** 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. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. 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
