[coreboot-gerrit] [XS] Change in coreboot[main]: arch/x86/include/smm: use inline asm from drivers/smmstore/ramstage

[Felix Held (Code Review)]

Attention is currently required from: Jérémy Compostella.

Felix Held has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/79827?usp=email )

Change subject: arch/x86/include/smm: use inline asm from drivers/smmstore/ramstage
......................................................................

arch/x86/include/smm: use inline asm from drivers/smmstore/ramstage

call_smm is currently unused and the inline assembly code for more or
less the same functionality in drivers/smmstore/ramstage is both easier
to understand and also tells the compiler that this piece of code might
change global memory. Also having too much in the clobber list might
only have some performance impact, which should however be negligible
compared to the SMI handler being called, while missing something in the
clobber list might cause hard to debug problems.

This is a preparation to make drivers/smmstore/ramstage use call_smm
instead of having its own inline assembly implementation for this.

Signed-off-by: Felix Held 
Change-Id: I73837cab75429014897486b38a5c56f93a850f96
---
M src/arch/x86/include/smm.h
1 file changed, 5 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/27/79827/1

diff --git a/src/arch/x86/include/smm.h b/src/arch/x86/include/smm.h
index e6db9dc..c0d96c0 100644
--- a/src/arch/x86/include/smm.h
+++ b/src/arch/x86/include/smm.h
@@ -13,8 +13,11 @@
 {
    u32 res = 0;
    __asm__ __volatile__ (
-		"outb %b0, %3"
+		"outb %%al, %%dx"
    	: "=a" (res)
-		: "a" ((subcmd << 8) | cmd), "b" (arg), "i" (APM_CNT));
+		: "a" ((subcmd << 8) | cmd),
+		  "b" (arg),
+		  "d" (APM_CNT)
+		: "memory");
    return res;
 }