From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Mon, 7 Aug 2017 19:35:53 +0100 Subject: [PATCH 02/14] fork: allow arch-override of VMAP stack alignment In-Reply-To: <1502130965-18710-1-git-send-email-mark.rutland@arm.com> References: <1502130965-18710-1-git-send-email-mark.rutland@arm.com> Message-ID: <1502130965-18710-3-git-send-email-mark.rutland@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: James Morse Cc: Laura Abbott Cc: Will Deacon Cc: linux-kernel at 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