lkml.org 
[lkml]   [2011]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] arm: mm: Poison freed init memory
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.


\
 
 \ /
  Last update: 2011-01-05 21:29    [W:0.205 / U:0.232 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site