From 66f93c5a02d5ba6ef17fef459143961382593212 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Thu, 15 Nov 2018 12:34:27 +1000 Subject: [PATCH] powerpc/64: Fix kernel stack 16-byte alignment MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 4c2de74cc869 ("powerpc/64: Interrupts save PPR on stack rather than thread_struct") changed sizeof(struct pt_regs) % 16 from 0 to 8, which causes the interrupt frame allocation on kernel entry to put the kernel stack out of alignment. Quadword (16-byte) alignment for the stack is required by both the 64-bit v1 ABI (v1.9 § 3.2.2) and the 64-bit v2 ABI (v1.1 § 2.2.2.1). Add a pad field to fix alignment, and add a BUILD_BUG_ON to catch this in future. Fixes: 4c2de74cc869 ("powerpc/64: Interrupts save PPR on stack rather than thread_struct") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/ptrace.h | 1 + arch/powerpc/kernel/setup_64.c | 2 ++ 2 files changed, 3 insertions(+) diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h index f73886a1a7f5..0b8a735b6d85 100644 --- a/arch/powerpc/include/asm/ptrace.h +++ b/arch/powerpc/include/asm/ptrace.h @@ -54,6 +54,7 @@ struct pt_regs #ifdef CONFIG_PPC64 unsigned long ppr; + unsigned long __pad; /* Maintain 16 byte interrupt stack alignment */ #endif }; #endif diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 2a51e4cc8246..236c1151a3a7 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -636,6 +636,8 @@ static void *__init alloc_stack(unsigned long limit, int cpu) { unsigned long pa; + BUILD_BUG_ON(STACK_INT_FRAME_SIZE % 16); + pa = memblock_alloc_base_nid(THREAD_SIZE, THREAD_SIZE, limit, early_cpu_to_node(cpu), MEMBLOCK_NONE); if (!pa) {