Re: [PATCH] consider stack access while checking for alternatesignal stack
From: Roland McGrath
Date: Tue Oct 20 2009 - 17:11:56 EST
> >+#ifdef CONFIG_STACK_GROWSUP
> >+ return sp >= current->sas_ss_sp &&
> >+ sp - current->sas_ss_sp < current->sas_ss_size;
> CONFIG_STACK_GROWSUP is wrong: If your stack grows up and sp ==
> sas_ss_sp + size than you are using the last entry in your sig stack
> which will be not recognized correctly.
+ sp - current->sas_ss_sp <= current->sas_ss_size;
> The case where sp == sas_ss_sp
> is also not detected correctly but this should not happen in real life.
So you say that sp==sas_ss_sp should not be considered "on the sig stack"?
> That is the PRE case which is the only relevant since we don't have any
> POST architectures. The check here produces the same results as my
> variant so it is okay :)
> So you prefer the smaller patch with comments around it?
Yes, I think it is far clearer and easier to read than what you posted.
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