Messages in this thread | | | Date | Wed, 5 Jan 2011 20:26:45 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH] arm: mm: Poison freed init memory |
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On Wed, Jan 05, 2011 at 11:47:25AM -0800, Stephen Boyd wrote: > Poisoning __init marked memory can be useful when tracking down > obscure memory corruption bugs. When a pointer is 0xCCCCCCCC in an
That's a bad idea for a value. With a 3GB page offset and 256MB or more memory, accesses to such an address will always succeed.
There's two things to be considered when selecting a possible poison value:
1. what value is guaranteed to provoke an undefined instruction exception? 2. what value when used as an address and dereferenced is mostly always going to abort?
1 for ARM mode implies an 0xe7fXXXfX value. For Thumb mode 0xdeXX. We use this space for breakpoints.
2 unfortunately depends on the platform.
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