4.104.114.84.95
Last change
on this file since d5b004b was
6f9c75c3,
checked in by Joel Sherrill <joel.sherrill@…>, on 01/16/98 at 16:56:48
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Ralf Corsepius reported a number of missing CVS Id's:
RTEMS is under CVS control and has been since rtems 3.1.16 which was
around May 1995. So I just to add the $Id$. If you notice other files
with missing $Id$'s let me know. I try to keep w\up with it.
Now that you have asked -- I'll attach a list of files lacking an RCS-Id to
this mail. This list has been generated by a little sh-script I'll also
enclose.
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Property mode set to
100644
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File size:
1.4 KB
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Rev | Line | |
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[fc7bc51] | 1 | # |
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[6f9c75c3] | 2 | # $Id$ |
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[fc7bc51] | 3 | # |
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| 4 | |
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| 5 | This directory contains a stack bounds checker. It provides two |
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| 6 | primary features: |
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| 7 | |
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| 8 | + check for stack overflow at each context switch |
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| 9 | + provides an educated guess at each task's stack usage |
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| 10 | |
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| 11 | The stack overflow check at context switch works by looking for |
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| 12 | a 16 byte pattern at the logical end of the stack to be corrupted. |
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| 13 | The "guesser" assumes that the entire stack was prefilled with a known |
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| 14 | pattern and assumes that the pattern is still in place if the memory |
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| 15 | has not been used as a stack. |
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| 16 | |
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| 17 | Both of these can be fooled by pushing large holes onto the stack |
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| 18 | and not writing to them... or (much more unlikely) writing the |
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| 19 | magic patterns into memory. |
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| 20 | |
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| 21 | This code has not been extensively tested. It is provided as a tool |
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| 22 | for RTEMS users to catch the most common mistake in multitasking |
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| 23 | systems ... too little stack space. Suggestions and comments are appreciated. |
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| 24 | |
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| 25 | NOTES: |
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| 26 | |
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| 27 | 1. Stack usage information is questionable on CPUs which push |
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| 28 | large holes on stack. |
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| 29 | |
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| 30 | 2. The stack checker has a tendency to generate a fault when |
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| 31 | trying to print the helpful diagnostic message. If it comes |
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| 32 | out, congratulations. If not, then the variable Stack_check_Blown_task |
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| 33 | contains a pointer to the TCB of the offending task. This |
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| 34 | is usually enough to go on. |
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| 35 | |
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| 36 | FUTURE: |
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| 37 | |
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| 38 | 1. Determine how/if gcc will generate stack probe calls and support that. |
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| 39 | |
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| 40 | 2. Get accurate stack usage numbers on i960.. it pushes very large |
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| 41 | holes on the stack. |
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