| Message ID | 1502801449-29246-3-git-send-email-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Aug 15, 2017 at 5:50 AM, Mark Rutland <mark.rutland@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.rutland@arm.com> > Cc: Andy Lutomirski <luto@amacapital.net> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: James Morse <james.morse@arm.com> > Cc: Laura Abbott <labbott@redhat.com> > Cc: Will Deacon <will.deacon@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 >
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,
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. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Laura Abbott <labbott@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-kernel@vger.kernel.org --- kernel/fork.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)