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Re: setting of initial bottom of stack variable in pthread.c (again)
- From: Jay <j2list468 at yahoo dot com>
- To: libc-ports at sourceware dot org
- Date: Tue, 22 Aug 2006 08:22:50 -0700 (PDT)
- Subject: Re: setting of initial bottom of stack variable in pthread.c (again)
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> What I'm trying to say is that if you read the code
> that's there today,
> it tries to preserve alignment + 2 * STACK_SIZE for
> Oho! OK, now we know what's going on.
>
> We always adjust the rlimit down in the
> !FLOATING_STACKS case (the
> #if's make this a little hard to see). So it's not
> shocking that
> large mallocs get "in that stack".
>
> But it still shouldn't break. It looks like you're
> letting the
> thread library allocate stacks, and it is
> deliberately trying
> to allocate one there:
>
> [pid 2189] old_mmap(0xbfa00000, 2097152,
> PROT_READ|PROT_WRITE|PROT_EXEC,
> MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xbfa00000
>
> But why is it doing that? thread_segment should
> pick
> THREAD_STACK_START_ADDRESS, which should be
> determined by
> __pthread_initial_thread_bos. Then here's the code
> which
> does the mmap:
>
> new_thread = default_new_thread;
> new_thread_bottom = (char *) (new_thread + 1)
> - stacksize;
> map_addr = new_thread_bottom - guardsize;
> res_addr = mmap(map_addr, stacksize +
> guardsize,
> PROT_READ | PROT_WRITE |
> PROT_EXEC,
> MAP_PRIVATE | MAP_ANONYMOUS,
> -1, 0);
>
> And that's supposed to map the thread at
> __pthread_initial_thread_bos
> minus STACK_SIZE. Which is apparently not happening
> for you. So
> what does it think it's mapping?
I put some printf's into the thread segment function.
For some reason THREAD_STACK_START_ADDRESS = BFE00000
while __pthread_initial_thread_bos = BFA00000, so I
believe I need to figure out why these two are
different. My first guess is going to be that
THREAD_STACK_START_ADDRESS is defined somewhere else
so it never gets set to __pthread_initial_thread_bos
as in internals.h
Thanks
Jay
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