From fb66e81e6c58b0825e85b2c0afabbe032f103d6e Mon Sep 17 00:00:00 2001 From: Marshall Dawson Date: Tue, 11 Jul 2017 17:39:01 -0600 Subject: [PATCH] x86/lapic/secondary.S: Align stack for _secondary_start At a process _start, the stack is expected to be aligned to a 16-byte boundary. Upon entry to any function the stack frame must have the end of any arguments also aligned. In other words the value of %esp+4 or %rsp+8 is always a multiple of 16 (1). Align the stack down inside _secondary_start and preserve proper alignment for the call to secondary_cpu_init. Although 4-byte alignment is the minimum requirement for i386, some AMD platforms use SSE instructions which expect 16-byte. 1) http://wiki.osdev.org/System_V_ABI See "Initial Stack and Register State" and "The Stack Frame" in the supplements. BUG=chrome-os-partner:62841664 Change-Id: I72b7a474013e5caf67aedfabeb8d8d2553499b73 Signed-off-by: Marshall Dawson Reviewed-on: https://review.coreboot.org/20537 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin --- src/cpu/x86/lapic/secondary.S | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/cpu/x86/lapic/secondary.S b/src/cpu/x86/lapic/secondary.S index a36502b1ac..27ee697db1 100644 --- a/src/cpu/x86/lapic/secondary.S +++ b/src/cpu/x86/lapic/secondary.S @@ -69,6 +69,8 @@ __ap_protected_start: /* Set the stack pointer, and flag that we are done */ xorl %eax, %eax movl secondary_stack, %esp + andl $0xfffffff0, %esp + sub $12, %esp /* maintain 16-byte alignment for the call below */ movl secondary_cpu_index, %edi pushl %edi movl %eax, secondary_stack