[Qemu-devel] [Bug 1066909] [NEW] App-level clone emulation for microblaze is broken

[Qemu-devel] [Bug 1066909] [NEW] App-level clone emulation for microblaze is broken

[Bugdal]

Public bug reported:

When CLONE_THREAD is used, the new process starts with the program
counter pointing to the system call instruction, rather than the
instruction immediately following it. This causes an infinite cascade
(linear growth, not exponential) of thread creation, which quickly
crashes when the threads start running and they're all using the same
stack.

I'm using qemu 1.1.2 packaged with Debian, but I'm not aware of any
fixes since then that would address the problem.

I can provide a test program if needed; a short C program using
syscall() directly or an even-shorter asm program can demonstrate the
issue without need for debugging around pthread library routines.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1066909

Title:
  App-level clone emulation for microblaze is broken

Status in QEMU:
  New

Bug description:
  When CLONE_THREAD is used, the new process starts with the program
  counter pointing to the system call instruction, rather than the
  instruction immediately following it. This causes an infinite cascade
  (linear growth, not exponential) of thread creation, which quickly
  crashes when the threads start running and they're all using the same
  stack.

  I'm using qemu 1.1.2 packaged with Debian, but I'm not aware of any
  fixes since then that would address the problem.

  I can provide a test program if needed; a short C program using
  syscall() directly or an even-shorter asm program can demonstrate the
  issue without need for debugging around pthread library routines.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1066909/+subscriptions

[Qemu-devel] [Bug 1066909] Re: App-level clone emulation for microblaze is broken

[Bugdal]

Here is a minimal test case showing the problem.


** Attachment added: "minimal test case"
   https://bugs.launchpad.net/qemu/+bug/1066909/+attachment/3399581/+files/badclone.s

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https://bugs.launchpad.net/bugs/1066909

Title:
  App-level clone emulation for microblaze is broken

Status in QEMU:
  New

Bug description:
  When CLONE_THREAD is used, the new process starts with the program
  counter pointing to the system call instruction, rather than the
  instruction immediately following it. This causes an infinite cascade
  (linear growth, not exponential) of thread creation, which quickly
  crashes when the threads start running and they're all using the same
  stack.

  I'm using qemu 1.1.2 packaged with Debian, but I'm not aware of any
  fixes since then that would address the problem.

  I can provide a test program if needed; a short C program using
  syscall() directly or an even-shorter asm program can demonstrate the
  issue without need for debugging around pthread library routines.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1066909/+subscriptions

[Qemu-devel] [Bug 1066909] Re: App-level clone emulation for microblaze is broken

[Bugdal]

I accidentally posted the patch, which is here, on the wrong bug report
(1068900 instead of here). Apologies. For reference here is the patch;
it was committed and fixes this issue:

https://lists.eait.uq.edu.au/pipermail/microblaze-
linux/2012-October/005760.html

Issue # 1068900, where I mistakenly posted the patch, is unrelated and
not fixed; it should be reopened and this issue (1066909) should be
marked fixed.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1066909

Title:
  App-level clone emulation for microblaze is broken

Status in QEMU:
  New

Bug description:
  When CLONE_THREAD is used, the new process starts with the program
  counter pointing to the system call instruction, rather than the
  instruction immediately following it. This causes an infinite cascade
  (linear growth, not exponential) of thread creation, which quickly
  crashes when the threads start running and they're all using the same
  stack.

  I'm using qemu 1.1.2 packaged with Debian, but I'm not aware of any
  fixes since then that would address the problem.

  I can provide a test program if needed; a short C program using
  syscall() directly or an even-shorter asm program can demonstrate the
  issue without need for debugging around pthread library routines.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1066909/+subscriptions

[Qemu-devel] [Bug 1066909] Re: App-level clone emulation for microblaze is broken

[Aurelien Jarno]

** Changed in: qemu
       Status: New => Fix Committed

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You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1066909

Title:
  App-level clone emulation for microblaze is broken

Status in QEMU:
  Fix Committed

Bug description:
  When CLONE_THREAD is used, the new process starts with the program
  counter pointing to the system call instruction, rather than the
  instruction immediately following it. This causes an infinite cascade
  (linear growth, not exponential) of thread creation, which quickly
  crashes when the threads start running and they're all using the same
  stack.

  I'm using qemu 1.1.2 packaged with Debian, but I'm not aware of any
  fixes since then that would address the problem.

  I can provide a test program if needed; a short C program using
  syscall() directly or an even-shorter asm program can demonstrate the
  issue without need for debugging around pthread library routines.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1066909/+subscriptions

[Qemu-devel] [Bug 1066909] Re: App-level clone emulation for microblaze is broken

[Thomas Huth]

** Changed in: qemu
       Status: Fix Committed => Fix Released

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You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1066909

Title:
  App-level clone emulation for microblaze is broken

Status in QEMU:
  Fix Released

Bug description:
  When CLONE_THREAD is used, the new process starts with the program
  counter pointing to the system call instruction, rather than the
  instruction immediately following it. This causes an infinite cascade
  (linear growth, not exponential) of thread creation, which quickly
  crashes when the threads start running and they're all using the same
  stack.

  I'm using qemu 1.1.2 packaged with Debian, but I'm not aware of any
  fixes since then that would address the problem.

  I can provide a test program if needed; a short C program using
  syscall() directly or an even-shorter asm program can demonstrate the
  issue without need for debugging around pthread library routines.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1066909/+subscriptions