Messages in this thread | | | Date | Wed, 21 Jun 2006 15:27:26 -0400 | From | Sonny Rao <> | Subject | Re: Possible bug in do_execve() |
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On Wed, Jun 21, 2006 at 02:09:10PM -0500, Serge E. Hallyn wrote: <snip> > > Yeah, I proposed a similar patch to Anton, and it would quiet the > > warning on powerpc, but that's not the point. It happens that powerpc > > doesn't use 0 as a context id, but that may not be true on another > > architecture. That's really what I'm concerned about. > > FWIW, ppc and cris do the NO_CONTEXT check, while others don't > even have a arch-specific 'mm->context.id'.
Good point. I probably stated that concern too narrowly. Probably what I should say is: What is the pre-condition for calling destroy_context() ? Is it that init_new_context() must have succeeded? Or is it merely that mm.context has been zeroed out?
Here's destroy context on sparc64:
void destroy_context(struct mm_struct *mm) { unsigned long flags, i;
for (i = 0; i < MM_NUM_TSBS; i++) tsb_destroy_one(&mm->context.tsb_block[i]);
spin_lock_irqsave(&ctx_alloc_lock, flags);
if (CTX_VALID(mm->context)) { unsigned long nr = CTX_NRBITS(mm->context); mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63)); }
spin_unlock_irqrestore(&ctx_alloc_lock, flags); }
It seems to assume that mm->context is valid before doing a check.
Since I don't have a sparc64 box, I can't check to see if this actually breaks things or not.
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