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[PPC64] Fix trapstk overflow
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Authored by luporl on Oct 30 2019, 9:27 PM.
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Details

Summary

In some scenarios, the 4K trapstk may overflow, corrupting tmpstk.

This was observed during remote debugging, with the following steps:

At remote host (R):

  • enter kdb during boot
  • switch to gdb backend

At local host (L):

  • attach gdb to R
  • try to read an invalid memory position

At R:

  • a DSI trap occurs and kdb restarts (all this occurs on trapstk)
  • while printing the stacktrace, trapstk overflows and corrupts tmpstk

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Repository
rS FreeBSD src repository - subversion
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