issues w/init

[Kumar Gala]

On Apr 17, 2009, at 12:03 PM, Benjamin Herrenschmidt wrote:

> On Fri, 2009-04-17 at 08:23 -0500, Kumar Gala wrote:
>> I can and might have already done this, need to double check.  But
>> what I was seeing from elf_map is that we don't get PROT_EXEC set for
>> this PHDR, but get VM_MAY_EXEC.  I'm not clear on what VM_MAY_EXEC is
>> intended for.
>
> Looking at a 2.6.29 tree here, I don't see any reference to  
> VM_MAY_EXEC
> but I see a VM_MAYEXEC :-) Though it shouldn't be relevant here.
>
> What I see, and what should be checked is:
>
> 1- In binfmt_elf.c, what happens with this statement ?
>
>        if (elf_read_implies_exec(loc->elf_ex, executable_stack))
>                current->personality |= READ_IMPLIES_EXEC;

on ppc32 noting as its elf_read_implies_exec is not implemented.

> (ie. is the personality flag set ?)
>
> 2- When the phdr's are mmap'ed, do you hit this:
>
>        if ((prot & PROT_READ) && (current->personality &  
> READ_IMPLIES_EXEC))
>                if (!(file && (file->f_path.mnt->mnt_flags &  
> MNT_NOEXEC)))
>                        prot |= PROT_EXEC;
>
> (Which should later be turned into VM_EXEC by calc_vm_prot_bits().
>
> If any of these isn't happening, then we need to figure out why.

As I said before current->personality = 0 in ppc32 in the setup I've  
got. (because we don't have elf_read_implies_exec defined).  I can  
define it and doing so makes this all work properly.  I'm just  
questioning if defining elf_read_implies_exec for ppc32 is actually  
the right answer or not.

- k