On Tue, Aug 15, 2017 at 5:50 AM, Mark Rutland <mark.rutl...@arm.com> wrote: > In some cases, an architecture might wish its stacks to be aligned to a > boundary larger than THREAD_SIZE. For example, using an alignment of > double THREAD_SIZE can allow for stack overflows smaller than > THREAD_SIZE to be detected by checking a single bit of the stack > pointer. > > This patch allows architectures to override the alignment of VMAP'd > stacks, by defining THREAD_ALIGN. Where not defined, this defaults to > THREAD_SIZE, as is the case today.
This looks okay, but it might make sense to move that to a header file so THREAD_ALIGN is always available. > > Signed-off-by: Mark Rutland <mark.rutl...@arm.com> > Cc: Andy Lutomirski <l...@amacapital.net> > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > Cc: Catalin Marinas <catalin.mari...@arm.com> > Cc: James Morse <james.mo...@arm.com> > Cc: Laura Abbott <labb...@redhat.com> > Cc: Will Deacon <will.dea...@arm.com> > Cc: linux-kernel@vger.kernel.org > --- > kernel/fork.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/fork.c b/kernel/fork.c > index 17921b0..696d692 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -217,7 +217,10 @@ static unsigned long *alloc_thread_stack_node(struct > task_struct *tsk, int node) > return s->addr; > } > > - stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE, > +#ifndef THREAD_ALIGN > +#define THREAD_ALIGN THREAD_SIZE > +#endif > + stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, > VMALLOC_START, VMALLOC_END, > THREADINFO_GFP, > PAGE_KERNEL, > -- > 1.9.1 > -- Andy Lutomirski AMA Capital Management, LLC
