[S] Change in coreboot[main]: ext_stage_cache: Make sure variables are initialized

[Arthur Heymans (Code Review)]

Arthur Heymans has submitted this change. ( https://review.coreboot.org/c/coreboot/+/84040?usp=email )

Change subject: ext_stage_cache: Make sure variables are initialized
......................................................................

ext_stage_cache: Make sure variables are initialized

GCC LTO incorrectly warns about this it seems.

This also exits gracefully from stage-cache code if no smm region is
found.

Change-Id: Ib1851295646258e97c489dc7402b9df3fcf092c1
Signed-off-by: Arthur Heymans 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84040
Reviewed-by: Nico Huber 
Tested-by: build bot (Jenkins) 
---
M src/cpu/x86/smm/tseg_region.c
M src/lib/ext_stage_cache.c
2 files changed, 7 insertions(+), 6 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Nico Huber: Looks good to me, approved

diff --git a/src/cpu/x86/smm/tseg_region.c b/src/cpu/x86/smm/tseg_region.c
index 413d5fc..90e61dc 100644
--- a/src/cpu/x86/smm/tseg_region.c
+++ b/src/cpu/x86/smm/tseg_region.c
@@ -53,8 +53,6 @@
    	sub_size = ied_size;
    	break;
    default:
-		*start = 0;
-		*size = 0;
    	return -1;
    }

@@ -65,11 +63,10 @@

void stage_cache_external_region(void **base, size_t *size)
 {
-	if (smm_subregion(SMM_SUBREGION_CACHE, (uintptr_t *)base, size)) {
+	*base = NULL;
+	*size = 0;
+	if (smm_subregion(SMM_SUBREGION_CACHE, (uintptr_t *)base, size))
    	printk(BIOS_ERR, "No cache SMM subregion.\n");
-		*base = NULL;
-		*size = 0;
-	}
 }

void smm_list_regions(void)
diff --git a/src/lib/ext_stage_cache.c b/src/lib/ext_stage_cache.c
index 462a635..427c9c3 100644
--- a/src/lib/ext_stage_cache.c
+++ b/src/lib/ext_stage_cache.c
@@ -16,6 +16,8 @@

imd = &imd_stage_cache;
    stage_cache_external_region(&base, &size);
+	if (base == NULL || size == 0)
+		return;
    imd_handle_init(imd, (void *)(size + (uintptr_t)base));

printk(BIOS_DEBUG, "External stage cache:\n");
@@ -32,6 +34,8 @@

imd = &imd_stage_cache;
    stage_cache_external_region(&base, &size);
+	if (base == NULL || size == 0)
+		return;
    imd_handle_init(imd, (void *)(size + (uintptr_t)base));
    if (imd_recover(imd))
    	printk(BIOS_DEBUG, "Unable to recover external stage cache.\n");