Change in coreboot[master]: arch/x86: Save resume vector to stack in x86_64 mode

[Iru Cai (vimacs) (Code Review)]

Attention is currently required from: Arthur Heymans, Patrick Rudolph, Iru Cai.
Iru Cai (vimacs) has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/55947 )

Change subject: arch/x86: Save resume vector to stack in x86_64 mode
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Patch Set 3:

(1 comment)

File src/arch/x86/wakeup.S:

https://review.coreboot.org/c/coreboot/+/55947/comment/a546dd50_255831b0 
PS2, Line 20: It's OK to overwrite the return address at (%rsp) because this
            : 	 * function doesn't return.
> Is that happening? This looks like a 32bit op so I would expect the upper 4 bytes of 4(%rsp) to be p […]

What I said is that (%rsp) has the 8-byte return address from the caller of __wakeup in 64-bit mode, and move to 4(%rsp) writes its higher 4 bytes.