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.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
