Re: [PATCH 1/2] powerpc: ptrace CHECK_FULL_REGS

From: Roland McGrath
Date: Mon Sep 24 2007 - 21:00:01 EST

> Yup, I think I ditched most of them.. for some reason I decided it
> couldn't happen, but maybe I'm wrong ?

Well, it's a BUG_ON. It's supposed to be for something that "can't happen".
That's why it's a sanity check, not a wild assertion. ;-)

The 2/2 patch is an example of a bug that CHECK_FULL_REGS catches.
In the status quo, using PTRACE_PEEKUSR in a bug case crashes while using
PTRACE_GETREGS in the same place might get bogus data. (In the actual bug
thus found, the data is not bogus and only the bit that FULL_REGS checks is.)

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