Messages in this thread Patch in this message | | | From | David Howells <> | Subject | Re: [uClinux-dev] Re: [PATCH] FDPIC: respect PT_GNU_STACK exec markings when creating NOMMU stack | Date | Thu, 03 Dec 2009 17:58:04 +0000 |
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Mike Frysinger <vapier.adi@gmail.com> wrote:
> i have seen a few apps use brk()/sbrk() to query the size of things (like > e2fsprogs)
We do actually record the size of the brk segment, so maybe we could icache flush brk as it is increased (if it is increased):
diff --git a/mm/nommu.c b/mm/nommu.c index 3754b16..2ea823d 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -432,6 +432,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) /* * Ok, looks good - let it rip. */ + flush_icache_range(mm->brk, brk); return mm->brk = brk; }
It might also be worth making the availability of brk() a config option under NOMMU.
> > Probably VM_DATA_DEFAULT_FLAGS should not include VM_EXEC for either > > Blackfin or FRV, but it may be required for SH. The if-statement that > > calls elf_read_implies_exec() will be optimised away unless the arch > > specifically sets it (which none of FRV, Blackfin or SH do). > > while true, wont the later personality test (in VM_DATA_DEFAULT_FLAGS) > be left there ? guess it's not that big of a deal.
I think we could justify altering FRV and Blackfin to get rid of that test, since we don't make use of read-implies-exec in those arches, but I think that should be a separate patch.
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