Ahmed Karaman]

** Summary changed:

- Changing executable page permissions with mmap causes user-mode failures
+ Problems related to checking page crossing in use_goto_tb()

** Description changed:

- The discussion that led to this bug discovery can be found in this 
+ The discussion that led to this bug discovery can be found in this
  mailing list thread:
  https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg05426.html
  
- A workaround for this problem would be to check for page crossings for 
- both the user and system modes in the use_goto_tb() function across 
+ A workaround for this problem would be to check for page crossings for
+ both the user and system modes in the use_goto_tb() function across
  targets. Some targets like "hppa" already implement this fix but others
  don't.
  
- To solve the root cause of this problem, the linux-user/mmap.c should 
- be fixed to do all the invalidations required. By doing so, up to 6.93% 
- performance improvements will be achieved.
+ To solve the root cause of this problem, the linux-user/mmap.c should
+ be fixed to do all the invalidations required. By doing so, better
+ performance results could be achieved, compared to the case of the
+ workaround described above.

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https://bugs.launchpad.net/bugs/1880722

Title:
  Problems related to checking page crossing in use_goto_tb()

Status in QEMU:
  New

Bug description:
  The discussion that led to this bug discovery can be found in this
  mailing list thread:
  https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg05426.html

  A workaround for this problem would be to check for page crossings for
  both the user and system modes in the use_goto_tb() function across
  targets. Some targets like "hppa" already implement this fix but others
  don't.

  To solve the root cause of this problem, the linux-user/mmap.c should
  be fixed to do all the invalidations required. By doing so, better
  performance results could be achieved, compared to the case of the
  workaround described above.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1880722/+subscriptions

[Bug 1880722] Re: Problems related to checking page crossing in use_goto_tb()

[Thomas Huth]

The QEMU project is currently moving 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 the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
valid, then you have two options:

1) If you already have an account on gitlab.com, please open a new ticket
for this problem in our new tracker here:

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

and then close this ticket here on Launchpad (or let it expire auto-
matically after 60 days). Please mention the URL of this bug ticket on
Launchpad in the new ticket on GitLab.

2) If you don't have an account on gitlab.com and don't intend to get
one, but still would like to keep this ticket opened, then please switch
the state back to "New" within the next 60 days (otherwise it will get
closed as "Expired"). We will then eventually migrate the ticket auto-
matically to the new system.

Thank you and sorry for the inconvenience.


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

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Title:
  Problems related to checking page crossing in use_goto_tb()

Status in QEMU:
  Incomplete

Bug description:
  The discussion that led to this bug discovery can be found in this
  mailing list thread:
  https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg05426.html

  A workaround for this problem would be to check for page crossings for
  both the user and system modes in the use_goto_tb() function across
  targets. Some targets like "hppa" already implement this fix but others
  don't.

  To solve the root cause of this problem, the linux-user/mmap.c should
  be fixed to do all the invalidations required. By doing so, better
  performance results could be achieved, compared to the case of the
  workaround described above.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1880722/+subscriptions

[Bug 1880722] Re: Problems related to checking page crossing in use_goto_tb()

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

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

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Title:
  Problems related to checking page crossing in use_goto_tb()

Status in QEMU:
  Expired

Bug description:
  The discussion that led to this bug discovery can be found in this
  mailing list thread:
  https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg05426.html

  A workaround for this problem would be to check for page crossings for
  both the user and system modes in the use_goto_tb() function across
  targets. Some targets like "hppa" already implement this fix but others
  don't.

  To solve the root cause of this problem, the linux-user/mmap.c should
  be fixed to do all the invalidations required. By doing so, better
  performance results could be achieved, compared to the case of the
  workaround described above.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1880722/+subscriptions