cpu/x86/smm/smmhandler.c: Get revision using C code

This allows to remove some assembly code.

Tested with QEMU Q35 to still print the revision correctly.

Change-Id: I36fb0e8bb1f46806b11ef8102ce74c0d10fd3927
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44319
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/cpu/x86/smm/smihandler.c

@@ -141,9 +141,10 @@ bool smm_region_overlaps_handler(const struct region *r)
  * @param smm_revision revision of the smm state save map
  */
 
-void smi_handler(u32 smm_revision)
+void smi_handler(void)
 {
 	unsigned int node;
+	const uint32_t smm_rev = smm_revision();
 	smm_state_save_area_t state_save;
 	u32 smm_base = SMM_BASE; /* ASEG */
 
@@ -171,7 +172,7 @@ void smi_handler(u32 smm_revision)
 
 	printk(BIOS_SPEW, "\nSMI# #%d\n", node);
 
-	switch (smm_revision) {
+	switch (smm_rev) {
 	case 0x00030002:
 	case 0x00030007:
 		state_save.type = LEGACY;
@@ -199,7 +200,7 @@ void smi_handler(u32 smm_revision)
 				       SMM_AMD64_ARCH_OFFSET, node);
 		break;
 	default:
-		printk(BIOS_DEBUG, "smm_revision: 0x%08x\n", smm_revision);
+		printk(BIOS_DEBUG, "smm_revision: 0x%08x\n", smm_rev);
 		printk(BIOS_DEBUG, "SMI# not supported on your CPU\n");
 		/* Don't release lock, so no further SMI will happen,
 		 * if we don't handle it anyways.

src/cpu/x86/smm/smmhandler.S

@@ -165,10 +165,6 @@ untampered_lapic:
 	addl	$SMM_STACK_SIZE, %ebx
 	movl	%ebx, %esp
 
-	/* Get SMM revision */
-	movl	$0xa8000 + 0x7efc, %ebx	/* core 0 address */
-	subl	%ebp, %ebx		/* subtract core X offset */
-
 #if defined(__x86_64__)
 	/* Backup IA32_EFER. Preserves ebx. */
 	movl	$(IA32_EFER), %ecx
@@ -179,13 +175,7 @@ untampered_lapic:
 	/* Enable long mode. Preserves ebx. */
 #include <cpu/x86/64bit/entry64.inc>
 
-	mov	(%ebx), %rdi
-
-#else
-	movl	(%ebx), %eax
-	pushl	%eax
 #endif
-
 	/* Call C handler */
 	call	smi_handler
 

src/include/cpu/x86/smi_deprecated.h

@@ -15,6 +15,6 @@ void smm_init_completion(void);
 #endif
 
 /* Entry from smmhandler.S. */
-void smi_handler(u32 smm_revision);
+void smi_handler(void);
 
 #endif