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
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