Marshall Dawson has uploaded this change for review. ( https://review.coreboot.org/20528
Change subject: arch/x86/assembly_entry: align stack for car_stage_entry ......................................................................
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).
Change the method for executing car_stage_entry from jmp to call. This should keep the stack aligned 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.
Change-Id: I8a15514f551a8e17e9fe77b8402fe0d2b106972e Signed-off-by: Marshall Dawson marshalldawson3rd@gmail.com --- M src/arch/x86/assembly_entry.S 1 file changed, 1 insertion(+), 1 deletion(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/28/20528/1
diff --git a/src/arch/x86/assembly_entry.S b/src/arch/x86/assembly_entry.S index 56a5b63..465c02f 100644 --- a/src/arch/x86/assembly_entry.S +++ b/src/arch/x86/assembly_entry.S @@ -63,7 +63,7 @@ jz debug_spinloop #endif
- jmp car_stage_entry + call car_stage_entry
/* This is here for linking purposes. */ .weak car_stage_entry