From ce9c88348cb1380199b8f57a435a51a7edb470a0 Mon Sep 17 00:00:00 2001 From: Marshall Dawson Date: Fri, 7 Jul 2017 16:09:56 -0600 Subject: [PATCH] arch/x86/assembly_entry: Align stack for car_stage_entry At 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 and change the method for executing car_stage_entry from jmp to call which should preserve proper alignment regardless of a 32- or 64-bit build. 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: I8a15514f551a8e17e9fe77b8402fe0d2b106972e Signed-off-by: Marshall Dawson Reviewed-on: https://review.coreboot.org/20528 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin --- src/arch/x86/assembly_entry.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/arch/x86/assembly_entry.S b/src/arch/x86/assembly_entry.S index 56a5b630c8..220cc6e400 100644 --- a/src/arch/x86/assembly_entry.S +++ b/src/arch/x86/assembly_entry.S @@ -63,7 +63,8 @@ debug_spinloop: jz debug_spinloop #endif - jmp car_stage_entry + andl $0xfffffff0, %esp + call car_stage_entry /* This is here for linking purposes. */ .weak car_stage_entry